Tire for motorcycle

Abstract

To provide a tire for a motor cycle, improved in drainage performance and uneven abrasion resistance performance.SOLUTION: A tire 1 for a motor cycle is provided, comprising first grooves 3 including first oblique portions 5 and second oblique portions 6 and a second groove 4 which is small in length in a tire circumferential direction. The first oblique portion 5 is extended obliquely in a first tire circumferential direction F from a first end 8 at a tread end Te side toward a tire equator C side. The second oblique portion 6 is joined to the first oblique portion 5, and is extended obliquely in the first tire circumferential direction F up to a second end 9, toward the tread end Te side. The second groove 4, extended obliquely with respect to the tire circumferential direction, has an inner end 4i in a tire axial direction at the tire equator C side, where the inner end 4i is positioned closer to inside in the tire axial direction than the first end 8 of and the second end 9 of the first groove 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire for a motorcycle.

Background Art

[0002] Patent Document 1 below describes a motorcycle tire including a first inclined groove extending obliquely, a second inclined groove disposed on the trailing side of the first inclined groove and extending along the first inclined groove, and an inclined narrow groove inclined in the opposite direction to the first inclined groove and communicating with the inner end of the second inclined groove. Such a first inclined groove, second inclined groove, and inclined narrow groove are said to improve drainage performance from straight running to turning.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to enhance drainage performance, for example, it is conceivable to increase the groove volume of the first inclined groove or the second inclined groove. However, such a motorcycle tire has a problem that the rigidity of the tread portion decreases and the resistance to uneven wear deteriorates.

[0005] The present invention has been devised in view of the above actual situation, and the main object is to provide a motorcycle tire with improved drainage performance and resistance to uneven wear.

Means for Solving the Problems

[0006] The present invention relates to a motorcycle tire having a tread portion, wherein the tread portion is provided with a first groove and a second groove having a length in the tire circumferential direction smaller than that of the first groove. The first groove includes a first inclined portion and a second inclined portion. The first inclined portion extends inclined in a first tire circumferential direction from a first end on the tread end side toward the tire equator side. The second inclined portion is connected to the first inclined portion and extends inclined in the first tire circumferential direction toward the tread end side to a second end. The second end is a closed end not connected to other grooves. The second groove extends inclined with respect to the tire circumferential direction and has an inner end in the tire axial direction on the tire equator side. The inner end of the second groove is located on the inner side in the tire axial direction of the first end and the second end of the first groove.

[0007] It is desirable that in the motorcycle tire according to the present invention, the second groove is inclined in the same direction as the first inclined portion.

[0008] It is desirable that in the motorcycle tire according to the present invention, the tread portion has a crown region that contacts the ground during straight running, and at least a part of each of the first inclined portion and the second inclined portion is located within the crown region.

[0009] It is desirable that in the motorcycle tire according to the present invention, the first end of the first inclined portion or the second end of the second inclined portion is located outside the crown region in the tire axial direction.

[0010] It is desirable that in the motorcycle tire according to the present invention, the inner end of the second groove is located within the crown region.

[0011] It is desirable that in the motorcycle tire according to the present invention, the outer end in the tire axial direction of the second groove is located outside the crown region in the tire axial direction.

[0012] The motorcycle tire according to the present invention is the motorcycle tire according to any one of claims 1 to 6, wherein the inner end of the second groove is a closed end not connected to other grooves.

[0013] For the motorcycle tire according to the present invention, it is desirable that the inner end of the second groove communicates with the second inclined portion.

[0014] For the motorcycle tire according to the present invention, it is desirable that the groove depth of the connection portion of the second inclined portion and the second groove is smaller than the groove depth of the second groove.

[0015] For the motorcycle tire according to the present invention, it is desirable that the groove depth of the connection portion of the second inclined portion is 20% to 80% of the groove depth of the second groove.

Advantages of the Invention

[0016] By adopting the above configuration, the motorcycle tire of the present invention can exhibit excellent drainage performance and wear resistance.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a developed view of the tread portion 2 of the motorcycle tire 1 (hereinafter sometimes simply referred to as "tire") of the present embodiment. The tire 1 of the present embodiment is preferably used for on-road driving on, for example, a dry asphalt road surface. However, the tire 1 of the present invention is not limited to such a mode.

[0019] As shown in FIG. 1, the tread portion 2 of the tire 1 of the present embodiment is provided with a first groove 3 and a second groove 4 having a length in the tire circumferential direction smaller than that of the first groove 3.

[0020] The first groove 3 of the present embodiment includes a first inclined portion 5 and a second inclined portion 6. The first inclined portion 5 of the present embodiment extends inclined in the first tire circumferential direction F from the first end 8 on the tread end Te side toward the tire equator C side. Further, the second inclined portion 6 of the present embodiment is connected to the first inclined portion 5 and extends inclined in the first tire circumferential direction F toward the tread end Te side to the second end 9. Such a first groove 3 can smoothly discharge the water in the groove to the outside in the tire axial direction by utilizing the rotation of the tire 1. Thereby, the drainage performance is improved. Further, the first groove 3 as described above suppresses a local decrease in the rigidity in the tire circumferential direction of the tread portion 2 as compared with, for example, a groove extending along the tire circumferential direction. Thereby, the deterioration of the uneven wear resistance performance is suppressed. The first tire circumferential direction F means either one of the tire circumferential directions in this specification, and in the present embodiment, it is the lower side in FIG. 1.

[0021] The second end 9 is, for example, a closed end not connected to other grooves. Thereby, a decrease in the rigidity of the tread portion 2 is suppressed in the vicinity of the second end 9, and as a result, the uneven wear resistance performance is improved. Since the second end 9 of the present embodiment is not connected to the sipe (not shown), the above-described action is more effectively exhibited. In this specification, a groove is a groove-shaped body having a groove width of 1.5 mm or more. Further, a sipe is a cut-shaped body having a width of less than 1.5 mm.

[0022] The second groove 4 extends obliquely with respect to the tire circumferential direction and has an inner end 4i in the tire axial direction on the tire equator C side. And the inner end 4i of the second groove 4 in the present embodiment is located on the inner side in the tire axial direction than the first end 8 and the second end 9 of the first groove 3. Such a layout of the first groove 3 and the second groove 4 can effectively collect the water between the road surface and the tread surface 2a in the inner region in the tire axial direction of the tread portion 2 that is relatively difficult to drain water when driving on a wet road surface, and drain the water. Therefore, the drainage performance is improved. Further, since the inner end 4i is displaced in the tire axial direction with respect to the first end 8 and the second end 9, it suppresses a local decrease in the rigidity of the tread portion 2 and enhances the uneven wear resistance performance. The inner end 4i of the second groove 4 is the end portion on the innermost side in the tire axial direction of the groove center line 4n of the second groove 4 described later.

[0023] The tire rotation direction N is specified for the tread portion 2. In the present embodiment, the tire rotation direction N is opposite to the first tire circumferential direction F. That is, the first groove 3 extends continuously from the first end 8 to the trailing side in the tire rotation direction N. The second groove 4 extends continuously from the inner end 4i to the tire rotation direction N side. The first end 8 is, for example, a closed end that is not connected to other grooves and sipes.

[0024] The tread portion 2 has a crown region Cr that contacts the ground during straight running, and a pair of shoulder regions Sh arranged on both sides in the tire axial direction of the crown region Cr. The phrase "contacts the ground during straight running" means that when a normal load is applied to the tire 1 in a normal state that is rim-mounted on a normal rim (not shown), filled with a normal internal pressure, and unloaded, and is grounded on a plane at a camber angle of 0°. The developed width Tc of the crown region Cr is 20% to 30% of the tread developed width TWe. Also, the outer edge in the tire axial direction of each shoulder region Sh is the tread end Te. Unless otherwise specified, in this specification, the dimensions and the like of each part of the tire 1 are values measured in the normal state. Further, the tread developed width TWe is the distance in the tire axial direction between the tread ends Te, Te when the tread portion 2 is developed on a plane.

[0025] The "regular rim" is the rim defined for each tire in the standard system including the standards on which Tire 1 is based. For example, in JATMA, it is the standard rim; in TRA, it is the "Design Rim"; and in ETRTO, it is the "Measuring Rim".

[0026] The "regular internal pressure" is the air pressure defined for each tire in the standard system including the standards on which Tire 1 is based. In JATMA, it is the maximum air pressure; in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and in ETRTO, it is the "INFLATION PRESSURE".

[0027] The "regular load" is the load defined for each tire in the standard system including the standards on which the tire is based. In JATMA, it is the "maximum load capacity"; in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and in ETRTO, it is the "LOAD CAPACITY".

[0028] In this embodiment, each of the first groove 3 and the second groove 4 is provided on both sides of the tire equator C. The first groove 3 is, for example, arranged alternately in the tire circumferential direction with the tire equator C interposed therebetween. The second groove 4 is, for example, arranged alternately in the tire circumferential direction with the tire equator C interposed therebetween. Also, on each of both sides of the tire equator C, the first groove 3 and the second groove 4 are arranged alternately in the tire circumferential direction.

[0029] The first inclined portion 5 of the first groove 3 continuously inclines in the first tire circumferential direction F from the first end 8 toward the tire equator C side. Such a first inclined portion 5 makes the movement in the groove smoother and improves the drainage performance. From the same viewpoint, the second inclined portion 6 continuously inclines in the direction opposite to the first tire circumferential direction F from the second end 9 toward the tire equator C side.

[0030] At least a part of each of the first inclined portion 5 and the second inclined portion 6 is located within the crown region Cr. Thereby, the water in the crown region Cr located on the tire equator C side where drainage is difficult can be accumulated and drained by the first inclined portion 5 and the second inclined portion 6.

[0031] The first end 8 of the first inclined portion 5 or the second end 9 of the second inclined portion 6 is located, for example, outside the crown region Cr in the tire axial direction. Thereby, even during straight running, the water in the first groove 3 can be discharged outside the crown region Cr, so that the drainage performance is enhanced. In the present embodiment, the first end 8 of the first inclined portion 5 is located in the shoulder region Sh. The second end 9 of the second inclined portion 6 is located in the crown region Cr in the present embodiment. Note that the second end 9 may be located in the shoulder region Sh.

[0032] FIG. 2 is an enlarged view of the first groove 3 in FIG. 1. As shown in FIG. 2, a part of the first groove 3 is located, for example, on the tire equator C. In the present embodiment, the first groove 3 is formed so as to straddle the tire equator C. The first groove 3 of the present embodiment extends such that the second portion 14 and the second inclined portion 6 described later are located on the tire equator C.

[0033] The first groove 3 has a separation point 3a that is most separated from the first end 8 in the tire axial direction. In the present embodiment, the separation point 3a is located on the opposite side of the tire axial direction across the tire equator C from the first end 8. The distance La in the tire axial direction between the separation point 3a and the tire equator C is desirably 15% or less, and more desirably 10% or less, of the developed width Tc of the crown region Cr. Since the distance La is 15% or less of the developed width Tc, the water on the tire equator C where drainage is most difficult can be effectively removed. In the present embodiment, the first inclined portion 5 and the second inclined portion 6 are separated at the separation point 3a. The separation point 3a may be located, for example, on one side in the tire axial direction from the same tire equator C as the first end 8.

[0034] The first inclined portion 5 of the present embodiment includes a first portion 13 including the first end 8, a second portion 14 continuous with the second inclined portion 6, and a third portion 15 connecting the first portion 13 and the second portion 14.

[0035] The first portion 13, the second portion 14, and the third portion 15 are, for example, arc-shaped convex toward the tire equator C side in a tread plan view. Such first portion 13 and second portion 14 smooth the flow of water in the groove to improve drainage performance, and suppress a decrease in the rigidity of the tread portion 2 to maintain high uneven wear resistance.

[0036] In the present embodiment, the groove width Wz of the third portion 15 is formed smaller than the groove width Wx of the first portion 13 and the groove width Wy of the second portion 14. Such first inclined portion 5 suppresses slippage when the third portion 15 contacts the ground with the first portion 13 and the second portion 14 to improve uneven wear resistance, and the first portion 13 and the second portion 14 with relatively large groove widths suppress a decrease in drainage performance.

[0037] Each of the first portion 13, the second portion 14, and the third portion 15 includes an equal-width portion 16 extending with the same groove width. Such equal-width portion 16 suppresses a local decrease in the rigidity of the tread portion 2. The "same groove width" means that the absolute value of the difference between the maximum value (not shown) and the minimum value (not shown) of the groove width is 10% or less of the maximum value. In the present embodiment, the total length of the equal-width portion 16a of the first portion 13 is 80% or more of the total length of the first portion 13. The total length of the equal-width portion 16b of the second portion 14 is, for example, 80% or more of the total length of the second portion 14. The total length of the equal-width portion 16c of the third portion 15 is, for example, 80% or more of the total length of the third portion 15. The groove widths Wx to Wz of the first portion 13 to the third portion 15 are the groove widths at the equal-width portion 16.

[0038] The groove width Wx of the first portion 13 is substantially the same as the groove width Wy of the second portion 14. The "substantially the same" means a mode in which the absolute value of the difference between the groove width Wx of the first portion 13 and the groove width Wy of the second portion 14 is 1 mm or less.

[0039] In order to enhance the drainage performance while suppressing slippage during grounding, the groove width Wz of the third part 15 is desirably 35% or more, more desirably 40% or more, desirably 65% or less, and more desirably 60% or less of the groove width Wx of the first part 13. The groove width Wx of the first part 13 is desirably 10% or more, more desirably 12% or more, desirably 20% or less, and more desirably 18% or less of the tire axial direction width Tc of the crown region Cr.

[0040] The cross-sectional area of the third part 15 is desirably 20% to 80% of the cross-sectional area of the first part 13 and the cross-sectional area of the second part 14. Since the cross-sectional area of the third part 15 is 20% or more of the cross-sectional area of the first part 13 and the cross-sectional area of the second part 14, the drainage performance is enhanced. Since the cross-sectional area of the third part 15 is 80% or less of the cross-sectional area of the first part 13 and the cross-sectional area of the second part 14, the resistance to uneven wear performance is maintained. Each "cross-sectional area" is the maximum value of the area in the cross-section perpendicular to the respective center lines of each of the parts 13 to 15.

[0041] The first inclined portion 5 includes a pair of groove edges 19, 19 extending in its longitudinal direction. Each groove edge 19 forms the first part 13, the second part 14, and the third part 15. Each of the groove edges 19c forming the third part 15 is located closer to the groove center line 5n of the first inclined portion 5 than the groove edge 19a forming the first part 13 and the groove edge 19b forming the second part 14. Such a first inclined portion 5 can more effectively suppress slippage during grounding.

[0042] The angle θ1 of the first inclined portion 5 with respect to the tire circumferential direction is desirably 45 degrees or less. Since the angle θ1 of the first inclined portion 5 is 45 degrees or less, smooth movement of water in the groove due to the rotation of the tire 1 is ensured. For this reason, the angle θ1 of the first inclined portion 5 is more desirably 40 degrees or less. The angle θ1 of the first inclined portion 5 is the angle at the intermediate position 5c in the tire circumferential direction of the first inclined portion 5.

[0043] The second inclined portion 6 is located on the trailing side in the tire rotation direction N with respect to the first inclined portion 5. For this reason, it is desirable that the angle θ2 of the second inclined portion 6 with respect to the tire circumferential direction be smaller than the angle θ1 of the first inclined portion 5. Thereby, the smoothness of the water flow within the second inclined portion 6 is enhanced, and the drainage performance can be further improved. From such a viewpoint, the angle θ2 of the second inclined portion 6 is desirably 30 degrees or less, and more desirably 25 degrees or less. The angle θ2 of the second inclined portion 6 is the angle at the intermediate position 6c in the tire circumferential direction of the second inclined portion 6.

[0044] The angle θ1 of the first inclined portion 5 and the angle θ2 of the second inclined portion 6 are each desirably 5 degrees or more. Thereby, a decrease in the rigidity in the tire circumferential direction in the vicinity of the first inclined portion 5 and the second inclined portion 6 can be suppressed. For this reason, the angle θ1 of the first inclined portion 5 and the angle θ2 of the second inclined portion 6 are each more desirably 10 degrees or more.

[0045] The groove width W2 of the second inclined portion 6, for example, becomes smaller from the first inclined portion 5 side toward the second end 9. Such a second inclined portion 6 maintains high resistance to uneven wear performance. In this embodiment, the groove width W2 of the second inclined portion 6 gradually decreases from the first inclined portion 5 side toward the second end 9. Note that the second inclined portion 6 is not limited to such a mode. For example, a mode in which the groove width W2 decreases stepwise toward the second end 9 may also be acceptable. Also, the groove width W2 of the second inclined portion 6 is desirably smaller than the groove width Wy of the second portion 14, for example, and may further be the same from the first inclined portion 5 side toward the second end 9.

[0046] Since the second inclined portion 6 is arranged on the trailing side in the tire rotation direction N with respect to the first inclined portion 5, particularly when traveling straight, the slip at the time of grounding of the first inclined portion 5 is transmitted significantly. For this reason, it is desirable that the average groove width (not shown) of the second inclined portion 6 is formed smaller than the average groove width (not shown) of the first inclined portion 5. Thereby, the second inclined portion 6 receives the slip of the first inclined portion 5, enhancing the uneven wear resistance performance. The average groove width of the first inclined portion 5 is a value obtained by dividing the groove area of the first inclined portion 5 by the total length of the first inclined portion 5. The average groove width of the second inclined portion 6 is a value obtained by dividing the groove area of the second inclined portion 6 by the total length of the second inclined portion 6.

[0047] In order to effectively exhibit the above-described action, it is desirable that the groove width Wd at the intermediate position 6c of the second inclined portion 6 is formed smaller than the groove width Wz of the third portion 15. The groove width Wd of the second inclined portion 6 is desirably 20% or more of the groove width Wz of the third portion 15, more desirably 30% or more, desirably 80% or less, and more desirably 70% or less.

[0048] FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1 (cross-sectional view of the first groove 3). As shown in FIG. 3, in this embodiment, the groove depth D2 of the second inclined portion 6 is formed smaller than the groove depth D1 of the first inclined portion 5. Such a second inclined portion 6 further effectively exhibits the above-described action. In this specification, the "groove depth" is the maximum groove depth within the groove.

[0049] If the groove depth D2 of the second inclined portion 6 is excessively smaller than the groove depth D1 of the first inclined portion 5, there is a possibility that the drainage performance may deteriorate. For this reason, the groove depth D2 of the second inclined portion 6 is desirably 30% or more, more desirably 40% or more, desirably 90% or less, and more desirably 80% or less of the groove depth D1 of the first inclined portion 5.

[0050] Although not particularly limited, in the present embodiment, the groove depth Da of the first portion 13 is formed to be smaller than the groove depth Db of the second portion 14. It is the same as that. Further, the groove depth Dc of the third portion 15 is formed to be smaller than, for example, the groove depth Da of the first portion 13 and the groove depth Db of the second portion 14. Note that the groove depth Da of the first portion 13 may be the same as the groove depth Db of the second portion 14, for example.

[0051] FIG. 4 is a developed view of the tread portion 2. As shown in FIG. 2, in the present embodiment, the second groove 4 is inclined in the same direction as the first inclined portion 5. The second groove 4 extends continuously, for example, from the inner end 4i toward the outside in the tire axial direction in the direction opposite to the first tire circumferential direction F.

[0052] The inner end 4i of the second groove 4 is located, for example, within the crown region Cr. Such a second groove 4 further enhances the drainage performance. The distance Lb in the tire axial direction between the inner end 4i and the tire equator C is desirably 20% or more of the width Tc in the tire axial direction of the crown region Cr, more desirably 25% or more, desirably 40% or less, and more desirably 35% or less.

[0053] The inner end 4i of the second groove 4 is, for example, a closed end that is not connected to other grooves. Thereby, a local decrease in the rigidity of the crown region Cr is suppressed, and the uneven wear resistance performance is improved. In the present embodiment, the inner end 4i of the second groove 4 is not connected to the sipe either.

[0054] In the present embodiment, the outer end 4e of the second groove 4 in the tire axial direction is located in the shoulder region Sh. Thereby, since the length of the second groove 4 is ensured to be large, the drainage performance is improved. In order to enhance the uneven wear resistance performance, the outer end 4e of the second groove 4 of the present embodiment is displaced in the tire axial direction from the first end 8 and the second end 9 of the first groove 3. Although not particularly limited, the outer end 4e of the second groove 4 is located, for example, inside the first end 8 in the tire axial direction.

[0055] The angle θ3 of the second groove 4 with respect to the tire circumferential direction is preferably the same as the angle θ1 of the first inclined portion 5. Thereby, since the change in the length in the tire circumferential direction of the tread surface 2a between the second groove 4 and the first inclined portion 5 is suppressed, the uneven wear resistance performance is improved. The "same" includes not only the case where the absolute value of the difference between the angle θ3 of the second groove 4 and the angle θ1 of the first inclined portion 5 is 0 degree, but also modes of 5 degrees or less, or 10 degrees or less.

[0056] In order to effectively exhibit such an action, the angle θ3 of the second groove 4 is preferably 5 degrees or more, more preferably 10 degrees or more, preferably 45 degrees or less, and more preferably 40 degrees or less. The angle θ3 of the second groove 4 is the angle at the intermediate position 4c in the tire axial direction of the second groove 4.

[0057] The second groove 4 includes an outer portion 20 including an outer end 4e, an inner portion 21 including an inner end 4i, and an intermediate portion 22 connecting the outer portion 20 and the inner portion 21. The outer portion 20, the inner portion 21, and the intermediate portion 22 are each formed to include an equal-width portion 23 extending with the same groove width. The total length of the equal-width portion 23 of the outer portion 20 is 80% or more of the total length of the outer portion 20. The total length of the equal-width portion 23 of the inner portion 21 is 80% or more of the total length of the inner portion 21. The total length of the equal-width portion 23 of the intermediate portion 22 is 80% or more of the total length of the intermediate portion 22.

[0058] The groove width Wt of the intermediate portion 22 is formed to be smaller than the groove width Wr of the outer portion 20 and the groove width Ws of the inner portion 21. Thereby, the slip at the time of grounding is suppressed and the uneven wear resistance performance is improved.

[0059] Although not particularly limited, the groove width Wt of the intermediate portion 22 is preferably 35% or more of the groove width Wr of the outer portion 20, more preferably 40% or more, preferably 55% or less, and more preferably 50% or less. The groove width Wr of the outer portion 20 is preferably 10% or more of the width Tc in the tire axial direction of the crown region Cr, more preferably 12% or more, preferably 20% or less, and more preferably 18% or less.

[0060] The second groove 4 includes a pair of groove edges 25, 25 extending in its longitudinal direction. Each groove edge 25 forms an outer portion 20, an inner portion 21, and an intermediate portion 22. Each of the groove edges 25 forming the intermediate portion 22 is located closer to the groove center line 4n of the second groove 4 than the groove edge 25 forming the outer portion 20 and the groove edge 25 forming the inner portion 21. Such a second groove 4 can more effectively suppress slippage during grounding.

[0061] FIG. 5(a) is a developed view of the tread portion 2 of another embodiment. FIG. 5(b) is a cross-sectional view taken along line B-B of FIG. 5(a). The same components as those of the tread portion 2 in this embodiment may be denoted by the same reference numerals and detailed descriptions thereof may be omitted. As shown in FIG. 5, in this embodiment, the inner end 4i of the second groove 4 communicates with the second inclined portion 6. Such a second groove 4 enhances drainage performance.

[0062] The groove depth D2a of the connection portion 6j of the second inclined portion 6 with the second groove 4 is smaller than the groove depth D3 of the second groove 4. The groove depth D2a of the connection portion 6j is preferably 20% or more, more preferably 30% or more, preferably 80% or less, and more preferably 70% or less of the groove depth D3 of the second groove 4. Such a connection portion 6j maintains high resistance to uneven wear. The groove depth D2a of the connection portion 6j is, for example, the same as the maximum groove depth D2 of the second inclined portion 6.

[0063] FIG. 6 is an enlarged view of the first groove 3 of another embodiment. The same components as those of the first groove 3 in this embodiment may be denoted by the same reference numerals and detailed descriptions thereof may be omitted. As shown in FIG. 6, in this embodiment, in the third portion 15, the groove edge 19i on the trailing side in the tire rotation direction N is arranged so as to approach the groove edge 19e in the tire rotation direction N.

[0064] As described above, one embodiment of the tire of the present invention has been described in detail. However, the present invention is not limited to the above specific embodiments and can be implemented in various forms.

Example

[0065] Tires having the basic pattern of FIG. 1 were prototyped, and the drainage performance and uneven wear resistance performance of each prototype tire were tested. The common specifications and test methods for each prototype tire are as follows.

[0066] <Drainage performance> Using an inside drum tester with a well-known structure having a diameter of 3 m, the braking force was measured when each prototype tire was run on the drum surface with a water depth of 5.0 mm. The braking force was measured twice for each prototype tire when the peripheral speed of the drum was 100 km / h and 70 km / h, and the difference between these was calculated. The results are shown in an index with the difference in braking force of Comparative Example 1 set to 100. The smaller the numerical value, the higher the braking force during wet running and the better the drainage performance. Tire size: 120 / 70ZR17 Vertical load: 1.5 kN Internal pressure: 250 kPa

[0067] <Uneven wear resistance performance> Each prototype tire was mounted on the front wheel of the following test vehicle. The test rider drove this vehicle on a dry asphalt circuit course. After the run, the test rider visually evaluated the uneven wear resistance performance based on the uneven wear that occurred on the tire. The results are shown in a score with Comparative Example 1 set to 100. The smaller the numerical value, the better. Tire size: 120 / 70ZR17 (front wheel), 180 / 55ZR17 (rear wheel) Rim size: MT3.50×17 (front wheel), MT5.50×17 (rear wheel) Internal pressure: 250 kPa (front wheel), 290 kPa (rear wheel) Displacement: 1300 cc Travel distance: 5000 km Average speed: 120 km / h All the rear tires have the same specifications. Test vehicle: An on-road motorcycle with a displacement of 1300 cc The test results are shown in Table 1. In Table 1, "A" indicates that the inner end is located inside the tire axis direction from the first end and outside the tire axis direction from the second end. "B" indicates that the inner end is located more inward in the tire axis direction than the first end and the second end. "Tc" and "D1" of the comparative example and the example are the same.

[0068]

Table 1

[0069] As a result of the test, it was confirmed that the tire of the example has excellent drainage performance and resistance to uneven wear.

Explanation of Signs

[0070] 1 Motorcycle tire 3 First groove 4 Second groove 4i Inner end of the second groove 5 First inclined portion 6 Second inclined portion 8 First end 9 Second end C Tire equator F First tire circumferential direction Te Tread end

Claims

1. A motorcycle tire having a tread portion, The tread portion is provided with a first groove and a second groove having a length in a tire circumferential direction smaller than that of the first groove, The first groove includes a first inclined portion and a second inclined portion, The first inclined portion extends from a first end on a tread end side toward a tire equator side in a first tire circumferential direction at an incline, the second inclined portion is connected to the first inclined portion and inclined in the first tire circumferential direction toward the tread end side to extend to a second end, The second end is a closed end that is not connected to any other groove. The second groove extends obliquely with respect to the tire circumferential direction and has an inner end in the tire axial direction on the tire equator side, the inner end of the second groove is located axially inward of the first end and the second end of the first groove, a portion of the first groove is located on a tire equator, and the second inclined portion of the first groove is continuously inclined from the second end toward the tire equator side in a direction opposite to the first tire circumferential direction, The second groove is inclined in the same direction as the first inclined portion. Tires for motorcycles.

2. The tread portion has a crown region that comes into contact with the ground during straight-line driving, The motorcycle tire according to claim 1 , wherein at least a portion of each of the first inclined portion and the second inclined portion is located within the crown region.

3. A motorcycle tire as described in claim 2, wherein the first end of the first inclined portion or the second end of the second inclined portion is located outside the crown region in the tire axial direction.

4. A motorcycle tire as described in claim 2 or 3, wherein the inner end of the second groove is located within the crown region.

5. A motorcycle tire as described in any one of claims 2 to 4, wherein an axially outer end of the second groove is located axially outside the crown region.

6. A motorcycle tire as described in any one of claims 1 to 5, wherein the inner end of the second groove is a closed end that is not connected to other grooves.

7. A tire for a motorcycle having a tread portion, The tread portion is provided with a first groove and a second groove having a length in a tire circumferential direction smaller than that of the first groove, The first groove includes a first inclined portion and a second inclined portion, The first inclined portion extends from a first end on a tread end side toward a tire equator side in a first tire circumferential direction at an incline, The second inclined portion is connected to the first inclined portion, and is inclined in the first tire circumferential direction toward the tread end side and extends to a second end, The second end is a closed end that is not connected to other grooves, The second groove extends while being inclined with respect to the tire circumferential direction, and has an inner end in the tire axial direction on the tire equator side, The inner end of the second groove is located on the inner side in the tire axial direction than the first end and the second end of the first groove, A part of the first groove is located on the tire equator, and the second inclined portion of the first groove continuously inclines in the direction opposite to the first tire circumferential direction from the second end toward the tire equator side, The inner end of the second groove communicates with the second inclined portion, A tire for a motorcycle.

8. The groove depth of the connection portion of the second inclined portion with the second groove is smaller than the groove depth of the second groove. The tire for a motorcycle according to claim 7.

9. The groove depth of the connection portion of the second inclined portion is 20% to 80% of the groove depth of the second groove. The tire for a motorcycle according to claim 8.

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