Patent Application
20220324268
The present technology relates to a pneumatic tire.
An indicator of a brand or the like may be attached to a tire side portion of a pneumatic tire. In order to improve the visibility and appearance of the indicator of the brand or the like, there is a demand for tires with high self-cleaning performance that can easily wash away the deposits on the tire side portions by rain or cleaning the vehicle. If an organic cleaning agent is used, cracks may occur due to deterioration of a side rubber, and it is necessary to improve the cleaning performance with only water. From the perspective of taking into consideration of the influence on the environment due to the outflow of the cleaning agent, a tire having high cleaning performance only with water without using a cleaning agent is useful.
Japan Patent No. 3422715 discloses a pneumatic tire in which the visibility of a decorative portion provided on a sidewall portion is enhanced. Japan Patent No. 4371625 discloses a pneumatic tire in which a ridge is provided on a sidewall portion to suppress deterioration of appearance due to cracks occurring on a rubber surface.
Japan Patent Nos. 3422715 and 4371625 do not take both the visibility performance and the cleaning performance into consideration, and there is room for improvement in both the visibility performance and the cleaning performance.
The present technology provides a pneumatic tire capable of enhancing both visibility performance and cleaning performance.
A pneumatic tire according to an aspect of the present technology is a pneumatic tire including a tread portion, a sidewall portion, and a bead portion, a serration region being provided in a predetermined region of the sidewall portion, the serration region being formed by arranging a plurality of ridges, the plurality of ridges protruding from a base surface in parallel to each other and periodically, a length Lb of one cycle of the plurality of ridges along the base surface being 0.5 mm or more and 0.7 mm or less, and the pneumatic tire including a plane portion surrounded by the serration region.
Preferably, when a length of the one cycle of the plurality of ridges along the base surface is defined as the length Lb, and a length along a contour of the ridge per the one cycle in a cross-sectional view along a direction orthogonal to an extension direction of the plurality of ridges is defined as a length Lr, a ratio Lr/Lb of the length Lr to the length Lb is 1.2 or more and 2.0 or less.
Preferably, a ratio PH/RH of a height PH of the plane portion from the base surface to a height RH of each of the plurality of ridges from the base surface is 0.6 or more and 1.4 or less.
Preferably, an angle θp between a side wall of the plane portion and the base surface is 45° or more and 75° or less, in a cross-sectional view along a tire radial direction of a connection portion between each of the plurality of ridges and the plane portion.
Preferably, in a cross-sectional view along a tire radial direction of a connection portion between each of the plurality of ridges and the plane portion, in a portion where a contour line of a top surface of the plane portion and a contour line of a side wall of the plane portion intersect each other, the contour lines are connected by an arc that is single, and a ratio RP/PH of a radius of curvature RP of the arc to a height PH of the plane portion from the base surface is 0.5 or more and less than 1.0.
Preferably, an opening width La between the ridges that are adjacent is 0.15 mm or more and 0.35 mm or less, in a cross-sectional view along a direction orthogonal to an extension direction of the ridge.
Preferably, a ratio La/Lb of the opening width La to the length Lb is 0.3 or more and 0.6 or less.
Preferably, the base surface includes a flat portion having no unevenness, the flat portion is a straight line in a cross-sectional view along a direction orthogonal to an extension direction of the ridge, and a length of the straight line is 0.15 mm or more.
Preferably, a ratio RH/Lb, to the length Lb, of a height RH from the base surface to a maximum projection position of the ridge is 0.11 or more and 0.3 or less.
Preferably, in a tire meridian cross-section, a ratio LH/SH, to a tire cross-sectional height SH, of a length LH in a tire radial direction of a range in the tire radial direction of the serration region is 0.2 or more and 0.4 or less.
Preferably, in a tire meridian cross-section, when a height along a tire radial direction from a measurement point of a rim diameter of a rim on which the pneumatic tire is mounted to a position on inner side of the serration region in the tire radial direction is defined as AH, a ratio AH/SH of the height AH to a tire cross-sectional height SH is 0.3 or more and 0.5 or less.
Preferably, an angle θr between a flat portion of the base surface having no unevenness and a wall surface of the ridge is 60° or more and 85° or less.
Preferably, an angle θc in an extension direction of the ridge with respect to a tire radial direction is within a range of ±20° with respect to the tire radial direction.
Preferably, an arithmetic mean roughness Ra of rubber on a surface of the ridge is 0.1 μm or more and 5 μm or less.
Preferably, the pneumatic tire further includes a first protrusion portion extending in a tire circumferential direction at a position on an outer side of the serration region in a tire radial direction, and a second protrusion portion extending in the tire circumferential direction at a position on an inner side of the serration region in the tire radial direction.
Preferably, a protrusion height of the first protrusion portion and the second protrusion portion from a tire profile smoothly changes along the tire circumferential direction, and the protrusion height changes in a range of 40% or more and 100% or less with respect to a maximum value of the protrusion height.
Preferably, the protrusion height of the first protrusion portion and the second protrusion portion from the tire profile is 0.7 mm or less.
According to the pneumatic tire according to the present technology, both the visibility performance and the cleaning performance can be improved.
Embodiments of the present technology are described in detail below with reference to the drawings. In the embodiments described below, identical or substantially similar components to those of other embodiments have identical reference signs, and descriptions of those components are 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. Furthermore, the plurality of modified examples described in the embodiments can be combined as desired within the scope apparent to one skilled in the art.
In the following description, “tire width direction” refers to the direction parallel to the rotation axis (not illustrated) of a pneumatic tire 1. “Outer side in the tire width direction” refers to the side away from a tire equatorial plane (tire equator line) in the tire width direction. “Tire circumferential direction” refers to the circumferential direction with the rotation axis as the center axis. “Tire radial direction” refers to the direction orthogonal to the rotation axis. “Inner side in the tire radial direction” refers to the side toward the rotation axis in the tire radial direction. “Outer side in the tire radial direction” refers to the side away from the rotation axis in the tire radial direction. “Tire equatorial plane” is the plane orthogonal to the rotation axis that passes through the center of the tire width of the pneumatic tire 1. “Tire width” is the width in the tire width direction between components located on the outer side in the tire width direction, or in other words, the distance between the components that are the most distant from the tire equatorial plane in the tire width direction. Furthermore, “tire equator line” refers to the line in the circumferential direction of the pneumatic tire 1 that lies on the tire equatorial plane.
Shoulder portions 8 are located at both ends of the tread portion 2 in the tire width direction. Sidewall portions 30 are arranged on an inner side of the shoulder portion 8 in the tire radial direction. The sidewall portions 30 are arranged at two locations on both sides of the pneumatic tire 1 in the tire width direction. The surface of the sidewall portion 30 is formed as a tire side portion 31. The tire side portions 31 are located on both sides in the tire width direction. The two tire side portions 31 each face an opposite side of a side in the tire width direction where the tire equatorial plane CL is located.
In this case, the tire side portion 31 refers to a surface that uniformly continues in a range on the outer side in the tire width direction from a ground contact edge T of the tread portion 2 and on the outer side in the tire radial direction from a rim check line R. Further, the ground contact edge T refers to both outermost edges in the tire width direction of a region in which the tread surface 3 of the tread portion 2 of the pneumatic tire 1 contacts the road surface with the pneumatic tire 1 assembled on a regular rim, inflated to the regular internal pressure, and loaded with 70% of the regular load. The ground contact edge T is continuous in the tire circumferential direction. Moreover, the rim check line R refers to a line used to confirm whether the tire has been mounted on the rim correctly and, typically, on a front side surface of bead portions 10, the rim check line R is closer to the outer side in the tire radial direction than a rim flange (not illustrated) and is an annular convex line continuing in the tire circumferential direction along a portion approximate to the rim flange.
The non-ground contact region of the connection portion between the profile of the tread portion 2 and the profile of the sidewall portion 30 is called a buttress portion. A buttress portion 32 constitutes a side wall surface on an outer side of the shoulder portion 8 in the tire width direction.
Note that “regular rim” refers to an “applicable rim” defined by the Japan Automobile Tyre Manufacturers Association (JATMA), a “Design Rim” defined by The Tire and Rim Association, Inc. (TRA), or a “Measuring Rim” defined by The European Tyre and Rim Technical Organisation (ETRTO). Additionally, “regular internal pressure” refers to a “maximum air pressure” defined by JATMA, the maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. Additionally, “regular load” refers to a “maximum load capacity” defined by JATMA, a maximum value in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.
The bead portion 10 is located on an inner side of each of the sidewall portions 30 in the tire radial direction located on both sides in the tire width direction. The bead portions 10 are arranged at two locations on both sides of the tire equatorial plane CL, similarly to the sidewall portions 30. Each bead portion 10 is provided with a bead core 11, and a bead filler 12 is provided on an outer side in the tire radial direction of the bead core 11.
A plurality of belt layers 14 are provided on an inner side of the tread portion 2 in the tire radial direction. The belt layers 14 include a plurality of cross belts 141, 142 and a belt cover 143 and form a multilayer structure. Of these, the cross belts 141 and 142 are formed by performing a rolling process on a plurality of coating rubber-covered belt cords made of steel or an organic fiber material. The cross belts 141 and 142 have a belt angle of 20° or more and 55° or less in absolute value. Furthermore, the belt cords of the cross belts 141, 142 have different set inclination angles of the fiber direction of the belt cords with respect to the tire circumferential direction, and the belts are layered so that the fiber directions of the belt cords intersect each other, i.e., a crossply structure. The belt cover 143 is formed by performing a rolling process on coating rubber-covered steel or a plurality of cords made of an organic fiber material. The belt cover 143 has a belt angle of 0° or more and 10° or less in absolute value. The belt cover 143 is disposed in a layered manner an outer side of the cross belts 141, 142 in the tire radial direction.
A carcass 13 containing the cords of radial plies is continuously provided on an inner side in the tire radial direction of the belt layer 14 and on a side of the sidewall portion 30 close to the tire equatorial plane CL. The carcass 13 has a single layer structure made of one carcass ply or a multilayer structure made of a plurality of layered carcass plies. The carcass 13 spans the bead cores 11 disposed on both sides in the tire width direction in a toroidal shape, forming the backbone of the tire. Specifically, the carcass 13 is disposed to span from one bead portion 10 to the other bead portion 10 among the bead portions 10 located on both sides in the tire width direction and turns back toward the outer side in the tire width direction along the bead cores 11 at the bead portions 10 so as to wrap around the bead cores 11 and the bead fillers 12. The carcass ply of the carcass 13 is formed by performing a rolling process on a plurality of coating rubber-covered carcass cords made of steel or an organic fiber material, such as aramid, nylon, polyester, rayon, and the like. The carcass ply has a carcass angle of 80° or more and 95° or less in absolute value, the carcass angle being an inclination angle of the fiber direction of the carcass cords with respect to the tire circumferential direction.
At the bead portion 10, a rim cushion rubber 17 is disposed on the inner side in the tire radial direction and the outer side in the tire width direction of the bead core 11 and a turned back portion of the carcass 13, the rim cushion rubber 17 forming a contact surface of the bead portion 10 against the rim flange. Additionally, an innerliner 15 is formed along the carcass 13 on an inner side of the carcass 13 or on an inner portion side of the carcass 13 in the pneumatic tire 1.
In
Further, when a height along the tire radial direction from a measurement point of the rim diameter of the rim (not illustrated) on which the pneumatic tire 1 is mounted, to a position on an inner side of the serration region H in the tire radial direction is defined as AH, a ratio AH/SH of the height AH to the tire cross-sectional height SH is 0.3 or more and 0.5 or less.
The tire side portion 31 may be provided with a decorative portion for the purpose of improving the appearance of the pneumatic tire 1 and displaying various kinds of information. The decorative portion may include various kinds of information such as a brand name, a logo mark, or a product name for identifying the pneumatic tire 1 or for illustrating those to users.
In
The ten plane portions F1 to F5 and F1′ to F5′ illustrated in
Focusing on the boundaries between the plane portions F1, F2, F3, F4, and F5 and the serration region H, it can be considered that the plane portions F1, F2, F3, F4, and F5 are adjacent to the serration region H. By providing the plane portion surrounded by the serration region H, the visibility of the serration region is improved due to the contrast between the serration region H and the plane portion. In addition, the plane portions F1 to F5 may be surfaces having an identical height to the tire profile.
Here, attention is directed to the plane portion F3. Assuming that the entire circumference of the tire is 100%, a length L1 in the tire circumferential direction of a side F31 on an inner side of the plane portion F3 in the tire radial direction is preferably 1% or more and 99% or less of the tire circumferential length at the position of the side F31. A length L2 in the tire circumferential direction of a side F32 on an outer side of the plane portion F3 in the tire radial direction is preferably 1% or more and 99% or less of the tire circumferential length at the position of the side F32. A length LM in the tire circumferential direction at a position half a maximum length LF in the tire radial direction of the plane portion F3 is preferably 1% or more and 99% or less of the tire circumferential length at that position. The same applies to the other plane portions F1, F2, F4, and F5. The maximum length LF of each of the plane portions F1, F2, F3, F4, and F5 in the tire radial direction is preferably 50% or more and 90% or less of the length LH.
As illustrated in
A ratio PH/RH of a height PH from a base surface 50 of the plane portion F to a height RH from the base surface 50 of each of the plurality of ridges 51 is preferably 0.6 or more and 1.4 or less. The height PH of the plane portion F may be lower than the height RH of the ridge 51. By setting the height PH of the plane portion F to be lower than the height RH of the ridge 51 or not to greatly exceed the height RH even if it is higher than the height RH of the ridge 51, the cleaning property can be ensured without water being blocked at the plane portion. If the ratio PH/RH exceeds 1.4, water is blocked at the plane portion of the connection portion, and the cleaning performance cannot be improved, which is not preferable.
In
Further, the surface of the member forming the contour of each of the ridges 51a and 51b described above has a hydrophilic property. By providing the ridges 51a and 51b on the member having the hydrophilic property, the hydrophilic property can be enhanced.
An arithmetic mean roughness Ra of the rubber on the surfaces of the ridges 51a and 51b is preferably 0.1 μm or more and 5 μm or less. The hydrophilic property can be increased by optimizing the surface roughness. The hydrophilic property is increased by increasing the surface roughness. However, if the roughness is too large, it becomes difficult for water to enter the recess portion of the roughness, and the hydrophilic property deteriorates. The arithmetic mean roughness Ra is more preferably 0.2 μm or more and 4 μm or less. The arithmetic mean roughness Ra is measured according to JIS (Japanese Industrial Standard)-B0601.
Returning to
As illustrated in
Further, a length of one cycle of the plurality of ridges 51a and 51b along the base surface 50 is defined as Lb. That is, the length Lb is the length of one pitch of the plurality of ridges 51a and 51b. A ratio Lr/Lb of the length Lr to the length Lb is preferably 1.2 or more and 2.0 or less. By increasing the surface area of the ridge, the hydrophilic property of the serration region H can be improved, and the self-cleaning effect of the sidewall portion 30 when sludge is attached can be enhanced. If the ratio Lr/Lb exceeds 2.0 when the cross-sectional shape of the ridge is complex or fine, water will not enter the base surface 50 and the hydrophilic property is lowered, which is not preferable. If the ratio Lr/Lb is less than 1.2, the effect of improving the cleaning performance by the improvement in the hydrophilic property is small, which is not preferable. The ratio Lr/Lb is more preferably 1.3 or more and 1.5 or less.
The length Lb is preferably 0.5 mm or more and 0.7 mm or less. If the length Lb is less than 0.5 mm, it becomes difficult for water to enter the base surface 50 and the hydrophilic property is lowered, which is not preferable. If the length Lb exceeds 0.7 mm, the cleaning performance deteriorates, which is not preferable. If the length Lb is smaller than 0.5 mm, it becomes difficult for water to enter the base surface 50, and the hydrophilic property and the cleaning performance are deteriorated, which is not preferable.
Further, the length Lb is more preferably 0.52 mm or more, and further preferably 0.54 mm or more. When the length Lb is 0.52 mm or more, favorable results are obtained in terms of the visibility performance and the cleaning performance. Further, when the length Lb is 0.54 mm or more, more favorable results are obtained in terms of the visibility performance and the cleaning performance.
In
Here, the top surface U of the ridges 51a and 51b and the wall surface 53 of the ridges 51a and 51b may be connected by a curved line, and the boundary between the top surface U and the wall surface 53 may not be clear. In that case, the opening width La is measured on the basis of the intersection point between a line extended from a linear portion of the top surface U of the ridge 51 and a line extended from a linear portion of the wall surface 53 of the ridge 51.
Returning to
The height RH from the base surface 50 to the maximum projection position of the ridges 51a and 51b is preferably 0.08 mm or more and 0.15 mm or less. As described above, since the length Lb is preferably 0.5 mm or more and 0.7 mm or less, a ratio RH/Lb of the height RH to the length Lb is preferably 0.11 or more and 0.3 or less. When the value of the ratio RH/Lb is within this range, favorable results are obtained in terms of the visibility performance and the cleaning performance.
As illustrated in
Here, the base surface 50 and the wall surfaces 53 of the ridges 51a and 51b may be connected by a curved line, and the boundary between the base surface 50 and the wall surface 53 may not be clear. In that case, as illustrated in
Returning to
Here, the base surface 50 and the wall surfaces of the ridges 51a and 51b may be connected by a curved line, and the boundary between the base surface 50 and the wall surface 53 may not be clear. In that case, as illustrated in
By R-chamfering the corner between the top surface FU and the side wall FS of the plane portion F, it becomes difficult to block the spread of water, and the cleaning performance can be improved. If the ratio RP/PH is larger than 0.5, the length Lr of the connection portion cannot be sufficiently ensured, and the wettability of the connection portion deteriorates, which is not preferable. If the ratio RP/PH is less than 0.1, a sufficient blocking suppressing effect is not obtained, which is not preferable.
As illustrated in
In
As illustrated in
In
The angle θc is preferably an angle within a range of ±20° with respect to the direction toward the outer side in the tire radial direction. By extending the extension direction of the ridge 51 at an angle close to the tire radial direction, the water adhering to the tire surface can be easily wetted and spread in the tire radial direction, and the deposits on the tire surface can be easily washed away. The angle θc is more preferably an angle within the range of ±10° with respect to the tire radial direction.
The angle θc does not have to be the angle within the above range over the entire length from the end 51T1 to the end 51T2 of the ridge 51. That is, with respect to an imaginary line S51 connecting the ends 51T1 and the ends 51T2 of the ridge 51 by a straight line, the angle θc may be any angle within the above range in a length L80 of 80% at the central portion of a total length L51 excluding a length L10 of 10% at both end portions.
In a ridge 51′ illustrated in
Returning to
Further, it is preferable that the protrusion heights of the protrusion portion B1 and the protrusion portion B2 from the tire profile change smoothly along the tire circumferential direction. The protrusion heights of the protrusion portion B1 and the protrusion portion B2 from the tire profile may be the largest in the portion C1 and a portion C2 in
The protrusion heights of the protrusion portion B1 and the protrusion portion B2 from the tire profile preferably change in a range of 40% or more and 100% or less with respect to the maximum value. By periodically and smoothly changing the protrusion heights of the protrusion portion B1 and the protrusion portion B2 from the tire profile in the tire circumferential direction, air between the green tire and the mold can be efficiently discharged during vulcanization molding of the tire.
When the pneumatic tire 1 is mounted on a regular rim and inflated to the regular internal pressure, a protrusion height BH of the protrusion portion B1 and the protrusion portion B2 from the tire profile is 0.7 mm or less. By reducing the height of the protrusion portion extending in the tire circumferential direction, the water can smoothly flow out of the tire without blocking the water flow, and the cleaning performance is not reduced. It is more preferable that the protrusion heights of the protrusion portion B1 and the protrusion portion B2 from the tire profile are 0.2 mm or more and 0.5 mm or less.
In the examples, tests for the contact angle, the cleaning performance, and the visibility performance, which are indicators of the hydrophilic property, were conducted on a plurality of types of pneumatic tires of different conditions (see Tables 1 to 5). In these tests, pneumatic tires having the size of 245/45R20 103W (20×8J) were assembled on a specified rim and inflated to a specified air pressure.
As for the contact angle, the contact angle of the obtained serration region sample with respect to water was measured by a measuring instrument. The measuring instrument used for the measurement is DM-901 available from Kyowa Interface Science Co., Ltd. The measurement was performed in accordance with JIS R3257. 2 (μl) of pure water was dropped to form water droplets, and the contact angle of the water droplets 30 seconds after the dropping was measured by the θ/2 method.
As for the cleaning performance, after mounting the pneumatic tire 1 on a 3000 cc rear-wheel drive vehicle and driving 40 km on a general road and 100 km on a highway under rainy weather conditions, the tires, completely dry, were washed for 30 seconds using a high-pressure washer (a water pressure of 100 bar and a flow rate of 300 L/h). The amount of dirt adhering to the tire side surface after washing was evaluated by sensory evaluation by three evaluators. The perfect score of 10 points was assigned to the appearance with black luster before the start of the test run. The smaller the degree of gray or white and the closer to black luster, the higher the score. Conversely, the larger the degree of gray or white, the lower the score. The evaluation was based on the average value of the total scores of the three evaluators. The score was set in 0.5 point increments, and the higher scores close to 10 points indicate better cleaning performance.
As for the visibility performance, a brand indicator was provided in the serration region, and how noticeable the brand indicator was was visually evaluated. The results are expressed as index values and evaluated, with the pneumatic tire of Conventional Example being assigned as 100. Larger values indicate superior visibility performance of the brand indicator.
The pneumatic tires of Examples 1 to 42 illustrated in Tables 1 to 5 include those in which the length Lb of one cycle of the ridge is 0.5 mm or more and 0.7 mm or less and those not, those in which the serration region H includes a plane portion and those not, those in which the ratio Lr/Lb of length Lr to length Lb of 1.2 or more and 2.0 or less and those not, those in which the ratio PH/RH of the height PH of the plane portion to the ridge height RH is 0.6 or more and 1.4 or less and those not, those in which the angle θp between the side wall of the plane portion and the base surface is 45° or more and 75° or less and those not, those in which the ratio RP/PH of the radius of curvature RP of the arc to the height PH of the plane portion is 0.5 or more and less than 1.0 and those not, those in which the opening width La is 0.15 mm or more and 0.35 mm or less and those not, those in which the ratio La/Lb is 0.3 or more and 0.6 or less and those not, those in which the length of the straight line of the flat portion of the base surface is 0.15 mm or more and those not, those in which the ratio RH/Lb of 0.11 or more and 0.3 or less and those not, those in which the ratio LH/SH of 0.2 or more and 0.4 or less and those not, those in which the ratio AH/SH of 0.3 or more 0.5 or less and those not, those in which the angle θr is 60° or more and 85° or less and those not, those in which the angle θc is within the range of ±20° with respect to the tire radial direction and those not, those in which the arithmetic mean roughness Ra of the rubber on the surface of the ridge is 0.1 μm or more and 5 μm or less and those not, those in which the protrusion height of the first protrusion portion and the second protrusion portion from the tire profile changes in the range of 40% or more and 100% or less with respect to the maximum value of the protrusion height and those not, and those in which the protrusion height from the tire profile of the first protrusion portion B1 and the second protrusion portion B2 is 0.7 mm or less and those not.
In the tire of Conventional Example in Table 1, the length Lb is 0.5 mm, no plane portion is provided in the serration region H, the ratio Lr/Lb is 1.2, the ratio PH/RH is 1.8, the angle θp is 90°, the opening width La is 0.12 mm, the ratio La/Lb is 0.24, the length of the straight line of the flat portion of the base surface is 0.03 mm, the ratio RH/Lb is 0.80, the ratio LH/SH is 0.16, the ratio AH/SH is 0.55, the angle θr is 50°, the angle θc is 45°, the arithmetic mean roughness Ra of rubber on the surface of the ridge is 10 μm, and the protrusion height of the first protrusion portion B1 and the second protrusion portion B2 from the tire profile is 0.8 mm.
In the tire of Comparative Example 1 in Table 1, the length Lb is 0.6 mm, the serration region H does not include a plane portion, the ratio PH/RH is 1.8, the angle θp is 90°, the opening width La is 0.12 mm, the ratio La/Lb is 0.20, the length of the straight line of the flat portion of the surface of the base surface is 0.03 mm, the ratio RH/Lb is 0.25, the ratio LH/SH is 0.16, the ratio AH/SH is 0.55, the angle θr is 50°, the angle θc is 45°, the arithmetic mean roughness Ra of the rubber on the surface of the ridge is 10 μm, and the protrusion height of the first protrusion portion B1 and the second protrusion portion B2 from the tire profile is 0.8 mm.
Referring to Tables 1 to 5, it can be seen that favorable results are obtained when the length Lb is 0.5 mm or more and 0.7 mm or less and the serration region H includes a plane portion, when the ratio Lr/Lb of the length Lr to the length Lb is 1.2 or more and 2.0 or less, when the ratio PH/RH is 0.6 or more and 1.4 or less, when the angle θp is 45° or more and 75° or less and those not, when the ratio RP/PH is 0.5 or more and less than 1.0, when the opening width La is 0.15 mm or more and 0.35 mm or less, when the ratio La/Lb is 0.3 or more and 0.6 or less, when the length of the straight line of the flat portion of the base surface is 0.15 mm or more, when the ratio RH/Lb is 0.11 or more and 0.3 or less, when the ratio LH/SH is 0.2 or more and 0.4 or less, when the ratio AH/SH is 0.3 or more and 0.5 or less, when the angle θr is 60° or more and 85° or less, when the angle θc is within the range of ±20° with respect to the tire radial direction, when the arithmetic mean roughness Ra of the rubber on the surface of the ridge is 0.1 μm or more and 5 μm or less, when the protrusion height of the first protrusion portion and the second protrusion portion from the tire profile changes in the range of 40% or more and 100% or less with respect to the maximum value of the protrusion height, and when the protrusion height of the first protrusion portion B1 and the second protrusion portion B2 from the tire profile is 0.7 mm or less.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-144028 | Aug 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/027531 | 7/15/2020 | WO |
