Patent Application
20230110465
The present technology relates to a tire.
In general, good steering stability performance can be obtained by making the contact patch shape of the tire appropriate. Japan Patent No. 5387707 discloses a technology for improving the contact patch shape by allowing the land portion to project toward the outer side in the tire radial direction with respect to the standard contour line of the entire tread portion.
The tire described in Japan Patent No. 5387707 includes a land portion projecting toward the outer side in the tire radial direction. However, since the projection amount is not large, the contact patch shape cannot be significantly improved, and there is room for improvement from the viewpoint of achieving both dry steering stability performance and wet steering stability performance in a compatible manner.
The present technology provides a tire capable of achieving both dry steering stability performance and wet steering stability performance in a compatible manner.
A tire according to a certain aspect of the present technology is a tire including: a plurality of circumferential main grooves provided in a tread portion, the plurality of circumferential main grooves extending in a tire circumferential direction; and a plurality of land portions defined by the plurality of circumferential main grooves, the plurality of land portions including: a center land portion closest to a tire equatorial plane; a first shoulder land portion including one ground contact edge of ground contact edges on both sides in a tire width direction with respect to the tire equatorial plane; and a first middle land portion between the first shoulder land portion and the center land portion, in a tire meridian cross-sectional view, a line connecting, by a single arc, a ground contact edge located in the first shoulder land portion, a midpoint of a length of the center land portion in the tire width direction, and a midpoint of a length of the first middle land portion in the tire width direction being defined as a first virtual profile, an end portion of the center land portion on a side of the first middle land portion being recessed toward an inner side in a tire radial direction relative to the first virtual profile, an end portion of the first middle land portion on a side of the center land portion being recessed toward the inner side in the tire radial direction relative to the first virtual profile, a recess amount of the end portion of the center land portion on the side of the first middle land portion being larger than a recess amount of the end portion of the first middle land portion on the side of the center land portion, and in the tire meridian cross-sectional view, a distance between intersection points of the first virtual profile and extension lines extended from groove walls, on sides of the center land portion, of circumferential main grooves adjacent to both end portions of the center land portion in the tire width direction being defined as Wc, and a ground contact edge of the center land portion being located on a more inner side than a position at a distance of 0.03Wc from the end portion of the center land portion on the side of the first middle land portion.
Preferably, in the tire meridian cross-sectional view, a distance between intersection points of the first virtual profile and extension lines extended from groove walls, on sides of the first middle land portion, of circumferential main grooves adjacent to both end portions of the first middle land portion in the tire width direction is defined as Wa, and a ground contact edge of the first middle land portion is located on a more inner side than a position at a distance of 0.03Wa from the end portion of the first middle land portion on the side of the center land portion.
Preferably, a difference between the recess amount of the end portion of the center land portion on the side of the first middle land portion and the recess amount of the end portion of the first middle land portion on the side of the center land portion is 0.1 mm or more and 0.8 mm or less.
Preferably, a groove width of the circumferential main groove adjacent to the end portion of the center land portion in the tire width direction is equal to or larger than a groove width of a circumferential main groove adjacent to the first shoulder land portion.
Preferably, a length of the center land portion in the tire width direction is 105% or more and 120% or less of a length of the first middle land portion in the tire width direction.
Preferably, an end portion of the first shoulder land portion on the inner side in the tire width direction is recessed toward the inner side in the tire radial direction relative to the first virtual profile, and a recess amount of the end portion of the center land portion on an outer side in the tire width direction is larger than a recess amount of the end portion of the first shoulder land portion on the inner side in the tire width direction.
Preferably, an end portion of the first middle land portion on a side of the first shoulder land portion is recessed toward the inner side in the tire radial direction relative to the first virtual profile, and a recess amount of the end portion of the first middle land portion on the side of the first shoulder land portion is equal to or larger than a recess amount of the end portion of the first shoulder land portion on a side of the first middle land portion.
Preferably, the first shoulder land portion includes a lug groove extending in the tire width direction, the lug groove includes a chamfer in a groove depth direction and a groove width direction, and a chamfer length in the groove width direction is larger than a chamfer length in the groove depth direction.
Preferably, the tire further includes: a second shoulderland portion including another ground contact edge of the ground contact edges on both sides in the tire width direction with respect to the tire equatorial plane; and a second middle land portion between the second shoulder land portion and the center land portion, wherein in the tire meridian cross-sectional view, a line connecting, by a single arc, a ground contact edge located in the second shoulder land portion, the midpoint of the length of the center land portion in the tire width direction, and a midpoint of a length of the second middle land portion in the tire width direction is defined as a second virtual profile, an end portion of the center land portion on a side of the second middle land portion is recessed toward the inner side in the tire radial direction relative to the second virtual profile, an end portion of the second middle land portion on a side of the center land portion is recessed toward the inner side in the tire radial direction relative to the second virtual profile, a recess amount of the end portion of the center land portion on the side of the second middle land portion is larger than a recess amount of the end portion of the second middle land portion on the side of the center land portion, and in the tire meridian cross-sectional view, a distance between intersection points of the second virtual profile and the extension lines extended from the groove walls, on the sides of the center land portion, of the circumferential main grooves adjacent to both end portions of the center land portion in the tire width direction is defined as Wc′, and a ground contact edge of the center land portion is located on a more inner side than a position at a distance of 0.03Wc′ from the end portion of the center land portion on the side of the second middle land portion.
Preferably, in the tire meridian cross-sectional view, a distance between intersection points of the second virtual profile and extension lines extended from groove walls, on sides of the second middle land portion, of circumferential main grooves adjacent to both end portions of the second middle land portion in the tire width direction is defined as Wb, and a ground contact edge of the second middle land portion is located on a more inner side than a position at a distance of 0.03Wb from the end portion of the second middle land portion on the side of the center land portion.
Preferably, a difference between the recess amount of the end portion of the center land portion on the side of the second middle land portion and the recess amount of the end portion of the second middle land portion on the side of the center land portion is 0.1 mm or more and 0.8 mm or less.
Preferably, a groove width of the circumferential main groove adjacent to the end portion of the center land portion in the tire width direction is equal to or larger than a groove width of a circumferential main groove adjacent to the second shoulder land portion.
Preferably, a length of the center land portion in the tire width direction is 105% or more and 120% or less of a length of the second middle land portion in the tire width direction.
Preferably, an end portion of the second shoulder land portion on the inner side in the tire width direction is recessed toward the inner side in the tire radial direction relative to the second virtual profile, and a recess amount of the end portion of the center land portion on the outer side in the tire width direction is larger than a recess amount of the end portion of the second shoulder land portion on the inner side in the tire width direction.
Preferably, an end portion of the second middle land portion on a side of the second shoulder land portion is recessed toward the inner side in the tire radial direction relative to the second virtual profile, and a recess amount of the end portion of the second middle land portion on the side of the second shoulder land portion is equal to or larger than a recess amount of the end portion of the second shoulder land portion on a side of the second middle land portion.
Preferably, the second shoulder land portion includes a lug groove extending in the tire width direction, the lug groove includes a chamfer in a groove depth direction and a groove width direction, and a chamfer length in the groove width direction is larger than a chamfer length in the groove depth direction.
Preferably, rubber constituting the tread portion has a hardness of 65 or more at 20° C.
The tire according to the present technology can achieve both dry steering stability performance and wet steering stability performance in a compatible manner.
Embodiments of the present technology will be described in detail below with reference to the drawings. In the embodiments described below, identical or similar components to those of other embodiments have identical reference signs, and descriptions of those components will be either simplified or omitted. The present technology is not limited by the embodiments. Constituents of the embodiments include elements that are substantially identical or that can be substituted and easily conceived by one skilled in the art. Note that it is possible to combine the configurations described below as desired. Moreover, various omissions, substitutions, and changes to the configurations can be carried out within the scope of the present technology.
In
Hereinafter, the tire radial direction refers to the direction orthogonal to the rotation axis (not illustrated) of the tire 1. An inner side in the tire radial direction refers to the side toward the rotation axis in the tire radial direction. An outer side in the tire radial direction refers to the side away from the rotation axis in the tire radial direction. Moreover, a tire circumferential direction refers to the circumferential direction with the rotation axis as the central axis. In addition, a tire width direction refers to a direction parallel with the rotation axis. An inner side in the tire width direction refers to the side toward the tire equatorial plane (tire equatorial line) CL in the tire width direction, and an outer side in the tire width direction refers to the side away from the tire equatorial plane CL in the tire width direction.
Furthermore, an outer side in the vehicle width direction and an inner side in the vehicle width direction are defined as vehicle width directions when the tire is mounted on a vehicle. Additionally, left and right regions demarcated by the tire equatorial plane CL are defined as an outer side region in the vehicle width direction and an inner side region in the vehicle width direction, respectively. Furthermore, the tire includes a mounting direction indicator (not illustrated) that indicates the tire mounting direction with respect to a vehicle. Examples of the mounting direction indicator include a mark and a recess/protrusion on a sidewall portion of the tire. For example, Regulation No. 30 of the Economic Commission for Europe Regulation (ECE R30) mandates that a vehicle mounting direction indicator be provided on the sidewall portion on the outer side in the vehicle width direction in a case where the tire is mounted on a vehicle.
In
The specified rim refers to a “standard rim” specified by JATMA, a “Design Rim” specified by the Tire and Rim Association, Inc. (TRA), or a “Measuring Rim” specified by the European Tyre and Rim Technical Organisation (ETRTO). Additionally, the specified internal pressure refers to a “maximum air pressure” specified by JATMA, the maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. Additionally, the specified load refers to a “maximum load capacity” specified by JATMA, the maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “LOAD CAPACITY” specified by ETRTO. However, in JATMA, in the case of a tire for a passenger vehicle, the specified internal pressure is an air pressure of 180 kPa, and the specified load is 88% of the maximum load capacity at the specified internal pressure.
The tread surface 3 is provided with a plurality of circumferential main grooves 21, 22, 23, and 24. A plurality ofland portions 20C, 20Ma, 20Mb, 20Sa, and 20Sb are defined by the circumferential main grooves 21, 22, 23 and 24. The land portion 20C is the center land portion closest to the tire equatorial plane CL. When a circumferential main groove is provided on the tire equatorial plane CL, the land portions on both sides of the circumferential main groove in the tire width direction are the land portions closest to the tire equatorial plane CL, that is, the center land portions. The land portion 20Sa is a first shoulder land portion including one ground contact edge TOUT of the ground contact edges TOUT and TIN on both sides in the tire width direction with respect to the tire equatorial plane CL. 20Ma denotes a first middle land portion located between the first shoulder land portion 20S a and the center land portion 20C. The land portion 20Sb is a second shoulder land portion including the other ground contact edge TIN of the ground contact edges TOUT and TIN on both sides in the tire width direction with respect to the tire equatorial plane CL. The land portion 20Mb is a second middle land portion between the second shoulder land portion 20Sb and the center land portion 20C. The land portions 20C, 20Ma, 20Mb, 20Sa and 20Sb each may be a rib-like land portion continuous in the tire circumferential direction, or may be a land portion including block rows divided by a groove extending in the tire width direction.
The tire 1 has an annular structure with the tire rotation axis being as the center, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair of rim cushion rubbers 17, 17 (see
The pair of bead cores 11, 11 include one or a plurality of bead wires made of steel and wound annularly multiple times and are embedded in bead portions 10 to configure the cores of the left and right bead portions 10. The pair of bead fillers 12, 12 are disposed on the outer side in the tire radial direction of the pair of bead cores 11, 11 to reinforce the bead portions 10.
The carcass layer 13 has a single layer structure including one carcass ply, or a multilayer structure including a plurality of carcass plies being layered, and the carcass layer 13 extends in a toroidal shape between the bead cores 11, 11 at the left and right, and constitutes the backbone of the tire. Additionally, both end portions of the carcass layer 13 are turned back toward outer sides in the tire width direction to wrap the bead cores 11 and the bead fillers 12, and are fixed. Moreover, the carcass ply of the carcass layer 13 is made by covering a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, or rayon) with a coating rubber and performing a rolling process on the carcass cords, and has a cord angle of 80 degrees or more and 100 degrees or less. The cord angle is defined as the inclination angle in the longitudinal direction of the carcass cord with respect to the tire circumferential direction.
In the configuration of
The belt layer 14 is formed by layering a plurality of belt plies, and is disposed around the outer circumference of the carcass layer 13. The belt layer 14 includes a pair of cross belts 141, 142, a belt cover 143, and a belt edge cover 144. In this example, a plurality of the belt covers 143 are provided.
The pair of cross belts 141, 142 are made by covering a plurality of belt cords made of steel or an organic fiber material with a coating rubber and performing a rolling process on the belt cords, and have a cord angle of 15 degrees or more and 55 degrees or less as an absolute value. Further, the pair of cross belts 141, 142 have cord angles (defined as inclination angles in longitudinal directions of the belt cords with respect to the tire circumferential direction) of mutually opposite signs and are layered such that the longitudinal directions of the belt cords intersect each other (so-called crossply structure). Furthermore, the pair of cross belts 141, 142 are disposed in a layered manner on an outer side in the tire radial direction of the carcass layer 13.
The belt cover 143 and the belt edge covers 144 are made by covering a plurality of belt cover cords made of steel or an organic fiber material with coating rubber, and have a cord angle 0 degree or more and 10 degrees or less as an absolute value. Additionally, for example, a strip material is formed of one or a plurality of belt cover cords covered with coating rubber, and the belt cover 143 and the belt edge covers 144 are made by winding this strip material multiple times and in a spiral-like manner in the tire circumferential direction around outer circumferential surfaces of the cross belts 141, 142. Additionally, the belt cover 143 is disposed completely covering the cross belts 141, 142, and the pair of belt edge covers 144, 144 are disposed covering the left and right edge portions of the cross belts 141, 142 from the outer side in the tire radial direction.
The tread rubber 15 is disposed in the outer circumferences of the carcass layer 13 and the belt layer 14 in the tire radial direction and constitutes a tread portion 2 of the tire. Shoulder portions 8 are located at both end portions of the tread portion 2 in the tire width direction.
The pair of sidewall rubbers 16, 16 are disposed on respective outer sides in the tire width direction of the carcass layer 13 and constitute left and right sidewall portions 30. For example, in the configuration of
The pair of rim cushion rubbers 17, 17 extend from an inner side in the tire radial direction of the left and right bead cores 11, 11 and the turned back portions 132 of the carcass layer 13 toward the outer side in the tire width direction, and constitute rim fitting surfaces of the bead portions 10. The rim fitting surface is a contact surface of the bead portion 10 with the rim flange (not illustrated).
The innerliner 18 is an air permeation preventing layer disposed on the tire inner surface and covering the carcass layer 13, and suppresses oxidation caused by exposure of the carcass layer 13 and also prevents leaking of the air in the tire. Additionally, the innerliner 18 is made of, for example, a rubber composition containing butyl rubber as a main component, a thermoplastic resin, and a thermoplastic elastomer composition containing an elastomer component blended with a thermoplastic resin.
As illustrated in
As illustrated in
As illustrated in
Here, the groove width of the circumferential main groove 23 adjacent to the end portion of the center land portion 20C in the tire width direction is preferably equal to or larger than the groove width of the circumferential main groove 21 adjacent to the first shoulder land portion 20S a. Further, the groove width of the circumferential main groove 23 is equal to or larger than the groove width of the circumferential main groove 24 adjacent to the second shoulder land portion 20Sb. When the circumferential main groove is provided on the tire equatorial plane CL, the groove width of the circumferential main groove is preferably equal to or larger than the groove width of the circumferential main groove adjacent to the shoulder land portion. By making the groove width of the circumferential main groove for receiving the water discharged in the center land portion 20C wider than the groove width of the other circumferential main grooves, the drainage performance can be further improved.
The circumferential main grooves 21, 22, 23 and 24 have a groove width of 4.0 mm or more and 24.6 mm or less, and a groove depth of 5.5 mm or more and 8.0 mm or less. The circumferential main grooves 21, 22, 23, and 24 may be grooves provided with a wear indicator, or may be narrow grooves without a wear indicator.
The groove width is measured as a distance between groove walls opposed to each other in a groove opening portion when the tire is mounted on a specified rim, inflated to a specified internal pressure, and in an unloaded state. In a configuration in which the groove opening portion includes a notch portion or a chamfered portion, the groove width is measured with intersection points between an extension line of the tread contact surface and extension lines of the groove walls as measurement points, in a cross-sectional view parallel with the groove width direction and the groove depth direction.
The groove depth is measured as a distance from the tread contact surface to a maximum groove depth position when the tire is mounted on a specified rim, inflated to the specified internal pressure, and in an unloaded state. Additionally, in a configuration in which a groove bottom includes partial recess/projection portions or a sipe, the groove depth is measured excluding the partial recess/projection portions or the sipe.
The hardness of the rubber constituting the tread portion 2 is preferably 65 or more. If the hardness of the rubber constituting the tread portion 2 is lower than the above, the bulging portion of the land portion, which has been a non-ground contact region under a normal load, is crushed under a high load. This is not preferable because the non-ground contact region becomes small, and the effect of achieving both wet steering stability performance and dry steering stability performance in a compatible manner becomes small. The hardness mentioned above is JIS (Japanese Industrial Standard)-A hardness which is durometer hardness measured at a temperature of 20° C. using a type A durometer in accordance with JIS K 6253.
Returning to
Here, the midpoint of the land portion is defined as follows.
In the example illustrated in
Here, when a chamfer or a notch is provided at the end portion of the land portion, the midpoint is defined as follows.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
Here, referring to
Returning to
The same applies to the end portions in the tire width direction of the second middle land portion 20Mb described with reference to
The same applies to the end portions in the tire width direction of the center land portion 20C described with reference to
At this time, the ground contact edge of the center land portion 20C is located on a more inner side of the center land portion 20C in the tire width direction than a position at a distance of 0.03Wc from each of both end portions of the center land portion 20C. In other words, the point B projected onto the center land portion 20C in the normal direction of the first virtual profile PR1 from the point A moved by the distance of 0.03Wc along the first virtual profile PR1 from the intersection point E toward the center of the center land portion 20C does not touch the ground. Further, the point B′ projected onto the center land portion 20C in the normal direction of the first virtual profile PR1 from the point A′ moved by the distance of 0.03Wc along the first virtual profile PR1 from the intersection point E′ toward the center of the center land portion 20C does not touch the ground.
In the example described with reference to
When the second virtual profile PR2 is used as a reference for the inner side in the vehicle width direction, in
In
In
The width We of the center land portion 20C is preferably 105% or more and 120% or less of the widths Wa and Wb of the adjacent first middle land portion 20Ma and second middle land portion 20Mb. In other words, it is preferable that Wc/Wa, which is the ratio of the width We to the width Wa, be 1.05 or more and 1.20 or less. Further, it is preferable that Wc/Wb, which is the ratio of the width We to the width Wb, be 1.05 or more and 1.20 or less. By making the length of the center land portion 20C having a large ground contact length in the tire width direction larger than that of the adjacent land portion, it is possible to secure the dry steering stability performance while maintaining the drainage performance. The ratio Wc/Wa and the ratio Wc/Wb exceeding 1.20 deteriorates the drainage performance and is not preferable.
Further, it is preferable that the groove opening portions of the lug grooves L1, L2 and L3 be provided with chamfers. In particular, the lug groove L1 of the shoulder land portion 20Sa has a great effect of contributing to drainage performance. Therefore, it is preferable that the groove opening portion of the lug groove L1 be provided with a chamfer.
Further, as illustrated in
Referring to
As described above, a structure is employed in which the end portion of the center land portion and the end portion of the middle land portion on both sides of the circumferential main groove are recessed toward the inner side in the tire radial direction relative to the virtual profile, the recess amount of the former end portion is larger than that of the latter end portion, and a range of 0.03Wc (or 0.03Wc′) from the end portion of the center land portion on the middle land portion side does not touch the ground, so that an appropriate contact patch shape of the tire can be obtained. This structure can improve the dry steering stability performance and the wet steering stability performance.
Since the dry steering stability performance and the wet steering stability performance are particularly effective on the outer side in the vehicle width direction, the dry steering stability performance and the wet steering stability performance can be improved by adopting the above-mentioned structure at least on the outer side in the vehicle width direction. Further, by adopting the above-mentioned structure on the inner side in the vehicle width direction, it is possible to improve the dry steering stability performance and the wet steering stability performance.
In the above-mentioned structure, the bulge of the center land portion, which requires drainage performance is made larger than the bulge of the adjacent land portion, and the width of the circumferential main groove adjacent to the center land portion is made relatively wide. As a result, water can be effectively discharged from the land portion to the circumferential main groove. In addition, because of an increase in the amount of bulge, the end portion of the center land portion in the tire width direction does not touch the ground, so that the actual ground contact area decreases, the ground contact pressure increases, and the wet steering stability performance is improved. If the amounts of the bulges of all the land portions are increased, the wet steering stability performance would be enhanced, but the dry steering stability performance would be deteriorated since the ground contact area is too small. According to the above-mentioned structure, the dry steering stability performance and the wet steering stability performance can be improved.
In the present example, tests for dry steering stability performance and wet steering stability performance were performed on a plurality of types of tires of different conditions (see Tables 1 to 6). In these tests, 255/35ZR19 (96Y) 19×9J pneumatic tires were assembled on a specified rim and inflated to an air pressure of 230 kPa. A vehicle was an FR (Front engine-Rear wheel drive) sedan with an engine displacement of 3500 cc. A sensory evaluation of dry steering stability performance and wet steering stability performance was conducted on a test course by a test driver on a predetermined road surface and at a predetermined speed. The evaluation was conducted using index values, with the reference (100) assigned to the tire of Conventional Example, and a larger value means superior performance. When the evaluation value is “95” or higher, the performance required for the tire is secured.
The tires of Examples 1 to 31 include a plurality of circumferential main grooves provided in the tread portion and extending in the tire circumferential direction, and a plurality of land portions defined by the plurality of circumferential main grooves, and, on a vehicle outer side region, there are provided a center land portion closest to a tire equatorial plane, a first shoulder land portion including one ground contact edge of the ground contact edges on both sides in the tire width direction with respect to the tire equatorial plane, and a first middle land portion between the first shoulder land portion and the center land portion. In the tires of Examples 1 to 31, on the vehicle outer side, the end portion of the center land portion on the first middle land portion side is recessed toward the inner side in the tire radial direction relative to the first virtual profile, the end portion of the first middle land portion on the center land portion side is recessed toward the inner side in the tire radial direction relative to the first virtual profile, a recess amount of the end portion of the center land portion on the first middle land portion side is larger than a recess amount of the end portion of the first middle land portion on the center land portion side, and when, in the tire meridian cross-sectional view, the distance between the intersection points of the first virtual profile and the extension lines extended from the groove walls, on the center land portion sides, of the circumferential main grooves adjacent to both end portions of the center land portion in the tire width direction is defined as Wc, the ground contact edge of the center land portion is located on a more inner side than a position at a distance of 0.03Wc from the end portion of the center land portion on the first middle land portion side.
Further, in the tires of Examples 17 to 31, on the vehicle inner side, the end portion of the center land portion on the second middle land portion side is recessed toward the inner side in the tire radial direction relative to the second virtual profile, the end portion of the second middle land portion on the center land portion side is recessed toward the inner side in the tire radial direction relative to the second virtual profile, a recess amount of the end portion of the center land portion on the second middle land portion side is larger than the recess amount of the end portion on the center land portion side of the second middle land portion, and when, in the tire meridian cross-sectional view, the distance between the intersection points of the second virtual profile and the extension lines extended from the groove walls, on the center land portion sides, of the circumferential main grooves adjacent to both end portions of the center land portion in the tire width direction is defined as Wc′, the ground contact edge of the center land portion is located on a more inner side than a position at a distance of 0.03Wc′ from the end portion of the center land portion on the second middle land portion side.
In the tire of Conventional Example, the recess amount from the virtual profile is uniform. In the tire of Comparative Example 1, the recess amount of the end portion of the center land portion on the second middle land portion side is smaller than the recess amount of the end portion of the second middle land portion on the center land portion side. In the tires of Comparative Example 3 and Comparative Example 4, the recess amount of the end portion of the center land portion on the second middle land portion side is identical to the recess amount of the end portion of the second middle land portion on the center land portion side. In the tire of Comparative Example 2, the ground contact edge of the center land portion is located on a more outer side than a position at a distance of 0.03Wc from the end portion of the center land portion on the first middle land portion side. When the recess amount in Table 1 is a negative value, it indicates the projection amount.
According to the tires of Examples 1 to 31, it can be seen that satisfactory results are obtained when, at least on the vehicle outer side, the end portion of the center land portion on the first middle land portion side is recessed toward the inner side in the tire radial direction relative to the first virtual profile, the end portion of the first middle land portion on the center land portion side is recessed toward the inner side in the tire radial direction relative to the first virtual profile, the recess amount of the end portion of the center land portion on the first middle land portion side is larger than the recess amount of the end portion of the first middle land portion on the center land portion side, and when, in the meridian cross-sectional view, the distance between the intersection points of the first virtual profile and the extension lines extended from the groove walls, on the center land portion sides, of the circumferential main grooves adjacent to both end portions of the center land portion in the tire width direction is defined as Wc, the ground contact edge of the center land portion is located on a more inner side than a position at a distance of 0.03Wc from the end portion of the center land portion on the first middle land portion side.
Further, according to the tires of Examples 17 to 31, it can be seen that satisfactory results are obtained when, on the vehicle inner side, the end portion of the center land portion on the second middle land portion side is recessed toward the inner side in the tire radial direction relative to the second virtual profile, the end portion of the second middle land portion on the center land portion side is recessed toward the inner side in the tire radial direction relative to the second virtual profile, the recess amount of the end portion of the center land portion on the second middle land portion side is larger than the recess amount of the end portion of the second middle land portion on the center land portion side, and when, in the tire meridian cross-sectional view, the distance between the intersection points of the second virtual profile and the extension lines extended from the groove walls, on the center land portion sides, of the circumferential main grooves adjacent to both end portions of the center land portion in the tire width direction is defined as Wc′, the ground contact edge of the center land portion is located on a more inner side than a position at a distance of 0.03Wc′ from the end portion of the center land portion on the second middle land portion side.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-066220 | Apr 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/014222 | 4/1/2021 | WO |
