Patent Application
20240042801
The present disclosure relates to a pneumatic tire that provides improved wet steering stability and dry steering stability.
Japan Unexamined Patent Publication No. 2017-24657 A discloses a pneumatic tire that includes four main grooves extending along a tire circumferential direction on a tread surface of a tread portion. In the document, the main grooves are formed in a wave shape having periodic amplitudes and with a groove width being constant in the tire circumferential direction.
Further, according to Japan Unexamined Patent Publication No. 2017-24657 A, since each of the main grooves is formed in a wave shape having periodic amplitudes, the main grooves are as a whole widened and thus can provide good drainage properties and maintain braking performance on wet road surfaces. Further, since the groove width of each main groove is constant in the tire circumferential direction, rigidity near each land portion formed by the main grooves is made uniform, and thus wear resistance performance can be improved.
A pneumatic tire including main grooves that are formed in a wave shape having periodic amplitudes, as in the pneumatic tire disclosed in Japan Unexamined Patent Publication No. 2017-24657 A, has both wet steering stability from drainage properties and the like and dry steering stability from wear resistance and the like.
However, a pneumatic tire having both higher wet steering stability and dry steering stability has been demanded.
The present disclosure provides a pneumatic tire that provides wet steering stability and dry steering stability in a compatible manner.
The present disclosure provides the following features.
A pneumatic tire in which a mounting direction with respect to a vehicle is designated, the pneumatic tire including
The pneumatic tire according to Aspect 1, in which a vehicle mounting outer side chamfered portion, the chamfer width of which is constant, is formed at an edge portion on a vehicle mounting outer side of at least the circumferential main groove disposed on a vehicle mounting innermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to Aspect 2, in which the following relationship (1) is satisfied, where WAI is a chamfer width of the vehicle mounting inner side chamfered portion and WAO is a chamfer width of the vehicle mounting outer side chamfered portion:
W
AO
<W
AI (1).
The pneumatic tire according to any one of Aspects 1 to 3, in which the following relationship (2) is satisfied, where SSI is a total groove area on the vehicle mounting inner side of the circumferential main groove with respect to a tire equatorial plane and SSO is a total groove area on a vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane:
S
SO
<S
SI (2).
The pneumatic tire according to any one of Aspects 1 to 4, in which an average groove width of the circumferential main groove on the vehicle mounting inner side is larger than an average groove width of the circumferential main groove on a vehicle mounting outer side in relation to two of the circumferential main grooves adjacent to each other.
The pneumatic tire according to any one of Aspects 1 to 5, in which an average groove width of the circumferential main groove on the vehicle mounting inner side is larger than an average groove width of the circumferential main groove on a vehicle mounting outer side in all combinations of two of the circumferential main grooves adjacent to each other.
The pneumatic tire according to any one of Aspects 1 to 6, in which, in a tire meridian cross-sectional view, the following relationship (3) is satisfied, where dG is a maximum value of a length in a tire radial direction from a tire surface profile, when the circumferential main groove is not present, to a groove bottom of the circumferential main groove and dCI is a maximum value of a length in the tire radial direction from the tire surface profile to an innermost position in the tire radial direction of the vehicle mounting inner side chamfered portion:
0.05<dCI/dG<0.40 (3).
The pneumatic tire according to any one of Aspects 1 to 7, in which, in a tire meridian cross-sectional view, in relation to at least the circumferential main groove disposed on a vehicle mounting innermost side, of the plurality of circumferential main grooves, the following relationship (4) is satisfied, where θG1 is an inclination angle of a vehicle mounting inner side groove wall of the circumferential main groove with respect to a tire radial direction and θGO is an inclination angle of a vehicle mounting outer side groove wall of the circumferential main groove with respect to the tire radial direction:
θGI<θGO (4).
The pneumatic tire according to any one of Aspects 1 to 8, further comprising first inclined grooves, second inclined grooves, third inclined grooves, and fourth inclined grooves, in which
The pneumatic tire according to Aspect 9, further comprising fifth inclined grooves disposed such that both ends of the fifth inclined grooves terminate in the land portion adjacent on the vehicle mounting outer side to the circumferential main groove disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves, the fifth inclined grooves being shorter in groove length than the fourth inclined grooves.
The pneumatic tire according to Aspect 10, in which with respect to the tire width direction, the third inclined groove and the fourth inclined groove extend across ground contact edges, respectively, and the fifth inclined groove terminates at a tire equatorial plane side with respect to the ground contact edge.
The pneumatic tire according to Aspect 10 or 11, in which an orientation of an acute angle formed by each of the second inclined groove, the third inclined groove, and the fourth inclined groove with respect to the tire width direction is equal to an orientation of an acute angle formed by the first inclined groove with respect to the tire width direction, and an orientation of an acute angle formed by the fifth inclined groove with respect to the tire width direction is different from the orientation of the acute angle formed by the first inclined groove with respect to the tire width direction.
The pneumatic tire according to any one of Aspects 9 to 11, in which an orientation of an acute angle formed by each of the second inclined groove and the fourth inclined groove with respect to the tire width direction is equal to an orientation of an acute angle formed by the first inclined groove with respect to the tire width direction, and an orientation of an acute angle formed by the third inclined groove with respect to the tire width direction is different from the orientation of the acute angle formed by the first inclined groove with respect to the tire width direction.
The pneumatic tire according to any one of Aspects 9 to 13, in which with respect to the tire circumferential direction, a terminating end portion on the vehicle mounting outer side of the third inclined groove terminates between end portions on the vehicle mounting inner side of two of the first inclined grooves adjacent to each other, and/or a terminating end portion on the vehicle mounting inner side of the fourth inclined groove terminates between end portions on the vehicle mounting outer side of two of the second inclined grooves adjacent to each other.
The pneumatic tire according to any one of Aspects 9 to 14, in which the first inclined grooves extend toward the respective vehicle mounting sides to communicate with a portion projected toward the vehicle mounting inner side and a portion recessed toward the vehicle mounting outer side of the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to any one of Aspects 9 to 15, in which the terminating end portion on the vehicle mounting inner side of the second inclined groove is in communication with a portion projected toward the vehicle mounting outer side of the circumferential main groove disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to any one of Aspects 9 to 16, in which the following relationship (5) is satisfied, where LIG1 is a length in the tire width direction of a portion of the first inclined groove, which extends toward the vehicle mounting outer side from the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and LL is a length in the tire width direction of the land portion adjacent on the vehicle mounting outer side to the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
0.20<LIG1/LL<0.60 (5).
The pneumatic tire according to any one of Aspects 9 to 17, in which the terminating end portion in the vehicle mounting outer side direction of the second inclined groove terminates between two of the fourth inclined grooves adjacent to each other in the tire circumferential direction, and
0.40<LG2G4/LG4G4<0.60 (6).
The pneumatic tire according to any one of Aspects 9 to 18, in which the following relationships (7) to (10) are satisfied, where in a tire meridian cross-sectional view, dG is a maximum value of a length in a tire radial direction from a tire surface profile, when the circumferential main groove and the inclined grooves are not present, to a groove bottom of the circumferential main groove and dIG1, dIG2, dIG3, and dIG4 are respectively maximum values of lengths in the tire radial direction from the tire surface profile to groove bottoms of the first inclined groove, the second inclined groove, the third inclined groove, and the fourth inclined groove:
0.05<dIG1/dG<0.85 (7),
0.05<dIG2/dG<0.85 (8),
0.05<dIG3/dG<0.85 (9), and
0.05<dIG4/dG<0.85 (10).
The pneumatic tire according to any one of Aspects 9 to 19, in which the following relationship (11) is satisfied, where in a tire meridian cross-sectional view, dG1 is a maximum value of a length in a tire radial direction from a tire surface profile, when the circumferential main groove and the inclined grooves are not present, to a groove bottom of the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, dIG1′ is a maximum value of a length in the tire radial direction from the tire surface profile to a groove bottom in a portion of the first inclined groove, which is located on the vehicle mounting outer side from the circumferential main groove, as a starting point, disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and dIG1″ is a maximum value of a length in the tire radial direction length from the tire surface profile to a groove bottom in a portion of the first inclined groove, which is located on the vehicle mounting inner side from the circumferential main groove, as a starting point, disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
d
IG1′
<d
IG1″
<d
G1 (11).
The pneumatic tire according to any one of Aspects 9 to 20, in which the following relationship (12) is satisfied, where LIG1 is a length in the tire width direction of a portion of the first inclined groove, which extends toward the vehicle mounting outer side from the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and LIG2 is a length in the tire width direction of a portion of the first inclined groove, which extends toward the vehicle mounting inner side from the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
L
IG1
<L
IG2 (12).
A pneumatic tire in which a mounting direction with respect to a vehicle is designated, the pneumatic tire including:
The pneumatic tire according to Aspect 22, in which a terminating end portion in a vehicle mounting outer side direction of the first inclined grooves terminates in a land portion adjacent on the vehicle mounting outer side to the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and a terminating end portion in a vehicle mounting inner side direction of the first inclined grooves terminates in a land portion adjacent on a vehicle mounting inner side to the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to Aspect 22 or 23, in which a terminating end portion in a vehicle mounting outer side direction of the second inclined groove terminates in a land portion adjacent on the vehicle mounting outer side to the circumferential main groove disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves, and a terminating end portion in a vehicle mounting inner side direction of the second inclined groove terminates in communication with the circumferential main groove disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to any one of Aspects 22 to 24, in which the following relationship (13) is satisfied, where LIG1 is a length in the tire width direction of a portion of the first inclined groove, which extends toward the vehicle mounting outer side from the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and LIG2 is a length in the tire width direction of a portion of the first inclined groove, which extends toward a vehicle mounting inner side from the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
L
IG1
<L
IG2 (13).
The pneumatic tire according to any one of Aspects 22 to 25, in which the first inclined grooves extend toward the respective vehicle mounting sides to communicate with a portion projected toward a vehicle mounting inner side and a portion recessed toward the vehicle mounting outer side of the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to any one of Aspects 22 to 26, in which the following relationship (14) is satisfied, where LIG1 is a length in the tire width direction of a portion of the first inclined groove, which extends toward the vehicle mounting outer side from the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and LL is a length in the tire width direction of a land portion adjacent on the vehicle mounting outer side to the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
0.20<LIG1/LL<0.60 (14).
The pneumatic tire according to any one of Aspects 22 to 27, in which the following relationship (15) is satisfied, where in a tire meridian cross-sectional view, dG1 is a maximum value of a length in a tire radial direction from a tire surface profile, when the circumferential main groove and the inclined grooves are not present, to a groove bottom of the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, dIG1′ is a maximum value of a length in the tire radial direction from the tire surface profile to a groove bottom in a portion of the first inclined groove, which is located on the vehicle mounting outer side from the circumferential main groove, as a starting point, disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and dIG1″ is a maximum value of a length in the tire radial direction length from the tire surface profile to a groove bottom in a portion of the first inclined groove, which is located on a vehicle mounting inner side from the circumferential main groove, as a starting point, disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
d
IG1′
<d
IG1″
<d
G1 (15).
The pneumatic tire according to any one of Aspects 22 to 28, in which a terminating end portion on a vehicle mounting inner side of the second inclined groove is in communication with a portion projected toward the vehicle mounting outer side of the circumferential main groove disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves.
The pneumatic tire according to any one of Aspects 22 to 29, further comprising third inclined grooves and fourth inclined grooves, in which
The pneumatic tire according to Aspect 30, further comprising fifth inclined grooves disposed such that both ends of the fifth inclined grooves terminate in the land portion adjacent on the vehicle mounting outer side to the circumferential main groove disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves, the fifth inclined grooves being shorter in groove length than the fourth inclined grooves.
The pneumatic tire according to Aspect 31, in which with respect to the tire width direction, the third inclined groove and the fourth inclined groove extend across ground contact edges, respectively, and the fifth inclined groove terminates at a tire equatorial plane side with respect to the ground contact edge.
The pneumatic tire according to Aspect 31 or 32, in which an orientation of an acute angle formed by each of the second inclined groove, the third inclined groove, and the fourth inclined groove with respect to the tire width direction is equal to an orientation of an acute angle formed by the first inclined groove with respect to the tire width direction, and an orientation of an acute angle formed by the fifth inclined groove with respect to the tire width direction is different from the orientation of the acute angle formed by the first inclined groove with respect to the tire width direction.
The pneumatic tire according to any one of Aspects 30 to 32, in which an orientation of an acute angle formed by each of the second inclined groove and the fourth inclined groove with respect to the tire width direction is equal to an orientation of an acute angle formed by the first inclined groove with respect to the tire width direction, and an orientation of an acute angle formed by the third inclined groove with respect to the tire width direction is different from the orientation of the acute angle formed by the first inclined groove with respect to the tire width direction.
The pneumatic tire according to any one of Aspects 30 to 34, in which with respect to the tire circumferential direction, a terminating end portion on the vehicle mounting outer side of the third inclined groove terminates between end portions on the vehicle mounting inner side of two of the first inclined grooves adjacent to each other, and/or a terminating end portion on the vehicle mounting inner side of the fourth inclined groove terminates between end portions on the vehicle mounting outer side of two of the second inclined grooves adjacent to each other.
The pneumatic tire according to any one of Aspects 30 to 35, in which
0.40<LG2G4/LG4G4<0.60 (16).
The pneumatic tire according to any one of Aspects 30 to 36, in which the following relationships (17) to (20) are satisfied, where in a tire meridian cross-sectional view, dG is a maximum value of a length in a tire radial direction from a tire surface profile, when the circumferential main groove and the inclined grooves are not present, to a groove bottom of the circumferential main groove and dIG1, dIG2, dIG3, and dIG4 are respectively maximum values of lengths in the tire radial direction from the tire surface profile to groove bottoms of the first inclined groove, the second inclined groove, the third inclined groove, and the fourth inclined groove:
0.05<dIG1/dG<0.85 (17),
0.05<dIG2/dG<0.85 (18),
0.05<dIG3/dG<0.85 (19), and
0.05<dIG4/dG<0.85 (20).
The pneumatic tire according to any one of Aspects 22 to 37, in which the following relationship (21) is satisfied, where SSI is a total groove area on a vehicle mounting inner side of the circumferential main groove with respect to a tire equatorial plane and SSO is a total groove area on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane:
S
SO
<S
SI (21).
The pneumatic tire according to any one of Aspects 22 to 38, in which an average groove width of the circumferential main groove on a vehicle mounting inner side is larger than an average groove width of the circumferential main groove on the vehicle mounting outer side in relation to any one pair of two of the circumferential main grooves adjacent to each other.
The pneumatic tire according to any one of Aspects 22 to 39, in which an average groove width of the circumferential main groove on a vehicle mounting inner side is larger than an average groove width of the circumferential main groove on the vehicle mounting outer side in all combinations of two of the circumferential main grooves adjacent to each other.
The pneumatic tire according to any one of Aspects 22 to 40, in which in a tire meridian cross-sectional view, in relation to at least the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, the following relationship (22) is satisfied, where Ow is an inclination angle of a vehicle mounting inner side groove wall of the circumferential main groove with respect to a tire radial direction and θGO is an inclination angle of a vehicle mounting outer side groove wall of the circumferential main groove with respect to the tire radial direction:
θGI<θGO (22).
According to the present disclosure, a pneumatic tire that provides wet steering stability and dry steering stability in a compatible manner can be provided.
Hereinafter, embodiments of a pneumatic tire according to the present technology will be described in detail with reference to the drawings. Note that the embodiments and the drawings do not limit the present technology. Constituents of the embodiments include constituents that can be substituted or easily conceived by one skilled in the art or substantially identical constituents. In addition, various modes included in the embodiments can be combined as desired within the scope of obviousness by one skilled in the art.
Hereinafter, “tire radial direction” refers to a direction orthogonal to a tire rotation axis (not illustrated).
In the present disclosure, “tire circumferential direction” refers to a circumferential direction about the tire rotation axis as a center axis. In the present disclosure, “tire width direction” is a direction parallel with the tire rotation axis. Note that “tire equatorial plane” refers to a plane that is orthogonal to the tire rotation axis and that passes through the center of a tire width of the tire.
In the present disclosure, “vehicle mounting inner side” refers to the side closer to the vehicle with reference to a certain position on the pneumatic tire in a state where the pneumatic tire of the present disclosure is mounted on the vehicle. “Vehicle mounting outer side” refers to the side farther from the vehicle with reference to a certain position on the pneumatic tire in a state where the pneumatic tire of the present disclosure is mounted on the vehicle.
Additionally, in the descriptions below, “regular rim” refers to an “applicable rim” defined by JATMA (The Japan Automobile Tyre Manufacturers Association, Inc.), a “Design Rim” defined by TRA (The Tire and Rim Association, Inc.), or a “Measuring Rim” defined by ETRTO (The European Tyre and Rim Technical Organisation). Additionally, a regular internal pressure refers to a “maximum air pressure” specified by JATMA, a maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. Moreover, “specified load” refers to the “maximum load capacity” defined by JATMA, the maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.
As illustrated in
In a tire plan view, the groove center lines of the circumferential main grooves 110, 120 are periodically displaced in the tire width direction W as they extend in the tire circumferential direction C.
Vehicle mounting inner side chamfered portions 111, 121 having a constant chamfer width are formed at edge portions on the vehicle mounting inner side of the circumferential main grooves 110, 120.
Here, that the groove width is constant means that a ratio of the minimum value of the groove width to the maximum value of the groove width is 0.90 or more. The ratio of the minimum value of the groove width to the maximum value of the groove width may be 0.90 or more, 0.92 or more, 0.95 or more, or 0.99 or more. Note that the ratio of the minimum value of the groove width to the maximum value of the groove width is 1.00 or less. Here, the “groove width” of the circumferential main groove is a length in the tire width direction of the circumferential main groove. Note that the average groove width of the circumferential main groove is an average value of groove widths of the circumferential main groove entirely in the circumferential direction of the pneumatic tire, and may be simply calculated, for example, as an arithmetic average of groove widths at any different hundred points in the circumferential direction of the circumferential main groove.
Further, the “groove center line” means a line connecting, in the tire circumferential direction, center points in the width direction of the groove. Furthermore, that “the groove center line is periodically displaced in the tire width direction as it extends in the tire circumferential direction C” means that the groove center line is periodically displaced to the vehicle mounting inner side WI and the vehicle mounting outer side WO as it extends in the tire circumferential direction C. This periodic displacement can be in, for example, a shape in which recesses and protrusions are alternately repeated with respect to the tire width direction W, and more specifically, a wave shape, a zigzag shape, or the like which has amplitudes with respect to the tire width direction W. Here, the wave shape may be, for example, a rectangular wave, a triangular wave, a sine wave, or the like, but is not limited thereto. Note that the periods of the periodic displacements of each of the circumferential main grooves are preferably the same. In particular, when the periodic displacement is in a wave shape, the wavelength and/or the amplitude of each circumferential main groove is preferably equal.
Further, that the chamfer width is constant means that a ratio of the minimum value of the chamfer width to the maximum value of the chamfer width is 0.90 or more. The ratio of the minimum value of the chamfer width to the maximum value of the chamfer width may be 0.90 or more, 0.92 or more, or more, or 0.99 or more. Note that the ratio of the minimum value of the chamfer width to the maximum value of the chamfer width is 1.00 or less. Here, the “chamfer width” is a length in the tire width direction of the chamfered portion.
Additionally,
Reasonably, in consideration of the length in the tire width direction of the tread portion of the tire, the number of circumferential main grooves is preferably two or more and five or less. The number of circumferential main grooves may be two or more, three or more, or four or more, and may be five or less, four or less, or three or less.
Thus, in addition to the example illustrated in
The mounting direction with respect to the vehicle is designated for the pneumatic tire illustrated in
Although not limited by the principle, the principle by which wet steering stability and dry steering stability can be achieved in a compatible manner in the pneumatic tire according to Basic Embodiment of the present disclosure is as follows.
The pneumatic tire according to Basic Embodiment of the present disclosure includes a plurality of circumferential main grooves in the tread surface of the tread portion. Additionally, in a tire plan view, the groove center lines of the plurality of circumferential main grooves are periodically displaced in the tire width direction as they extend in the tire circumferential direction.
In the pneumatic tire according to Basic Embodiment of the present disclosure, with such a shape of the circumferential main groove, the groove area can be increased with respect to a linear circumferential main groove having an equal groove width, and thus higher drainage properties can be obtained.
Further, due to such a shape of the circumferential main groove, so-called edge portions of a land portion defined and formed by the circumferential main grooves include not only a tire circumferential component but also a tire width direction component. As a result, the land portion defined and formed by the circumferential main grooves of the present embodiment can exhibit excellent rigidity not only against the force from the tire width direction but also against the force from the tire circumferential direction, and can realize dry steering stability excellent, particularly, in circuit running in which a severe load situation is expected.
In addition, in the pneumatic tire according to Basic Embodiment of the present disclosure, a vehicle mounting inner side chamfered portion having a constant chamfer width is formed at the edge portion on the vehicle mounting inner side of the circumferential main groove. Accordingly, by setting a gentle inclination angle with respect to the tire radial direction, in particular, to a side wall on the vehicle mounting inner side, on which chipping of a block is likely to occur due to wear, of side walls of the circumferential main groove, rigidity of the land portion including this side wall can be enhanced. In addition, by providing the chamfered portion, the groove area is further increased, and thus drainage properties can be enhanced. As a result, excellent wet steering stability, in particular, in circuit running in which a severe load situation is expected can be realized.
As described above, the pneumatic tire according to Basic Embodiment of the present disclosure can achieve wet steering stability and dry steering stability in a compatible manner due to the aforementioned improvement in rigidity of the land portion and the aforementioned improvement in drainage properties. Note that as described above, the pneumatic tire of the present embodiment is a tire suitable, in particular, for circuit running in which a severe load situation is expected.
As illustrated in
Note that in
Further, in
In general, dry steering stability and wet steering stability are efficiently improved by preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side. This is because ground contact pressure tends to be relatively high on the vehicle mounting outer side and relatively low on the vehicle mounting inner side.
In the pneumatic tire according to Additional Embodiment 1-1 of the present disclosure, in at least the circumferential main groove disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, the chamfered portion having a constant chamfer width is also formed at the edge portion on the vehicle mounting outer side of the circumferential main groove, in addition to at the edge portion on the vehicle mounting inner side of the circumferential main groove.
Thus, in the pneumatic tire according to Additional Embodiment 1-1 of the present disclosure, the circumferential main groove with the chamfered portions formed on both vehicle mounting sides, of the plurality of circumferential main grooves, is preferentially set as the circumferential main groove disposed on the vehicle mounting innermost side. Consequently, in the case of viewing the tread surface as a whole, drainage properties can be efficiently improved while a decrease in rigidity is suppressed.
As a result, the pneumatic tire according to Additional Embodiment 1-1 of the present disclosure can provide more improved wet steering stability.
As illustrated in
W
AO
<W
AI (1).
For example, when a vehicle turns, of both side walls of the circumferential main groove, a relatively large stress is applied to the land portion including the side wall on the vehicle mounting outer side compared with the land portion including the side wall on the vehicle mounting inner side. Accordingly, it is desirable to preferentially enhance rigidity of the land portion on the vehicle mounting outer side of the land portions located on both sides of the circumferential main groove over rigidity of the land portion on the vehicle mounting inner side. In the pneumatic tire according to Additional Embodiment 1-2 of the present disclosure, by setting the chamfer width of the vehicle mounting outer side chamfered portion to be smaller than the chamfer width of the vehicle mounting inner side chamfered portion, the rigidity of the land portion on the vehicle mounting outer side of the circumferential main groove is preferably enhanced.
As a result, the pneumatic tire according to Additional Embodiment 1-2 of the present disclosure can efficiently provide enhanced rigidity of the land portion and provide more improved wet steering stability and dry steering stability while achieving the effects of Additional Embodiment 1-1.
Note that a ratio WAI/WAO of the chamfer width WAI of the vehicle mounting inner side chamfered portion to the chamfer width WAO of the vehicle mounting outer side chamfered portion is preferably greater than 1.3 and smaller than 3.0. WAI/WAO may be more than 1.3, 1.5 or more, 1.7 or more, or 1.9 or more, and may be less than 3.0, 2.8 or less, 2.6 or less, or 2.4 or less.
In relation to any one of Basic Embodiment 1 and Additional Embodiments 1-1 and 1-2, the pneumatic tire according to Additional Embodiment 1-3 of the present disclosure satisfies the following relationship (2), where SSI is a total groove area on the vehicle mounting inner side of the circumferential main groove with respect to a tire equatorial plane CL and SSO is a total groove area on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane.
S
SO
<S
SI (2)
Here, in a plan view of the tread surface of the pneumatic tire, the total groove area means the sum of the groove areas, including the chamfered portions, in a predetermined region. Accordingly, for example, the total groove area on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL is the sum of the areas of the circumferential main groove disposed on the vehicle mounting inner side with respect to the tire equatorial plane CL, the circumferential main groove located on the vehicle mounting inner side with respect to the tire equatorial plane CL, and the chamfered portions formed on these circumferential main grooves.
In
Accordingly, in
Further, in
Accordingly, in
By preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side as described above, dry steering stability and wet steering stability are efficiently improved.
In the pneumatic tire according to Additional Embodiment 1-3 of the present disclosure, the total groove area SSI on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL is increased to efficiently enhance drainage properties, and meanwhile, the total groove area SSO on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane is decreased to efficiently enhance rigidity of the land portion.
As a result, the pneumatic tire according to Additional Embodiment 1-3 of the present disclosure can provide more improved wet steering stability and dry steering stability.
Note that a ratio SSI/SSO of the total groove area SSI on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL to the total groove area SSO on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane is larger than 1.1 and smaller than 1.5. SSI/SSO may be more than 1.1, 1.2 or more, 1.3 or more, or 1.4 or more, and may be less than 1.5, 1.4 or less, 1.3 or less, or 1.2 or less.
As illustrated in
More specifically, in
By preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side as described above, dry steering stability and wet steering stability are efficiently improved.
In relation to the two adjacent circumferential main grooves, in the pneumatic tire according to Additional Embodiment 1-4 of the present disclosure, the average groove width of the circumferential main grooves on the vehicle mounting inner side is increased to efficiently improve drainage properties, and meanwhile, the average groove width of the circumferential main grooves on the vehicle mounting direction outer side is decreased to efficiently improve rigidity of the land portion defined and formed around the circumferential main groove.
As a result, the pneumatic tire according to Additional Embodiment 1-4 of the present disclosure can provide more improved wet steering stability and dry steering stability.
In relation to any one of Basic Embodiment 1 and Additional Embodiments 1-1 to 1-4, in the pneumatic tire according to Additional Embodiment 1-5 of the present disclosure, an average groove width of the circumferential main groove on the vehicle mounting inner side is larger than an average groove width of the circumferential main groove on the vehicle mounting outer side in all combinations of two of the circumferential main grooves adjacent to each other.
In other words, the pneumatic tire according to Additional Embodiment 1-5 of the present disclosure is configured such that the average groove width of the plurality of circumferential main grooves decreases from the vehicle mounting inner side toward the vehicle mounting outer side.
By preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side as described above, dry steering stability and wet steering stability are efficiently improved.
In the pneumatic tire according to Additional Embodiment 1-5 of the present disclosure, the average groove width of the circumferential main grooves disposed on the vehicle mounting inner side is increased to efficiently improve drainage properties, and meanwhile, the average groove width of the circumferential main grooves disposed on the vehicle mounting outer side is decreased to efficiently improve rigidity of the land portion defined and formed around the circumferential main groove.
As a result, the pneumatic tire according to Additional Embodiment 1-5 of the present disclosure can provide more improved wet steering stability and dry steering stability.
As illustrated in
0.05<dCI/dG<0.40 (3)
In the pneumatic tire according to Additional Embodiment 1-6 of the present disclosure, dCI/dG is smaller than 0.30. Accordingly, the land portion located on the vehicle mounting inner side of the circumferential main groove can further secure the volume, and thus, the land portion can realize more excellent rigidity. On the other hand, dCI/dG is greater than 0.05. Accordingly, the chamfered portion is not set too small, and drainage properties are reliably improved.
As a result, the pneumatic tire according to Additional Embodiment 1-6 of the present disclosure can provide more improved wet steering stability and dry steering stability.
Note that dCI/dG may be more than 0.05, 0.08 or more, 0.10 or more, or more, 0.20 or more, 0.25 or more, 0.28 or more, or 0.30 or more, and may be less than 0.40, 0.35 or less, 0.30 or less, 0.27 or less, 0.26 or less, 0.25 or less, 0.23 or less, 0.20 or less, or 0.18 or less. dCI/dG is particularly preferably greater than 0.05 and less than 0.25.
Although not illustrated in the drawings, in an example of the pneumatic tire according to Basic Embodiment of the present disclosure illustrated in
As illustrated in
θGI<θGO (4)
In the pneumatic tire according to Additional Embodiment 1-7 of the present disclosure, the inclination angle θGI with respect to the tire radial direction of the vehicle mounting inner side groove wall 210a of the first circumferential main groove 210 is smaller than the inclination angle θ GO with respect to the tire radial direction of the vehicle mounting outer side groove wall 210b of the first circumferential main groove 210.
Here, when profile lines from land portion surfaces located on both sides of the first circumferential main groove 210 to the groove bottom are compared on both vehicle mounting sides of the groove 210, an angle variation when transitioning from the surface profile of the chamfered portion 211 to the groove profile is relatively small on the vehicle mounting inner side WI, and an angle variation when transitioning from the surface profile of the chamfered portion 212 to the groove profile is relatively large on the vehicle mounting outer side WO. In other words, assuming that stresses almost equal and in opposite directions in the tire width direction are applied to the land portions located on both sides of the groove 210, due to the shapes of both land portions, it is clear that the land portion located on the vehicle mounting outer side with respect to the groove 210 is less likely to be worn and has higher rigidity. In other words, this configuration agrees with the aforementioned view that it is preferable to preferentially increase the rigidity on the vehicle mounting outer side.
Additionally, when the groove center line of the first circumferential main groove 210 is set as a reference, the groove volume on the vehicle mounting inner side is larger than the groove volume on the vehicle mounting outer side. This configuration also agrees with the aforementioned view that it is preferable to preferentially increase drainage properties on the vehicle mounting inner side.
As a result, the pneumatic tire according to Additional Embodiment 1-7 of the present disclosure can provide more improved wet steering stability and dry steering stability.
As illustrated in
Note that as illustrated in
A ratio θGO/θGI of the inclination angle θGO with respect to the tire radial direction of the vehicle mounting outer side groove wall of the circumferential main groove to the inclination angle θGI with respect to the tire radial direction of the vehicle mounting inner side groove wall of the circumferential main groove is preferably greater than 2.0 and smaller than 5.0.
θGO/θGI may be more than 2.0, 2.5 or more, 3.0 or more, or 3.5 or more, and may be less than 5.0, 4.5 or less, 4.0 or less, or 3.5 or less.
θGI may be more than 0° and 30° or less. θGI may be more than 0°, 1° or more, 5° or more, 10° or more, or 15° or more, and may be 30° or less, 25° or less, 20° or less, 15° or less, or 10° or less.
As illustrated in
Referring to
The second inclined groove 140 extends toward the vehicle mounting outer side from the second circumferential main groove 120, as a starting point, disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves. A terminating end portion in the vehicle mounting outer side direction WO of the second inclined groove 140 terminates in the land portion adjacent on the vehicle mounting outer side to the second circumferential main groove 120, and a terminating end portion in the vehicle mounting inner side direction WI of the second inclined groove 140 terminates in communication with the second circumferential main groove 120.
The third inclined groove 150 is disposed such that both ends thereof terminate in the land portion adjacent on the vehicle mounting inner side to the first circumferential main groove 110.
The fourth inclined groove 160 is disposed such that both ends thereof terminate in the land portion adjacent on the vehicle mounting outer side to the second circumferential main groove 120.
As described above, the pneumatic tire according to Additional Embodiment 1-8 of the present disclosure includes two inclined grooves on each of the vehicle mounting inner side and the vehicle mounting outer side and thus has high drainage properties. In particular, since each of the first inclined groove and the second inclined groove is connected to the circumferential main groove, the water flowing into the circumferential main groove is easily discharged to the vehicle mounting inner side and the vehicle mounting outer side. The water discharged to the vehicle mounting inner side and the vehicle mounting outer side by the first inclined groove and the second inclined groove further flows respectively into the third inclined groove and the fourth inclined groove, and is likely to be discharged to the tire outer side along these inclined grooves. As a result, the pneumatic tire according to Additional Embodiment 1-8 of the present disclosure has higher drainage properties.
As illustrated in
As described above, the pneumatic tire according to Additional Embodiment 1-9 of the present disclosure includes the aforementioned fifth inclined grooves 170, and thus drainage properties are further improved as compared with Additional Embodiment 8. In addition, since the groove length of the fifth inclined groove 170 is shorter than that of the fourth inclined groove 160, a decrease in block rigidity of the land portion due to the arrangement of the fifth inclined groove 170 is small.
As a result, the pneumatic tire according to Additional Embodiment 1-9 of the present disclosure has higher drainage properties than Additional Embodiment 1-8 while suppressing a decrease in block rigidity.
As illustrated in
In the pneumatic tire according to Additional Embodiment 1-10 of the present disclosure, the third inclined groove 150 and the fourth inclined groove 160 extend across the ground contact edges EI and EO, respectively, and thus water is discharged more easily from the inner side toward the outer side of the tire. Thus, the pneumatic has higher drainage properties than the pneumatic tire according to Additional Embodiment 1-9 of the present disclosure. In addition, since the fifth inclined groove 170 terminates at the tire equatorial plane CL side with respect to the ground contact edge EO, a decrease in block rigidity of the land portion due to the arrangement of the fifth inclined groove 170 can be further suppressed.
As a result, the pneumatic tire according to Additional Embodiment 1-10 of the present disclosure has higher drainage properties than Additional Embodiment 1-9 while suppressing a decrease in block rigidity.
As illustrated in
In the pneumatic tire according to Additional Embodiment 1-11 of the present disclosure, the orientation of the acute angle formed by the fifth inclined groove 170 with respect to the tire width direction W is different from the orientation of the acute angle formed by each of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 with respect to the tire width direction W. Thus, in one rotation direction of the pneumatic tire, drainage properties can be enhanced particularly by the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160, and in the meantime, in the other rotation direction of the pneumatic tire, drainage properties can be slightly enhanced by the fifth inclined groove having a small length.
In general, when a vehicle travels forward, the traveling speed of the vehicle is high, and thus particularly high drainage properties are required for a pneumatic tire. On the other hand, when the vehicle travels backward, the traveling speed of the vehicle is usually not high, and thus drainage properties required for the pneumatic tire are low compared with when the vehicle travels forward.
Although depending on the mounting orientation of the tire to the advancement direction of the vehicle, the pneumatic tire according to Additional Embodiment 1-11 of the present disclosure can provide improved drainage properties by the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160, for example, when the vehicle travels forward, and in the meantime, can provide improved drainage properties by the fifth inclined groove 170 when the rotation direction of the tire is reversed, that is, for example, when the vehicle travels backward. Additionally, since the groove length of the fifth inclined groove 170 is shorter than that of the fourth inclined groove 160, drainage properties are low compared with the fourth inclined groove 160; however, a decrease in block rigidity of the land portion due to the arrangement of the fifth inclined groove 170 is small. As a result, drainage properties and block rigidity when the vehicle moves forward and backward can be provided in a compatible manner.
As illustrated in
Although depending on the mounting orientation of the tire with respect to the advancement direction of the vehicle, the pneumatic tire according to Additional Embodiment 1-12 of the present disclosure can provide improved drainage properties by the first inclined groove 240, the second inclined groove 250, and the fourth inclined groove 270, for example, when the vehicle travels forward, and in the meantime, can provided improved drainage properties by the third inclined groove 260 when the rotation direction of the tire is reversed, that is, for example, when the vehicle travels backward. Since the third inclined groove 260 is disposed on the vehicle mounting inner side, drainage properties on the vehicle mounting inner side, in particular, when the vehicle travels backward, can be particularly improved.
In a state where the tire is mounted on the vehicle, when the tire equatorial direction is inclined toward the vehicle inner side from the direction perpendicular to the ground surface, the tire ground contact area is slightly larger on the vehicle mounting inner side than on the vehicle direction outer side. As a result, in such a case, by applying the pneumatic tire according to Additional Embodiment 1-12 of the present disclosure, wet steering stability, for example, at the time of traveling backward, can be particularly improved.
As illustrated in
In the pneumatic tire according to Additional Embodiment 1-13 of the present disclosure, with the configuration as described above, the water flowing from the first circumferential main groove 110 and the second circumferential main groove 120 into the first inclined groove 130 and the second inclined groove 140, respectively, is efficiently collected by the third inclined groove 150 and the fourth inclined groove 160, respectively, and is easily discharged to the tire outer side. From such a viewpoint, with respect to the tire width direction W, the terminating end portion on the vehicle mounting outer side of the third inclined groove 150 further preferably terminates between the terminating end portions on the vehicle mounting inner side of the two first inclined grooves 130 adjacent to each other. Similarly, with respect to the tire width direction W, the terminating end portion on the vehicle mounting inner side of the fourth inclined groove 160 further preferably terminates between the terminating end portions on the vehicle mounting outer side of the two second inclined grooves 140 adjacent to each other.
As illustrated in
In the pneumatic tire according to Additional Embodiment 1-14 of the present disclosure, the first inclined groove 130 extends from a portion projected toward the vehicle mounting inner side of first circumferential main groove 110. Thus, the groove length of a portion on the vehicle mounting inner side of the first inclined groove 130 with respect to the first circumferential main groove 110 can be decreased compared with a case where the first inclined groove extends from a portion recessed toward the vehicle mounting inner side of the first circumferential main groove. As a result, a decrease in block rigidity of the land portion in a portion on the vehicle mounting inner side with respect to the first circumferential main groove 110 can be suppressed while improving drainage properties by the first inclined groove 130 in a portion on the vehicle mounting inner side with respect to the first circumferential main groove 110. On the other hand, the first inclined groove 130 extends from a portion recessed toward the vehicle mounting outer side of the first circumferential main groove 110. Thus, a portion being a terminating end portion on the vehicle mounting outer side of the first inclined groove 130 with respect to the first circumferential main groove 110 can be located farther away from the tire equatorial plane CL while the length of the inclined groove is increased as compared with a case where the first inclined groove extends from a portion recessed toward the vehicle mounting outer side of the first circumferential main groove. As a result, drainage properties can be improved while suppressing a decrease in block rigidity of the land portion near the tire equatorial plane CL. Note that a portion projected toward the vehicle mounting inner side does not need to be the apex of a projection, but is particularly preferably the apex of a projection. Similarly, a portion recessed toward the vehicle mounting inner side does not need to be the bottom point of a recess, but is particularly preferably the bottom point of a recess.
As illustrated in
In the pneumatic tire according to Additional Embodiment 1-15 of the present disclosure, with the aforementioned configuration, the groove length of a portion on the vehicle mounting outer side of the second inclined groove 140 with respect to the second circumferential main groove 120 can be decreased compared with a case where the second inclined groove extends from a portion recessed toward the vehicle mounting inner side of the second circumferential main groove. Additionally, since the second inclined groove 140 extends from a portion projected toward the vehicle mounting outer side of the second circumferential main groove 120, the water flowing through the second circumferential main groove 120 easily flows into the second inclined groove 140. As a result, a decrease in block rigidity of the land portion in a portion on the vehicle mounting outer side with respect to the second circumferential main groove 120 can be suppressed while improving drainage properties by the second inclined groove 140 in a portion on the vehicle mounting outer side with respect to the second circumferential main groove 120. Note that a portion projected toward the vehicle mounting outer side does not need to be the apex of a projection, but is particularly preferably the apex of a projection.
As illustrated in
0.20<LIG1/LL<0.60 (5).
When LIG1/LL is larger than 0.20, drainage properties of the land portion adjacent on the vehicle mounting outer side to the first circumferential main groove 110, that is, the land portion near the tire equatorial plane CL, can be particularly improved. On the other hand, when LIG1/LL is smaller than 0.60, a decrease in block rigidity of the land portion near the tire equatorial plane CL can be particularly suppressed. In other words, the pneumatic tire according to the Additional Embodiment 1-16 of the present disclosure can particularly provide drainage properties and block rigidity near the tire equatorial plane CL in a compatible manner by satisfying the above relationship (5).
Here, LIG1/LL may be more than 0.20, 0.25 or more, or 0.30 or more, and may be less than 0.60, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, or 0.30 or less.
As illustrated in
0.40<LG2G4/LG4G4<0.60 (6).
When the above relationship (6) is satisfied, the terminating end portion in the vehicle mounting outer side direction WO of the second inclined groove 140 terminates near the center between the two fourth inclined grooves 160 adjacent to each other in the tire circumferential direction. Accordingly, the delivery of water between the second inclined groove 140 and the fourth inclined groove 160 is more efficiently performed.
Here, LG2G4/LG4G4 may be more than 0.40, 0.43 or more, or 0.45 or more, and may be less than 0.60, 0.58 or less, or 0.55 or less.
In relation to any one of Additional Embodiments 1-8 to 1-17, the pneumatic tire according to Additional Embodiment 1-18 of the present disclosure satisfies the following relationships (7) to (10), where in a tire meridian cross-sectional view, dG is a maximum value of lengths in the tire radial direction from the tire surface profile, when the circumferential main grooves and the inclined grooves are not present, to the groove bottoms of the first and second circumferential main grooves 110 and 120 and dIG1, dIG2, dIG3, and dIG4 are respectively maximum values of lengths in the tire radial direction from the tire surface profile to the groove bottoms of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160:
0.05<dIG1/dG<0.85 (7),
0.05<dIG2/dG<0.85 (8),
0.05<dIG3/dG<0.85 (9), and
0.05<dIG4/dG<0.85 (10).
In the pneumatic tire of the present disclosure according to Additional Embodiment 1-18, the maximum values (dIG1, dIG2, dIG3, and dIG4) of the lengths in the tire radial direction from the tire surface profile to the groove bottoms of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 are smaller than the maximum value dG of the lengths in the tire radial direction from the tire surface profile to the groove bottoms of the first and second circumferential main grooves 110 and 120. Thus, drainage properties can be improved while suppressing a decrease in block rigidity of the tire due to each of the inclined grooves 130, 140, 150, 160. Here, when 0.05<dIG1 (or dIG2, dIG3, dIG4)/dG, the depths of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 are sufficiently large, and thus drainage properties are particularly improved. On the other hand, when dIG1 (or dIG2, dIG3, dIG4)/dG<0.85, the depths of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 are not too large, and in particular, a decrease in block rigidity can be suppressed.
Here, dIG1 (or dIG2, dIG3, dIG4)/dG may be more than 0.05, 0.1 or more, or more, or 0.3 or more, and may be less than 0.85, 0.80 or less, 0.70 or less, or 0.60 or less.
In relation to any one of Additional Embodiments 1-8 to 1-18, the pneumatic tire according to Additional Embodiment 1-19 of the present disclosure satisfies the following relationship (11), where in a tire meridian cross-sectional view, dG1 is a maximum value of a length in the tire radial direction from the tire surface profile, when the circumferential main grooves and the inclined grooves are not present, to the groove bottom of the first circumferential main groove 110 disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, dIG1′ is a maximum value of a length in the tire radial direction from the tire surface profile to a groove bottom in a portion of the first inclined groove 130, which is located in the vehicle mounting outer side direction WO from the first circumferential main groove 110, as a starting point, disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves, and dIG1″ is a maximum value of a length in the tire radial direction from the tire surface profile to a groove bottom in a portion of the first inclined groove 130, which is located in the vehicle mounting inner side direction WI from the first circumferential main groove 110, as a starting point, disposed on the vehicle mounting innermost side, of the plurality of circumferential main grooves:
d
IG1′
<d
IG1″
<d
G1 (11).
In the pneumatic tire according to Additional Embodiment 1-19 of the present disclosure, dIG1′<dIG1″ is established, and thus the inclined groove is shallow in the land portion near the tire equatorial plane CL while improving drainage properties by the first inclined groove 130. Consequently, a decrease in block rigidity of the land portion near the tire equatorial plane CL can be particularly suppressed.
As illustrated in
L
IG1
<L
IG2 (12)
Referring to
Here, a ratio LIG1/LIG2 is particularly preferably 0.20 or more and 0.40 or less. LIG1/LIG2 may be 0.20 or more, 0.25 or more, or 0.30 or more, and may be or less, 0.35 or less, or 0.30 or less.
The pneumatic tire according to Basic Embodiment 2 of the present disclosure is a pneumatic tire in which the mounting direction with respect to the vehicle is designated as illustrated in
Further, in a tire plan view, the groove center lines of the circumferential main grooves 110 and 120 (210, 220, and 230 in
Referring to
In the pneumatic tire according to Basic Embodiment 2 of the present disclosure, chamfering of the circumferential main groove is not an essential configuration different from the pneumatic tire according to Basic Embodiment 1 described above and Additional Embodiments thereof of the present disclosure. Obviously, wet steering stability and dry steering stability of the pneumatic tire according to Basic Embodiment 2 of the present disclosure is further improved with the presence of chamfering as in the pneumatic tire according to Basic Embodiment 1 described above and Additional Embodiments thereof of the present disclosure.
As illustrated in
Referring to
As illustrated in
Referring to
As illustrated in
L
IG1
<L
IG2 (13)
Referring to
Here, the ratio LIG1/LIg2 is particularly preferably 0.20 or more and 0.40 or less. LIG1/LIG2 may be 0.20 or more, 0.25 or more, or 0.30 or more, and may be 0.40 or less, 0.35 or less, or 0.30 or less.
As illustrated in
Referring to
As illustrated in
0.20<LIG1/LL<0.60 (14).
Referring to
Here, LIG1/LL may be more than 0.20, 0.25 or more, or 0.30 or more, and may be less than 0.60, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, or 0.30 or less.
As illustrated in
d
IG1′
<d
IG1″
<d
G1 (15).
Referring to
As illustrated in
Referring to
As illustrated in
Referring to
The second inclined groove 140 extends toward the vehicle mounting outer side from the second circumferential main groove 120, as a starting point, disposed on the vehicle mounting outermost side, of the plurality of circumferential main grooves. The terminating end portion in the vehicle mounting outer side direction WO of the second inclined groove 140 terminates in the land portion adjacent on the vehicle mounting outer side to the second circumferential main groove 120, and the terminating end portion in the vehicle mounting inner side direction WI of the second inclined groove 140 terminates in communication with the second circumferential main groove 120.
The third inclined groove 150 is disposed such that both ends thereof terminate in the land portion adjacent on the vehicle mounting inner side to the first circumferential main groove 110.
The fourth inclined groove 160 is disposed such that both ends thereof terminate in the land portion adjacent on the vehicle mounting outer side to the second circumferential main groove 120.
As described above, the pneumatic tire according to Additional Embodiment 2-8 of the present disclosure includes two inclined grooves on each of the vehicle mounting inner side and the vehicle mounting outer side and thus has high drainage properties. In particular, since each of the first inclined groove and the second inclined groove is connected to the circumferential main groove, the water flowing into the circumferential main groove is easily discharged to the vehicle mounting inner side and the vehicle mounting outer side. The water discharged to the vehicle mounting inner side and the vehicle mounting outer side by the first inclined groove and the second inclined groove further flows respectively into the third inclined groove and the fourth inclined groove, and is likely to be discharged to the tire outer side along these inclined grooves. As a result, the pneumatic tire according to Additional Embodiment 2-8 of the present disclosure has higher drainage properties.
As illustrated in
As described above, the pneumatic tire according to Additional Embodiment 2-9 of the present disclosure includes the aforementioned fifth inclined groove 170, and thus drainage properties are further improved as compared with Additional Embodiment 2-8. In addition, since the groove length of the fifth inclined groove 170 is shorter than that of the fourth inclined groove 160, a decrease in block rigidity of the land portion due to the arrangement of the fifth inclined groove 170 is small.
As a result, the pneumatic tire according to Additional Embodiment 2-9 of the present disclosure has higher drainage properties than Additional Embodiment 2-8 while suppressing a decrease in block rigidity.
As illustrated in
In the pneumatic tire according to Additional Embodiment 2-10 of the present disclosure, the third inclined groove 150 and the fourth inclined groove 160 extend across the ground contact edges EI and EO, respectively, and thus water is discharged more easily from the inner side toward the outer side of the tire. Thus, the pneumatic has higher drainage properties than the pneumatic tire according to Additional Embodiment 2-9 of the present disclosure. In addition, since the fifth inclined groove 170 terminates at the tire equatorial plane CL side with respect to the ground contact edge EO, a decrease in block rigidity of the land portion due to the arrangement of the fifth inclined groove 170 can be further suppressed.
As a result, the pneumatic tire according to Additional Embodiment 2-10 of the present disclosure has higher drainage properties than Additional Embodiment 2-9 while suppressing a decrease in block rigidity.
As illustrated in
In the pneumatic tire according to Additional Embodiment 2-11 of the present disclosure, the orientation of the acute angle formed by the fifth inclined groove 170 with respect to the tire width direction W is different from the orientation of the acute angle formed by each of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 with respect to the tire width direction W. Thus, in one rotation direction of the pneumatic tire, drainage properties can b e enhanced particularly by the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160, and in the meantime, in the other rotation direction of the pneumatic tire, drainage properties can be slightly enhanced by the fifth inclined groove having a small length.
In general, when a vehicle travels forward, the traveling speed of the vehicle is high, and thus particularly high drainage properties are required for a pneumatic tire. On the other hand, when the vehicle travels backward, the traveling speed of the vehicle is usually not high, and thus drainage properties required for the pneumatic tire are low compared with when the vehicle travels forward.
Although depending on the mounting orientation of the tire to the advancement direction of the vehicle, the pneumatic tire according to Additional Embodiment 2-11 of the present disclosure can provide improved drainage properties by the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160, for example, when the vehicle travels forward, and in the meantime, can provide improved drainage properties by the fifth inclined groove 170 when the rotation direction of the tire is reversed, that is, for example, when the vehicle travels backward. Additionally, since the groove length of the fifth inclined groove 170 is shorter than that of the fourth inclined groove 160, drainage properties are low compared with the fourth inclined groove 160; however, a decrease in block rigidity of the land portion due to the arrangement of the fifth inclined groove 170 is small. As a result, drainage properties and block rigidity when the vehicle moves forward and backward can be provided in a compatible manner.
As illustrated in
Although depending on the mounting orientation of the tire with respect to the advancement direction of the vehicle, the pneumatic tire according to Additional Embodiment 2-12 of the present disclosure can provide improved drainage properties by the first inclined groove 130, the second inclined groove 140, and the fourth inclined groove 160, for example, when the vehicle travels forward, and in the meantime, can provided improved drainage properties by the third inclined groove 150 when the rotation direction of the tire is reversed, that is, for example, when the vehicle travels backward. Since the third inclined groove 150 is disposed on the vehicle mounting inner side, drainage properties on the vehicle mounting inner side, in particular, when the vehicle travels backward, can be particularly improved.
In a state where the tire is mounted on the vehicle, when the tire equatorial direction is inclined toward the vehicle inner side from the direction perpendicular to the ground surface, the tire ground contact area is slightly larger on the vehicle mounting inner side than on the vehicle direction outer side. As a result, in such a case, by applying the pneumatic tire according to Additional Embodiment 2-12 of the present disclosure, wet steering stability, for example, at the time of traveling backward, can be particularly improved.
As illustrated in
Referring to
As illustrated in
0.40<LG2G4/LG4G4<0.60 (16).
When the above relationship (15) is satisfied, the terminating end portion in the vehicle mounting outer side direction WO of the second inclined groove 140 terminates near the center between the two fourth inclined grooves 160 adjacent to each other in the tire circumferential direction. Accordingly, the delivery of water between the second inclined groove 140 and the fourth inclined groove 160 is more efficiently performed. Note that although not illustrated in
Here, LG2G4/LG4G4 may be more than 0.40, 0.43 or more, or 0.45 or more, and may be less than 0.60, 0.58 or less, or 0.55 or less.
In relation to any one of Additional Embodiments 2-8 to 2-14, the pneumatic tire according to Additional Embodiment 2-15 of the present disclosure satisfies the following relationships (17) to (20), where in a tire meridian cross-sectional view, dG is the maximum value of lengths in the tire radial direction from the tire surface profile, when the circumferential main grooves and the inclined grooves are not present, to the groove bottoms of the first and second circumferential main grooves 110 and 120 and dIG1, dIG2, dIG3, and dIG4 are respectively the maximum values of lengths in the tire radial direction from the tire surface profile to the groove bottoms of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160:
0.05<dIG1/dG<0.85 (17),
0.05<dIG2/dG<0.85 (18),
0.05<dIG3/dG<0.85 (19), and
0.05<dIG4/dG<0.85 (20).
In the pneumatic tire of the present disclosure according to Additional Embodiment 2-15, the maximum values (dIG1, dIG2, dIG3, and dIG4) of the lengths in the tire radial direction from the tire surface profile to the groove bottoms of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 are smaller than the maximum value dG of lengths in the tire radial direction from the tire surface profile to the groove bottoms of the first and second circumferential main grooves 110 and 120. Thus, drainage properties can be improved while suppressing a decrease in block rigidity of the tire due to each of the inclined grooves 130, 140, 150, 160. Here, when 0.05<dIG1 (or dIG2, dIG3, dIG4)/dG, the depths of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 are sufficiently large, and thus drainage properties are particularly improved. On the other hand, when dIG1 (or dIG2, dIG3, dIG4)/dG<0.85, the depths of the first inclined groove 130, the second inclined groove 140, the third inclined groove 150, and the fourth inclined groove 160 are not too large, and in particular, a decrease in block rigidity can be suppressed.
Here, dIG1 (or dIG2, dIG3, dIG4)/dG may be more than 0.05, 0.1 or more, 0.2 or more, or 0.3 or more, and may be less than 0.85, 0.80 or less, 0.70 or less, or 0.60 or less.
In relation to any one of Basic Embodiment 2 and Additional Embodiments 2-1 and 2-15, the pneumatic tire according to Additional Embodiment 2-16 of the present disclosure satisfies the following relationship (21), where SSI is the total groove area on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL and SSO is the total groove area on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane.
S
SO
<S
SI (21)
Here, in a plan view of the tread surface of the pneumatic tire, the total groove area means the sum of the groove areas, including the chamfered portions, in a predetermined region. Accordingly, for example, the total groove area on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL is the sum of the areas of the circumferential main groove disposed on the vehicle mounting inner side with respect to the tire equatorial plane CL, the circumferential main groove located on the vehicle mounting inner side with respect to the tire equatorial plane CL, and the chamfered portions formed on these circumferential main grooves.
In
Accordingly, in
Further, in
Accordingly, in
By preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side as described above, dry steering stability and wet steering stability are efficiently improved.
In the pneumatic tire according to Additional Embodiment 2-16 of the present disclosure, the total groove area SSI on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL is increased to efficiently enhance drainage properties, and meanwhile, the total groove area SSO on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane is decreased to efficiently enhance rigidity of the land portion.
As a result, the pneumatic tire according to Additional Embodiment 2-16 of the present disclosure can provide more improved wet steering stability and dry steering stability.
Note that a ratio SSI/SSO of the total groove area SSI on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane CL to the total groove area SSO on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane is larger than 1.1 and smaller than 1.5. SSI/SSO may be more than 1.1, 1.2 or more, 1.3 or more, or 1.4 or more, and may be less than 1.5, 1.4 or less, 1.3 or less, or 1.2 or less.
As illustrated in
More specifically, in
By preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side as described above, dry steering stability and wet steering stability are efficiently improved.
In relation to the two adjacent circumferential main grooves, in the pneumatic tire according to Additional Embodiment 2-17 of the present disclosure, the average groove width of the circumferential main groove on the vehicle mounting inner side is increased to efficiently improve drainage properties, and meanwhile, the average groove width of the circumferential main groove on the vehicle mounting direction outer side is decreased to efficiently improve rigidity of the land portion defined and formed around the circumferential main groove.
As a result, the pneumatic tire according to Additional Embodiment 2-17 of the present disclosure can provide more improved wet steering stability and dry steering stability.
In the pneumatic tire according to Additional Embodiment 2-18 of the present disclosure, an average groove width of the circumferential main grooves on the vehicle mounting inner side is larger than an average groove width of the circumferential main grooves on the vehicle mounting outer side in all pairs of two of the circumferential main grooves adjacent to each other in relation to any one of Basic Embodiment 2 and Additional Embodiments 2-1 to 2-17.
In other words, the pneumatic tire according to Additional Embodiment 2-18 of the present disclosure is configured such that the average groove width of the plurality of circumferential main grooves decreases from the vehicle mounting inner side toward the vehicle mounting outer side.
By preferentially enhancing drainage properties on the vehicle mounting inner side and preferentially enhancing rigidity on the vehicle mounting outer side as described above, dry steering stability and wet steering stability are efficiently improved.
In the pneumatic tire according to Additional Embodiment 2-18 of the present disclosure, the average groove width of the circumferential main groove disposed on the vehicle mounting inner side is increased to efficiently improve drainage properties, and meanwhile, the average groove width of the circumferential main groove disposed on the vehicle mounting outer side is decreased to efficiently improve rigidity of the land portion defined and formed around the circumferential main groove.
As a result, the pneumatic tire according to Additional Embodiment 2-18 of the present disclosure can provide more improved wet steering stability and dry steering stability.
As illustrated in
θGI<θGO (22)
In the pneumatic tire according to Additional Embodiment 2-19 of the present disclosure, the inclination angle θGI with respect to the tire radial direction of the vehicle mounting inner side groove wall 210a of the first circumferential main groove 210 is smaller than the inclination angle θGO with respect to the tire radial direction of the vehicle mounting outer side groove wall 210b of the first circumferential main groove 210.
Here, when profile lines from land portion surfaces located on both sides of the first circumferential main groove 210 to the groove bottom are compared on both vehicle mounting sides of the groove 210, an angle variation when transitioning from the surface profile of the chamfered portion 211 to the groove profile is relatively small on the vehicle mounting inner side WI, and an angle variation when transitioning from the surface profile of the chamfered portion 212 to the groove profile is relatively large on the vehicle mounting outer side WO. In other words, assuming that stresses almost equal and in opposite directions in the tire width direction are applied to the land portions located on both sides of the groove 210, due to the shapes of both land portions, it is clear that the land portion located on the vehicle mounting outer side with respect to the groove 210 is less likely to be worn and has higher rigidity. In other words, this configuration agrees with the aforementioned view that it is preferable to preferentially increase the rigidity on the vehicle mounting outer side.
Additionally, when the groove center line of the first circumferential main groove 210 is set as a reference, the groove volume on the vehicle mounting inner side is larger than the groove volume on the vehicle mounting outer side. This configuration also agrees with the aforementioned view that it is preferable to preferentially increase drainage properties on the vehicle mounting inner side.
As a result, the pneumatic tire according to Additional Embodiment 2-19 of the present disclosure can provide more improved wet steering stability and dry steering stability.
As illustrated in
Note that as illustrated in
The ratio θGO/θGI of the inclination angle θGO with respect to the tire radial direction of the vehicle mounting outer side groove wall of the circumferential main groove to the inclination angle θGI with respect to the tire radial direction of the vehicle mounting inner side groove wall of the circumferential main groove is preferably greater than 2.0 and smaller than 5.0.
θGO/θGI may be more than 2.0, 2.5 or more, 3.0 or more, or 3.5 or more, and may be less than 5.0, 4.5 or less, 4.0 or less, or 3.5 or less.
θGI may be more than 0° and 30° or less. θGI may be more than 0°, 1° or more, 5° or more, 10° or more, or 15° or more, and may be 30° or less, 25° or less, 20° or less, 15° or less, or 10° or less.
Pneumatic tires of Inventive Examples 1 to 6 and Conventional Example 1 were produced according to the “conditions” indicated in Table 1 below. Note that the tire size of the pneumatic tire in each Example was 255/35R19 (defined by JATMA).
In Table 1, “wave shape” for “shape of circumferential main groove” means that the groove center line of the circumferential main groove has a wave shape that amplifies in the tire width direction as it extends in the tire circumferential direction.
In Table 1, “vehicle mounting inner side chamfered portion” is a chamfer disposed at an edge portion on the vehicle mounting inner side of the circumferential main groove. In a certain example, “Yes” for “vehicle mounting inner side chamfered portion” means that the “vehicle mounting inner side chamfered portion” is present in all of the circumferential main grooves in the example. Also, in a certain example, “No” for “vehicle mounting inner side chamfered portion” means that the “vehicle mounting inner side chamfered portion” is not present in any of the circumferential main grooves in the example.
In Table 1, “vehicle mounting outer side chamfered portion” is a chamfer disposed at an edge portion on the vehicle mounting outer side of the circumferential main groove. In a certain example, “Yes” for “vehicle mounting outer side chamfered portion” means that the “vehicle mounting outer side chamfered portion” is present in all of the circumferential main grooves in the example. Also, in a certain example, “No” for “vehicle mounting outer side chamfered portion” means that the “vehicle mounting outer side chamfered portion” is not present in any of the circumferential main grooves in the example.
In Table 1, “WAI” is the chamfer width of the vehicle mounting inner side chamfered portion and “WAO” is the chamfer width of the vehicle mounting outer side chamfered portion. Further, “SSI” is a total groove area on the vehicle mounting inner side of the circumferential main groove with respect to the tire equatorial plane, and “SSO” is a total groove area on the vehicle mounting outer side of the circumferential main groove with respect to the tire equatorial plane. Furthermore, “dCI” is the maximum value of the length in the tire radial direction from the tire surface profile to the innermost position in the tire radial direction of the vehicle mounting inner side chamfered portion, and “dG” is the maximum value of the length in the tire radial direction from the tire surface profile, when the circumferential main groove is not present, to the groove bottom of the circumferential main groove. Additionally, “θGI” is an inclination angle of the vehicle mounting inner side groove wall of the circumferential main groove with respect to the tire radial direction, and “θGO” is an inclination angle of the vehicle mounting outer side groove wall of the circumferential main groove with respect to the tire radial direction.
Pneumatic tires of Inventive Examples 7 to 12 and Conventional Example 2 were produced according to the “conditions” indicated in Table 2 below. Note that the tire size of the pneumatic tire in each Example was 255/35R19 (defined by JATMA).
In Table 2, “Yes” for “vehicle mounting outer side chamfered portion” means that the “vehicle mounting outer side chamfered portion” is, of the three circumferential main grooves, present only in the circumferential main grooves other than the circumferential main groove on the vehicle mounting outermost side, that is, only in the two circumferential main grooves on the vehicle mounting inner side. Also, in a certain example, “No” for “vehicle mounting outer side chamfered portion” means that the “vehicle mounting outer side chamfered portion” is not present in any of the circumferential main grooves in the example.
The definition of the conditions is otherwise the same as in Table 1.
The tires of each Example were mounted on JATMA standard rim wheels having a rim size of 19×9.0J, adjusted to an internal pressure of 240 kPa, and mounted onto a front-wheel drive vehicle as a test vehicle having an engine displacement of 2.0 L.
Then, the test vehicle was driven at a speed of from 10 km/h to 180 km/h on a flat-circuit test course having a dry road surface, and a test driver performed sensory evaluation on steering characteristics when changing lanes and when cornering and on stability when traveling straight. The dry steering stability is displayed as an index value with Conventional Example used as a reference at 100. A larger index value indicates better dry steering stability. The results are indicated in Tables 1 and 2.
The tires of each Example were mounted on JATMA standard rim wheels having a rim size of 19×9.0J, adjusted to an internal pressure of 240 kPa, and mounted onto a front-wheel drive vehicle as a test vehicle having an engine displacement of 2.0 L.
Then, the test vehicle was driven and decelerated from a speed of 180 km/h to be stopped on a flat-circuit test course having a dry road surface, and the reciprocal of the travel distance was calculated. The wet steering stability is displayed as an index value with Conventional Example used as a reference at 100. A larger index value indicates better wet steering stability. The results are indicated in Tables 1 and 2.
As can be seen from Tables 1 and 2, any of the pneumatic tires of Inventive Examples 1 to 12, complying with the technical scope of the present technology, provides improved dry steering stability and wet steering stability in a well-balanced manner compared with the pneumatic tires of Conventional Examples 1 and 2, not complying with the technical scope of the present technology.
Regarding Inventive Example 1, the tire in which the average groove width of the first circumferential main groove 110 was equal to the average groove width of the second circumferential main groove 120 was produced as Inventive Example 1-1, and the tire in which the average groove width of the first circumferential main groove 110 was larger than the average groove width of the second circumferential main groove 120 was produced as Inventive Example 1-2. Note that the tire size of the pneumatic tire in each Example was 255/35R19 (defined by JATMA).
Also, regarding Inventive Example 7, the tire in which the average groove widths of the first circumferential main groove 210, the second circumferential main groove 220, and the third circumferential main groove 230 were equal was produced as Inventive Example 7-1, and the tire in which the average groove width is larger in the order of the third circumferential main groove 230, the second circumferential main groove 220, and the first circumferential main groove 210 was produced as Inventive Example 7-2. Note that the tire size of the pneumatic tire in each Example was 255/35R19 (defined by JATMA).
The aforementioned “evaluation of dry steering stability” and the aforementioned “evaluation of wet steering stability” were conducted on the pneumatic tires of Inventive Examples 1-1, 1-2, 7-1, and 7-2. Note that in these Inventive Examples, wet steering stability was evaluated when the vehicle was traveling forward and when the vehicle was traveling backward.
When the evaluations of dry steering stability and wet steering stability in Inventive Example 1-1 were 100, the evaluations of dry steering stability and wet steering stability in Inventive Example 1-2 were 99 and 101. Also, when the evaluations of dry steering stability and wet steering stability in Inventive Example 7-1 were 100, the evaluations of dry steering stability and wet steering stability in Inventive Example 7-2 were 99 and 101.
The pneumatic tires of Inventive Examples 13 to 21 were produced based on the groove shape illustrated in
Referring to
Regarding the shape of the first inclined groove 130, the “starting point” is a starting point at which the first inclined groove 130 starts from the first circumferential groove 110, and the “inner side starting point” is a starting point on the inner side in the tire width direction with respect to the first circumferential groove 110, that is, a starting point on the tire equatorial line CL side as viewed from the first circumferential groove 110. On the other hand, the “outer side starting point” is a starting point on the outer side in the tire width direction with respect to the first circumferential groove 110, that is, a starting point on the side opposite to the tire equatorial line CL side as viewed from the first circumferential groove 110. Similarly, regarding the shape of the second inclined groove 140, the “starting point” is a starting point at which the second inclined groove 140 starts from the second circumferential groove 120, and the “outer side starting point” is a starting point on the outer side in the tire width direction with respect to the second circumferential groove 120, that is, a starting point on the side opposite to the tire equatorial line CL side as viewed from the second circumferential groove 120. In addition, that the starting point is “recessed” means that the starting point of the inclined groove is located in a recessed portion of the circumferential main groove, and conversely, that the starting point is “projected” means that the starting point of the inclined groove is located in a projected portion of the circumferential main groove. Table 4 is similarly understood with reference to
Note that the first inclined groove 130 (240 in
The aforementioned “evaluation of dry steering stability” and the aforementioned “evaluation of wet steering stability” were conducted on the pneumatic tires of Inventive Examples 13 to 29. Note that in these Inventive Examples, wet steering stability was evaluated when the vehicle was traveling forward and when the vehicle was traveling backward.
The results are indicated in Tables 3 and 4.
As can be seen from Tables 3 and 4, any of the pneumatic tires of Inventive Examples 13 to 29, complying with the technical scope of the present technology, provides improved dry steering stability and wet steering stability in a well-balanced manner. Note that in Tables 3 and 4, “to” representing a numerical range does not include endpoints. In other words, “0.2 to 0.6” means more than 0.2 and less than 0.6. Similarly, “0.4 to 0.6” means more than 0.4 and less than 0.6.
Regarding the configuration related to the first inclined groove 130, the pneumatic tires of Inventive Examples 30 and 31 were produced based on the groove shape illustrated in
The aforementioned “evaluation of dry steering stability” and the aforementioned “evaluation of wet steering stability” were conducted on the pneumatic tires of Inventive Examples 30 and 31. Note that in these Inventive Examples, wet steering stability was evaluated when the vehicle was traveling forward and when the vehicle was traveling backward.
When the evaluations of dry steering stability and the wet steering stability in Inventive Example 30 were 100, the evaluations of dry steering stability and wet steering stability in Inventive Example 31 were 101 and 101.
The pneumatic tires of Inventive Examples 32 to 48 were produced based on the groove shape illustrated in
Referring to
Regarding the shape of the first inclined groove 130, the “starting point” is a starting point at which the first inclined groove 130 starts from the first circumferential groove 110, and the “inner side starting point” is a starting point on the inner side in the tire width direction with respect to the first circumferential groove 110, that is, a starting point on the tire equatorial line CL side as viewed from the first circumferential groove 110. On the other hand, the “outer side starting point” is a starting point on the outer side in the tire width direction with respect to the first circumferential groove 110, that is, a starting point on the side opposite to the tire equatorial line CL side as viewed from the first circumferential groove 110. Similarly, regarding the shape of the second inclined groove 140, the “starting point” is a starting point at which the second inclined groove 140 starts from the second circumferential groove 120, and the “outer side starting point” is a starting point on the outer side in the tire width direction with respect to the second circumferential groove 120, that is, a starting point on the side opposite to the tire equatorial line CL side as viewed from the second circumferential groove 120. In addition, that the starting point is “recessed” means that the starting point of the inclined groove is located in a recessed portion of the circumferential main groove, and conversely, that the starting point is “projected” means that the starting point of the inclined groove is located in a projected portion of the circumferential main groove. Table 4 is similarly understood with reference to
Note that the first inclined groove 130 (240 in
As can be seen from Tables 5 and 6, any of the pneumatic tires of Inventive Examples 32 to 63, complying with the technical scope of the present technology, provides improved dry steering stability and wet steering stability in a well-balanced manner.
Regarding Inventive Example 32, the tire in which the average groove width of the first circumferential main groove 110 was equal to the average groove width of the second circumferential main groove 120 was produced as Inventive Example 32-1, and the tire in which the average groove width of the first circumferential main groove 110 was larger than the average groove width of the second circumferential main groove 120 was produced as Inventive Example 32-2. Note that the tire size of the pneumatic tire in each Example was 255/35R19 (defined by JATMA).
Also, regarding Inventive Example 49, the tire in which the average groove widths of the first circumferential main groove 210, the second circumferential main groove 220, and the third circumferential main groove 230 were equal was produced as Inventive Example 49-1, and the tire in which the average groove width is larger in the order of the third circumferential main groove 230, the second circumferential main groove 220, and the first circumferential main groove 210 was produced as Inventive Example 49-2.
The aforementioned “evaluation of dry steering stability” and the aforementioned “evaluation of wet steering stability” were conducted on the pneumatic tires of Inventive Examples 32-1,32-2, 49-1, and 49-2. Note that in these Inventive Examples, wet steering stability was evaluated when the vehicle was traveling forward and when the vehicle was traveling backward.
When the evaluations of dry steering stability and wet steering stability in Inventive Example 32-1 were 100, the evaluations of dry steering stability and wet steering stability in Inventive Example 32-2 were 99 and 101. When the evaluations of dry steering stability and wet steering stability in Inventive Example 49-1 were 100, the evaluations of dry steering stability and wet steering stability in Inventive Example 49-2 were 99 and 101.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-219405 | Dec 2020 | JP | national |
| 2021-175912 | Oct 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/045019 | 12/7/2021 | WO |
