Motorcycle tires

Abstract

To provide a motorcycle tire that is able to achieve both drainage performance and durability.SOLUTION: A motorcycle tire 1 is manufactured using a pair of molds divided in the axial direction of the tire. The motorcycle tire 1 has a tread portion 2 with a plurality of grooves 3 formed therein. A split position P for the pair of molds is provided in the tread portion 2 and at a position not intersecting the grooves 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motorcycle tire manufactured using a pair of molds that are divided in the tire axial direction. [Background technology]

[0002] Conventionally, motorcycle tires having a plurality of grooves in the tread portion for drainage have been known. For example, Patent Document 1 below proposes a motorcycle tire having a main inclined groove, a sub inclined groove, and a center main groove in the tread portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-131899 A Summary of the Invention [Problem to be solved by the invention]

[0004] Motorcycle tires such as those in Patent Document 1 are generally manufactured using a pair of molds that are split in the tire axial direction. However, the motorcycle tire in Patent Document 1 has problems in which cracks occur at the bottom of the grooves where the split positions of the pair of molds intersect with the grooves in the tread portion, or where rubber that is caught in the split positions forms a film that impedes drainage.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a motorcycle tire which is capable of achieving both drainage performance and durability. [Means for solving the problem]

[0006] The present invention relates to a motorcycle tire manufactured using a pair of molds that are divided in the tire axial direction, and is characterized in that the tire has a tread portion in which a plurality of grooves are formed, and that the tread portion has dividing positions for the pair of molds provided at positions that do not intersect with the grooves.

[0007] In the motorcycle tire of the present invention, the distance in the tire axial direction between the groove wall of the groove closest to the split position and the split position is preferably 1 to 10 mm.

[0008] In the motorcycle tire of the present invention, it is preferable that the grooves include a pair of inclined grooves extending in a direction inclined with respect to the circumferential direction of the tire, on either side of the tire equator.

[0009] In the motorcycle tire of the present invention, it is preferable that a rotational direction of the tire is specified, and the distance of the inclined groove from the tire equator gradually increases from the leading side to the trailing side in the rotational direction.

[0010] In the motorcycle tire of the present invention, it is preferable that an angle of the inclined groove with respect to the tire circumferential direction is smaller on a leading side in the rotational direction than on a trailing side.

[0011] In the motorcycle tire of the present invention, it is preferable that the length of the longest inclined groove in the tire axial direction is 50% or more of the half width of the tread.

[0012] In the motorcycle tire of the present invention, it is preferable that 15 to 29 pairs of the inclined grooves are formed in the circumferential direction of the tire.

[0013] In the motorcycle tire of the present invention, it is preferable that the grooves include a circumferential groove extending in the circumferential direction of the tire on the tire equator.

[0014] In the motorcycle tire of the present invention, it is preferable that the circumferential groove extends in a zigzag shape including bent portions disposed on one side and the other side of the tire equator and a connecting portion connecting the bent portions.

[0015] In the motorcycle tire of the present invention, it is preferable that the bent portion includes a shallow groove portion in which the groove depth gradually decreases.

[0016] In the motorcycle tire of the present invention, it is preferable that the split position is provided at a position away from the tire equator.

[0017] In the motorcycle tire of the present invention, the distance between the split position and the tire equator is preferably 5% to 20% of the tread half width.

[0018] In the motorcycle tire of the present invention, it is preferable that the grooves are not provided on the tire equator.

[0019] The present invention is a tire set of a front tire and a rear tire to be mounted on a motorcycle, characterized in that the front tire is one of the motorcycle tires described above, and the rear tire is the other motorcycle tire described above. Effect of the Invention

[0020] The motorcycle tire of the present invention has a tread portion in which a plurality of grooves are formed, and the tread portion is provided with a pair of mold dividing positions at positions that do not intersect with the grooves. Since the mold dividing positions and the grooves in the tread portion do not intersect with each other, such a motorcycle tire can suppress the occurrence of cracks at the groove bottoms and improve durability.

[0021] In addition, in the motorcycle tire of the present invention, even if rubber gets caught in the grooves, no film is formed in the grooves, so there is no risk of a decrease in drainage. Therefore, the motorcycle tire of the present invention can achieve both drainage performance and durability. [Brief description of the drawings]

[0022] [Figure 1] 1 is a development view showing an embodiment of a tread portion of a motorcycle tire according to the present invention. [Diagram 2] FIG. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. 11 is a development view showing a tread portion of a motorcycle tire according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a development view showing a tread portion 2 of a motorcycle tire 1 of this embodiment. As shown in Fig. 1, the motorcycle tire 1 of this embodiment has a tread portion 2 including a tread surface 2a that contacts the road surface during traveling. The motorcycle tire 1 of this embodiment is suitably used as a front tire for a motorcycle. A plurality of grooves 3 are formed in the tread portion 2 of this embodiment.

[0024] The motorcycle tire 1 of this embodiment is manufactured using a pair of dies (not shown) that are divided in the tire axial direction. Therefore, the tread portion 2 of this embodiment is provided with dividing positions P of the pair of dies. The dividing positions P of this embodiment are provided at positions that do not intersect with the grooves 3.

[0025] In such a motorcycle tire 1, the dividing position P of the mold does not intersect with the grooves 3 of the tread portion 2, so the occurrence of cracks at the groove bottoms is suppressed and durability can be improved. Furthermore, in the case of this motorcycle tire 1, even if rubber gets caught in the dividing position P, no film is formed in the grooves 3, so there is no risk of drainage deterioration. Therefore, the motorcycle tire 1 of this embodiment can achieve both drainage performance and durability.

[0026] In a more preferred embodiment, the motorcycle tire 1 is specified in the tire rotation direction R. In such a motorcycle tire 1, grooves 3 can be provided in accordance with the tire rotation direction R, and drainage performance can be improved.

[0027] The groove 3 of this embodiment includes a pair of inclined grooves 4 extending in a direction inclined with respect to the tire circumferential direction on either side of the tire equator C, and a circumferential groove 5 extending in the tire circumferential direction on the tire equator C. Such grooves 3 can further improve the drainage performance of the motorcycle tire 1 by the inclined grooves 4 and the circumferential groove 5. In addition, since such circumferential grooves 5 are provided on the tire equator C, the cornering response from the time of upright rolling is good, and the handling performance of the motorcycle tire 1 can be improved.

[0028] The inclined grooves 4 include, for example, a first inclined groove 4A, a second inclined groove 4B, a third inclined groove 4C, and a fourth inclined groove 4D, each having a different groove width and length. The inclined grooves 4 are not limited to this embodiment, and for example, the number of types, groove width, length, and shape can be appropriately changed.

[0029] It is desirable that the distance L1 from the tire equator C of the inclined groove 4 gradually increases from the leading side to the trailing side in the rotational direction R. Here, the distance L1 is the distance in the tire axial direction in a developed view of the tread portion 2. Such an inclined groove 4 can promote drainage of the contact surface by rolling, and can improve the drainage performance of the motorcycle tire 1.

[0030] The angle θ of the inclined groove 4 with respect to the tire circumferential direction is desirably smaller on the leading side in the rotational direction R than on the trailing side. Here, the angle θ is the angle with respect to the tire circumferential direction in a developed view of the tread portion 2. Such inclined groove 4 can further promote drainage of the contact surface during upright rolling, and can improve the drainage performance of the motorcycle tire 1.

[0031] The axial length L2 of the longest inclined groove 4 is preferably 50% or more of the tread half width W. In this embodiment, the first inclined groove 4A is the longest inclined groove 4. Here, the length L2 is the axial length of the tire in the developed view of the tread portion 2, and the tread half width W is the axial width of the tire from the tire equator C to the tread end Te in the developed view of the tread portion 2.

[0032] Such a motorcycle tire 1 can promote drainage from the ground contact surface by the long inclined grooves 4, and improve the drainage performance. From this viewpoint, the length L2 is more preferably 70% or more of the tread half width W, and further preferably 90% or more of the tread half width W.

[0033] In the motorcycle tire 1, it is preferable that 15 to 29 pairs of inclined grooves 4 are formed in the tire circumferential direction. In this embodiment, 15 to 29 pairs of the first inclined groove 4A, the second inclined groove 4B, the third inclined groove 4C, and the fourth inclined groove 4D are each formed in the tire circumferential direction. Such a motorcycle tire 1 is suitable for achieving both drainage performance and durability, and the rigidity of the tread portion 2 can be optimized, so that handling performance can also be improved.

[0034] The circumferential groove 5 of this embodiment includes bent portions 5a arranged on one side and the other side of the tire equator C, and a connecting portion 5b connecting the bent portions 5a. Therefore, the circumferential groove 5 of this embodiment extends in a zigzag shape in the tire circumferential direction. Such a motorcycle tire 1 can improve the drainage performance of the circumferential groove 5, while suppressing the water film from being pushed forward in the traveling direction and causing poor visibility. The circumferential groove 5 may extend, for example, linearly in the tire circumferential direction, or may extend in a wavy shape.

[0035] Fig. 2 is an enlarged view of the circumferential groove 5, Fig. 3 is a cross-sectional view taken along line AA in Fig. 2, and Fig. 4 is a cross-sectional view taken along line BB in Fig. 2. As shown in Figs. 2 to 4, the bent portion 5a of the circumferential groove 5 of this embodiment includes a shallow groove portion 5c in which the groove depth gradually decreases.

[0036] Such shallow groove portion 5c can promote drainage at bent portion 5a and improve the drainage performance of motorcycle tire 1. In addition, since shallow groove portion 5c has a gradually changing groove depth, it is possible to suppress a decrease in rigidity in the contact patch during upright rolling, and it is possible to improve the durability of motorcycle tire 1.

[0037] The shallow groove portion 5c is desirably provided on the trailing side in the rotational direction R. Such a shallow groove portion 5c can also promote drainage of the connecting portion 5b on the leading side in the rotational direction R, and can further improve the drainage performance of the motorcycle tire 1. In addition, this shallow groove portion 5c optimizes the rigidity of the tread portion 2, and is also useful for improving the handling performance of the motorcycle tire 1.

[0038] 1, the dividing position P is provided, for example, at a position away from the tire equator C. Of a pair of upper and lower dies, the dividing position P is desirably provided on the upper die side. In this embodiment, the dividing position P is provided between the inclined groove 4 and the circumferential groove 5. Such a motorcycle tire 1 can suppress the dividing position P from intersecting with the inclined groove 4 and the circumferential groove 5, and can achieve both drainage performance and durability.

[0039] The distance L3 between the dividing position P and the tire equator C is preferably 5% to 20% of the tread half width W. Here, the distance L3 is the distance in the tire axial direction in a developed view of the tread portion 2. By making the distance L3 5% or more of the tread half width W, it is possible to suppress intersection of the dividing position P and the circumferential groove 5, and it is possible to improve the durability of the motorcycle tire 1. From this viewpoint, the distance L3 is more preferably 6% or more of the tread half width W, and further preferably 7% or more.

[0040] By making the distance L3 20% or less of the tread half width W, undercutting at the tire equator C can be suppressed and the removal operation from the mold can be easily performed. From this viewpoint, the distance L3 is more preferably 16% or less of the tread half width W, and further preferably 12% or less.

[0041] Distances d1, d2 in the tire axial direction between the groove wall of the groove 3 closest to the dividing position P and the dividing position P are preferably 1 to 10 mm. Here, the distances d1, d2 are distances in the tire axial direction in a developed view of the tread portion 2. The distances d1, d2 include, for example, a first distance d1 on one side of the dividing position P in the tire axial direction and a second distance d2 on the other side.

[0042] The first distance d1 in this embodiment is the distance in the tire axial direction between the dividing position P and the circumferential groove 5. The second distance d2 in this embodiment is the distance in the tire axial direction between the dividing position P and the first inclined groove 4A. The first distance d1 and the second distance d2 may be the same as or different from each other.

[0043] By making the distances d1 and d2 1 mm or more, it is possible to reliably avoid the intersection of the slit position P and the groove 3, and improve the durability of the motorcycle tire 1. From this viewpoint, the distances d1 and d2 are more preferably 2 mm or more, and further preferably 3 mm or more.

[0044] By making the distances d1 and d2 10 mm or less, it is possible to reduce the area where the grooves 3 are not present and improve the drainage performance of the motorcycle tire 1. From this viewpoint, the distances d1 and d2 are more preferably 8 mm or less, and further preferably 6 mm or less.

[0045] Fig. 5 is a development view showing a tread portion 12 of a motorcycle tire 11 of another embodiment. As shown in Fig. 5, the motorcycle tire 11 of this embodiment has a tread portion 12 including a tread surface 12a that comes into contact with the road surface during traveling, similar to the above-mentioned motorcycle tire 1. The motorcycle tire 11 of this embodiment is suitably used as a rear tire for a motorcycle. The tread portion 12 of this embodiment has a plurality of grooves 13 formed therein, similar to the above-mentioned tread portion 2.

[0046] The motorcycle tire 11 of this embodiment is manufactured using a pair of dies (not shown) that are divided in the tire axial direction, similar to the above-mentioned motorcycle tire 1. Therefore, the tread portion 12 of this embodiment also has dividing positions P of the pair of dies. The dividing positions P of this embodiment are also provided at positions that do not intersect with the grooves 13.

[0047] In such a motorcycle tire 11, the dividing position P of the mold does not intersect with the grooves 13 of the tread portion 12, so the occurrence of cracks at the groove bottoms can be suppressed and durability can be improved. Furthermore, in the case of this motorcycle tire 11, even if rubber gets caught in the dividing position P, no film is formed in the grooves 13, so there is no risk of drainage deterioration. Therefore, like the motorcycle tire 1 described above, the motorcycle tire 1 of this embodiment can achieve both drainage and durability.

[0048] The motorcycle tire 11 of this embodiment has a specified tire rotation direction R, similar to the above-described motorcycle tire 1. Such a motorcycle tire 11 can be provided with grooves 13 according to the tire rotation direction R, and can improve drainage performance.

[0049] The groove 13 of this embodiment includes a pair of inclined grooves 14 that extend in a direction inclined with respect to the tire circumferential direction, sandwiching the tire equator C. The inclined grooves 14 include, for example, a first inclined groove 14A, a second inclined groove 14B, a third inclined groove 14C, and a fourth inclined groove 14D that are different from one another in groove width and length. The inclined grooves 14 are not limited to this embodiment, and for example, the number of types, groove width, length, and shape can be appropriately changed.

[0050] It is desirable that the distance L1 of the inclined groove 14 from the tire equator C gradually increases from the leading side to the trailing side in the rotational direction R, similar to the inclined groove 4 described above. Such an inclined groove 14 can promote drainage of the contact surface by rolling, and can improve the drainage performance of the motorcycle tire 11.

[0051] The angle θ of the inclined groove 14 with respect to the tire circumferential direction is desirably smaller on the leading side than on the trailing side in the rotational direction R, similar to the inclined groove 4 described above. Such inclined groove 14 can further promote drainage of the contact surface during upright rolling, and can improve the drainage performance of the motorcycle tire 11.

[0052] The length L2 in the tire axial direction of the longest inclined groove 14 is preferably 50% or more of the tread half-width W, more preferably 70% or more of the tread half-width W, and even more preferably 90% or more of the tread half-width W, similar to the above-mentioned inclined groove 4. In this embodiment, the first inclined groove 14A is the longest inclined groove 14. In such a motorcycle tire 11, the long inclined groove 14 promotes drainage from the ground contact surface, thereby improving drainage performance.

[0053] The grooves 13 in this embodiment are not provided on the tire equator C. Such a motorcycle tire 1 can distribute distortion of the contact surface during upright rolling and improve wear resistance even when used as a rear tire that is subjected to a heavy load.

[0054] The dividing position P in this embodiment is located on the tire equator C. The dividing position P may be located, for example, at a position away from the tire equator C. When the dividing position P is located at a position away from the tire equator C, it is preferable that the dividing position P is located on the upper mold side of the pair of upper and lower molds. The dividing position P in this embodiment is located between the inclined groove 14 on one side of the tire equator C and the inclined groove 14 on the other side. Such a motorcycle tire 11 prevents the dividing position P from intersecting with the grooves 13, and can achieve both drainage performance and durability.

[0055] A distance L3 between the dividing position P and the tire equator C is preferably 20% or less of the tread half width W. By making the distance L3 20% or less of the tread half width W, undercutting at the tire equator C is suppressed, and the removal operation from the mold can be easily performed. From this viewpoint, this distance is more preferably 16% or less of the tread half width W, and even more preferably 12% or less.

[0056] Distances d1, d2 in the tire axial direction between the groove wall of the groove 3 closest to the dividing position P and the dividing position P are preferably 1 to 10 mm. Here, the distances d1, d2 are distances in the tire axial direction in a developed view of the tread portion 2. The distances d1, d2 include, for example, a first distance d1 on one side of the dividing position P in the tire axial direction and a second distance d2 on the other side.

[0057] The first distance d1 in this embodiment is the distance in the tire axial direction between the scoring position P and the first inclined groove 14A on one side in the tire axial direction of the scoring position P. The second distance d2 in this embodiment is the distance in the tire axial direction between the scoring position P and the first inclined groove 14A on the other side in the tire axial direction of the scoring position P. The first distance d1 and the second distance d2 may be the same as or different from each other.

[0058] By making the distances d1 and d2 1 mm or more, it is possible to reliably avoid the intersection of the slit position P and the groove 3, and improve the durability of the motorcycle tire 1. From this viewpoint, the distances d1 and d2 are more preferably 2 mm or more, and further preferably 3 mm or more.

[0059] By making the distances d1 and d2 10 mm or less, it is possible to reduce the area where the grooves 3 are not present and improve the drainage performance of the motorcycle tire 1. From this viewpoint, the distances d1 and d2 are more preferably 8 mm or less, and further preferably 6 mm or less.

[0060] As shown in Fig. 1 and Fig. 5, motorcycle tires 1, 11 are preferably used as a tire set of a front tire and a rear tire to be mounted on a motorcycle, for example. The front tire of this embodiment is the motorcycle tire 1 shown in Fig. 1. The rear tire of this embodiment is the motorcycle tire 11 shown in Fig. 5.

[0061] Such a tire set can exhibit excellent drainage because the motorcycle tire 1 including the circumferential groove 5 is mounted on the front tire which is involved in steering. Also, this tire set can exhibit excellent durability because the motorcycle tire 11 which does not have grooves 13 on the tire equator C is mounted on the rear tire which is subjected to a high load. Therefore, the tire set of this embodiment can achieve both drainage and durability.

[0062] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified in various ways. EXAMPLES

[0063] Motorcycle tires having the tread portions shown in Figs. 1 and 5 were prototyped based on the specifications in Tables 1 and 2, respectively. As a comparative example, a motorcycle tire having the same inclined grooves as those in the tread portions shown in Figs. 1 and 5, in which the slit positions intersect with the grooves, was prototyped. Using the prototype motorcycle tires, drainage, durability, and handling performance were tested. The main common specifications and test methods are as follows:

[0064] <Common specifications> Front tire: A motorcycle tire having the tread portion shown in FIG. 1. Front tire size: 110 / 70-13M / C Front wheel rim size: 13×3.00MT Rear tire: A motorcycle tire having the tread portion shown in FIG. 5. Rear tire size: 130 / 70-13M / C Rear wheel rim size: 13×3.50MT

[0065] <Drainage> The front tire was set to an air pressure of 200 kPa, and the rear tire was set to an air pressure of 225 kPa. The tires were attached to the front and rear wheels of a medium-sized scooter, and the test driver ran the tires on a wet road surface and evaluated the drainage performance on a scale of 1 to 10 using his senses. Similar tests were conducted by 20 test drivers, and the total score was calculated. The results were expressed as an index, with the total score of the comparative example being 100, and the higher the value, the better the drainage performance.

[0066] <Durability> The rear tire was aired to 280kPa and mounted on a drum testing machine, and run for 4 hours under a load of 2.67kN, then for 6 hours under a load of 2.89kN, and then for 24 hours under a load of 3.13kN, after which the state of cracks was evaluated. The results are expressed as an index with the comparative example being 100, with a higher index indicating better durability.

[0067] <Handling performance> The front tire air pressure was set to 200 kPa, and the rear tire air pressure was set to 225 kPa. The tires were attached to the front and rear wheels of a medium-sized scooter, and the test driver drove the scooter around a circuit course. The test driver's senses evaluated the handling performance on a 10-point scale. Similar tests were conducted by 20 test drivers, and the total score was calculated. The results were expressed as an index, with the total score of the comparative example being 100, and the higher the value, the better the handling performance.

[0068] The test results are shown in Tables 1 and 2. [Table 1]

[0069] [Table 2]

[0070] As a result of the test, it was confirmed that the motorcycle tires of the examples were superior in drainage and durability to the comparative example, and achieved both drainage and durability. [Explanation of symbols]

[0071] 1. Motorcycle tires 2 Tread section 3 grooves

Claims

1. A motorcycle tire manufactured using a pair of molds that are divided in the tire axial direction, A tire has a tread portion having a plurality of grooves formed therein, A pair of die split positions are provided in the tread portion at positions that do not intersect with the grooves, a distance in the tire axial direction between the groove wall of the groove closest to the split position and the split position is 1 to 10 mm; The groove includes a circumferential groove extending in a circumferential direction of the tire on the tire equator. Tires for motorcycles.

2. The motorcycle tire according to claim 1 , wherein the circumferential groove extends in a zigzag shape and includes bent portions disposed on one side and the other side of a tire equator and a connecting portion connecting the bent portions.

3. The motorcycle tire according to claim 2 , wherein the bent portion includes a shallow groove portion in which the groove depth gradually decreases.

4. A motorcycle tire manufactured using a pair of molds that are divided in the tire axial direction, A tire has a tread portion having a plurality of grooves formed therein, A pair of die split positions are provided in the tread portion at positions that do not intersect with the grooves, The groove includes a circumferential groove extending in a circumferential direction of the tire on the tire equator, The circumferential groove extends in a zigzag shape including bent portions disposed on one side and the other side of a tire equator and a connecting portion connecting the bent portions, The bent portion includes a shallow groove portion in which the groove depth gradually decreases. Tires for motorcycles.

5. The motorcycle tire according to claim 1 , wherein the dividing position is provided at a position away from a tire equator.

6. The motorcycle tire according to claim 5, wherein a distance between the split position and the tire equator is 5% to 20% of a half tread width.

7. The motorcycle tire according to claim 1 , wherein the grooves include a pair of inclined grooves extending in a direction inclined with respect to a circumferential direction of the tire, on either side of the tire equator.

8. The direction of tire rotation is specified. The motorcycle tire according to claim 7 , wherein a distance of the inclined groove from the tire equator gradually increases from a leading side to a trailing side in the rotational direction.

9. The motorcycle tire according to claim 8 , wherein an angle of the inclined groove with respect to the tire circumferential direction is smaller on a leading side in the rotational direction than on a trailing side.

10. 10. The motorcycle tire according to claim 7, wherein the longest inclined groove has an axial length that is equal to or greater than 50% of a half width of the tread.

11. The motorcycle tire according to any one of claims 7 to 10, wherein 15 to 29 pairs of the inclined grooves are formed in the tire circumferential direction.

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