Tyre for motorcycles

Abstract

The present application improves the water drainage without impairing the resistance to eccentric wear and the resistance to vibration. A motorcycle tire (1) has a plurality of first transverse grooves (8) formed in a tread portion (2). The first transverse grooves (8) include a first groove portion (11) disposed in a crown portion (Cr), a second groove portion (12) disposed in a first shoulder portion (S1), and a third groove portion (13) connecting the first groove portion (11) and the second groove portion (12). The third groove portion (13) has a groove depth and a groove width smaller than those of the first groove portion (11) and the second groove portion (12). More than 80% of the length (L3) of the third groove portion (13) in the tire axial direction is disposed in the first shoulder portion (S1).

Description

Technical Field

[0001] This invention relates to motorcycle tires. Background Technology

[0002] Patent Document 1 describes a motorcycle tire with main grooves and secondary grooves on the tread surface. The main grooves include a first main groove and a second main groove located axially outward of the first main groove. The secondary grooves include open secondary grooves and semi-open secondary grooves. The open secondary grooves are configured such that one end connects to the first main groove and the other end connects to the second main groove.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-104329

[0004] Typically, to improve tire drainage, it is effective to incorporate long, wide grooves extending from the crown area of ​​the tread to the shoulder area within the contact patch. However, such grooves cause significant surface deformation of the tread upon contact with the ground, potentially leading to vibration and uneven wear during driving. This trend is particularly pronounced in bias-ply tires, which have lower tread rigidity than radial tires. Therefore, it is necessary to improve drainage without compromising resistance to uneven wear and vibration. Summary of the Invention

[0005] The present invention was made in view of the above-mentioned actual situation, and its purpose is to provide a motorcycle tire that can improve drainage performance without compromising wear resistance and vibration resistance.

[0006] The present invention provides a motorcycle tire having a tread portion comprising: a crown portion, which is a region of 50% of the tread width centered on the tire equator; and a first shoulder portion, which is a region outside the crown portion. A plurality of first lateral grooves are formed in the tread portion, each of the first lateral grooves comprising: a first groove portion disposed in the crown portion; a second groove portion disposed in the first shoulder portion; and a third groove portion connecting the first groove portion and the second groove portion. The groove depth and groove width of the third groove portion are respectively smaller than the groove depth and groove width of the first groove portion and the second groove portion. A portion of the third groove portion having a tire axial length of more than 80% is disposed in the first shoulder portion.

[0007] The preferred embodiment of the motorcycle tire of the present invention is that the first groove is configured not to cross the tire equator.

[0008] The motorcycle tires involved in this invention are preferably inclined in the same direction relative to the tire axial direction, wherein the first groove, the second groove and the third groove are inclined in the same direction.

[0009] The preferred embodiment of the motorcycle tire of the present invention is that the groove width of the third groove is 15% to 50% of the groove width of the first groove and the groove width of the second groove.

[0010] The preferred embodiment of the motorcycle tire of the present invention is that the groove depth of the third groove is 15% to 50% of the groove depth of the first groove and the groove depth of the second groove.

[0011] The preferred motorcycle tire of the present invention is that the first groove includes a first groove edge located on one side of the tire circumferential direction and a second groove edge located on the other side of the tire circumferential direction, the second groove includes a first groove edge located on one side of the tire circumferential direction and a second groove edge located on the other side of the tire circumferential direction, and the third groove is disposed near the second groove edge side of the first groove and near the first groove edge side of the second groove.

[0012] The preferred motorcycle tire of the present invention includes a first lateral groove that further comprises a fourth groove extending outward from the second groove toward the axial direction of the tire, wherein the groove depth and groove width of the fourth groove are smaller than the groove depth and groove width of the first groove and the second groove, respectively.

[0013] The motorcycle tires of the present invention are preferably in which the first groove, the second groove, the third groove and the fourth groove are inclined in the same direction relative to the tire axial direction.

[0014] The preferred embodiment of the motorcycle tire of the present invention is that the tread portion is designated with a tire rotation direction, and the first groove is located on the side that touches the ground first in the tire rotation direction than the second groove.

[0015] The preferred motorcycle tire of the present invention is a tire carcass with a bias-ply structure.

[0016] The present invention provides a pair of motorcycle tires, wherein the motorcycle tires described in any one of technical solutions 1 to 10 are used as a front wheel tire and a rear wheel tire, wherein the land ratio of the tread portion of the rear wheel tire is greater than the land ratio of the tread portion of the front wheel tire.

[0017] The motorcycle tire of the present invention, by adopting the above-described structure, can improve water drainage without compromising its resistance to uneven wear and vibration. Attached Figure Description

[0018] Figure 1 This is a unfolded view of the tread portion of an embodiment of the present invention.

[0019] Figure 2 (a) is Figure 1 An enlarged view of the first horizontal groove, (b) is... Figure 1 A sectional view along line AA.

[0020] Figure 3 yes Figure 1 BB line section view.

[0021] Figure 4 yes Figure 1 An enlarged view of the first horizontal groove.

[0022] Figure 5 This is a development diagram of the tread area according to another embodiment.

[0023] Explanation of reference numerals in the attached figures

[0024] 1...motorcycle tire; 2...tread; 8...first lateral groove; 11...first groove; 12...second groove; 13...third groove; Cr...crown; S1...first shoulder; L3...length of the third groove. Detailed Implementation

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0026] Figure 1 This is a developed view of the tread portion 2 of the motorcycle tire (hereinafter, sometimes simply referred to as "tire") 1 of the present invention. The tire 1 of this embodiment is suitable for road travel, such as on dry asphalt surfaces. However, the tire 1 of the present invention is not limited to such usage.

[0027] In this embodiment, the tread portion 2 includes: a crown portion Cr, which is a region representing 50% of the tread unfolded width TWe centered on the tire equator C; and a first shoulder portion S1, which is the region outside the crown portion Cr (to the left of the crown portion Cr in the figure). Additionally, the tread portion 2 includes a second shoulder portion S2, which is a region on the opposite side of the first shoulder portion S1 (to the right of the crown portion Cr in the figure), separated from the tire equator C. The crown portion Cr is the region that primarily contacts the ground during straight-line driving. The first shoulder portion S1 and the second shoulder portion S2 are the regions that primarily contact the ground during cornering. In this specification, the tread unfolded width TWe is the axial distance between the tread ends Te, Te, when the tread portion 2 is unfolded into a flat surface.

[0028] In this embodiment, the tread portion 2 has a plurality of first lateral grooves 8. Each first lateral groove 8 includes: a first groove portion 11 disposed on the crown portion Cr; a second groove portion 12 disposed on the first shoulder portion S1; and a third groove portion 13 connecting the first groove portion 11 and the second groove portion 12. Since the first lateral grooves 8 extend from the crown portion Cr to the first shoulder portion S1, they make contact with the ground over a large area from straight-line driving to turning driving, thus improving drainage performance. Furthermore, such first lateral grooves 8 are larger than the contact area during driving, so air trapped between the road surface and the groove is expelled from the non-contact area, thus improving noise reduction.

[0029] Figure 2 (a) is an enlarged view of the first horizontal groove 8. Figure 2 (b) is Figure 1 A sectional view along line AA. (e.g.) Figure 2 As shown, the groove depth D3 and groove width W3 of the third groove 13 are formed to be smaller than the groove depths D1 and D2 of the first groove 11 and the groove widths W1 and W2 of the second groove 12, respectively. This third groove 13 suppresses deformation of the first groove 11 and the second groove 12 and deflection of the first lateral groove 8 during driving, thus not compromising wear resistance or vibration resistance. Furthermore, in a wide tire 1 where the thickness of the rubber in the tread 2 is easily reduced, the third groove 13 improves handling stability, i.e., transition characteristics, during cornering. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in a tire 1 under normal conditions.

[0030] The aforementioned "normal state" refers to the unloaded state in which tire 1 is assembled on a normal rim (illustration omitted) and filled with normal internal pressure.

[0031] The aforementioned "standard rim" refers to the rim that specifies the size of each tire within a specification system that includes the tire's specifications. For example, if it is JATMA, it is a "standard rim"; if it is TRA, it is a "Design Rim"; and if it is ETRTO, it is a "Measuring Rim".

[0032] The aforementioned "standard internal pressure" refers to the air pressure specified for each tire within the specification system, including the specifications on which the tire is based. If it is JATMA, it is the "maximum air pressure"; if it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES"; and if it is ETRTO, it is "INFLATION PRESSURE".

[0033] The third groove 13, with more than 80% of its axial length L3, is disposed on the first shoulder S1. Therefore, during cornering, the rigidity of the first shoulder S1, which experiences a large camber thrust, can be maintained at a high level, suppressing vibrations and uneven wear during driving. Furthermore, this design reduces tire flex concentration, thus suppressing the formation of groove bottom cracks. In this embodiment, the third groove 13, with 100% of its axial length L3, is disposed on the first shoulder S1.

[0034] The tread pattern 2 of this embodiment is suitable for front wheel tires of motorcycles. Furthermore, the tread pattern 2 of this embodiment can also be used for rear wheel tires.

[0035] Figure 3 yes Figure 1 A BB-line sectional view. For example... Figure 3 As shown, the tread surface 2a of the tire 1 is curved into an arc shape that bulges outward in the radial direction of the tire, so as to obtain sufficient contact area even when turning with a large camber angle.

[0036] The tire 1 includes, for example, a tire carcass 6 mounted between the bead portions 4 and 4, and a belt layer 7 disposed on the radial outer side of the tire carcass 6 and inside the tread portion 2.

[0037] The tire carcass 6 is, for example, composed of two carcass plies 6A and 6B disposed radially inside and outside the tire. Each carcass ply 6A and 6B is, for example, formed in a bias-ply configuration where the carcass cords (not shown) are arranged at an angle of 30 to 45 degrees relative to the tire circumference. Each carcass ply 6A and 6B is made of a known material. Furthermore, compared to a radial tire 1, the bias-ply configuration tire 1 has the characteristics of lower rigidity and greater flexibility in the tread portion 2. In the present invention, due to the above-described structure, not only radial tires 1 but also bias-ply tires 1 can improve vibration resistance and resistance to uneven wear.

[0038] The belt layer 7 is composed of one or more belt cords formed by spirally winding belt cords (not shown) relative to the tire circumference at an angle of 5 degrees or less. In this embodiment, it is composed of one belt cord. The belt cord is made of a known material.

[0039] like Figure 1 As shown, the tread portion 2 of this embodiment is designated with the tire rotation direction N. Furthermore, in this embodiment, the first groove 11 is located on the side that touches the ground first, in the tire rotation direction N, compared to the second groove 12. Therefore, water in the first lateral groove 8 flows smoothly from the tire equator C side to the tread end Te side due to the rotation of the tire 1 and is thus discharged smoothly, improving drainage performance.

[0040] The first lateral groove 8 is provided on both sides of the tire equator C, for example. In this embodiment, the first lateral grooves 8 are alternately arranged in the tire circumferential direction, across the tire equator C. In this embodiment, the first lateral groove 8 is arranged not to cross the tire equator C. In other words, the first groove portion 11 is arranged not to cross the tire equator C. This arrangement maintains the tread rigidity near the tire equator C, which has a large ground pressure, and maintains resistance to uneven wear and vibration. In this specification, grooves and sipes of the same shape arranged on both sides of the tire equator C (hereinafter referred to as "grooves, etc.") are described as grooves, etc., on the side of the first tire shoulder S1, and descriptions of grooves, etc., on the side of the second tire shoulder S2 are sometimes omitted.

[0041] like Figure 2 As shown in (a), the first groove 11, the second groove 12, and the third groove 13 are inclined in the same direction relative to the tire axis, for example. This allows for smoother water flow within the first transverse groove 8. The angles θ1 of the first groove 11 relative to the tire axis, θ2 of the second groove 12 relative to the tire axis, and θ3 of the third groove 13 relative to the tire axis are each 20 to 60 degrees. The absolute values ​​of the differences between the angles θ1 of the first groove 11, θ2 of the second groove 12, and θ3 of the third groove 13 (|θ1-θ2|, |θ2-θ3|, |θ3-θ1|) are 30 to 50 degrees. In this specification, the angles θ1 to θ3 of each groove 11 to 13 are the average of their maximum and minimum values.

[0042] The first groove 11 includes, for example, a first groove edge 11e located on one side of the tire circumferential direction (lower side in the figure) and a second groove edge 11i located on the other side of the tire circumferential direction (upper side in the figure). The second groove edge 11i of the first groove 11 includes, for example, a bend F, the angle α of which varies locally with respect to the tire axial direction via the bend F. The second groove edge 11i includes an outer portion 15 located outside the tire axial direction of the bend F and an inner portion 16 located inside the tire axial direction of the bend F. The first groove edge 11e of the first groove 11 does not have a bend and extends smoothly. The first groove edge 11e and the second groove edge 11i are connected, for example, to the inner end 8i of the first lateral groove 8. In this specification, the inner end 8i is the innermost end of the groove centerline 8c of the first lateral groove 8 in the tire axial direction. In addition, in this specification, the inner end 8i includes an arc portion with a radius of curvature r of 2 mm or less.

[0043] The first groove edge 11e and the outer side portion 15, for example, include an arc-shaped portion R that protrudes to either side in the tire circumferential direction. In this embodiment, the arc-shaped portion R of the first groove edge 11e and the outer side portion 15 is formed to protrude towards the rear contact side in the tire rotation direction N. The inner side portion 16 of this embodiment extends in a straight line.

[0044] Figure 4 This is an enlarged view of the first horizontal groove, 8. (See image below.) Figure 4 As shown, the angle α1 of the inner side portion 16 relative to the tire axial direction is formed to be greater than the angle α2 of the first groove edge 11e relative to the tire axial direction. In other words, the first groove 11 formed in the inner side portion 16 is formed such that the groove width w decreases towards the inner end 8i. Such a first groove 11 suppresses the reduction of tread rigidity of the crown portion Cr and can smoothly guide water and air into the first groove 11 by utilizing the rotation of the tire 1.

[0045] The second groove 12 includes, for example, a first groove edge 12e located on one side of the tire circumferential direction and a second groove edge 12i located on the other side of the tire circumferential direction. The first groove edge 12e and the second groove edge 12i each include, for example, an arcuate portion R protruding to either side of the tire circumferential direction. In this embodiment, the arcuate portion R of the first groove edge 12e and the second groove edge 12i is formed to protrude towards the rear contact side in the tire rotation direction N.

[0046] In this embodiment, the third groove 13 is positioned near the second groove edge 11i of the first groove 11 and near the first groove edge 12e of the second groove 12. In other words, the first transverse groove 8 in this embodiment is formed such that an imaginary line 12k, formed by smoothly extending the groove center line 12c of the second groove 12 inward toward the tire axial direction, is located on the rear contact side relative to the tire rotation direction N of the third groove 13. In this configuration, since the position of deformation of the first transverse groove 8 upon contact with the ground can be offset in the tire circumferential direction, the generation of groove bottom cracks can be suppressed.

[0047] The third groove 13 includes, for example, a first groove edge 13e located on one side of the tire circumferential direction and a second groove edge 13i located on the other side of the tire circumferential direction. The first groove edge 13e of the third groove 13 is formed, for example, to include a crank-shaped portion K extending in a crank-like manner toward the second groove edge 13i side of the third groove 13. The second groove edge 13i of the third groove 13 is formed to include, for example, an arc-shaped portion R protruding toward the side opposite to the second groove edge 11i of the first groove 11.

[0048] In this specification, the third groove 13 is defined as the portion between the first groove 11 and the second groove 12 where the groove width w decreases sharply. The third groove 13 refers to the portion where the change in groove width w relative to the unit length of the groove is 0.4 or more.

[0049] like Figure 2As shown in (a), the groove width W3 of the third groove 13 is preferably 15% or more, more preferably 20% or more, more preferably 50% or less, and more preferably 45% or less, of the groove width W1 of the first groove 11 and the groove width W2 of the second groove 12. Since the groove width W3 of the third groove 13 is 15% or more of the groove width W1 of the first groove 11 and the groove width W2 of the second groove 12, drainage performance is maintained. Since the groove width W3 of the third groove 13 is 50% or less of the groove width W1 of the first groove 11 and the groove width W2 of the second groove 12, resistance to eccentric wear and vibration is improved. In this specification, the groove width W3 of the third groove 13 is the minimum groove width of the third groove 13. In this specification, the groove width W1 of the first groove 11 and the groove width W2 of the second groove 12 are the maximum groove widths of the first groove 11 and the second groove 12. Although not specifically limited, the groove width W1 of the first groove 11 is 3.5 to 7.0 mm.

[0050] like Figure 2 As shown in (b), according to the same viewpoint, the groove depth D3 of the third groove 13 is preferably 15% or more, more preferably 20% or more, more preferably 50% or less, and more preferably 45% or less, of the groove depth D1 of the first groove 11 and the groove depth D2 of the second groove 12. In this specification, the groove depth D3 of the third groove 13 is the minimum groove depth of the third groove 13. In this specification, the groove depth D1 of the first groove 11 and the groove depth D2 of the second groove 12 are the maximum groove depths of the first groove 11 and the second groove 12. Although not particularly limited, the groove depth D1 of the first groove 11 is 3.0 to 7.5 mm.

[0051] like Figure 2 As shown in (a), the length L3 of the third groove 13 is preferably the tire axial unfolded width Ws of the first tire shoulder S1. Figure 1 The content of (as shown) is 10% or more, more preferably 15% or more, preferably 30% or less, and more preferably 25% or less.

[0052] The first lateral groove 8 also includes, for example, a fourth groove 14 extending outward from the second groove 12 in the axial direction of the tire. The groove depth D4 and groove width W4 of the fourth groove 14 are formed to be smaller than the groove depths D1 and D2 of the first groove 11 and the groove widths W1 and W2 of the second groove 12, respectively. Such a fourth groove 14 also improves drainage performance and suppresses the reduction of resistance to eccentric wear and vibration. In addition, the fourth groove 14 touches the ground when cornering with a large camber angle. By setting the groove depth D4 and groove width W4 of such a fourth groove 14 as described above, even when cornering with a large camber angle, it is possible to prevent the tread surface (tread 2a) from losing rigidity when touching the ground, so that the vehicle body can stand up smoothly, thus making the handling easier.

[0053] The groove depth D4 and groove width W4 of the fourth groove 14 are substantially the same as, for example, the groove depth D3 and groove width W3 of the third groove 13. This fourth groove 14 effectively performs the aforementioned function. "Substantially the same" means that the difference between the groove depth D4 of the fourth groove 14 and the groove depth D3 of the third groove 13 is within 2 mm. Furthermore, it means that the difference between the groove width W4 of the fourth groove 14 and the groove width W3 of the third groove 13 is within 2 mm.

[0054] In this embodiment, the fourth groove 14 is inclined in the same direction as the second groove 12 relative to the tire circumference. This fourth groove 14 maintains smooth water flow within the first transverse groove 8.

[0055] The outer end 14a of the fourth groove 14 in the tire axial direction is disposed at the first shoulder S1. In other words, the fourth groove 14 does not span the tread end Te, but forms an end at the first shoulder S1. This fourth groove 14 inhibits the reduction of the rigidity of the tread portion 2 on the tread end Te with large lateral forces.

[0056] The fourth groove 14 is positioned near the second groove edge 12i of the second groove 12. The fourth groove 14 includes a first groove edge 14e located on one side of the tire circumferential direction and a second groove edge 14i located on the other side of the tire circumferential direction. The second groove edge 14i of the fourth groove 14 extends in an arc formation with the second groove edge 12i of the second groove 12. The first groove edge 14e of the fourth groove 14 is formed to include a crank-shaped portion K extending in a crank-like manner toward the second groove edge 14i side of the fourth groove 14.

[0057] like Figure 2 As shown in (b), the bottom 11s of the first groove 11 is smoothly connected to the bottom 13s of the third groove 13. The bottom 12s of the second groove 12 is smoothly connected to the bottom 13s of the third groove 13. Furthermore, the bottom 12s of the second groove 12 is smoothly connected to the bottom 14s of the fourth groove 14. This first transverse groove 8 suppresses the formation of groove bottom cracks and allows water to flow smoothly within the groove. The term "smoothly connected" refers to the shape formed by each groove bottom 11s to 14s consisting of an inner arcuate portion 17a protruding radially inward towards the tire and an outer arcuate portion 17b disposed on the outer side of the tire radial direction, which is further outward than the inner arcuate portion 17a and protrudes radially outward towards the tire.

[0058] like Figure 1 As shown, the tread portion 2 may also be provided with, for example, a circumferential groove 20, a second lateral groove 21, a third lateral groove 22, and a sipe 23. In this specification, the first lateral groove 8, the circumferential groove 20, etc., are grooves with a maximum width exceeding 1.5 mm. In this specification, the sipe is a groove with a maximum width of 1.5 mm or less.

[0059] The circumferential groove 20 extends continuously along the tire circumference, for example, on the tire equator C. In this embodiment, the circumferential groove 20 is formed in a sawtooth shape and is composed of alternating first portions 20A that are inclined to one side (downward to the left in the figure) relative to the tire circumference and second portions 20B that are connected to the first portions 20A and inclined in the opposite direction to the first portions 20A relative to the tire circumference.

[0060] The circumferential groove 20 includes a pair of groove edges 20e, 20e extending along its length. Since the circumferential groove 20 extends in a serrated pattern along the tire equator C, each groove edge 20e, 20e alternately forms an outer portion 25, which is either outside the tire axial direction, and an inner portion 26, which is inside the tire axial direction than the outer portion 25. At the junction of the first portion 20A and the second portion 20B, the outer portion 25 is formed to include an axial portion J extending along the tire axial direction. This axial portion J concentrates water between the road surface and the tread surface 2a into the circumferential groove 20, thereby improving drainage.

[0061] In this embodiment, the second lateral groove 21, the third lateral groove 22, and the sipe 23 are respectively disposed on both sides of the tire equator C. The second lateral groove 21, the third lateral groove 22, and the sipe 23, for example, slope from the tire equator C toward the tread end Te towards the rear contact side in the tire rotation direction N. In this embodiment, the second lateral groove 21, the third lateral groove 22, and the sipe 23 extend in an arc shape protruding toward the rear contact side in the tire rotation direction N. The second lateral groove 21, the third lateral groove 22, and the sipe 23, for example, do not communicate with the tread end Te, but instead form an end within the first tire shoulder S1.

[0062] The second lateral groove 21 extends, for example, from the crown portion Cr to the first shoulder portion S1. In this embodiment, the second lateral groove 21 is formed such that its axial length is greater than that of the first lateral groove 8. The inner end 21i of the second lateral groove 21 is, for example, positioned closer to the tire equator C than the inner end 8i of the first lateral groove 8.

[0063] The third lateral groove 22 extends, for example, from the crown portion Cr to the first shoulder portion S1. The third lateral groove 22 is formed such that its axial length is less than that of the first lateral groove 8. The inner end 22i of the third lateral groove 22 is positioned closer to the tread end Te than the inner end 8i of the first lateral groove 8. The outer end 22e of the third lateral groove 22 is positioned further away from the outer end 8e of the first lateral groove 8. Figure 4 (As shown) The position near the equator C side of the tire.

[0064] like Figure 4 As shown, the sipe 23 is disposed on the first tire shoulder S1. The inner end 23i of the sipe 23 in the tire axial direction is disposed on the first tire shoulder S1. The outer end 23e of the sipe 23 in the tire axial direction is disposed between the outer end 8e of the first lateral groove 8 and the outer end 22e of the third lateral groove 22.

[0065] Figure 5 This is a developed view of the tread portion 2 according to another embodiment. Structures identical to those in this embodiment are sometimes labeled with the same reference numerals, and their descriptions are omitted. The tread portion 2 of this embodiment is suitable for a rear wheel tire of a motorcycle. Furthermore, this tread portion 2 can also be used for a front wheel tire.

[0066] like Figure 5 As shown, the tread portion 2 of this embodiment includes a first lateral groove 8, a second lateral groove 21, a third lateral groove 22, and a sipe 23. In this embodiment, the tread portion 2 does not have circumferential grooves. For example, two sipes 23 are provided between the first lateral groove 8 and the second lateral groove 21.

[0067] In this embodiment, the inner end 21i of the second lateral groove 21 is located on the inner side of the tire axis than the inner end 21i of the second lateral groove 21 in this embodiment. This suppresses the reduction in water drainage performance. The shortest distance Lb between the inner end 21i of the second lateral groove 21 and the tire equator C is preferably 0.5% or more, more preferably 0.7% or more, more preferably 2.5% or less, and more preferably 2.0% or less of the unfolded width Wc of the crown portion Cr.

[0068] The motorcycle is equipped with a front tire and a rear tire (illustrations omitted). The rear tire is almost unaffected by the driver's steering wheel operation. For such a tire, grip is more important than handling performance. Therefore, the tread area ratio 2 of the rear tire is preferably greater than that of the front tire. In particular, the tread area ratio 2 of the rear tire is preferably 80% or more.

[0069] The above describes in detail the particularly preferred embodiments of the present invention, but the present invention is not limited to the embodiments shown in the figures and can be implemented in various ways.

[0070] Example

[0071] A prototype with Figure 1 The prototype tires were designed with a basic tread pattern for motorcycles. Furthermore, the handling performance, water drainage performance, resistance to uneven wear, and high-speed durability of each prototype tire were tested. The general specifications and testing methods for each prototype tire are as follows.

[0072] Handling performance, resistance to uneven wear, durability, vibration resistance, noise performance

[0073] Each prototype tire was installed on the front wheel of a motorcycle (1500cc displacement) under the following conditions. The rear wheel tire used a tire with the same tread pattern. Then, test riders drove the motorcycle on a test track on dry asphalt, and the riders' sensory evaluations were used to assess the handling ease, vibration, and noise levels. Additionally, the riders' sensory evaluations were used to assess the occurrence of uneven wear, groove bottom cracks, and kerf bottom cracks after driving. The results are expressed as a score of 100 (Comparative Example 1). Higher scores indicate better performance. A score of 95 or higher is considered acceptable.

[0074] Front tire specifications (size, rim, internal pressure): 110 / 70-13M / C, 13×3.00MT, 200kPa

[0075] Rear wheel tire specifications (size, rim, internal pressure): 130 / 70-13M / C, 13×3.50MT, 225kPa

[0076] <Drainage>

[0077] Using the aforementioned vehicle, test riders rode it on a test route on a wet asphalt surface, and the ease of riding was evaluated by the riders' senses. The results will be expressed as a score of 100 (Comparative Example 1). A higher score indicates better drainage. A score of 95 or higher is considered acceptable.

[0078] The test results are shown in Table 1.

[0079] In Table 1, "A" indicates that the second trench is located... Figure 1 The location.

[0080] In Table 1, "B" means that the second groove is located in the crown area.

[0081] In Table 1, "C" indicates that the third trench is located... Figure 1 The location.

[0082] In Table 1, “D” means that the third groove is located in the crown of the fetus.

[0083] In Table 1, “E” means that 80% of the length of the third groove is located in the first shoulder.

[0084] In Table 1, “F” means that 70% of the length of the third groove is located in the first shoulder.

[0085] In Table 1, "G" indicates that the bottom of each part of the first transverse groove is... Figure 2 The shape shown in (b).

[0086] In Table 1, “H” means that the bottom of each part of the first horizontal groove is connected in a straight line.

[0087] In Table 1, "I" signifies that the inner side of the first groove is... Figure 1 Its form.

[0088] In Table 1, “J” means that the inner part of the first groove extends with a uniform width.

[0089] The length of the third groove is the same.

[0090] Table 1

[0091]

[0092] The test results show that, compared with the comparative example tires, the tires of the embodiment do not compromise the resistance to uneven wear and vibration, but improve water drainage.

Claims

1. A motorcycle tire having a tread pattern, wherein, The tread portion includes: a crown portion, which is 50% of the tread width centered on the tire equator; and a first shoulder portion, which is the outer region of the crown portion. Multiple first transverse grooves are formed on the tread surface. Each of the first lateral grooves includes: a first groove portion disposed on the crown portion; a second groove portion disposed on the first shoulder portion; and a third groove portion connecting the first groove portion and the second groove portion. The depth and width of the third groove are smaller than the depth and width of the first groove and the second groove, respectively. More than 80% of the tire's axial length of the third groove is disposed on the first tire shoulder.

2. The motorcycle tire according to claim 1, wherein, The first groove is configured not to cross the tire equator.

3. The motorcycle tire according to claim 1 or 2, wherein, The first groove, the second groove, and the third groove are inclined in the same direction relative to the tire axial direction.

4. The motorcycle tire according to claim 1 or 2, wherein, The width of the third groove is 15% to 50% of the width of the first groove and the width of the second groove.

5. The motorcycle tire according to claim 1 or 2, wherein, The depth of the third groove is 15% to 50% of the depth of the first groove and the depth of the second groove.

6. The motorcycle tire according to claim 1 or 2, wherein, The first groove includes a first groove edge located on one side of the tire circumferential direction and a second groove edge located on the other side of the tire circumferential direction. The second groove includes a first groove edge located on one side of the tire circumferential direction and a second groove edge located on the other side of the tire circumferential direction. The third groove is disposed near the second groove edge side of the first groove, and is disposed near the first groove edge side of the second groove.

7. The motorcycle tire according to claim 1 or 2, wherein, The first transverse groove further includes a fourth groove portion that extends outward from the second groove portion in the tire axial direction. The depth and width of the fourth groove are less than the depth and width of the first groove and the second groove, respectively.

8. The motorcycle tire according to claim 7, wherein, The first groove, the second groove, the third groove, and the fourth groove are inclined in the same direction relative to the tire axial direction.

9. The motorcycle tire according to claim 1, 2 or 8, wherein, The tread section specifies the tire's rotation direction. The first groove is located on the side that touches the ground first, in the direction of tire rotation, compared to the second groove.

10. The motorcycle tire according to claim 1, 2 or 8, wherein, A fetal body with an oblique cross structure.

11. A motorcycle tire pair, wherein the motorcycle tires of any one of claims 1 to 10 are used as a front wheel tire and a rear wheel tire, wherein, The land-to-tread ratio of the rear tire is greater than that of the front tire.

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