Tire for motor cycle

Abstract

To suppress a blow damage of a tread rubber due to heat generation at the time of traveling in highway.SOLUTION: In a tire for motor cycle, a tread part includes a crown region Cr laterally passing a tire equator, and a pair of shoulder regions Sh on the outside of a tire axial direction of the crown region Cr. The tread rubber 10 includes: a front layer 11 formed of a first rubber and arranged outside a tire radial direction; a bottom layer 13 formed of a third rubber and arranged inside the tire radial direction; and an intermediate layer 12 formed of a second rubber and arranged between the front layer 11 and the bottom layer 13. Regarding a loss tangent tanδ at 100°C, the second rubber is larger than the first rubber and the third rubber. The front layer 11 and the bottom layer 13 extend in the pair of shoulder regions Sh and the crown region Ct. A pair of the intermediate layers 12 respectively extend the pair of shoulder regions Sh and are not arranged in the crown region Cr. In the crown region Cr, the front layer 11 and the bottom layer 13 are directly connected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 below describes a motorcycle tire with a multi-layered tread rubber. The tread rubber includes a cap rubber that forms the tread surface and a base rubber disposed radially inward of the cap rubber, and the loss tangent tanδ of the cap rubber is smaller than the loss tangent tanδ of the base rubber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7056227 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] Motorcycle tires having a tread rubber with a multilayer structure as described above can achieve both wear resistance and handling stability during high-speed driving, compared to motorcycle tires made of a single-structure tread rubber. Therefore, in recent years, multilayer tread rubbers have been increasingly adopted for motorcycle tires. In particular, motorcycle tires suitable for sports driving such as racing have attempted to provide high grip performance by arranging a rubber layer with a large loss tangent tanδ inside the cap rubber.

[0005] However, rubber with a large loss tangent tanδ has a large hysteresis loss and is prone to heat generation, making it susceptible to high temperatures during continuous high-speed driving. Furthermore, if a rubber layer with a large loss tangent tanδ is covered with a cap rubber, it is difficult to cool it with the wind from the road. Therefore, with tread rubber of this type with a multi-layer structure, there is a risk of blowout damage to the tread rubber due to heat generation.

[0006] Furthermore, in racing, high grip is most required during cornering, where the vehicle body is tilted to create a camber angle in the tires, particularly in mid-bank (when accelerating) and full-bank (while cornering) situations where the shoulder area of ​​the tread rubber contacts the ground. Therefore, motorcycle tires are desired to have increased grip during cornering.

[0007] On the other hand, when driving straight, if the grip of the tread rubber is too high, the rubber's energy loss can limit the vehicle's maximum speed.

[0008] The present invention has been devised in consideration of the above problems, and its main object is to provide a motorcycle tire that can suppress blowout damage to the tread rubber due to heat generation during high-speed running. In a preferred embodiment, the present invention also aims to improve grip force during cornering. Furthermore, in a preferred embodiment, the present invention also aims to increase the maximum speed during straight running. [Means for solving the problem]

[0009] The present invention is a tire for a motorcycle, comprising: a tread portion having a pair of tread edges; a pair of sidewall portions; a pair of bead portions; a carcass disposed so as to straddle the pair of bead portions; a tread reinforcing layer disposed radially outward of the carcass and having reinforcing cords; and a tread rubber disposed radially outward of the tread reinforcing layer, wherein the tread portion includes a crown region crossing the tire equatorial plane and a pair of shoulder regions axially outward of the crown region, the pair of shoulder regions including the pair of tread edges, and the tread rubber includes a surface layer made of a first rubber disposed radially outward of the tire, The tire is for a motorcycle, comprising: a bottom layer made of a third rubber disposed radially inward; and an intermediate layer made of a second rubber disposed between the surface layer and the bottom layer, wherein the loss tangent tanδ of the second rubber at 100°C is greater than the loss tangent tanδ of the first rubber at 100°C and the loss tangent tanδ of the third rubber at 100°C, the surface layer and the bottom layer extend from one of the pair of shoulder regions through the crown region to the other of the pair of shoulder regions, and the intermediate layer consists of a pair of intermediate layers each extending through the pair of shoulder regions, and each intermediate layer is discontinued at an inner end in the axial direction of the tire so as not to be positioned in the crown region, and in the crown region, the surface layer and the bottom layer are directly connected. [Effects of the Invention]

[0010] The motorcycle tire of the present invention can suppress blow damage to the tread rubber due to heat generation during high-speed running. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view of the motorcycle tire according to the present embodiment in a specified dimension state. [Figure 2] FIG. 2 is a partially enlarged view of the tread portion of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will now be described with reference to the drawings. It should be understood that the drawings include exaggerated representations and representations different from the dimensional ratios of actual structures to facilitate understanding of the present invention. Furthermore, when there are multiple embodiments, identical or common elements are designated by the same reference numerals throughout the specification, and redundant explanations are omitted. Furthermore, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the contents of the present invention, and the present invention is not limited to the specific configurations shown in the drawings.

[0013] FIG. 1 is a cross-sectional view of a motorcycle tire (hereinafter, sometimes simply referred to as "tire") according to this embodiment. The tire 1 according to this embodiment is suitable for use, for example, in racing on a circuit. Such a tire 1 is required to travel straight and turn at a relatively high speed, and therefore to have a high maximum speed and excellent grip when turning. However, the tire of the present invention is not limited to such racing tires.

[0014] The motorcycle tire of this embodiment is a pneumatic tire, and Fig. 1 shows a size-specific state. In this specification, the size-specific state is a state for specifying the shape of the tire 1, and refers to a no-load state in which the tire 1 is mounted on a regular rim (not shown) and the internal pressure is adjusted to 10 (kPa). Unless otherwise specified, the tire 1 is considered to be in this size-specific state.

[0015] In this specification, a "genuine rim" is a rim that is defined for each tire by a standard system that includes the standard on which tire 1 is based, and is, 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.

[0016] As shown in FIG. 1, the tire 1 includes a tread portion 2 having a pair of tread ends Te, a pair of sidewall portions 3, a pair of bead portions 4 each having a bead core 5 embedded therein, a carcass 6 extending across the pair of bead portions 4, a tread reinforcing layer 7 disposed radially outward of the carcass 6 and having reinforcing cords, and tread rubber 10 disposed radially outward of the tread reinforcing layer 7.

[0017] In this embodiment, the contact profile 2a (identified as a non-grooved profile when grooves are present) which is the outline of the outer surface of the tread portion 2 is, for example, an arc-shaped profile that protrudes radially outward. Furthermore, in the tire 1 of this embodiment, the tread width TW, which is the distance in the tire axial direction between a pair of tread edges Te, Te, constitutes the maximum tire width (tire cross-sectional width). Thus, the tread portion 2 of this embodiment has a structure unique to motorcycle tires that perform cornering by applying a camber angle to the tire by significantly tilting the vehicle body. In FIG. 1, H denotes the tire cross-sectional height measured from the bead baseline BL, and the tread edge Te of this embodiment is located radially inward of the center position of the tire cross-sectional height H.

[0018] The tread portion 2 of this embodiment includes a crown region Cr extending across the tire equatorial plane C, and a pair of shoulder regions Sh on the outer sides of the crown region Cr in the tire axial direction.

[0019] The crown region Cr is the portion that comes into contact with the road surface when the tire is traveling straight with a camber angle of zero or nearly zero. As an example, the crown region Cr is set to a range of 30 mm or more, preferably 40 mm or more, from the tire equatorial plane C. On the other hand, the crown region Cr is set to a range of 90 mm or less, preferably 80 mm or less, from the tire equatorial plane C.

[0020] The radius of curvature R of the contact-contact profile 2a of the crown region Cr is preferably smaller than, for example, 95% of the tire section width. For convenience, when the "nominal" section width is indicated on the sidewall portion 3, the tire section width is defined as the dimension calculated by multiplying that value by the unit of millimeters. However, when the tire section width is not indicated on the sidewall portion 3, the tire section width is actually measured under the specified dimensions.

[0021] When the radius of curvature R of the contact profile 2a of the crown region Cr is set small as described above, the motorcycle can be easily tilted when starting a turn, improving maneuverability at the beginning of the turn. From this perspective, it is desirable that the radius of curvature R of the contact profile 2a of the crown region Cr be 80% or less of the tire cross-sectional width. However, if the radius of curvature R of the contact profile 2a of the crown region Cr is too small, there is a risk that stability during straight-ahead driving may decrease. From this perspective, the radius of curvature R of the contact profile 2a of the crown region Cr may be set to, for example, 40% or more, preferably 50% or more of the tire cross-sectional width.

[0022] The pair of shoulder regions Sh are regions extending from the crown region Cr to the respective tread edges Te. The shoulder regions Sh are regions that come into contact with the road surface when the tire 1 is cornering with a camber angle applied.

[0023] The carcass 6 is made up of at least one carcass ply 6A, one carcass ply in this embodiment.

[0024] The carcass ply 6A of this embodiment is a cord ply material made of a plurality of aligned carcass cords and a topping rubber covering the cords. The carcass ply 6A includes a main body 6a extending in a toroidal shape between the bead cores of a pair of bead portions 4, and a turned-up portion 6b that is turned back around the bead core 5 of each bead portion 4 from the axially inner side to the outer side. In this embodiment, the outer end of the turned-up portion 6b terminates radially inward of the tread edge Te.

[0025] The carcass 6 of this embodiment has, for example, a radial structure, and the carcass cords are arranged at an angle of, for example, 75 to 90° with respect to the tire equatorial plane C. For the carcass cords, for example, organic fiber cords such as polyester, nylon, rayon, aromatic polyamide, etc. may be used. In another aspect, a bias structure ply may be used as the carcass 6.

[0026] In the bead portion 4 of this embodiment, a bead apex rubber 4a is disposed between the main portion 6a and the turned-up portion 6b of the carcass ply 6A. The bead apex rubber 4a extends, for example, in a tapered shape from the outer surface of the bead core 5 outward in the tire radial direction. The bead apex rubber 4a is made of hard rubber and increases the bending rigidity of the bead portion 4.

[0027] As shown in FIG. 2 , the tread reinforcing layer 7 of this embodiment includes a belt layer 8. The belt layer 8 includes, for example, two belt plies 8A and 8B. The belt plies 8A and 8B have reinforcing cords arranged, for example, at an angle of 15 to 45° with respect to the tire equatorial plane C. The belt plies 8A and 8B are overlapped in the tire radial direction so that the reinforcing cords cross each other. Steel cords are preferably used for the reinforcing cords of the belt layer 8.

[0028] The tread reinforcing layer 7 of this embodiment further includes a band layer 9 as an optional element. The band layer 9 is arranged on the outer side of the belt layer 8 in the tire radial direction. The band layer 9 of this embodiment includes a jointless band ply 9A formed by spirally winding a narrow strip of reinforcing cords covered with a topping rubber multiple times around the outer side of the belt layer 8. This jointless band ply 9A has reinforcing cords arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. Such a band layer 9 firmly fastens the belt layer 8 and helps to improve the high-speed durability of the tire 1. For the reinforcing cords of the band layer 9, organic fiber cords such as nylon, rayon, polyester, and aromatic polyamide can be used.

[0029] The tread reinforcing layer 7 may be composed of a belt layer 8 or a band layer 9.

[0030] Referring to FIG. 1 , the tread rubber 10 of this embodiment extends across the tire equatorial plane C from one tread edge Te to the other tread edge Te. The tread rubber 10 of this embodiment has a multilayer structure in which multiple types of rubber are layered in the tire radial direction. Specifically, the tread rubber 10 includes a surface layer 11 made of a first rubber disposed on the outer side in the tire radial direction, a bottom layer 13 made of a third rubber disposed on the inner side in the tire radial direction, and an intermediate layer 12 made of a second rubber disposed between the surface layer 11 and the bottom layer 13. The loss tangent tanδ of the second rubber at 100°C is greater than the loss tangent tanδ of the first rubber at 100°C and the loss tangent tanδ of the third rubber at 100°C (hereinafter, the notation of the temperature 100°C for tanδ may be omitted).

[0031] In this specification, the loss tangent tanδ of each rubber is a value measured under the following conditions using a viscoelasticity spectrometer such as the "IPLEXER (registered trademark)" manufactured by GABO Corporation on a test specimen taken from the tread rubber 10 of the tire 1. The test specimen has a shape of 20 mm in length, 4 mm in width, and 1 mm in thickness, with the long side extending in the tire circumferential direction. Measurement temperature: 100℃ Frequency: 5Hz Initial extension strain: 10% Dynamic strain amplitude: ±2.5%

[0032] In the tread rubber 10, the surface layer 11 and the bottom layer 13 extend from one of the pair of shoulder regions Sh through the crown region Cr to the other of the pair of shoulder regions Sh. In this embodiment, the surface layer 11 and the bottom layer 13 extend continuously from one end of the tread rubber 10 to the other end in the tire axial direction.

[0033] The intermediate layer 12 is composed of a pair of intermediate layers 12 each extending through a pair of shoulder regions Sh. The intermediate layers 12 are terminated at their axially inner ends 12i so as not to be disposed in the crown region Cr. In the crown region Cr, the surface layer 11 and the bottom layer 13 are directly connected between the inner ends 12i of the intermediate layers 12.

[0034] [Functions and Effects of the Tire of the Present Embodiment] The tread rubber 10 of the tire 1 gradually heats up due to the harsh continuous running conditions during a race. In the case of a motorcycle tire, the part that is most susceptible to heat accumulation is the crown region Cr, which is most strongly affected by high-speed straight running. In the tire 1 of this embodiment, the crown region Cr does not have the intermediate layer 12 made of the second rubber, which has the highest loss tangent tanδ among the tread rubber 10. As a result, the tire 1 of this embodiment is able to suppress blow damage in the crown region Cr, which is most susceptible to heat accumulation.

[0035] When cornering at a large camber angle, an intermediate layer 12 made of a second rubber with a large tan δ is required to increase grip, but when driving straight at high speeds, such high grip is not required. Therefore, an intermediate layer 12 made of a second rubber with a large tan δ is not particularly important in the crown region Cr. Rather, an intermediate layer 12 made of a second rubber with a large tan δ increases energy loss and rolling resistance, which may reduce the maximum speed when driving straight. In the tire 1 of this embodiment, the crown region Cr does not include an intermediate layer 12 made of a second rubber, thereby reducing the energy loss and rolling resistance of the tread rubber 10 when driving straight. Therefore, the tire 1 of this embodiment can increase the maximum speed when driving straight.

[0036] Furthermore, in the tread rubber 10 of this embodiment, an intermediate layer 12 made of a second rubber having a large tan δ is arranged in the shoulder region Sh that comes into contact with the road surface during cornering. Therefore, the tire 1 of this embodiment can exert high grip force during cornering.

[0037] A more preferred embodiment of the tire 1 of this embodiment will be described below.

[0038] As shown in FIG. 2 , each shoulder region Sh of this embodiment includes a transition region 20 on its axially inner side. The transition region 20 is a region where the thickness of the surface layer 11 increases toward the crown region Cr and the thickness of the intermediate layer 12 decreases toward the crown region Cr. In the transition region 20 of this embodiment, the thickness of the intermediate layer 12 continuously decreases up to its axially inner end 12i. Similarly, in the transition region 20, the thickness of the surface layer 11 continuously increases up to the inner end 12i of the intermediate layer 12.

[0039] In such a transition region 20, the physical properties of the tread rubber 10 gradually change between the crown region Cr and the shoulder region Sh. This, in addition to the above-mentioned effects, suppresses abrupt changes in handling between straight-line running and cornering, thereby providing excellent steering stability. To more effectively provide such effects, the length L of the transition region 20 (periphery length along the contact profile 2a) is preferably greater than the total thickness T1 of the tread rubber 10 in the crown region Cr, and is particularly preferably 1.2 times or more, and even more preferably 1.5 times or more, of the total thickness T1. In this specification, the total thickness T1 of the tread rubber 10 in the crown region Cr is the total thickness of the surface layer 11 and the bottom layer 13 in the crown region Cr. If this total thickness varies, it means the maximum thickness.

[0040] Each shoulder region Sh also includes a constant region 21 axially outward of the transition region 20, where the surface layer 11, mid layer 12, and bottom layer 13 extend at a constant thickness. In this specification, the term "constant thickness" refers to the thickness of the rubber, determined taking into account the tolerances inherent in a pneumatic tire, a molded rubber product. Specifically, a thickness where the difference between the maximum and minimum thicknesses is approximately 10% of the maximum thickness is considered to be at least constant. This constant region 21 ensures that the physical properties of the shoulder region Sh are constant axially, enabling stable cornering characteristics.

[0041] [Rubber thickness, etc.] In the crown region Cr, the total thickness T1 of the tread rubber 10 is preferably set in the range of 5.0 to 9.0 mm, for example.

[0042] By setting the total thickness T1 of the tread rubber 10 in the crown region Cr to 5.0 mm or more, it is possible to ensure sufficient grip force in the crown region Cr, improve straight-line stability when running on a circuit, and ensure sufficient rear braking force when braking upright. From this perspective, it is more desirable that the total thickness T1 of the tread rubber 10 in the crown region Cr be, for example, 5.5 mm or more.

[0043] By setting the total thickness T1 of the tread rubber 10 in the crown region Cr to 9.0 mm or less, a good balance between blow damage resistance and grip strength in the crown region Cr can be achieved. From this perspective, it is more desirable that the total thickness T1 of the tread rubber 10 in the crown region Cr be, for example, 8.5 mm or less.

[0044] In each shoulder region Sh, the total thickness T2 of the tread rubber 10 is also desirably set within the range of 5.0 to 9.0 mm, for example. The total thickness T1 of the tread rubber 10 in the shoulder region Sh is the total thickness of the surface layer 11, the intermediate layer 12, and the bottom layer 13 in the shoulder region Sh, and if this total thickness varies, it means the maximum thickness.

[0045] In each shoulder region Sh, the thickness t2 of the intermediate layer 12 is preferably 10% or more of the total thickness T2 of the tread rubber 10. By making the thickness t2 of the intermediate layer 12 10% or more of the total thickness T2, it is possible to increase the grip force in the shoulder regions Sh and improve the propulsion force when exiting a corner. From this perspective, it is even more preferable that the thickness t2 of the intermediate layer 12 be, for example, 20% or more of the total thickness T2 of the tread rubber 10.

[0046] In each shoulder region Sh, the thickness t2 of the intermediate layer 12 is preferably 60% or less of the total thickness T2 of the tread rubber 10. By setting the thickness t2 of the intermediate layer 12 to 60% or less of the total thickness T2, excessive heat accumulation in the shoulder region Sh can be suppressed. From this perspective, the thickness t2 of the intermediate layer 12 is more preferably, for example, 50% or less of the total thickness T2.

[0047] In the crown region Cr and the pair of shoulder regions Sh, the thickness t3 of the bottom layer 13 is preferably 5% or more of the total thickness of the surface layer 11 and the intermediate layer 12 (or the maximum total thickness if it varies). Generally, a high tan δ second rubber contains a large amount of oil. If this oil component migrates to the reinforcing cords on the inside of the tire, the grip-enhancing function of the intermediate layer 12 is reduced and the physical properties of the reinforcing cords are deteriorated. By specifying the thickness t3 of the bottom layer 13 as in this embodiment, the bottom layer 13 acts as a barrier, effectively preventing the oil in the second rubber from migrating to the tread reinforcing layer 7, thereby ensuring the high tan δ physical properties of the second rubber over a long period of time. From this perspective, the thickness t3 of the bottom layer 13 is more preferably 10% or more of the total thickness of the surface layer 11 and the intermediate layer 12.

[0048] In the crown region Cr and the pair of shoulder regions Sh, the thickness t3 of the bottom layer 13 is preferably 30% or less of the total thickness of the surface layer 11 and the intermediate layer 12. If the thickness t3 of the bottom layer 13 is large within the constraints of the total thickness of the tread rubber 10, the thicknesses of the surface layer 11 and the intermediate layer 12 will become thin, which may impair grip force and abrasion resistance. From this perspective, the thickness t3 of the bottom layer 13 is more preferably 20% or less of the total thickness of the surface layer 11 and the intermediate layer 12.

[0049] [loss tangent tanδ] In order to exert a high grip force during cornering, the loss tangent tanδ of the second rubber may be set to, for example, 0.30 or more, preferably 0.35 or more, and more preferably 0.40 or more. On the other hand, if the loss tangent tanδ of the second rubber is excessively large, there is a risk of increased energy loss. From this perspective, the loss tangent tanδ of the second rubber may be set to, for example, 0.60 or less, preferably 0.55 or less, and more preferably 0.50 or less, in combination with any of the above lower limit values.

[0050] In order to more effectively prevent blow damage due to heat accumulation during high-speed straight driving, the loss tangent tanδ of the first rubber forming the surface layer 11 may be set to, for example, 0.40 or less, preferably 0.35 or less, and more preferably 0.32 or less. Furthermore, from the viewpoint of preventing a significant decrease in grip force during high-speed straight driving, the loss tangent tanδ of the first rubber may be set to, for example, 0.20 or more, preferably 0.25 or more, and more preferably 0.27 or more, in combination with any of the above upper limit values.

[0051] To more effectively prevent blow damage due to heat accumulation during straight-line driving at high speeds, it is desirable that the loss tangent tanδ at 100°C of the third rubber forming the bottom layer 13 be smaller than the loss tangent tanδ at 100°C of the second rubber. In particular, the loss tangent tanδ of the third rubber at 100°C may be set to, for example, 0.35 or less, preferably 0.30 or less, and more preferably 0.28 or less. Furthermore, from the perspective of preventing a significant decrease in grip force during straight-line driving, the loss tangent tanδ of the third rubber may be set to, for example, 0.15 or more, preferably 0.20 or more, and more preferably 0.23 or more, in combination with any of the above upper limit values.

[0052] [300% modulus of first rubber] The 300% modulus at 100°C (hereinafter, the temperature 100°C may be omitted) of the first rubber forming the surface layer 11 is preferably greater than the 300% modulus at 100°C of the second rubber forming the mid layer 12. Although such a first rubber has inferior grip strength compared to the second rubber of the mid layer 12, it exhibits excellent wear resistance. Therefore, excellent wear resistance is exhibited over the entire range of the crown region Cr and the shoulder region Sh.

[0053] In this specification, the 300% modulus is the modulus when a rubber test piece is elongated by 300%, and refers to the tensile stress (MPa) M300 at 300% elongation measured at 100°C in accordance with JIS-K6251 "Vulcanized rubber and thermoplastic rubber - Determination of tensile properties."

[0054] In order to effectively exhibit the above-mentioned abrasion resistance, the 300% modulus of the first rubber may be, for example, 3.0 (MPa) M300 or more, preferably 3.5 (MPa) M300 or more, and more preferably 4.3 (MPa) M300 or more. In addition, in order to prevent a significant decrease in grip strength, the 300% modulus of the first rubber may be, for example, 7.0 (MPa) M300 or less, preferably 6.0 (MPa) M300 or less, and more preferably 5.0 (MPa) M300 or less.

[0055] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above specific disclosure, and can be implemented in various modified forms within the scope of the technical idea described in the claims.

[0056] [Note] The present invention includes the following aspects.

[0057] [Invention 1] A tire for a motorcycle, a tread portion having a pair of tread edges; A pair of sidewall portions; a pair of bead portions; a carcass disposed so as to straddle the pair of bead portions; a tread reinforcing layer disposed on the outer side of the carcass in the tire radial direction and having reinforcing cords; a tread rubber disposed radially outward of the tread reinforcing layer, the tread portion includes a crown region that crosses the tire equatorial plane and a pair of shoulder regions that are axially outward of the crown region, the pair of shoulder regions includes the pair of tread edges, The tread rubber includes a surface layer made of a first rubber disposed on the outer side in the tire radial direction, The tire includes a bottom layer made of a third rubber disposed on the inner side in the tire radial direction, and an intermediate layer made of a second rubber disposed between the surface layer and the bottom layer, The loss tangent tanδ of the second rubber at 100 ° C is greater than the loss tangent tanδ of the first rubber at 100 ° C and the loss tangent tanδ of the third rubber at 100 ° C, the top layer and the bottom layer extend from one of the pair of shoulder regions through the crown region to the other of the pair of shoulder regions; the intermediate layer is composed of a pair of intermediate layers extending through the pair of shoulder regions, respectively, and terminates at an inner end in the tire axial direction so as not to be disposed in the crown region, In the crown region, the surface layer and the bottom layer are directly connected to each other. Tires for motorcycles. [Invention 2] The motorcycle tire according to claim 1, wherein each of the pair of shoulder regions includes a transition region in which the thickness of the surface layer increases toward the crown region and the thickness of the intermediate layer decreases toward the crown region. [Invention 3] A motorcycle tire according to aspect 2, wherein each of the pair of shoulder regions includes a constant region, axially outward of the transition region, in which the surface layer, the intermediate layer, and the bottom layer extend with a constant thickness. [Invention 4] The motorcycle tire according to any one of claims 1 to 3, wherein the bottom layer has a constant thickness in the crown region and the pair of shoulder regions. [Invention 5] 5. The motorcycle tire according to any one of claims 1 to 4, wherein the 300% modulus at 100°C of the first rubber is greater than the 300% modulus at 100°C of the second rubber. [Invention 6] The motorcycle tire according to any one of claims 1 to 5, wherein, when mounted on a regular rim and in a no-load, specific dimensional state with the internal pressure adjusted to 10 (kPa), the radius of curvature of the contact profile of the crown region is smaller than 95% of the tire cross-sectional width. [Invention 7] 7. The motorcycle tire according to any one of claims 1 to 6, wherein the crown region is in a range of 30 to 90 mm from the tire equatorial plane. [Invention 8] The motorcycle tire according to any one of Inventions 1 to 7, wherein the total thickness of the tread rubber in the crown region is in the range of 5.0 to 9.0 mm. [Invention 9] In each of the pair of shoulder regions, the total thickness of the tread rubber is in the range of 5.0 to 9.0 mm, 9. The motorcycle tire according to claim 1, wherein the thickness of the intermediate layer is 10% to 60% of the total thickness of the tread rubber. [Invention 10] The motorcycle tire according to any one of claims 1 to 9, wherein in the crown region and the pair of shoulder regions, the thickness of the bottom layer is 5% to 30% of the total thickness of the surface layer and the intermediate layer. [Explanation of symbols]

[0058] 1. Motorcycle tires 2 Tread section 2a Grounding Profile 3 Sidewall 4 Bead section 6. Carcass 7 Tread reinforcement layer 10 Tread rubber 11 Surface layer 12 Middle Class 12i inner end 13 Bottom layer 20 Transition region 21 Constant Region C Tire equatorial plane Cr Crown region Sh Shoulder region

Claims

1. A tire for a motorcycle, a tread portion having a pair of tread edges; A pair of sidewall portions; a pair of bead portions; a carcass disposed so as to straddle the pair of bead portions; a tread reinforcing layer disposed on the outer side of the carcass in the tire radial direction and having reinforcing cords; a tread rubber disposed radially outward of the tread reinforcing layer, the tread portion includes a crown region that crosses the tire equatorial plane and a pair of shoulder regions that are axially outward of the crown region, the pair of shoulder regions includes the pair of tread edges, The tread rubber includes a surface layer made of a first rubber disposed on the outer side in the tire radial direction, The tire includes a bottom layer made of a third rubber disposed on the inner side in the tire radial direction, and an intermediate layer made of a second rubber disposed between the surface layer and the bottom layer, The loss tangent tanδ of the second rubber at 100 ° C is greater than the loss tangent tanδ of the first rubber at 100 ° C and the loss tangent tanδ of the third rubber at 100 ° C; the top layer and the bottom layer extend from one of the pair of shoulder regions through the crown region to the other of the pair of shoulder regions; the intermediate layer is composed of a pair of intermediate layers extending through the pair of shoulder regions, respectively, and terminates at an inner end in the tire axial direction so as not to be disposed in the crown region, In the crown region, the surface layer and the bottom layer are directly connected to each other. Tires for motorcycles.

2. 2. The motorcycle tire according to claim 1, wherein each of the pair of shoulder regions includes a transition region in which the thickness of the surface layer increases toward the crown region and the thickness of the intermediate layer decreases toward the crown region.

3. 3. The motorcycle tire according to claim 2, wherein each of the pair of shoulder regions includes a constant region, axially outward of the transition region, in which the surface layer, the intermediate layer, and the bottom layer extend with a constant thickness.

4. The motorcycle tire according to claim 3, wherein the bottom layer has a constant thickness in the crown region and the pair of shoulder regions.

5. 5. The motorcycle tire according to claim 1, wherein the 300% modulus at 100°C of the first rubber is greater than the 300% modulus at 100°C of the second rubber.

6. 5. The motorcycle tire according to claim 1, wherein, when the tire is mounted on a regular rim and in a no-load, specific dimensional state with the internal pressure adjusted to 10 kPa, the radius of curvature of the contact profile of the crown region is smaller than 95% of the tire cross-sectional width.

7. 5. The motorcycle tire according to claim 1, wherein the crown region has a range of 30 to 90 mm from the tire equatorial plane.

8. 5. The motorcycle tire according to claim 1, wherein the total thickness of the tread rubber in the crown region is in the range of 5.0 to 9.0 mm.

9. In each of the pair of shoulder regions, the total thickness of the tread rubber is in the range of 5.0 to 9.0 mm, 5. The motorcycle tire according to claim 1, wherein the thickness of the intermediate layer is 10% to 60% of the total thickness of the tread rubber.

10. 5. The motorcycle tire according to claim 1, wherein in the crown region and the pair of shoulder regions, a thickness of the bottom layer is 5% to 30% of a total thickness of the surface layer and the intermediate layer.

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