JP2020093723A - Pneumatic tire for motorcycle - Google Patents

Abstract

To provide a pneumatic tire for motorcycle capable of achieving wet performance and wear resistance.SOLUTION: On a pneumatic tire for a motorcycle, four or more zigzag-shaped peripheral grooves 10, and a plurality of lateral grooves 20 extending from the peripheral groove 12 to a center side are formed. The lateral grooves 20 comprise first lateral grooves 21 whose bottom is raised and second lateral grooves 22 whose bottom is not raised, these first lateral grooves 21 and second lateral grooves 22 are alternately arranged along a tire peripheral direction, groove depths of the peripheral groove 10 and lateral groove 20 are relatively shallow on a shoulder side, a cycle A of the peripheral groove 11 provided closest to the center side of a tread 1 satisfies a relationship of 0.2≤A/TDW≤0.4 to a development width TDW of the tread 1, a center land part 31 is partitioned between the pair of peripheral grooves 11, a minimum width B of the center land part 31 satisfies a relationship of 0.05≤B/TDW≤0.25 to a development width TDW of the tread, and a groove area ratio Xa of a region a provided on the center side of the tread 1 is 25%-33%.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire used in a two-wheeled vehicle, and more particularly to a pneumatic tire for a two-wheeled vehicle that enables both wet performance and wear resistance to be achieved.

Pneumatic tires for two-wheeled vehicles are designed to have a smaller radius of curvature in the tread portion than pneumatic tires for four-wheeled vehicles because they turn by the force of camber thrust (see, for example, Patent Document 1). ). In a pneumatic tire for a two-wheeled vehicle having such a structure, various proposals have been made regarding the arrangement of the grooves formed in the tread portion in order to ensure wet performance (for example, see Patent Documents 2 to 4). ..

By the way, a general front tire for a two-wheeled motor vehicle has a higher wet performance than a rear tire. Here, regarding the front tire, if the groove area ratio of the tread portion is increased in order to ensure wet performance, there is a problem that the wear life becomes short. One possible solution to such a problem is to use a tread compound having excellent wear resistance, but when using a tread compound having excellent wear resistance, there is a drawback that wet performance is deteriorated. Therefore, it is required to improve wear resistance without relying on the tread compound.

Japanese Patent Laid-Open No. 61-27707 JP, 2016-141225, A JP, 2016-175598, A JP, 2018-39333, A

An object of the present invention is to provide a pneumatic tire for a two-wheeled vehicle that enables both wet performance and wear resistance to be achieved at the same time.

The pneumatic tire for a two-wheeled motor vehicle according to the present invention for achieving the above-mentioned object is provided with four or more circumferential grooves extending in the tire circumferential direction while being bent in a zigzag shape in the tread portion, and the groove width of the circumferential groove. Are relatively narrower on the center side than on the shoulder side of the tread portion, and a plurality of lateral grooves extending from the circumferential groove located on the most shoulder side of the tread portion toward the center side are formed. Includes a first lateral groove which is raised and a second lateral groove which is not raised, and the first lateral groove and the second lateral groove are alternately arranged along the tire circumferential direction, and the groove depth of the circumferential groove and the lateral groove. The groove depth is relatively shallower on the shoulder side than on the center side of the tread portion, and the zigzag-shaped cycle A of the circumferential groove located closest to the center of the tread portion is the developed width of the tread portion. A center land portion that satisfies the relationship of 0.2≦A/TDW≦0.4 with respect to TDW and that extends in the tire circumferential direction between a pair of circumferential grooves located closest to the center of the tread portion. And the minimum width B in the tire width direction of the center land portion satisfies the relationship of 0.05≦B/TDW≦0.25 with respect to the development width TDW of the tread portion, and the center position of the tread portion is When the area from the to the shoulder edge is divided into four equal parts in the tire width direction along the tread surface and four areas a, b, c, d are defined in order from the center side of the tread portion, at least the groove area of the area a The ratio Xa is 25% to 33%.

In a pneumatic tire for a two-wheeled vehicle, the center portion of the tread portion tends to wear preferentially. On the other hand, in the present invention, four or more circumferential grooves that extend in the tire circumferential direction while being bent in a zigzag shape are formed in the tread portion, and the groove width of the circumferential groove is more centered than the shoulder side of the tread portion. Side grooves are relatively narrow, and a plurality of lateral grooves extending from the circumferential groove located on the most shoulder side of the tread portion toward the center side are formed. The lateral grooves are raised to the first raised lateral groove. The second lateral groove is not included, and the first lateral groove and the second lateral groove are alternately arranged along the tire circumferential direction, and the groove depth of the circumferential groove and the groove depth of the lateral groove are shoulders more than those on the center side of the tread portion. Is relatively shallow on the side, and the zigzag-shaped period A of the circumferential groove located closest to the center of the tread portion is 0.2≦A/TDW≦0.4 with respect to the spread width TDW of the tread portion. Satisfies the relationship, the minimum width B in the tire width direction of the center land portion satisfies the relationship of 0.05≦B/TDW≦0.25 with respect to the development width TDW of the tread portion, and is located on the center side of the tread portion. By adopting the tread pattern in which the groove area ratio Xa of the region a to be formed is 25% to 33%, both wet performance and wear resistance can be compatible. Also, in pneumatic tires for two-wheeled vehicles, a large amount of force is applied to the shoulder portion of the tread portion due to the camber thrust when turning, but the groove depth of the circumferential groove and the groove depth of the lateral groove are respectively larger than those on the center side of the tread portion. By making it relatively shallow on the side, the effect of improving wear resistance can be secured, at the same time, the rigidity of the shoulder portion of the tread portion can be sufficiently secured, and a sufficient camber thrust at the time of turning can be obtained.

In the present invention, the groove width Wi of the circumferential groove closest to the center of the tread portion and the groove width Wo of the circumferential groove closest to the shoulder of the tread portion are 0.5×Wo≦Wi≦0.8×. The groove depth Gi of the circumferential groove located closest to the center of the tread portion and the groove depth Go of the circumferential groove located closest to the shoulder of the tread portion are 0.6×Gi≦Go ≦0.9×Gi is satisfied, and the groove depth Gi of the circumferential groove located closest to the center of the tread portion and the maximum groove depth Gm of the first lateral groove are 0.3×Gi≦Gm≦0. It is preferable to satisfy the relationship of 6×Gi. By narrowing the groove width Wi of the circumferential groove on the center side and widening the groove width Wo of the circumferential groove on the shoulder side, it is possible to effectively improve wear resistance while maintaining good wet performance. .. Further, by increasing the groove depth Gi of the circumferential groove on the center side and shallowing the groove depth Go of the circumferential groove on the shoulder side, it is possible to sufficiently secure the rigidity of the shoulder portion of the tread portion while at the same time, to improve wear resistance. The sex can be effectively improved. Further, by optimizing the maximum groove depth Gm of the raised first lateral groove with respect to the groove depth Gi of the circumferential groove located closest to the center of the tread portion, wet performance and wear resistance are further improved. It can be compatible in both dimensions.

The inclination angle α of the circumferential groove located closest to the center of the tread portion with respect to the tire circumferential direction is in the range of 10°≦α≦25°, and at the communication position with the circumferential groove located closest to the shoulder of the tread portion. The inclination angle β of the second lateral groove with respect to the tire circumferential direction is in the range of 40°≦β≦70°, and the inclination of the first lateral groove with respect to the tire circumferential direction at the communication position with the circumferential groove located closest to the shoulder of the tread portion. The angle γ is preferably in the range of 40°≦γ≦70°. By setting the inclination angles α, β, γ in the above range, the wear resistance can be improved without lowering the wet performance.

The amplitude Vi of the circumferential groove located closest to the center of the tread portion satisfies the relationship 0.03≦Vi/TDW≦0.20 with respect to the development width TDW of the tread portion, and is located on the most shoulder side of the tread portion. The amplitude Vo of the circumferential groove to be formed preferably satisfies the relationship of 0.10≦Vo/TDW≦0.30 with respect to the development width TDW of the tread portion. By setting the amplitudes Vi and Vo of the circumferential groove within the above ranges, the wear resistance can be improved without lowering the wet performance.

It is preferable that the JIS hardness of the tread rubber layer arranged in the tread portion is 58 to 63, and the tan δ at 0° C. of the tread rubber layer is 0.4 to 0.6. By using the tread compound having such physical properties, the wear resistance can be improved without lowering the wet performance.

The height SLH of the shoulder edge of the tread portion satisfies the relationship of 0.55≦SLH/SH≦0.80 with respect to the tire section height SH, and the radius of curvature R of the center portion of the tread portion is the width TRW of the tread portion. It is preferable to satisfy the relationship of 0.45≦R/TRW≦0.65. As a result, it is possible to prevent early wear of the center side portion or the shoulder side portion of the tread portion.

When the area from the center position of the tread portion to the shoulder edge is divided into four equal parts in the tire width direction along the tread surface, and four areas a, b, c, d are defined in order from the center side of the tread portion, In addition to the groove area ratio Xa being 25% to 33%, the groove area ratio Xb of the region b is 20% to 28%, the groove area ratio Xc of the region c is 26% to 34%, and The groove area ratio Xd of d is preferably 13% to 26%. As a result, it is possible to optimize the groove area ratio in the entire area of the tread portion and to exhibit good wet performance. In particular, a front tire for a two-wheeled vehicle is required to have good wet performance during straight running and turning, so it is desirable to secure a sufficient groove area ratio over the entire area of the tread portion.

It is preferable that the center land portion does not include a groove component. By providing the center land portion that does not include the groove component and continuously extends in the tire circumferential direction, wear resistance can be maximized.

The present invention is preferably applied to a pneumatic tire for a two-wheeled vehicle having a bias structure. A pneumatic tire for a two-wheeled vehicle having a bias structure tends to have a high ground contact pressure in the center region of the tread portion, and therefore exhibits a remarkable effect on wear resistance.

In the present invention, various dimensions including the developed width TDW of the tread portion, the shoulder edge height SLH of the tread portion, the tire section height SH, the radius of curvature R of the center portion of the tread portion, and the width TRW of the tread portion are Is measured with the rim assembled to the rim and filled with the normal internal pressure. The “regular rim” is a rim that is defined for each tire in a standard system including a standard on which the tire is based. For example, JATMA is a standard rim, and TRA is “Design Rim” or ETRTO. In that case, "Measuring Rim" is set. "Regular internal pressure" is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. For JATMA, the maximum air pressure, and for TRA, the table "TIRE ROAD LIMITS AT VARIOUS". The maximum value described in "COLD INFORMATION PRESSSURES" is "INFLATION PRESSURE" for ETRTO.

It is a meridian half cross section which shows the pneumatic tire for two-wheeled vehicles which consists of embodiment of this invention. FIG. 2 is a development view showing a tread pattern of the pneumatic tire for motorcycles of FIG. 1. It is sectional drawing which shows the circumferential groove formed in the tread part of the pneumatic tire for two-wheeled vehicles of FIG. It is sectional drawing which shows the lateral groove formed in the tread part of the pneumatic tire for two-wheeled vehicles of FIG.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire for a two-wheeled vehicle (hereinafter, also referred to as a pneumatic tire) according to an embodiment of the present invention, FIG. 2 shows its tread pattern, and FIG. 3 shows a circumferential direction formed in the tread portion. The groove is shown, and FIG. 4 shows the lateral groove formed in the tread portion.

As shown in FIG. 1, the pneumatic tire of the present embodiment has a tread portion 1 extending in the tire circumferential direction and forming an annular shape, and a pair of sidewall portions 2 and 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3, 3 arranged inside the sidewall portions 2 in the tire radial direction.

Two carcass layers 4 are mounted between the pair of bead portions 3 and 3. These carcass layers 4 include a plurality of reinforcing cords extending while being inclined with respect to the tire radial direction, and the reinforcing cords are arranged so as to intersect each other between the layers. That is, this pneumatic tire has a bias structure. In the carcass layer 4, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of 25° to 40°, for example. As the reinforcing cord of the carcass layer 4, an organic fiber cord such as nylon or polyester is preferably used. The carcass layer 4 is locked to a bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

The tire internal structure described above shows a typical example of a pneumatic tire, but the present invention is not limited to this.

As shown in FIG. 2, the tread portion 1 is formed with four or more circumferential grooves 10 extending in the tire circumferential direction while bending in a zigzag shape. The groove width of the circumferential groove 10 is relatively narrower on the center side than on the shoulder side of the tread portion 1. The circumferential groove 10 includes a circumferential groove 11 located closest to the center of the tread portion 1 and a circumferential groove 12 located closest to the shoulder of the tread portion 1. Further, the tread portion 1 is formed with a plurality of lateral grooves 20 extending from the circumferential groove 12 located on the most shoulder side of the tread portion 1 toward the center side. The lateral groove 20 includes a lateral groove 21 (first lateral groove) whose bottom is raised and a lateral groove 22 (second lateral groove) which is not raised, and these lateral grooves 21 and 22 are arranged alternately along the tire circumferential direction. The groove depth of the circumferential groove 10 and the groove depth of the lateral groove 20 are relatively shallower on the shoulder side than on the center side of the tread portion 1. The groove depth may be changed stepwise, or may be gradually changed from the center position CL toward the shoulder edge E.

One end of the lateral groove 22 communicates with the circumferential groove 12 on the shoulder side and the other end communicates with the circumferential groove 11 on the center side, while the lateral groove 21 has one end on the shoulder side. To the circumferential groove 12, and the other end communicates with the lateral groove 22. Each of the lateral grooves 21 and 22 has a bent structure, and is inclined toward the tire rotation direction T side with respect to the tire width direction from the shoulder side of the tread portion 1 toward the center side. Similarly to the lateral groove 22, the lateral groove 21 may have the other end communicating with the circumferential groove 11 on the center side.

As a result, the center land portion 31 that continuously extends in the tire circumferential direction is defined between the pair of circumferential grooves 11 that are located closest to the center of the tread portion 1, and the most center portion of the tread portion 1 is defined. A plurality of intermediate blocks 32 are defined between the circumferential groove 11 located on the side and the circumferential groove 12 located on the most shoulder side of the tread portion 1, and the circumferential groove located on the most shoulder side of the tread portion 1 is divided. A shoulder land portion 33 continuously extending in the tire circumferential direction is defined on the outer side of 12. The center land portion 31 preferably extends continuously in the tire circumferential direction without containing a groove component from the viewpoint of wear resistance, but if necessary, a groove extending in the tire circumferential direction or the tire width direction may be provided. It may be formed.

In the pneumatic tire, the zigzag cycle A of the circumferential groove 11 located closest to the center of the tread portion 1 has a relationship of 0.2≦A/TDW≦0.4 with respect to the spread width TDW of the tread portion 1. And the minimum width B in the tire width direction of the center land portion 31 partitioned between the pair of circumferential grooves 11, 11 located closest to the center of the tread portion 1 is the deployment width TDW of the tread portion 1. On the other hand, the relationship of 0.05≦B/TDW≦0.25 is satisfied, and more preferably, the relationship of 0.08≦B/TDW≦0.20 is satisfied. The developed width TDW of the tread portion 1 is the width of the tread portion 1 measured along the tread surface of the tread portion 1. By adopting such a tread pattern, it is possible to achieve both wet performance and wear resistance. Further, in the pneumatic tire for a two-wheeled vehicle, a large force is applied to the shoulder portion of the tread portion 1 due to the camber thrust during turning, but the groove depth of the circumferential groove 10 and the groove depth of the lateral groove 20 are set to the center of the tread portion 1, respectively. By making it relatively shallower on the shoulder side than on the side, it is possible to ensure the effect of improving wear resistance and at the same time sufficiently secure the rigidity of the shoulder portion of the tread portion 1 to obtain sufficient camber thrust during turning. it can.

Here, with respect to the zigzag-shaped period A of the circumferential groove 11 located closest to the center of the tread portion 1, if the ratio A/TDW is smaller than 0.2, the drainage performance in the tire circumferential direction deteriorates and the wet Performance deteriorates, and conversely, when it is larger than 0.4, drainage performance in the tire width direction deteriorates, and wet performance deteriorates. Further, regarding the minimum width B in the tire width direction of the center land portion 31, if the ratio B/TDW is smaller than 0.05, the effect of improving the wear resistance decreases in the center region where the ground contact pressure is high, and conversely 0.25. If it is larger than this, the groove area ratio in the ground contact area is reduced, and the drainage performance is reduced. The circumferential groove 12 located on the most shoulder side of the tread portion 1 has an arbitrary cycle, but is preferably the same as the cycle A.

Further, in the above pneumatic tire, the lateral groove 20 includes a lateral groove 21 which is raised and a lateral groove 22 which is not raised, and these lateral grooves 21 and 22 are alternately arranged along the tire circumferential direction. The construction contributes to improving wear resistance while maintaining good wet performance.

In the pneumatic tire, the region from the center position CL of the tread portion 1 to the shoulder edge E is divided into four equal parts in the tire width direction along the tread surface, and four regions a, b, c are sequentially arranged from the center side of the tread portion 1. , D, it is necessary that at least the groove area ratio Xa of the region a is 25% to 33%. Further, the groove area ratio Xb of the region b is 20% to 28%, the groove area ratio Xc of the region c is 26% to 34%, and the groove area ratio Xd of the region d is 13% to 26%. Is preferred. The groove area ratios Xa to Xd are ratios of the groove areas to the areas of the regions a to d, and can be calculated, for example, from the range of one cycle A of the circumferential groove 10 having a zigzag shape.

By setting the groove area ratio Xa of the region a located on the center side of the tread portion 1 in the above range, good wet performance can be exhibited without impairing wear resistance. Furthermore, by setting the groove area ratio Xb of the region b, the groove area ratio Xc of the region c, and the groove area ratio Xd of the region d within the above ranges, good wet performance can be exhibited without impairing wear resistance. it can.

Here, when each of the groove area ratio Xa of the region a, the groove area ratio Xb of the region b, and the groove area ratio Xc of the region c is smaller than the lower limit value, the effect of improving the wet performance is deteriorated, and conversely, it is higher than the upper limit value. If it is too large, the effect of improving wear resistance decreases. On the other hand, if the groove area ratio Xd of the region d is too small, the effect of improving the wet performance is deteriorated, while if it is too large, the rigidity of the shoulder portion of the tread portion 1 is insufficient and sufficient camber thrust at the time of turning can be obtained. become unable.

In the pneumatic tire, as shown in FIG. 3, the groove width Wi of the circumferential groove 11 located closest to the center of the tread portion 1 and the groove width Wo of the circumferential groove 12 located closest to the shoulder of the tread portion 1. Satisfies the relation of 0.5×Wo≦Wi≦0.8×Wo, and the groove depth Gi of the circumferential groove 11 located on the most center side of the tread portion 1 and the most shoulder side of the tread portion 1 are provided. The groove depth Go of the circumferential groove 12 may satisfy the relationship of 0.6×Gi≦Go≦0.9×Gi. As described above, the wear resistance can be improved by narrowing the groove width Wi of the circumferential groove 11 on the center side located in the center region where wear is fast and increasing the rubber volume in the center region. On the other hand, by widening the groove width Wo of the circumferential groove 12 on the shoulder side, good wet performance can be maintained. In addition, the wear resistance can be improved by increasing the groove depth Gi of the circumferential groove 11 on the center side located in the center region where wear is fast and increasing the rubber volume in the center region. On the other hand, by making the groove depth Go of the shoulder side circumferential groove 12 shallow, it is possible to sufficiently secure the rigidity of the shoulder portion of the tread portion 1.

Here, if the ratio Wi/Wo between the groove width Wi of the circumferential groove 11 on the center side and the groove width Wo of the circumferential groove 12 on the shoulder side is smaller than 0.5, the wet performance deteriorates, and conversely 0. When it is larger than 8, the effect of improving the wear resistance decreases. Further, if the ratio Go/Gi between the groove depth Gi of the center side circumferential groove 11 and the groove depth Go of the shoulder side circumferential groove 12 is smaller than 0.6, the wet performance during turning deteriorates, On the other hand, when it is larger than 0.9, the wet performance at the time of straight traveling is deteriorated.

In the pneumatic tire, as shown in FIG. 4, the maximum groove depth Gm of the raised lateral groove 21 (first lateral groove) is larger than the maximum groove depth Gn of the lateral groove 22 (second lateral groove) not raised. It is getting shallower. It is preferable that the groove depth Gi of the circumferential groove 11 located closest to the center of the tread portion 1 and the maximum groove depth Gm of the lateral groove 21 satisfy the relationship of 0.3×Gi≦Gm≦0.6×Gi. By optimizing the maximum groove depth Gm of the raised lateral groove 21 with respect to the groove depth Gi of the circumferential groove 11 located closest to the center of the tread portion 1, wet performance and wear resistance can be improved. Can be compatible with. Here, if the ratio Gm/Gi between the groove depth Gi of the circumferential groove 11 located closest to the center of the tread portion 1 and the maximum groove depth Gm of the lateral groove 21 is smaller than 0.3, the wet performance deteriorates. On the other hand, if it is larger than 0.6, the effect of improving the wear resistance decreases.

In the pneumatic tire, as shown in FIG. 2, the inclination angle α of the circumferential groove 11 located closest to the center of the tread portion 1 with respect to the tire circumferential direction is in the range of 10°≦α≦25°. The inclination angle β of the lateral groove 22 with respect to the tire circumferential direction at the position of communication with the circumferential groove 12 located on the most shoulder side of 1 is in the range of 40°≦β≦70°, and is located on the most shoulder side of the tread portion 1. The inclination angle γ of the lateral groove 21 with respect to the tire circumferential direction at the position communicating with the circumferential groove 12 is preferably in the range of 40°≦γ≦70°. By setting the inclination angles α, β, γ in the above range, the wear resistance can be improved without lowering the wet performance.

Here, when the inclination angle α of the circumferential groove 11 on the center side is smaller than 10°, the drainage property in the tire width direction is deteriorated and wet performance is deteriorated. The wet performance is deteriorated due to deterioration of the drainage property of. When the inclination angle β of the lateral groove 22 at the position communicating with the circumferential groove 12 on the shoulder side is smaller than 40°, the drainage performance in the tire width direction is deteriorated and the wet performance is deteriorated. If it is too large, the drainage performance in the tire circumferential direction deteriorates and the wet performance deteriorates. Further, if the inclination angle γ of the lateral groove 21 at the position communicating with the circumferential groove 12 on the shoulder side is smaller than 40°, the drainage performance in the tire width direction is deteriorated and the wet performance is deteriorated. If it is too large, the drainage performance in the tire circumferential direction deteriorates and the wet performance deteriorates.

In the pneumatic tire, as shown in FIG. 2, the amplitude Vi of the circumferential groove 11 located closest to the center of the tread portion 1 is 0.03≦Vi/TDW≦0 with respect to the development width TDW of the tread portion 1. .20, and the amplitude Vo of the circumferential groove 12 located on the most shoulder side of the tread portion 1 has a relationship of 0.10≦Vo/TDW≦0.30 with respect to the development width TDW of the tread portion 1. Good to be satisfied. In particular, the amplitude Vo of the circumferential groove 12 located closest to the shoulder of the tread portion 1 is preferably larger than the amplitude Vi of the circumferential groove 11 located closest to the center of the tread portion 1. By setting the amplitudes Vi and Vo of the circumferential grooves 11 and 12 within the above ranges, the wear resistance can be improved without lowering the wet performance.

Here, with respect to the amplitude Vi of the circumferential groove 11 located closest to the center of the tread portion 1, if the ratio Vi/TDW is smaller than 0.03, the drainage performance in the tire width direction deteriorates, and the wet performance deteriorates. On the other hand, if it is larger than 0.20, the drainage performance in the tire circumferential direction is deteriorated and the wet performance is deteriorated. Further, regarding the amplitude Vo of the circumferential groove 12 located on the most shoulder side of the tread portion 1, if the ratio Vo/TDW is smaller than 0.10, the drainage performance in the tire width direction deteriorates, and the wet performance deteriorates. On the other hand, when it is larger than 0.30, the drainage property in the tire circumferential direction is deteriorated, and the wet performance is deteriorated.

In the pneumatic tire, the tread rubber layer 1A arranged in the tread portion 1 has a JIS hardness of 58 to 63, and the tread rubber layer 1A preferably has a tan δ at 0° C. of 0.4 to 0.6. By using the tread compound having such physical properties, both abrasion resistance and wet performance can be achieved. The JIS hardness is a durometer hardness measured according to JIS-K6253 using an A type durometer at a temperature of 23°C. Loss tangent (tan δ) is measured in accordance with JIS-K6394 using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho) at a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 0°C. Is done.

Here, when the JIS hardness of the tread rubber layer 1A is lower than 58, the wet performance tends to be improved, but the effect of improving the wear resistance is lowered, and conversely, when it is higher than 63, the wear resistance is excellent, Since tan δ tends to be low, wet performance is deteriorated. Further, if the tan δ at 0° C. of the tread rubber layer 1A is smaller than 0.4, the wet performance is deteriorated, and conversely if it is larger than 0.6, the effect of improving the wear resistance is deteriorated.

In the pneumatic tire, the height SLH of the shoulder edge E of the tread portion 1 satisfies the relationship of 0.55≦SLH/SH≦0.80 with respect to the tire cross-section height SH, and the height SLH of the center portion of the tread portion 1 is The radius of curvature R preferably satisfies the relationship of 0.45≦R/TRW≦0.65 with respect to the width TRW of the tread portion 1. The width TRW of the tread portion 1 is the width of the tread portion 1 measured parallel to the tire axial direction. As a result, it is possible to prevent early wear of the center side portion or the shoulder side portion of the tread portion 1.

Here, if the ratio SLH/SH is smaller than 0.55, the ground contact pressure at the center side portion of the tread portion 1 becomes high and premature wear tends to occur at that portion, and conversely if it is larger than 0.80. Early wear is likely to occur at the shoulder side portion of the tread portion 1. Further, if the ratio R/TRW is smaller than 0.45, the ground contact pressure at the center side portion of the tread portion 1 becomes high and premature wear is apt to occur at that portion. Premature wear is likely to occur at the shoulder side portion of the portion 1.

In a two-wheeled vehicle pneumatic tire having a tire size of 70/100-14, four circumferential grooves extending in the tire circumferential direction while being bent in a zigzag shape are formed in a tread portion, and the groove width of the circumferential groove is A plurality of lateral grooves extending toward the center side from the circumferential groove located on the most shoulder side of the tread portion are formed relatively narrower on the center side than on the shoulder side of the tread portion, and the lateral grooves are raised. The first lateral groove and the second lateral groove which is not raised, the first lateral groove and the second lateral groove are alternately arranged along the tire circumferential direction, and the groove depth of the circumferential groove and the groove depth of the lateral groove are respectively Tires of Examples 1 to 14 in which the tread portion is relatively shallower on the shoulder side than on the center side were manufactured.

In Examples 1 to 14, the ratio A/TDW between the zigzag-shaped period A of the circumferential groove located closest to the center of the tread portion and the spread width TDW of the tread portion, the pair of pairs located closest to the center of the tread portion. The ratio B/TDW of the minimum width B in the tire width direction of the center land portion divided between the circumferential grooves and the developed width TDW of the tread portion, and the area from the center position of the tread portion to the shoulder edge along the tread surface. The groove area ratios Xa to Xd of the four regions a to d defined by dividing the tire width direction into four equal parts, the groove width Wi of the circumferential groove located closest to the center of the tread portion, and the most shoulder of the tread portion. Ratio Wi/Wo to the groove width Wo of the circumferential groove located on the side, the groove depth Gi of the circumferential groove located on the most center side of the tread portion and the groove of the circumferential groove located on the most shoulder side of the tread portion. Ratio Go/Gi with depth Go, ratio Gm/Gi of maximum groove depth Gm of the raised first lateral groove and groove depth Gi of the circumferential groove located closest to the center of the tread portion, Gm/Gi, The inclination angle α of the circumferential groove located closest to the center with respect to the tire circumferential direction, the inclination angle β of the second lateral groove with respect to the tire circumferential direction at the communicating position with the circumferential groove located closest to the shoulder of the tread portion, and the tread portion The inclination angle γ of the first lateral groove with respect to the tire circumferential direction at the position communicating with the circumferential groove located closest to the shoulder, the amplitude Vi of the circumferential groove located closest to the center of the tread portion, and the expansion width TDW of the tread portion. The ratio Vi/TDW, the ratio Vo/TDW between the amplitude Vo of the circumferential groove located on the most shoulder side of the tread portion and the spread width TDW of the tread portion, the JIS hardness of the tread rubber layer and tan δ at 0° C., the tread portion of the tread portion. The ratio SLH/SH between the shoulder edge height SLH and the tire cross-section height SH, the ratio R/TRW between the radius of curvature R of the center of the tread portion and the width TRW of the tread portion, and the carcass structure (radial or bias) Was set as in Table 1 and Table 2. Further, the tires of Comparative Examples 1 to 9 were produced in which a part of the configuration was different from that of Example 1.

With respect to these test tires, the abrasion resistance and the wet performance were evaluated by the following evaluation methods, and the results are also shown in Tables 1 and 2.

Abrasion resistance:
Each test tire was assembled on a rim and mounted on a two-wheeled vehicle, and a real vehicle running test was performed under the conditions of air pressure of 280 kPa, load of 148 kg (80% of specified load), speed of 80 km/h, and running distance of 10,000 km, and then the tread portion. The amount of wear was measured. The evaluation results are shown as index values with Comparative Example 1 being 100, using the reciprocal of the measured value. The larger the index value, the better the abrasion resistance.

Wet performance:
Each test tire was assembled into a rim and mounted on a two-wheeled vehicle, and an actual vehicle running test was performed on a wet road surface by a test driver under the conditions of air pressure of 280 kPa and load of 148 kg (80% of specified load), and sensory evaluation was performed on wet performance. It was The evaluation results are shown as index values with Comparative Example 1 being 100. The larger the index value, the better the wet performance.

As is clear from Table 1 and Table 2, in all the tires of Examples 1 to 14, it was possible to improve wear resistance without impairing wet performance. On the other hand, Comparative Examples 1 to 9 were inferior to Examples 1 to 14 in the evaluation results of wet performance and wear resistance.

1 tread part 1A tread rubber layer 2 side wall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 10, 11, 12 circumferential groove 20, 21, 22 lateral groove 31 center land part 32 middle block 33 shoulder land part

Claims (9)

Four or more circumferential grooves extending in the tire circumferential direction are formed in the tread portion while bending in a zigzag shape, and the groove width of the circumferential groove is relatively narrower on the center side than on the shoulder side of the tread portion. A plurality of lateral grooves extending from the circumferential groove located on the most shoulder side of the tread portion toward the center side is formed, and the lateral groove includes a first lateral groove that is raised and a second lateral groove that is not raised, The first lateral grooves and the second lateral grooves are arranged alternately along the tire circumferential direction, and the groove depth of the circumferential groove and the groove depth of the lateral groove are relatively closer to the shoulder side than the center side of the tread portion. The cycle A of the zigzag shape of the circumferential groove located closest to the center of the tread portion has a relationship of 0.2≦A/TDW≦0.4 with respect to the spread width TDW of the tread portion. Satisfied, the center land portion extending in the tire circumferential direction is defined between the pair of circumferential grooves located closest to the center of the tread portion, and the minimum width B in the tire width direction of the center land portion is the above. Satisfies the relationship of 0.05≦B/TDW≦0.25 with respect to the development width TDW of the tread portion, and divides the area from the center position of the tread portion to the shoulder edge into four equal parts in the tire width direction along the tread surface. However, when four areas a, b, c, d are defined in order from the center side of the tread portion, the groove area ratio Xa of at least the area a is 25% to 33%. Pneumatic tires. The groove width Wi of the circumferential groove closest to the center of the tread portion and the groove width Wo of the circumferential groove closest to the shoulder of the tread portion are 0.5×Wo≦Wi≦0.8×Wo. The groove depth Gi of the circumferential groove located closest to the center of the tread portion and the groove depth Go of the circumferential groove located closest to the shoulder of the tread portion are 0.6×Gi≦Go. ≦0.9×Gi is satisfied, and the groove depth Gi of the circumferential groove located closest to the center of the tread portion and the maximum groove depth Gm of the first lateral groove are 0.3×Gi≦Gm≦ The pneumatic tire for a two-wheeled vehicle according to claim 1, wherein the relationship of 0.6×Gi is satisfied. The inclination angle α of the circumferential groove located closest to the center of the tread portion with respect to the tire circumferential direction is in the range of 10°≦α≦25°, and the tread portion communicates with the circumferential groove located closest to the shoulder. The inclination angle β of the second lateral groove with respect to the tire circumferential direction at the position is in the range of 40°≦β≦70°, and the first lateral groove at the communication position with the circumferential groove located on the most shoulder side of the tread portion. The pneumatic tire for a two-wheeled vehicle according to claim 1 or 2, wherein the inclination angle γ with respect to the tire circumferential direction is in the range of 40° ≤ γ ≤ 70°. The amplitude Vi of the circumferential groove located closest to the center of the tread portion satisfies the relationship of 0.03≦Vi/TDW≦0.20 with respect to the spread width TDW of the tread portion, and the most shoulder of the tread portion. 4. The amplitude Vo of the circumferential groove located on the side satisfies the relationship of 0.10≦Vo/TDW≦0.30 with respect to the expansion width TDW of the tread portion. The pneumatic tire for a two-wheeled vehicle according to item 1. The JIS hardness of the tread rubber layer arranged in the tread portion is 58 to 63, and the tan δ at 0° C. of the tread rubber layer is 0.4 to 0.6. The pneumatic tire for a two-wheeled vehicle according to any one of 1. The height SLH of the shoulder edge of the tread portion satisfies the relationship of 0.55≦SLH/SH≦0.80 with respect to the tire cross-section height SH, and the radius of curvature R of the center portion of the tread portion is the tread portion. The pneumatic tire for a two-wheeled vehicle according to any one of claims 1 to 5, wherein a relationship of 0.45 ≤ R/TRW ≤ 0.65 is satisfied with respect to the width TRW. The groove area ratio Xb of the region b is 20% to 28%, the groove area ratio Xc of the region c is 26% to 34%, and the groove area ratio Xd of the region d is 13% to 26%. The pneumatic tire for a motorcycle according to any one of claims 1 to 6, characterized in that. The pneumatic tire for a two-wheeled vehicle according to any one of claims 1 to 7, wherein the center land portion does not include a groove component. The pneumatic tire for a motorcycle according to any one of claims 1 to 8, which has a bias structure.

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