Motorcycle tires

Abstract

To provide a tire for a motor cycle, further improved in drainage performance without impairing uneven abrasion resistance performance.SOLUTION: A 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 first oblique portion 5 includes a first portion, a second portion and a third portion joining the first portion to the second portion. A groove width of the third portion is smaller than a groove width of the first portion and a groove width of the second portion. A second oblique portion 6 is joined to the first oblique portion 5, and is extended obliquely in the first tire circumferential direction F toward the tread end Te side.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The following Patent Document 1 describes a motorcycle tire provided with an inclined groove including a first portion on the crown region side, a second portion on the shoulder region side, and a third portion connecting the first portion and the second portion. The third portion has a groove width smaller than the first portion and the second portion. Such a third portion is said to enhance uneven wear resistance by suppressing slippage of the first portion and the second portion when the tire contacts the ground, and to suppress a decrease in drainage performance by the first portion and the second portion, which have a relatively large groove width. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-142586 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the tire of Patent Document 1 has room for further improvement in terms of drainage performance.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a motorcycle tire having improved drainage performance without impairing uneven wear resistance. [Means for solving the problem]

[0006] The present invention relates to a motorcycle tire having a tread portion, wherein a first groove is provided in the tread portion, the first groove including a first inclined portion and a second inclined portion, the first inclined portion extending at an incline in a first tire circumferential direction from a first end on the tread end side toward the tire equator side, the first inclined portion including a first portion including the first end, a second portion connected to the second inclined portion, and a third portion connecting the first portion and the second portion, the groove width of the third portion being smaller than the groove width of the first portion and the groove width of the second portion, and the second inclined portion is connected to the first inclined portion and extends at an incline in the first tire circumferential direction toward the tread end side.

[0007] In the motorcycle tire according to the present invention, it is preferable that a groove width of the second inclined portion becomes smaller toward the first tire circumferential direction.

[0008] In the motorcycle tire according to the present invention, it is preferable that a groove width at a middle position in the tire circumferential direction of the second inclined portion is smaller than a groove width of the third portion.

[0009] In the motorcycle tire according to the present invention, it is preferable that a groove depth of the second inclined portion is smaller than a groove depth of the first inclined portion.

[0010] In the motorcycle tire according to the present invention, it is preferable that the groove depth of the second inclined portion is 30% to 90% of the groove depth of the first inclined portion.

[0011] In the motorcycle tire according to the present invention, it is preferable that the tread portion has a crown region that comes into contact with the ground during straight-ahead driving, the second inclined portion has a second end that is a closed end portion that is not connected to other grooves, and the first end or the second end is located axially outside the crown region.

[0012] In the motorcycle tire according to the present invention, it is preferable that the cross-sectional area of ​​the third portion is 20% to 80% of the cross-sectional area of ​​the first portion and the cross-sectional area of ​​the second portion.

[0013] In the motorcycle tire according to the present invention, it is preferable that a tire rotation direction is specified for the tread portion, and that the tire rotation direction is opposite to the first tire circumferential direction.

[0014] In the motorcycle tire according to the present invention, an angle of the second inclined portion with respect to the tire circumferential direction is preferably 5 to 30 degrees.

[0015] In the motorcycle tire according to the present invention, it is preferable that an average groove width of the second inclined portion is smaller than an average groove width of the first inclined portion. Effect of the Invention

[0016] By adopting the above-mentioned configuration, the motorcycle tire of the present invention can further improve the drainage performance without impairing the uneven wear resistance performance. [Brief description of the drawings]

[0017] [Figure 1] 1 is a development view of a tread portion showing one embodiment of a tire of the present invention. [Diagram 2] FIG. 2 is an enlarged view of the first groove of FIG. [Diagram 3] 2 is a cross-sectional view taken along line AA in FIG. 1. [Figure 4] FIG. [Diagram 5] FIG. 4(a) is a development view of a tread portion of another embodiment, and FIG. 4(b) is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 11 is a plan view of a first groove in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0019] As shown in FIG. 1, a first groove 3 is provided in a tread portion 2 of a tire 1 of this embodiment.

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

[0021] Fig. 2 is an enlarged view of the first groove 3 in Fig. 1. As shown in Fig. 2, the first inclined portion 5 of the present embodiment includes a first portion 13 including the first end 8, a second portion 14 continuing to the second inclined portion 6, and a third portion 15 connecting the first portion 13 and the second portion 14.

[0022] In this embodiment, the groove width Wz of the third portion 15 is formed to be smaller than the groove width Wx of the first portion 13 and the groove width Wy of the second portion 14. In such a first inclined portion 5, the third portion 15 suppresses slippage of the first portion 13 and the second portion 14 when they contact the ground, thereby improving uneven wear resistance, and the first portion 13 and the second portion 14, which have relatively large groove widths, suppress a decrease in drainage performance.

[0023] 1, a tire rotation direction N is specified for the tread portion 2. In this 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 rear side of the tire rotation direction N.

[0024] The tread portion 2 has a crown region Cr that comes into contact with the ground during straight running, and a pair of shoulder regions Sh arranged on both sides of the crown region Cr in the tire axial direction. The term "comes into contact with the ground during straight running" means that the tire 1 is mounted on a regular rim (not shown), filled with regular internal pressure, and in a regular state where no load is applied, and the tire is placed on the ground on a flat surface with a camber angle of 0° under a regular load. The developed width Tc of the crown region Cr is 20% to 30% of the tread developed width TWe. The outer edge of each shoulder region Sh in the tire axial direction is the tread end Te. Unless otherwise specified, the dimensions of each part of the tire 1 in this specification are values ​​measured in the regular state. 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 flat surface.

[0025] The "genuine rim" is a rim that is defined for each tire by a standard system including the standard on which tire 1 is based, for example, a standard rim in the case of JATMA, a "Design Rim" in the case of TRA, and a "Measuring Rim" in the case of ETRTO.

[0026] The "normal internal pressure" is the air pressure determined for each tire by each standard in a standard system including the standard on which tire 1 is based, and is the maximum air pressure in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and "INFLATION PRESSURE" in the case of ETRTO.

[0027] The "normal load" is the load determined for each tire by each standard in the standard system including the standard on which the tire is based. In the case of JATMA, it is the "maximum load capacity." In the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." In the case of ETRTO, it is the "LOAD CAPACITY."

[0028] In the tread portion 2 of this embodiment, second grooves 4 are provided that are shorter in the tire circumferential direction than the first grooves 3. The second grooves 4 extend continuously from their axially inner ends 4i toward the tire rotation direction N. The inner ends 4i of the second grooves 4 are the axially innermost end portions of groove center lines 4n of the second grooves 4 described later.

[0029] In this embodiment, the first grooves 3 and the second grooves 4 are provided on both sides of the tire equator C. The first grooves 3 are, for example, arranged alternately in the tire circumferential direction on either side of the tire equator C. The second grooves 4 are, for example, arranged alternately in the tire circumferential direction on either side of the tire equator C. Furthermore, the first grooves 3 and the second grooves 4 are arranged alternately in the tire circumferential direction on both sides of the tire equator C.

[0030] The first inclined portion 5 of the first groove 3 is, for example, continuously inclined in the first tire circumferential direction F from the first end 8 toward the tire equator C. Such a first inclined portion 5 further smooths the movement within the groove, improving drainage performance.

[0031] The second inclined portion 6 of the first groove 3 is, for example, continuously inclined from the first inclined portion 5 toward the tread end Te side in the first tire circumferential direction F. The second inclined portion 6 has a second end 9 on the tread end Te side.

[0032] The second end 9 is, for example, a closed end that is not connected to other grooves. This suppresses a decrease in the rigidity of the tread portion 2 in the vicinity of the second end 9, and thus improves uneven wear resistance. Since the second end 9 of this embodiment is not connected to a sipe (not shown), the above-mentioned action is more effectively exerted. In this specification, a groove is a groove-shaped body with a groove width of 1.5 mm or more. Also, a sipe is a cut-shaped body with a width of less than 1.5 mm. The first end 8 is, for example, a closed end that is not connected to other grooves and sipes.

[0033] At least a portion of each of the first inclined portion 5 and the second inclined portion 6 is located within the crown region Cr. This allows water in the crown region Cr located on the tire equator C side, which is difficult to drain, to accumulate in the first inclined portion 5 and the second inclined portion 6 and be drained.

[0034] 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, on the outer side of the crown region Cr in the tire axial direction. This allows water in the first groove 3 to be discharged to the outer side of the crown region Cr even during straight running, improving drainage performance. In this 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 this embodiment. The second end 9 may be located in the shoulder region Sh.

[0035] 2, for example, a portion of the first groove 3 is located on the tire equator C. In this embodiment, the first groove 3 is formed so as to straddle the tire equator C. The first groove 3 in this embodiment extends so that a second portion 14 and a second inclined portion 6, which will be described later, are located on the tire equator C.

[0036] The first groove 3 has a separation point 3a that is the farthest from the first end 8 in the tire axial direction. In this embodiment, the separation point 3a is located on the opposite side of the tire axial direction from the first end 8 across the tire equator C. The distance La in the tire axial direction between the separation point 3a and the tire equator C is, for example, preferably 15% or less of the developed width Tc of the crown region Cr, more preferably 10% or less, and even more preferably 5% or less. Since the distance La is 15% or less of the developed width Tc, water on the tire equator C, which is the most difficult to drain, can be effectively removed. In this embodiment, the first inclined portion 5 and the second inclined portion 6 are separated by the separation point 3a. The separation point 3a may be located, for example, on one side of the tire axial direction from the tire equator C, which is the same as the first end 8.

[0037] The first portion 13, the second portion 14, and the third portion 15 are, for example, in a plan view of the tread, in a circular arc shape convex toward the tire equator C. Such first portion 13 and second portion 14 smooth the flow of water in the grooves to improve drainage performance, and also suppress a decrease in rigidity of the tread portion 2 to maintain high uneven wear resistance.

[0038] Each of the first portion 13, the second portion 14, and the third portion 15 includes a constant width portion 16 that extends with the same groove width. Such a constant 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 this embodiment, the total length of the constant 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 constant 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 constant 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 constant width portion 16.

[0039] The groove width Wx of the first portion 13 is substantially the same as the groove width Wy of the second portion 14. The term "substantially the same" refers to an embodiment 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.

[0040] In order to suppress slippage when contacting the ground and improve drainage performance, the groove width Wz of the third portion 15 is preferably 35% or more, more preferably 40% or more, and more preferably 65% ​​or less, and more preferably 60% or less of the groove width Wx of the first portion 13. The groove width Wx of the first portion 13 is preferably 10% or more, more preferably 12% or more, and more preferably 20% or less, and more preferably 18% or less of the tire axial width Tc of the crown region Cr.

[0041] The cross-sectional area of ​​the third portion 15 is preferably 20% to 80% of the cross-sectional area of ​​the first portion 13 and the cross-sectional area of ​​the second portion 14. Since the cross-sectional area of ​​the third portion 15 is 20% or more of the cross-sectional area of ​​the first portion 13 and the cross-sectional area of ​​the second portion 14, the drainage performance is improved. Since the cross-sectional area of ​​the third portion 15 is 80% or less of the cross-sectional area of ​​the first portion 13 and the cross-sectional area of ​​the second portion 14, the uneven wear resistance performance is maintained. Each "cross-sectional area" is the maximum area in a cross section perpendicular to the center line of each of the portions 13 to 15. The cross-sectional area of ​​the third portion 15 is more preferably 30% or more of the cross-sectional area of ​​the first portion 13 and the cross-sectional area of ​​the second portion 14, even more preferably 40% or more, even more preferably 70% or less, and even more preferably 60% or less.

[0042] The first inclined portion 5 includes a pair of groove edges 19, 19 extending in the longitudinal direction thereof. Each groove edge 19 forms a first portion 13, a second portion 14, and a third portion 15. The groove edge 19c forming the third portion 15 is located closer to the groove center line 5n of the first inclined portion 5 than the groove edge 19a forming the first portion 13 and the groove edge 19b forming the second portion 14. Such a first inclined portion 5 can further suppress slippage when touching the ground.

[0043] 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 grooves 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 of the first inclined portion 5 in the tire circumferential direction.

[0044] The second inclined portion 6 is located on the rear side of the first inclined portion 5 in the tire rotational direction N. For this reason, it is desirable to make the angle θ2 of the second inclined portion 6 with respect to the tire circumferential direction smaller than the angle θ1 of the first inclined portion 5. This increases the smoothness of the flow of water in the second inclined portion 6, and further improves the drainage performance. From this perspective, 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 of the second inclined portion 6 in the tire circumferential direction.

[0045] It is preferable that the angle θ1 of the first inclined portion 5 and the angle θ2 of the second inclined portion 6 are each 5 degrees or more. This makes it possible to suppress a decrease in the rigidity in the tire circumferential direction near the first inclined portion 5 and the second inclined portion 6. For this reason, it is more preferable that the angle θ1 of the first inclined portion 5 and the angle θ2 of the second inclined portion 6 are each 10 degrees or more.

[0046] In this embodiment, the groove width W2 of the second inclined portion 6 is smaller from the first inclined portion 5 side toward the second end 9. Such a second inclined portion 6 maintains high uneven wear resistance. In this embodiment, the groove width W2 of the second inclined portion 6 is gradually decreased from the first inclined portion 5 side toward the second end 9. Note that the second inclined portion 6 is not limited to such an embodiment, and may be, for example, an embodiment in which the groove width W2 is stepped toward the second end 9. In addition, the groove width W2 of the second inclined portion 6 is preferably smaller than the groove width Wy of the second portion 14, for example, and may be the same from the first inclined portion 5 side toward the second end 9.

[0047] Since the second inclined portion 6 is disposed on the rear side of the first inclined portion 5 in the tire rotation direction N, the slippage of the first inclined portion 5 at the time of contact with the ground is largely transmitted, especially during straight running. 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. As a result, the second inclined portion 6 receives the slippage of the first inclined portion 5, improving 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.

[0048] In order to effectively exert the above-mentioned 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, preferably 80% or less, and even more desirably 70% or less.

[0049] 3 is a cross-sectional view taken along line AA in 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 to be smaller than the groove depth D1 of the first inclined portion 5. Such a second inclined portion 6 further effectively exerts the above-mentioned action. In this specification, the "groove depth" is the maximum groove depth within the groove.

[0050] Drainage performance may be reduced 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. For this reason, the groove depth D2 of the second inclined portion 6 is preferably, for example, 30% or more of the groove depth D1 of the first inclined portion 5, more preferably 40% or more, more preferably 90% or less, and even more preferably 80% or less.

[0051] Although not particularly limited, in this 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. 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. The groove depth Da of the first portion 13 may be the same as the groove depth Db of the second portion 14.

[0052] FIG. 4 is a development view of the tread portion 2. As shown in FIG. 2, the second groove 4 extends, for example, at an incline with respect to the tire circumferential direction, and has an inner end 4i in the tire axial direction on the tire equator C side. The inner end 4i of the second groove 4 in this embodiment is located axially inside 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 and drain water between the road surface and the tread surface 2a in the inner region of the tire axial direction of the tread portion 2, which is relatively difficult to drain, during running on a wet road surface. Therefore, the drainage performance is improved. In addition, since the inner end 4i is offset in the tire axial direction from the first end 8 and the second end 9, a local decrease in the rigidity of the tread portion 2 is suppressed, and uneven wear resistance is improved.

[0053] In this embodiment, the second grooves 4 are inclined in the same direction as the first inclined portions 5. The second grooves 4 extend continuously from the inner ends 4i to the outside in the tire axial direction in the opposite direction to the first tire circumferential direction F, for example.

[0054] For example, the inner end 4i of the second groove 4 is located within the crown region Cr. Such second groove 4 further improves drainage performance. The axial distance Lb between the inner end 4i and the tire equator C is preferably 20% or more of the axial width Tc of the crown region Cr, more preferably 25% or more, more preferably 40% or less, and even more preferably 35% or less.

[0055] The inner end 4i of the second groove 4 is, for example, a closed end that is not connected to other grooves. This suppresses a local decrease in the rigidity of the crown region Cr, and improves uneven wear resistance. In this embodiment, the inner end 4i of the second groove 4 is not connected to the sipes.

[0056] In this embodiment, the axially outer ends 4e of the second grooves 4 are located in the shoulder region Sh. This ensures a large length of the second grooves 4, improving drainage performance. In order to improve uneven wear resistance, the outer ends 4e of the second grooves 4 in this embodiment are offset in the axial direction from the first ends 8 and second ends 9 of the first grooves 3. Although not particularly limited, the outer ends 4e of the second grooves 4 are, for example, positioned axially inward of the first ends 8.

[0057] It is desirable that the angle θ3 of the second groove 4 with respect to the tire circumferential direction is the same as the angle θ1 of the first inclined portion 5. This suppresses the change in the length of the tread surface 2a in the tire circumferential direction between the second groove 4 and the first inclined portion 5, thereby improving uneven wear resistance. The term "same" as used above includes cases 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 degrees, as well as cases where it is 5 degrees or less, or 10 degrees or less.

[0058] In order to effectively exert such an effect, the angle θ3 of the second groove 4 is preferably 5 degrees or more, more preferably 10 degrees or more, and is preferably 45 degrees or less, and even more preferably 40 degrees or less. The angle θ3 of the second groove 4 is the angle at the axial middle position 4c of the second groove 4.

[0059] 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 including a constant width portion 23 extending with the same groove width. The total length of the constant 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 constant 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 constant width portion 23 of the intermediate portion 22 is 80% or more of the total length of the intermediate portion 22.

[0060] The groove width Wt of the intermediate portion 22 is formed smaller than the groove width Wr of the outer portion 20 and the groove width Ws of the inner portion 21. This suppresses slippage when the tire comes into contact with the ground, improving uneven wear resistance.

[0061] Although not particularly limited, the groove width Wt of the intermediate portion 22 is preferably 35% or more, more preferably 40% or more, and more preferably 55% or less, and more preferably 50% or less of the groove width Wr of the outer portion 20. The groove width Wr of the outer portion 20 is preferably 10% or more, more preferably 12% or more, and more preferably 20% or less, and more preferably 18% or less of the tire axial width Tc of the crown region Cr.

[0062] The second groove 4 includes a pair of groove edges 25, 25 extending in the longitudinal direction. Each groove edge 25 forms an outer portion 20, an inner portion 21, and an intermediate portion 22. The groove edges 25 forming the intermediate portion 22 are each located closer to the groove center line 4n of the second groove 4 than the groove edges 25 forming the outer portion 20 and the groove edges 25 forming the inner portion 21. Such a second groove 4 can further suppress slippage during contact with the ground.

[0063] Fig. 5(a) is a development view of the tread portion 2 of another embodiment. Fig. 5(b) is a cross-sectional view taken along line BB in Fig. 5(a). The same components as those in the tread portion 2 of this embodiment are given the same reference numerals, and detailed description 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 second groove 4 improves drainage performance.

[0064] The groove depth D2a of the connecting 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 connecting portion 6j is preferably 20% or more of the groove depth D3 of the second groove 4, more preferably 30% or more, more preferably 80% or less, and even more preferably 70% or less. Such a connecting portion 6j maintains high uneven wear resistance. The groove depth D2a of the connecting portion 6j is, for example, the same as the maximum groove depth D2 of the second inclined portion 6.

[0065] Fig. 6 is an enlarged view of the first groove 3 of another embodiment. The same components as those of the first groove 3 of this embodiment are given the same reference numerals, and detailed description thereof may be omitted. As shown in Fig. 6, in this embodiment, in the third portion 15, the groove edge 19i on the rear side in the tire rotation direction N is disposed so as to approach the groove edge 19e in the tire rotation direction N.

[0066] Although the tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment and can be modified and carried out in various aspects. EXAMPLES

[0067] Tires with the basic pattern shown in Figure 1 were prototyped and the drainage performance and uneven wear resistance of each sample tire were tested. The common specifications and test methods for each sample tire are as follows:

[0068] <Drainage performance> The braking force was measured when each test tire was run on a drum surface with a water depth of 5.0 mm using a well-known inside drum testing machine with a diameter of 3 m. The braking force was measured twice for each test tire, at drum circumferential speeds of 100 km / h and 70 km / h, and the difference between these was calculated. The results are expressed as an index, with the difference in braking force of Comparative Example 1 set to 100. The smaller the value, the higher the braking force during wet running and the better the drainage performance. Tire size: 120 / 70ZR17 Vertical load: 1.5kN Internal pressure: 250kPa

[0069] <Resistant to uneven wear> Each sample 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 drive was completed, the test rider visually evaluated the uneven wear resistance performance based on the uneven wear that occurred on the tire. The results are shown as a score with Comparative Example 1 being 100. The smaller the value, the better the performance. Tire size: 120 / 70ZR17 (front wheel), 180 / 55ZR17 (rear wheel) Rim size: MT3.50 x 17 (front wheel), MT5.50 x 17 (rear wheel) Internal pressure: 250kPa (front wheels), 290kPa (rear wheels) Displacement: 1300cc Mileage: 5000km Average speed: 120km / h All rear tires are the same specification. Test vehicle: 1300cc on-road motorcycle Comparative Example 1 and Comparative Example 2 are embodiments in which the second inclined portion is not provided. "Wx" and "D1" are the same in the comparative example and the example. The test results are shown in Table 1.

[0070] [Table 1]

[0071] As a result of the test, it was confirmed that the tires of the examples had improved drainage performance without impairing uneven wear resistance. [Explanation of symbols]

[0072] 1. Motorcycle tires 3 First groove 5 1st slope 6 Second slope part 8 1st end 13 Part 1 14 Part 2 15 Part 3 C Tire Equator F First tire circumferential direction Te tread edge

Claims

1. A motorcycle tire having a tread portion, The tread portion is provided with a 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 first inclined portion includes a first portion including the first end, a second portion connected to the second inclined portion, and a third portion connecting the first portion and the second portion, a groove width of the third portion is smaller than a groove width of the first portion and a groove width of the second portion; the second inclined portion is connected to the first inclined portion and extends obliquely in the first tire circumferential direction toward the tread end side, The groove depth of the second inclined portion is smaller than the groove depth of the first inclined portion. Tires for motorcycles.

2. The motorcycle tire according to claim 1 , wherein a groove width of the second inclined portion decreases toward the first tire circumferential direction.

3. The motorcycle tire according to claim 1 or 2, wherein a groove width at a circumferential intermediate position of the second inclined portion is smaller than a groove width at the third portion.

4. A motorcycle tire as described in any one of claims 1 to 3, wherein the groove depth of the second inclined portion is 30% to 90% of the groove depth of the first inclined portion.

5. The tread portion has a crown region that comes into contact with the ground during straight-line driving, the second sloped portion has a second end that is a closed end that is not connected to any other groove; The motorcycle tire according to claim 1 , wherein the first end or the second end is located outside the crown region in the tire axial direction.

6. A motorcycle tire as described in any one of claims 1 to 5, wherein a cross-sectional area of ​​the third portion is 20% to 80% of the cross-sectional area of ​​the first portion and the cross-sectional area of ​​the second portion.

7. The tread portion has a specified tire rotation direction, The motorcycle tire according to claim 1 , wherein the tire rotation direction is opposite to the first tire circumferential direction.

8. A motorcycle tire as described in any one of claims 1 to 7, wherein an angle of the second inclined portion relative to the tire circumferential direction is 5 to 30 degrees.

9. A motorcycle tire as described in any one of claims 1 to 8, wherein the average groove width of the second inclined portion is smaller than the average groove width of the first inclined portion.

10. A motorcycle tire as described in any one of claims 1 to 9, wherein the groove width of the second inclined portion is smaller than the groove width of the second portion.

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