JP2020062988A - Pneumatic tires for motorcycles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for a two-wheeled vehicle capable of improving wear resistance without impairing wet performance. SOLUTION: The area from the center position CL of the tread portion 1 to the shoulder edge is divided into four equal parts in the tire width direction along the tread, and the four regions a, b, c and d are sequentially divided from the center side of the tread portion 1. When specified, the groove area ratio Xa of the region a is 8% to 14%, the groove area ratio Xb of the region b is 26% to 32%, and the groove area ratio Xc of the region c is 27% to 33%. Yes, the groove area ratio Xd of the region d is 5% to 16%, the relationship of Xc> Xb> Xa is satisfied, and the groove depth in the tread portion 1 is on the shoulder side of the center side of the tread portion 1. It is relatively shallow. [Selection diagram] Fig. 2

Description

  TECHNICAL FIELD The present invention relates to a pneumatic tire used for a two-wheeled vehicle, and more particularly to a pneumatic tire for a two-wheeled vehicle that is capable of improving wear resistance without impairing wet performance.

  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 due to the force of camber thrust (see, for example, Patent Document 1). ). In the 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 (see, for example, Patent Documents 2 to 4). .

  By the way, a general rear tire for a two-wheeled vehicle tends to have a larger load load than a front tire, and therefore has a problem of a shorter wear life than a front tire. One possible solution to such a problem is the use of a tread compound having excellent wear resistance. However, when a tread compound having excellent wear resistance is used, there is a drawback in that wet performance deteriorates. Therefore, it is required to improve the wear resistance without relying on the tread compound.

Japanese Patent Laid-Open No. 61-27707 JP, 2016-141225, A JP, 2016-175598, A JP, 2008-39333, A

  An object of the present invention is to provide a pneumatic tire for a two-wheeled vehicle, which can improve wear resistance without impairing wet performance.

  The pneumatic tire for a two-wheeled motor vehicle according to the present invention for achieving the above object, the region from the center position of the tread portion to the shoulder edge is equally divided into four in the tire width direction along the tread surface, and from the center side of the tread portion. When four regions a, b, c, d are defined in order, the groove area ratio Xa of the region a is 8% to 14%, the groove area ratio Xb of the region b is 26% to 32%, The groove area ratio Xc of the region c is 27% to 33%, the groove area ratio Xd of the region d is 5% to 16%, and the relationship of Xc> Xb> Xa is satisfied, and the tread portion is The groove depth at is relatively shallower on the shoulder side than on the center side of the tread portion.

  In a pneumatic tire for a two-wheeled vehicle, the center portion of the tread portion tends to wear preferentially. Therefore, in the present invention, the wear resistance can be improved by reducing the groove area ratio Xa of the region a located on the center side of the tread portion. Furthermore, by making the groove depth in the tread portion relatively deeper on the center side than on the shoulder side of the tread portion, a sufficient wear life can be ensured. On the other hand, by increasing the groove area ratio Xb of the region b and the groove area ratio Xc of the region c, it becomes possible to maintain good wet performance. Further, in a pneumatic tire for a two-wheeled vehicle, a large force is applied to the shoulder portion of the tread portion due to the camber thrust during turning, but the groove area ratio Xd of the region d is reduced and the groove depth in the tread portion is set to the center of the tread portion. By making the shoulder side relatively shallower than the shoulder side, 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, four or more circumferential grooves extending 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 grooves is relatively closer to the center side than the shoulder side of the tread portion. Is narrowed, 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 is formed, and the zigzag cycle of the circumferential groove located on the most center side of the tread portion is formed. A satisfies the relationship of 0.2 ≦ A / TDW ≦ 0.4 with respect to the development width TDW of the tread portion, and is in the tire circumferential direction between a pair of circumferential grooves located closest to the center of the tread portion. The extending center land portion is divided, and the minimum width B in the tire width direction of the center land portion satisfies the relationship of 0.1 ≦ B / TDW ≦ 0.3 with respect to the development width TDW of the tread portion. Preferred . Further, it is preferable that the lateral groove 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. By adopting such a tread pattern, it is possible to effectively improve wear resistance while maintaining good wet performance.

  In particular, 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 relationship is satisfied, and 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. It is preferable to satisfy the relationship of 0.9 × 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. . In addition, 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, while ensuring sufficient wear life, the rigidity of the shoulder portion of the tread portion can be ensured. Can be sufficiently secured.

  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 lateral groove with respect to the tire circumferential direction is preferably in the range of 40 ° ≦ β ≦ 70 °. By setting the inclination angles α and β in the above range, 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, wear resistance can be improved without lowering 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 cross-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 0.50 ≦ 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.

  The present invention is preferably applied to a pneumatic tire for a two-wheeled vehicle having a bias structure. A two-wheeled vehicle pneumatic tire 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 regular rim and filled with the regular 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, TRA is “Design Rim”, or ETRTO. If so, it is set to “Measuring Rim”. "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.

  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 its tread portion. It shows a groove.

  As shown in FIG. 1, the pneumatic tire according to the present embodiment includes 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 portion 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 is not limited to this.

  As shown in FIG. 2, the tread portion 1 is formed with four or more circumferential grooves 10 that extend 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 alternately arranged along the tire circumferential direction. 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 from the shoulder side of the tread portion 1 toward the center side with respect to the tire width direction.

  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 center land portion 31 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. Although the raised lateral groove 21 has a shallower groove depth than the lateral groove 22 not raised, the lateral groove 21 may have the same groove depth as the lateral groove 22 without being raised. Moreover, the other end of the lateral groove 21 may communicate with the circumferential groove 12 on the center side similarly to the lateral groove 22.

  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, the groove area ratio Xa of the region a is 8% to 14%, the groove area ratio Xb of the region b is 26% to 32%, and the groove area ratio Xc of the region c is 27% to 33%. Thus, the grooves are arranged so that the groove area ratio Xd of the region d is 5% to 16%. The magnitude relationship between the groove area ratios Xa to Xd is Xc> Xb> Xa, preferably Xc> Xb> Xa> Xd. The groove area ratios Xa to Xd are ratios of the groove areas to the respective areas of the regions a to d. For example, one cycle of the circumferential groove 11 located in the most center side of the tread portion 1 and having a zigzag shape. It can be calculated from the range of A. In addition to the requirements of the groove area ratios Xa to Xd, the groove depth in the tread portion 1 is 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.

  In the pneumatic tire for a motorcycle described above, the wear resistance can be improved by reducing the groove area ratio Xa of the region a located on the center side of the tread portion 1. Further, by making the groove depth in the tread portion 1 relatively deeper on the center side than on the shoulder side of the tread portion 1, a sufficient wear life can be secured. On the other hand, by increasing the groove area ratio Xb of the region b and the groove area ratio Xc of the region c, it becomes possible to maintain good wet performance. Further, in a 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 area ratio Xd of the region d is reduced and the groove depth in the tread portion 1 is reduced. By making it relatively shallower on the shoulder side than on the center side of 1, the rigidity of the shoulder portion of the tread portion 1 can be sufficiently secured and a sufficient camber thrust at the time of turning can be obtained.

  Here, if 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 wet performance deteriorates, and conversely, if it is larger than the upper limit value. Abrasion property decreases. Further, if the groove area ratio Xd of the region d is too small, the wet performance deteriorates, and conversely if it is too large, the rigidity of the shoulder portion of the tread portion 1 becomes insufficient, and it becomes impossible to obtain sufficient camber thrust during turning.

  In the pneumatic tire, the groove arrangement in the tread portion 1 is not particularly limited, but as described above, four or more circumferential grooves 10 extending in the tire circumferential direction while bending in a zigzag shape in the tread portion 1 are provided. The groove width of the circumferential groove 10 formed is relatively narrower on the center side than on the shoulder side of the tread portion 1. From the circumferential groove 12 located on the most shoulder side of the tread portion 1 toward the center side. A plurality of extending lateral grooves 20 are formed, and the zigzag-shaped cycle A of the circumferential groove 11 located on the most center side of the tread portion 1 is 0.2 ≦ A / TDW with respect to the spread width TDW of the tread portion 1. The relationship of ≦ 0.4 is satisfied, and the center land portion 31 extending in the tire circumferential direction is defined between the pair of circumferential grooves 11, 11 located closest to the center of the tread portion 1. , May minimum width B of the tire width direction of the center land portion 31 satisfies the relation of 0.1 ≦ B / TDW ≦ 0.3 with respect to the developed width TDW of the tread portion 1. 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. Further, 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 preferably arranged alternately along the tire circumferential direction. By adopting such a tread pattern, it is possible to effectively improve wear resistance while maintaining good wet performance.

  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, with respect to the minimum width B in the tire width direction of the center land portion 31, if the ratio B / TDW is smaller than 0.1, the effect of improving wear resistance is lowered in the center region where the ground contact pressure is high, and conversely 0.3. If it is larger than the above range, the groove area ratio in the ground contact area is reduced, and the drainage performance is reduced.

  In particular, 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 are 0.5. XWo ≦ Wi ≦ 0.8 × Wo is satisfied, and the groove depth Gi of the circumferential groove 11 located closest to the center of the tread portion 1 and the circumferential groove 12 located closest to the shoulder of the tread portion 1 are satisfied. The groove depth Go is preferably 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. Further, 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 circumferential groove 12 on the shoulder side 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 is deteriorated, and conversely, the value of 0. If it is larger than 8, the effect of improving wear resistance is lowered. Further, if the ratio Go / Gi of the groove depth Gi of the center side circumferential groove 11 to the groove depth Go of the shoulder side circumferential groove 12 is smaller than 0.6, the wet performance at the time of turning deteriorates, On the other hand, if 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. 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 20 with respect to the tire circumferential direction at the position communicating with the circumferential groove 12 located on the most shoulder side of 1 is preferably in the range of 40 ° ≦ β ≦ 70 °. By setting the inclination angles α and β 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. Wet performance deteriorates due to deterioration of the water drainage property of. Further, if the inclination angle β of the lateral groove 20 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, 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. JIS hardness is a durometer hardness measured according to JIS-K6253 using an A type durometer at a temperature of 23 ° C. The loss tangent (tan δ) is measured according to JIS-K6394 using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of frequency 20 Hz, initial strain 10%, dynamic strain ± 2%, and temperature 0 ° C. It is what 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 sectional height SH, and the height SLH of the center portion of the tread portion 1 is The radius of curvature R may satisfy the relationship of 0.50 ≦ 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. Thereby, 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 0.50, the ground contact pressure at the center side portion of the tread portion 1 becomes high and premature wear is apt to occur at the portion concerned. Conversely, if it is larger than 0.65, the tread portion becomes larger. Premature wear is likely to occur at the shoulder side portion of the portion 1.

  In a pneumatic tire for a two-wheeled vehicle having a tire size of 80 / 100-14, four regions defined by dividing the region 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. Conventional Example 1 and Comparative Examples 1 to 6 in which the groove area ratios Xa to Xd of a to d and the presence or absence of the structure in which the groove depth of the tread portion is shallow on the shoulder side are varied as shown in Table 1 and Table 2. And the tire of Examples 1-12 was produced.

  In Conventional Example 1, Comparative Examples 1 to 6 and Examples 1 to 12, four circumferential grooves extending in the tire circumferential direction while being bent in a zigzag shape are formed in the tread portion, and the tread portion is located on the most shoulder side. A plurality of lateral grooves extending from the circumferential groove toward the center side are formed. The ratio A / TDW of the zigzag-shaped period A of the circumferential groove located closest to the center of the tread portion to the development width TDW of the tread portion, the mutual relation of the pair of circumferential grooves 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 and the development width TDW of the tread portion, the groove width Wi of the circumferential groove located closest to the center of the tread portion, and the tread portion The ratio Wi / Wo with the groove width Wo of the circumferential groove located on the most shoulder side, the groove depth Gi of the circumferential groove located on the most center side of the tread portion, and the circumferential groove located on the most shoulder side of the tread portion. Ratio of the groove depth Go to the ratio Go / Gi, the inclination angle α of the circumferential groove located closest to the center of the tread portion to the tire circumferential direction, and the communication position with the circumferential groove located closest to the shoulder of the tread portion. Angle β of the lateral groove with respect to the tire circumferential direction, JIS hardness of the tread rubber layer and tan δ at 0 ° C., the ratio SLH / SH between the shoulder edge height SLH of the tread portion and the tire section height SH, and the center of the tread portion. The ratio R / TRW between the radius of curvature R of the portion and the width TRW of the tread portion and the carcass structure (radial or bias) are set as shown in Tables 1 and 2.

  With respect to these test tires, wear resistance and 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 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 by index values with the value of Conventional 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 Conventional Example 1 set to 100. The larger the index value, the better the wet performance. If the index value is "97" or more, it is within the allowable range.

  As is clear from Table 1 and Table 2, in all the tires of Examples 1 to 12, it was possible to improve wear resistance without impairing wet performance. On the other hand, Comparative Examples 1 to 6 were inferior to Examples 1 to 12 although the effect of improving wear resistance was recognized.

1 tread part 1A tread rubber layer 2 sidewall 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 (8)

  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, The groove area ratio Xa of a is 8% to 14%, the groove area ratio Xb of the region b is 26% to 32%, the groove area ratio Xc of the region c is 27% to 33%, and The groove area ratio Xd of the region d is 5% to 16%, the relationship of Xc> Xb> Xa is satisfied, and the groove depth in the tread portion is relatively closer to the shoulder side than the center side of the tread portion. A pneumatic tire for motorcycles, which is characterized by a shallow depth.   Four or more circumferential grooves extending 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 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 is formed, and the zigzag-shaped period A of the circumferential groove located on the most center side of the tread portion is formed. Satisfies the relationship of 0.2 ≦ A / TDW ≦ 0.4 with respect to the development width TDW of the tread portion, and the tire circumferential direction is provided between the pair of circumferential grooves located closest to the center of the tread portion. A center land portion extending in the area is defined, and the minimum width B in the tire width direction of the center land portion satisfies the relationship of 0.1 ≦ B / TDW ≦ 0.3 with respect to the development width TDW of the tread portion. thing Motorcycle pneumatic tire for a vehicle according to claim 1, wherein.   The lateral groove 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. A pneumatic tire for a motorcycle as described above.   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. Satisfying the relationship, 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. The pneumatic tire for a two-wheeled vehicle according to claim 2 or 3, which satisfies a relationship of ≤ 0.9 x Gi.   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 pneumatic tire for a two-wheeled vehicle according to any one of claims 2 to 4, wherein an inclination angle β of the lateral groove with respect to the tire circumferential direction at a position is in a range of 40 ° ≤ β ≤ 70 °.   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 motorcycle 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 6, wherein a relationship of 0.50 ≤ R / TRW ≤ 0.65 is satisfied with respect to the width TRW.   It has a bias structure, The pneumatic tire for two-wheeled vehicles in any one of Claims 1-7 characterized by the above-mentioned.

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