Motorcycle tire

Abstract

The invention provides a motorcycle tire which can improve operation stability performance by improving vibration absorption performance while maintaining high rigidity during driving. A motorcycle tire (1) includes a spacer layer (10) disposed between a main body portion (6a) of a carcass ply (6A) and an inner liner (9). The insulating rubber layer (10) extends from a first end (10e) on the tread portion (2) side to at least the bead core (5). The sidewall portion (3) includes an outermost end (t1) in a tire radial direction where a standard rim (R) is in contact with a tire outer surface (1s) of the sidewall portion (3). The tire outer surface (1s) of the sidewall section (3) has a side profile (3S) that accounts for 90% or more of the length (La) in the tire radial direction between the tread end (Te) and the outermost end (t1) from the tread end (Te). The side profile (3S) is a straight line or an arc having a radius of curvature (r) of 55 mm or more and protruding inward in the tire axial direction.

Description

Technical Field

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

[0002] In Patent Document 1 described below, there is disclosed a pneumatic tire having an interlayer disposed between a carcass and an inner liner. The interlayer is disposed at least in a sidewall portion.

[0003] Prior Art Documents Patent Document Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-074834 Summary of the Invention

[0004] Problems to be Solved by the Invention In the above-described tire, the rigidity of the sidewall portion is remarkably increased, and thus it is considered that the rigidity feeling during traveling is excellent. In recent years, in tires for motorcycles, it has been required to improve vibration absorption while maintaining a high rigidity feeling during traveling.

[0005] In view of the above actual situation, the present invention has been made, and a main object thereof is to provide a tire for a motorcycle that can improve handling stability by improving vibration absorption while maintaining a high rigidity feeling during traveling.

[0006] Means for Solving the Problems The present invention is a tire for a motorcycle, including: a tread portion that defines a pair of tread ends; a pair of sidewall portions that extend radially inward of the tire from the tread portion; a pair of bead portions that are provided on the radially inner side of the tire of the sidewall portions and are respectively provided with bead cores; a carcass that includes a carcass ply having an annular main body portion that extends between the pair of bead cores; an inner liner that is disposed on the inner cavity side of the tire of the carcass; and an interlayer rubber layer that is disposed between the main body portion and the inner liner in each of the pair of sidewall portions, and the interlayer rubber layer extends from at least a first end on the tread portion side to the bead core, respectively. In a standard state in a non-loaded state where the tire is assembled to a standard rim and filled with a standard internal pressure, each of the pair of sidewall portions includes a radially outermost end of the tire where the standard rim contacts the outer surface of the sidewall portion. In a tire meridian cross section in the standard state, each of the outer surfaces of the pair of sidewall portions has a side profile that occupies 90% or more of the tire radial length between the tread end and the outermost end from the tread end, and the side profile is a straight line or an arc having a curvature radius of 55 mm or more and convex inward in the tire axial direction.

[0007] Effects of the Invention By adopting the above structure, the present invention can improve vibration absorption while maintaining a high rigidity feeling during traveling, and can improve handling stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a tire meridian cross-sectional view of a motorcycle tire according to an embodiment of the present invention.

[0009] Figure 2 is a tire meridian cross-sectional view of tire 1.

[0010] Figure 3 is Figure 1 an enlarged view of the sidewall portion of tire 1.

[0011] Figure 4 is an enlarged view of the sidewall portion of another embodiment.

[0012] 1 Motorcycle tire 2 Tread surface 3 Sidewall portion 1s Tire outer surface 3S Side profile 5 Bead core 6A Body ply 6a Main body portion 9 Inner liner 10 Insulating rubber layer 10e First end R Standard rim t1 Outermost end Te Tread end DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described based on the drawings.

[0014] To assist in understanding the present invention, the drawings include exaggerated representations or representations of dimensional ratios different from the actual structure. In addition, in the case of multiple embodiments, in the specification, the same or common elements are labeled with the same reference numerals and repeated descriptions are omitted.

[0015] Figure 1 is a tire meridian cross-sectional view in a standard state of a tire rotation axis (not shown) including a motorcycle tire (hereinafter sometimes simply referred to as "tire") 1 according to an embodiment of the present invention. The tire 1 of this embodiment is preferably mounted on a motorcycle suitable for moving and traveling under load. However, the tire 1 of the present invention is not limited to such a manner.

[0016] In this specification, unless otherwise specified, the dimensions and the like of each part of the tire 1 are measured in the above standard state. The so-called "standard state" refers to a state in which the tire 1 is assembled on a standard rim R and filled with a standard internal pressure without load.

[0017] "Standard Rim R" is the rim specified for each tire in a specification system that includes the specifications on which the tire is based. For example, in the case of JATMA, it is the "Standard Rim"; in the case of TRA, it is the "Design Rim"; and in the case of ETRTO, it is the "Measuring Rim".

[0018] "Standard internal pressure" is the air pressure specified for each tire in a specification system that includes the specifications on which the tire is based. In the case of JATMA, it is the "maximum air pressure"; in the case of TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLDINFLATION PRESSUREES"; and in the case of ETRTO, it is the "INFLATIONPRESSURE".

[0019] The tire 1 of the present embodiment includes: a tread portion 2 that defines a pair of tread ends Te, a pair of sidewall portions 3 that extend radially inward of the tire from the tread portion 2, and a pair of bead portions 4 provided on the radially inner side of the sidewall portions 3. A bead core 5 is provided on each bead portion 4. The tread end Te corresponds to the end of the outer surface 1t of the tread portion 2 and is the end that contacts the road surface when turning with the maximum camber angle.

[0020] The tire 1 includes a carcass 6 and a liner 9 disposed on the inner cavity 1B side of the carcass 6. The carcass 6 includes a carcass ply 6A having an annular main body portion 6a that extends between a pair of bead cores 5. In addition, in each of the pair of sidewall portions 3 of the tire 1, an interlayer 10 is disposed between the main body portion 6a and the liner 9.

[0021] Each interlayer 10 extends at least from the first end 10e on the tread portion 2 side to the bead core 5. Such an interlayer 10 can improve the rigidity of the sidewall portion 3.

[0022] In the above standard state, each of the pair of sidewall portions 3 includes the outermost end t1 in the tire radial direction where the standard rim R contacts the outer surface 1s of the sidewall portion 3.

[0023] In the tire meridian cross-section in the above standard state, each tire outer surface 1s of a pair of sidewall portions 3 has a side profile 3S, which occupies more than 90% of the tire radial length La between the tread end Te and the outermost end t1 starting from the tread end Te. Further, the side profile 3S is an arc with a radius of curvature r1 of 55 mm or more and convex inward in the tire axial direction. Since the sidewall portion 3 having such a side profile 3S ensures a stroke amount for flexure over the entire sidewall portion 3, vibrations during running can be absorbed over the entire sidewall portion 3, thereby improving vibration absorbability. Accordingly, the motorcycle tire of the present invention has excellent handling stability performance. Further, even if the side profile 3S is a straight line (radius of curvature r1 is infinite), the same effect is exhibited, but it is preferably 300 mm or less and preferably 60 mm or more.

[0024] In addition, each tire outer surface 1s of a pair of sidewall portions 3 has a sub-side profile 3T, which occupies more than 5% of the tire radial length La starting from the outermost end t1. The sub-side profile 3T is formed by an arc convex inward in the tire axial direction. Such a sub-side profile 3T contributes to better absorption of vibrations during running over the entire sidewall portion 3. The radius of curvature r2 of the sub-side profile 3T is, for example, preferably 10.0 mm or more, more preferably 12.0 mm or more, and more preferably 17.0 mm or less, and further preferably 15.0 mm or less. The sub-side profile 3T and the side profile 3S are each formed by an arc of a single radius of curvature, for example.

[0025] The tire outer surface 1s of the present embodiment includes a top portion 14 connecting the side profile 3S and the sub-side profile 3T. The top portion 14 protrudes outward in the tire axial direction. The top portion 14 can be formed, for example, as a so-called rim line, which is provided so that it can be visually determined whether the tire 1 and the standard rim R are properly assembled during rim assembly. In the present embodiment, the top portion 14 extends continuously in the tire circumferential direction. The top portion 14 of the present embodiment is formed as a vertex. The top portion 14 is not limited to such a manner.

[0026] In the tire meridian cross-section in the standard state, the tire outer surface 1t of the tread portion 2 includes a tread profile 2S, which is an arc-shaped convex outward in the tire radial direction.

[0027] The tread profile 2S includes a pair of outer grounding positions 2e, which are the outermost grounding positions in the tire axial direction when a standard load is applied to the tire 1 in the above-mentioned standard state and the tire is grounded at an inclination angle of 30 degrees on each side outside the respective pair of tread ends Te. In addition, the tread profile 2S of the present embodiment includes a first portion 21 extending between the outer grounding positions 2e and a pair of second portions 22 extending between the pair of outer grounding positions 2e and the tread ends Te. The first portion 21 is the portion that is grounded during straight running and turning with a large turning radius. A relatively small lateral force acts on such a first portion 21. In addition, the second portion 22 is the portion that is grounded during turning with a small turning radius where the tread end Te contacts the road surface, and is the portion that is grounded within a range where the camber angle exceeds 30 degrees and is around 45 degrees. A relatively large lateral force acts on such a second portion 22.

[0028] The above-mentioned "standard load" is the load specified for each type of tire in the specification system including the specifications on which the tire is based. If it is JATMA, it is the "maximum load capacity". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSUREES". If it is ETRTO, it is the "LOADCAPACITY".

[0029] Preferably, the first portion 21 where a relatively small lateral force acts reduces the width of the contact surface (not shown) so as to absorb vibrations during driving by the flexure of the tread portion 2. On the contrary, it is preferable that the second portion 22 increases the width of the contact surface so as to improve the handling stability performance through stable turning. Therefore, in the tread profile 2S, the radius of curvature r4 of the second portion 22 is preferably larger than the radius of curvature r3 of the first portion 21. From straight running to turning with a small turning radius, in order to improve the handling stability performance, in the tread profile 2S, the radius of curvature r3 of the first portion 21 is preferably 40 mm or more, more preferably 45 mm or more, and preferably 60 mm or less, more preferably 55 mm or less. In addition, in the tread profile 2S, the radius of curvature r4 of the second portion 22 is preferably 70 mm or more, more preferably 75 mm or more, and preferably 100 mm or less, more preferably 95 mm or less.

[0030] If the difference (r4 - r3) between the radius of curvature r3 of the first portion 21 and the radius of curvature r4 of the second portion 22 is too large, during turning, near the outer grounding position 2e, the steering responsiveness and transient characteristics may deteriorate. Therefore, the difference (r4 - r3) is preferably 10.0 mm or more, more preferably 20.0 mm or more, and preferably 50.0 mm or less, more preferably 40.0 mm or less.

[0031] Although not particularly limited, in order to manufacture such a tire 1, in a mold (not shown) for forming the tread profile 2S, the radius of curvature of the forming surface for forming the first part 21 is preferably 40 to 60 mm, and the radius of curvature of the forming surface for forming the second part 22 is preferably 90 to 110 mm. In addition, in a mold (not shown) for forming the side profile 3S, the radius of curvature of the forming surface for forming the side profile 3S is preferably 50 to 60 mm. Further, in a mold (not shown) for forming the sub-side profile 3T, the radius of curvature of the forming surface for forming the sub-side profile 3T is preferably 10 to 15 mm.

[0032] Figure 2 is a tire meridian cross-sectional view of the tire 1. As Figure 2 shown, the carcass 6 of the present embodiment is formed of a single carcass ply 6A. The carcass ply 6A is connected to, for example, the main body portion 6a and includes a pair of folded-back portions 6b that are folded back from the inner side to the outer side in the tire axial direction around the bead core 5 and extend in the tire radial direction.

[0033] In addition, the tire 1 includes a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 in the tread portion 2. The belt layer 7 includes at least one, but in the present embodiment, includes two belt layers 7A and 7B disposed on the inner and outer sides in the tire radial direction. The inner belt layer 7A is adjacent to the carcass 6 on the outer side in the tire radial direction, for example. The two belt layers 7A and 7B and the carcass ply 6A each include, for example, cords and skim rubber (not shown) and are formed of known constituent materials.

[0034] The outer end 7s in the tire axial direction of the inner belt layer 7A is closer to the inner side in the tire axial direction than the outer end 7t in the tire axial direction of the outer belt layer 7B. The axial length Lb of the inner belt layer 7A is preferably 75% or more, more preferably 80% or more, and preferably 90% or less, more preferably 85% or less of the tread width TW. The tread width TW is the axial length between the tread ends Te.

[0035] The innerliner 9 has excellent airtightness. The innerliner 9 maintains the internal pressure of the tire 1. The innerliner 9 is formed of a known rubber material. In the present embodiment, the innerliner 9 extends between the bead toes 4e of each bead portion 4 to form the inner cavity surface 1b of the tire. In this specification, the bead toe 4e is the point that contacts the standard rim R at the innermost side in the tire axial direction.

[0036] Figure 3 is Figure 1 an enlarged view of the sidewall portion 3 of the tire 1. As Figure 3As shown, preferably, the first end 10e of the chafer layer 10 is located more radially outward of the tire than the intermediate position c1 in the tire radial direction of the side profile 3S. Such a chafer layer 10 effectively improves the rigidity of the sidewall portion 3.

[0037] The first end 10e is located, for example, in the tread portion 2. In the present embodiment, the first end 10e is located axially inward and radially outward of the outer end 7s of the inner belt layer 7A. Thus, the first end 10e is separated from the sidewall portion 3 where the flexure during running becomes relatively large, and thus the rigidity feeling can be further improved. Although not particularly limited, the axial separation distance Lc between the first end 10e and the outer end 7s of the inner belt layer 7A is preferably 1% or more, more preferably 5% or more, and preferably 20% or less, more preferably 15% or less of the tread width TW.

[0038] The chafer layer 10 includes an inner portion 11 and an outer portion 12. The inner portion 11 extends in the tire radial direction axially inward of the bead core 5. The inner portion 11 is disposed between the main body portion 6a and the inner liner 9. Such an inner portion 11 undergoes compressive deformation during running and applies a tensile force to the above-mentioned cords of the main body portion 6a, and thus contributes to improving the rigidity of the sidewall portion 3 and improving the handling stability performance. In addition, since such an inner portion 11 functions as a damper for the load during running, the vibration absorption performance is improved. The outer portion 12 is connected to the inner portion 11 and extends radially outward of the tire by folding back from the axially inner side to the axially outer side around the bead core 5. In the present embodiment, the outer portion 12 is disposed axially outward of the folded-back portion 6b.

[0039] The radial length L1 of the inner portion 11 in the tire radial direction is greater than the radial length L2 of the outer portion 12 in the tire radial direction. Thus, the outer portion 12 suppresses an excessive increase in the rigidity of the tire, and thus suppresses vibration during running and maintains a high vibration absorption performance. In addition, since the region where the inner portion 11 is disposed is farther from the flange Rf of the standard rim R than the region where the outer portion 12 is disposed, it is a region where a relatively large flexure occurs during running. Thus, since the inner portion 11 having a relatively large length L2 is disposed in the region where a large flexure occurs, the flexure of the tire 1 during running can be effectively suppressed, thereby improving the handling stability performance. The lengths L1 of the inner portion 11 and L2 of the outer portion 12 are the lengths from the radially inner end 5i of the bead core 5 in the tire radial direction in the present specification. In the present embodiment, the radially outer end 11e of the inner portion 11 is the first end 10e.

[0040] The outer end 12e of the outer side portion 12 is located on the outer side in the tire radial direction with respect to the outermost end t1. The outermost end t1 is the end where the rigidity of the bead portion 4 changes significantly in the tire radial direction. By disposing the outer end 12e on the outer side in the tire radial direction with respect to the outermost end t1, the change in the rigidity of the bead portion 4 can be suppressed, and thus the vibration absorption performance can be maintained at a high level. From the perspective of balancing vibration absorption performance and the rigidity feeling of the tire 1, the separation distance Ld in the tire radial direction between the outer end 12e of the outer side portion 12 and the outermost end t1 is preferably 10.0 mm or more, more preferably 20.0 mm or more, and preferably 60.0 mm or less, more preferably 50.0 mm or less, for example.

[0041] The outer end 12e of the outer side portion 12 is located on the inner side in the tire radial direction with respect to the outer end 6e of the folded-back portion 6b in the tire radial direction, for example. Thereby, the outer end 6e of the folded-back portion 6b and the outer end 12e of the outer side portion 12 are displaced in the tire radial direction, and the change in the rigidity of the sidewall portion 3 can be reduced, and thus the flexure during traveling can be reduced. In order to balance the turning performance and the vibration absorption performance, the separation distance Le in the tire radial direction between the outer end 12e of the outer side portion 12 and the outer end 6e of the folded-back portion 6b is preferably 5.0 mm or more, more preferably 10.0 mm or more, and preferably 30.0 mm or less, more preferably 25.0 mm or less, for example.

[0042] Such an insulating rubber layer 10 is formed of the following rubber composition. The loss tangent tanδ at 70°C is preferably 0.06 or more, more preferably 0.2 or more, and preferably 1.5 or less, more preferably 1.0 or less. Since the loss tangent tanδ is 0.06 or more, the vibration absorption effect can be maintained at a high level. Since the loss tangent tanδ is 1.5 or less, the reduction in rigidity due to heat generation can be suppressed, and thus the turning performance can be improved. In addition, the rubber hardness at 23°C is preferably 65° or more, more preferably 70° or more, and preferably 85° or less, further preferably 80° or less. Since the rubber hardness is 65° or more, the rigidity of the tire 1 is ensured, and thus the turning performance can be improved. Since the rubber hardness is 85° or less, a high vibration absorption effect can be maintained. Furthermore, the elongation at break at 23°C is preferably 200% or more, further preferably 350% or more. Since the elongation at break is 200% or more, the deformation of the sidewall portion 3 and the bead portion 4 can be suppressed, and thus the turning performance can be improved. If the elongation at break is too large, the vibration absorption performance may be reduced. Therefore, the elongation at break is preferably 550% or less, more preferably 500% or less.

[0043] In this specification, the "loss tangent tanδ" is a value measured using a viscoelastic spectrometer ("EPLEXOR Series" manufactured by GABO Co., Ltd.) under the conditions shown below in accordance with JIS-K6394.

[0044] Initial strain: 10% Amplitude: ±1% Frequency: 10 Hz Deformation mode: Tensile Measured temperature: 70 °C In addition, in this specification, "rubber hardness" is the durometer A hardness measured at a standard temperature of 23 °C ± 2 °C using a Type A durometer in accordance with JIS-K6253.

[0045] In addition, in this specification, "elongation at break" can be measured, for example, in accordance with JIS K6251 "Vulcanized rubbers and thermoplastic rubbers - Methods for determining tensile properties -".

[0046] Figure 4 is a tire meridian sectional view of the sidewall portion 3 of another embodiment. As Figure 4 shown, in this embodiment, the first end 10e of the separator rubber layer 10 is provided within the side profile 3S. The first end 10e is, for example, closer to the inner side in the tire radial direction than the intermediate position c1 in the tire radial direction of the side profile 3S. In addition, the length L1 of the inner portion 11 in the tire radial direction is greater than the length L2 of the outer portion 12 in the tire radial direction. In addition, the outer end 12e of the outer portion 12 in the tire radial direction is closer to the inner side in the tire radial direction than the outermost end t1. Such a separator rubber layer 10 reduces the mass of the tire 1 and improves the turning performance while maintaining a sense of rigidity.

[0047] The above has described in detail the particularly preferred embodiments of the present invention, but the present invention is not limited to the illustrated embodiments and can be implemented in various modified forms. Examples

[0048] A motorcycle tire having the Figure 1 basic structure was trial-produced according to the specifications in Table 1. And the sense of rigidity and vibration absorption of each test tire were tested. The test method is as follows.

[0049] <Sense of rigidity and vibration absorption> Each test tire was mounted on a 250 cc displacement motorcycle under the following conditions. The test driver drove the above vehicle on a test field of dry asphalt pavement. The sense of rigidity related to the straight-line driving stability of each test tire at this time and the absorption of vibrations generated when crossing gaps, etc. were evaluated by the sensory perception of the test driver. The results are shown as a score with Example 1 being 10. The larger the value, the better.

[0050] Tires: 90 / 80R17, 120 / 70R17 (front wheel, rear wheel) Inner pressure: 220 kPa, 200 kPa (front wheel, rear wheel) The test results are shown in Table 1.

[0051] In Example 2 of Table 1 and Comparative Example 2, the length of L1 is the same as that of L2 in Example 1, and the length of L2 in Example 2 and Comparative Example 2 is the same as that of L1 in Example 1.

[0052]

Table 1

[0053] As shown in Table 1, it can be understood that the tire of the example has better rigidity and vibration absorption, and more excellent handling stability performance compared with the tire of the comparative example.

[0054] [Supplementary Note] The present invention includes the following aspects.

[0055] [Invention 1] A motorcycle tire, comprising: A tread surface portion that defines a pair of tread ends; A pair of sidewall portions that extend radially inward of the tire from the tread surface portion; A pair of bead portions that are provided radially inward of the tire of the sidewall portions and are respectively provided with bead cores; A carcass that includes a carcass ply having an annular main body portion that extends between the pair of bead cores; An inner liner layer that is disposed on the inner cavity side of the tire of the carcass; and A separator rubber layer that is disposed between the main body portion and the inner liner layer in each of the pair of sidewall portions, The separator rubber layer extends at least from a first end on the tread surface portion side to the bead core respectively, In a standard state of a non-loaded state assembled to a standard rim and filled with a standard internal pressure, each of the pair of sidewall portions includes an outermost end in the tire radial direction where the standard rim contacts the outer surface of the sidewall portion, In a tire meridian section in the standard state, the outer surface of each of the pair of sidewall portions has a side profile that occupies more than 90% of the tire radial length between the tread end and the outermost end starting from the tread end, The side profile is a straight line or an arc that has a curvature radius of 55 mm or more and bulges inward in the tire axial direction.

[0056] [Invention 2] The motorcycle tire according to Invention 1, wherein, In a tire meridian section in the standard state, the outer surface of the tread surface portion includes an arc-shaped tread profile that bulges outward in the tire radial direction, The tread profile includes a first portion extending between a pair of outer grounding positions, the pair of outer grounding positions being the outermost grounding positions in the tire axial direction when a standard load is applied to the motorcycle tire in the standard state and the tire is grounded at an inclination angle of 30 degrees on each side of the respective pair of tread ends other than one side, The radius of curvature of the first portion is 40 to 60 mm.

[0057] [Invention 3] A motorcycle tire according to Invention 2, wherein The tread profile includes a pair of second portions extending between the pair of outer grounding positions and the tread ends, The radius of curvature of each of the pair of second portions is 70 to 100 mm.

[0058] [Invention 4] A motorcycle tire according to any one of Inventions 1 to 3, wherein the first end is located more radially outside than the intermediate position in the tire radial direction of the side profile.

[0059] [Invention 5] A motorcycle tire according to any one of Inventions 1 to 4, wherein the first end is located in the tread portion.

[0060] [Invention 6] A motorcycle tire according to any one of Inventions 1 to 5, wherein the chafer ply includes an inner portion and an outer portion, the inner portion is disposed between the main body portion and the inner liner, and the outer portion is connected to the inner portion and folded back from the inner side to the outer side in the tire axial direction around the bead core to extend radially outward of the tire.

[0061] [Invention 7] A motorcycle tire according to Invention 6, wherein the radial length of the inner portion in the tire radial direction is greater than the radial length of the outer portion.

[0062] [Invention 8] A motorcycle tire according to any one of Inventions 1 to 7, wherein the chafer ply is formed of a rubber composition having a loss tangent tanδ of 0.06 to 1.5 at 70°C.

[0063] [Invention 9] A motorcycle tire according to any one of Inventions 1 to 8, wherein the chafer ply is formed of a rubber composition having a rubber hardness of 65 to 85° at 23°C.

[0064] [Invention 10] The motorcycle tire according to any one of 1 to 9 of the present invention, wherein the cushion gum layer is formed of a rubber composition having an elongation at break of 200% or more at 23°C.

Claims

1. A motorcycle tire, characterized in that, Comprising: A tread face portion that defines a pair of tread ends; A pair of sidewall portions that extend radially inward of the tire from the tread face portion; A pair of bead portions that are provided radially inward of the tire of the sidewall portions and are respectively provided with bead cores; A carcass that includes a carcass ply having an annular main body portion that extends between the pair of bead cores; An inner liner layer that is disposed on the inner cavity side of the tire of the carcass; And A separator rubber layer that is disposed between the main body portion and the inner liner layer in each of the pair of sidewall portions, The separator rubber layer extends at least from a first end on the tread face portion side to the bead core respectively, In a standard state of a non-loaded state assembled to a standard rim and filled with a standard internal pressure, each of the pair of sidewall portions includes an outermost end in the tire radial direction where the standard rim contacts the outer surface of the sidewall portion, In a tire meridian cross section in the standard state, each of the outer surfaces of the pair of sidewall portions has a side profile that occupies more than 90% of the tire radial length between the tread end and the outermost end from the tread end, The side profile is a straight line or an arc with a radius of curvature of 55 mm or more and convex inward in the tire axial direction.

2. The motorcycle tire according to claim 1, wherein In a tire meridian cross section in the standard state, the outer surface of the tread face portion includes an arc-shaped tread profile that protrudes outward in the tire radial direction, The tread profile includes a first portion that extends between a pair of outer grounding positions, and the pair of outer grounding positions are the outermost grounding positions in the tire axial direction when a standard load is applied to the motorcycle tire in the standard state and the tire is inclined at an angle of 30 degrees on each side of the pair of tread ends and contacts the ground on a plane, The radius of curvature of the first portion is 40 to 60 mm.

3. The motorcycle tire according to claim 2, wherein The tread profile includes a pair of second portions that extend between the pair of outer grounding positions and the tread end, The radius of curvature of each of the pair of second portions is 70 to 100 mm.

4. The motorcycle tire according to any one of claims 1 to 3, wherein The first end is more radially outward than the intermediate position in the tire radial direction of the side profile.

5. The motorcycle tire according to any one of claims 1 to 3, wherein The first end is located in the tread face portion.

6. The motorcycle tire according to any one of claims 1 to 3, wherein The separator rubber layer includes an inner portion and an outer portion. The inner portion is disposed between the main body portion and the inner liner layer, and the outer portion is connected to the inner portion and extends radially outward around the bead core by folding back from the inner side to the outer side in the tire axial direction.

7. The motorcycle tire according to claim 6, wherein The tire radial length of the inner portion is greater than the tire radial length of the outer portion.

8. The motorcycle tire according to any one of claims 1 to 3, wherein The separator rubber layer is formed of a rubber composition having a loss tangent tanδ of 0.06 to 1.5 at 70°C.

9. The motorcycle tire according to any one of claims 1 to 3, characterized in that the separator rubber layer is formed of a rubber composition having a rubber hardness of 65 to 85° at 23°C.

10. The motorcycle tire according to any one of claims 1 to 3, characterized in that the separator rubber layer is formed of a rubber composition having an elongation at break of 200% or more at 23°C.

Images