Bias tires for two-wheeled vehicles

Abstract

Provided is a bias tire for a two-wheeled vehicle, which can improve the handling stability during cornering. The bias tire for a two-wheeled vehicle (1) includes a carcass (6) of a bias structure. It includes a tread rubber (7) forming a tread portion (2) and a sidewall rubber (8) forming a sidewall portion (3). The tread rubber (7) is connected to the sidewall rubber (8) via an interface (9). The outer end (9a) of the interface (9) in the tire axial direction is closer to the inner side of the tire radial direction than the end of the tread portion (2) in the tire axial direction, i.e., the tread end (Te), and is located on the outer surface of the tire.

Description

Technical Field

[0001] The present invention relates to a bias tire for a two-wheeled vehicle including a carcass having a bias structure. Background Art

[0002] Bias tires for motorcycles having a carcass with a bias structure are known in the past. For example, Patent Document 1 below proposes a bias tire for motorcycles that achieves both weight reduction and steering stability by determining the inclination angle of the carcass line.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2000-185511 Summary of the invention

[0004] However, in the bias tire for a two-wheeled vehicle of Patent Document 1, since the same rubber is used from the tread portion to the sidewall portion, there is room for further improvement in the steering stability performance during cornering.

[0005] The present invention has been made in view of the above-mentioned actual situation, and its main object is to provide a bias tire for a two-wheeled vehicle that can improve the steering stability during cornering.

[0006] The present invention is a bias tire for two-wheeled vehicles having a carcass with a bias structure, characterized in that it includes a tread rubber forming a tread portion and a sidewall rubber forming a sidewall portion, the tread rubber is connected to the sidewall rubber via an interface, the outer end of the interface in the tire axial direction is closer to the radial inside of the tire than the end of the tread portion in the tire axial direction, i.e., the tread end, and is located on the outer surface of the tire.

[0007] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that a distance in the tire radial direction between the outer end of the interface and the tread end is 20 mm or less.

[0008] In the bias tire for a two-wheeled vehicle of the present invention, preferably, the height of the outer end of the interface from the bead base line in the tire radial direction is 60% or more of the height of the tread end from the bead base line in the tire radial direction.

[0009] In the bias tire for a two-wheeled vehicle of the present invention, preferably, the loss tangent tanδS of the sidewall rubber at 70°C is smaller than the loss tangent tanδT of the tread rubber at 70°C.

[0010] In the bias tire for a two-wheeled vehicle of the present invention, it is preferred that, in the side wall rubber, the ratio of the natural rubber to 100 parts by mass of the rubber component is 30 parts by mass or more.

[0011] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that an end portion of the tread rubber in the tire axial direction is connected to the side wall rubber via the interface.

[0012] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that an inner end of the interface in the tire axial direction is located on an outer side in the tire radial direction than an outer end of the interface.

[0013] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that an inner end of the interface in the tire axial direction is located farther outward in the tire radial direction than the tread end.

[0014] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that the interface be curved convexly toward the inner side in the tire radial direction.

[0015] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that the interface be curved so as to be convex outward in the tire radial direction.

[0016] In the bias tire for a two-wheeled vehicle of the present invention, preferably, the side wall rubber includes a side wall main body portion forming the pair of side wall portions and a connecting portion connecting the pair of side wall main bodies.

[0017] In the bias tire for a two-wheeled vehicle of the present invention, it is preferable that the thickness of the connecting portion is 2.0 mm or less.

[0018] In the bias tire for a two-wheeled vehicle of the present invention, preferably, the tread portion includes a plurality of grooves, the grooves are provided with a plurality of slide marks for indicating the wear state of the tread portion, and the connecting portion is closer to the tire radial direction than the surface of the slide mark closest to the tire equator.

[0019] In the bias tire for a motorcycle of the present invention, it is preferable that an end portion of the interface in the tire axial direction be curved convexly toward the inner side in the tire radial direction.

[0020] In the bias tire for two-wheeled vehicles of the present invention, the tread rubber is connected to the sidewall rubber via an interface, and the outer end of the interface in the tire axial direction is located radially inward of the end of the tread portion in the tire axial direction, i.e., the tread end, and is located on the outer surface of the tire. Such a bias tire for two-wheeled vehicles can improve the steering stability during cornering by the tread rubber and the sidewall rubber. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a tire meridian cross-sectional view of the bias tire for a two-wheeled vehicle according to the first embodiment.

[0022] Figure 2 It is a tire meridian cross-sectional view of a bias tire for a two-wheeled vehicle according to a second embodiment.

[0023] Figure 3 It is a tire meridian cross-sectional view of a bias tire for a two-wheeled vehicle according to a third embodiment.

[0024] Figure 4 It is a development view of the tread portion of the third embodiment.

[0025] Description of symbols

[0026] 1: Bias tire for two-wheeled vehicles; 2: Tread portion; 3: Sidewall portion; 6: Carcass; 7: Tread rubber; 8: Sidewall rubber; 9: Interface; 9a: Outer end. DETAILED DESCRIPTION

[0027] Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

[0028] Figure 1 It is a tire meridian cross-sectional view of a bias tire 1 for a two-wheeled vehicle (hereinafter sometimes simply referred to as “tire 1”) in a standard state according to the first embodiment.

[0029] Here, the "standard state" refers to a state where the tire 1 is assembled on a standard rim and adjusted to a standard internal pressure and is unloaded. In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured under the standard state.

[0030] The “standard rim” is a rim whose specifications are prescribed for each tire in a specification system including the specifications based on the tire 1, for example, “standard rim” in JATMA, “design rim” in TRA, and “measuring rim” in ETRTO.

[0031] In addition, the "standard internal pressure" is the air pressure specified for each tire in the specification system including the specification on which the tire 1 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 AT VARIOUS COLD INFLATION PRESSURES", and if it is ETRTO, it is "INFLATION PRESSURE".

[0032] like Figure 1 As shown, the tire 1 of the first embodiment includes: a tread portion 2; a pair of sidewall portions 3 extending radially inward from both ends of the tread portion 2; and a pair of bead portions 4 located radially inward of the sidewall portions 3. For example, bead cores 5 are respectively embedded in the pair of bead portions 4.

[0033] The tread 2s, the outer surface of the tread portion 2, extends in an arc shape convex outward in the tire radial direction from the tire equator C to the tread end Te. The tread width Wt, which is the straight width in the tire axial direction between the tread ends Te, is preferably the maximum tire width.

[0034] Such a tire 1 can be turned by providing a large camber angle. Here, the tread end Te is an end of the tread portion 2 in the tire axial direction, and the tire equator C is the center between the tread ends Te in the tire axial direction.

[0035] The tire 1 of the first embodiment includes a carcass 6 of a bias structure extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. The carcass 6 includes a main body portion 6a spanning between a pair of bead cores 5 and a folded portion 6b connected to the main body portion 6a and folded around the bead core 5.

[0036] The carcass 6 of the bias structure includes at least one carcass ply, and in the first embodiment includes two carcass plies 6A and 6B. The carcass plies 6A and 6B include, for example, carcass cords arranged at an angle of 30° to 60° relative to the tire equator C. Preferably, the carcass plies 6A and 6B are arranged such that the inclination directions of the carcass cords are opposite to each other in such a manner that the carcass cords intersect each other between the plies.

[0037] The tire 1 of the first embodiment includes a tread rubber 7 forming a tread portion 2 and a pair of sidewall rubbers 8 forming a sidewall portion 3. The tread rubber 7 of the first embodiment is connected to the sidewall rubber 8 via an interface 9. That is, the tread rubber 7 and the sidewall rubber 8 of the first embodiment are formed of rubbers different from each other. In the first embodiment, the end 7a of the tread rubber 7 in the tire axial direction is connected to the sidewall rubber 8 via the interface 9.

[0038] Such a tire 1 can use rubber having excellent grip performance as the tread rubber 7 and rubber having excellent absorption performance as the sidewall rubber 8. Therefore, the tire 1 of the first embodiment can improve the steering stability during cornering.

[0039] The outer end 9a of the interface 9 in the first embodiment is located radially inward of the tread end Te of the tread portion 2 and on the outer surface of the tire. Even when the tire 1 is turned with a large camber angle, the tread rubber 7 always contacts the ground, and there is no possibility that the sidewall rubber 8 contacts the ground. Therefore, the sidewall rubber 8 of the tire 1 in the first embodiment does not contact the ground when turning, and the grip performance does not change drastically, which can improve the handling stability.

[0040] The distance L1 between the outer end 9a of the interface 9 and the tread end Te in the tire radial direction is preferably 20 mm or less. By making the distance L1 20 mm or less, the outer end 9a of the interface 9 can be located on the outer surface of the tire that deforms less during cornering, and the durability of the tire 1 can be improved. From this point of view, the distance L1 is more preferably 15 mm or less.

[0041] The height Ho of the outer end 9a of the interface 9 from the bead base line BL in the tire radial direction is preferably 60% or more, and more preferably 70% or more, of the height HS of the tread end Te from the bead base line BL in the tire radial direction. Such a tire 1 can make the outer end 9a of the interface 9 be located on the outer surface of the tire where deformation is small during cornering, and can improve durability. Here, the bead base line BL is equivalent to a line that specifies the rim diameter of a standard rim on which the tire 1 is mounted.

[0042] The height Ho of the outer end 9a of the interface 9 is preferably 98% or less, and more preferably 95% or less, of the height HS of the tread end Te. Such a tire 1 does not have the possibility of the sidewall rubber 8 contacting the ground even when turning with a large camber angle, thereby improving the steering stability of the tire 1 when turning.

[0043] The inner end 9b of the interface 9 in the first embodiment is located radially outward from the outer end 9a of the interface 9. Such a tire 1 is less likely to crack along the interface 9 even if loads are repeatedly applied near the interface 9, thereby improving durability.

[0044] The distance L2 in the tire radial direction between the outer end 9a and the inner end 9b of the interface 9 is preferably 30 mm or less. By setting the distance L2 to 30 mm or less, the outer end 9a of the interface 9 can be located on the outer surface of the tire that is less deformed during cornering, and the durability of the tire 1 can be improved. From this point of view, the distance L2 is more preferably 20 mm or less.

[0045] The axial inner end 9b of the interface 9 of the first embodiment is located radially outward from the tread end Te. Such a tire 1 is less likely to crack along the interface 9 even when a load is repeatedly applied near the interface 9, and can further improve durability.

[0046] The height Hi of the inner end 9b of the interface 9 from the bead base line BL in the tire radial direction is preferably 105% or more, more preferably 110% or more of the height HS of the tread end Te. Such a tire 1 can reduce the possibility of cracks occurring along the interface 9 and improve durability.

[0047] The height Hi of the inner end 9b of the interface 9 is preferably 130% or less, more preferably 120% or less of the height HS of the tread end Te. Such a tire 1 can position the outer end 9a of the interface 9 on the tire outer surface that deforms less during cornering, thereby improving durability.

[0048] The interface 9 of the first embodiment is curved convexly inward in the tire radial direction. Such an interface 9 has a small ratio of the sidewall rubber 8 near the end 7a of the tread rubber 7, so that the steering stability of the tire 1 can be improved when turning with a large camber angle.

[0049] The tire 1 may also include a reinforcing layer 10, for example, disposed on the tire radially outer side of the carcass 6 and inside the tread portion 2. The reinforcing layer 10 includes at least one reinforcing cord layer 10A, and in the first embodiment, one reinforcing cord layer. In this case, the inner end 9b of the interface 9 is located on the reinforcing layer 10. Such a tire 1 can suppress deformation during high-speed running and improve high-speed durability performance.

[0050] The loss tangent tanδS of the sidewall rubber 8 of the first embodiment at 70°C is smaller than the loss tangent tanδT of the tread rubber 7 at 70°C. Such a sidewall rubber 8 has excellent absorption performance and can improve the ride comfort performance of the tire 1. Here, the loss tangent tanδ at 70°C is a value measured using a "viscoelasticity spectrometer" under the conditions of measurement temperature: 70°C, initial deformation: 10%, amplitude: ±1%, frequency: 10 Hz, and deformation mode: tension according to the provisions of JIS-K6394.

[0051] The ratio of natural rubber to 100 parts by mass of the rubber component in the sidewall rubber 8 is preferably 30 parts by mass or more, more preferably 40 parts by mass or more. Such sidewall rubber 8 can suppress the occurrence of cracks and improve the durability of the tire 1.

[0052] Figure 2 This is a tire meridian cross-sectional view of a standard state of a bias tire 11 for a two-wheeled vehicle (hereinafter sometimes simply referred to as "tire 11") according to a second embodiment. Elements having the same functions as those in the above embodiment are denoted by the same reference numerals and their description is omitted.

[0053] like Figure 2 As shown, the tire 11 of the second embodiment includes: a tread portion 2; a pair of sidewall portions 3 extending radially inward from both ends of the tread portion 2; and a pair of bead portions 4 located radially inward of the sidewall portions 3. For example, bead cores 5 are respectively embedded in the pair of bead portions 4. Preferably, the tire 11 includes a carcass 6 of a bias structure and a reinforcing layer 10 arranged radially outward of the carcass 6 and inside the tread portion 2, similarly to the above-mentioned tire 1.

[0054] The tire 11 of the second embodiment includes a tread rubber 7 forming a tread portion 2 and a pair of sidewall rubbers 8 forming a sidewall portion 3. The tread rubber 7 of the second embodiment has an axial end 7a connected to the sidewall rubber 8 via an interface 12.

[0055] The outer end 12a of the interface 12 in the second embodiment is located radially inward of the tire and on the outer surface of the tire, relative to the tread end Te. Even when such a tire 11 is turned with a large camber angle, the tread rubber 7 always contacts the ground, and there is no possibility that the sidewall rubber 8 contacts the ground. Therefore, the tire 11 of the second embodiment, like the tire 1 described above, does not contact the ground when turning, does not cause a sharp change in grip performance, and can improve handling stability.

[0056] The inner end 12b of the interface 12 in the second embodiment in the tire axial direction is closer to the outer side in the tire radial direction than the outer end 12a of the interface 12. The inner end 12b of the interface 12 in the second embodiment is closer to the outer side in the tire radial direction than the tread end Te. Such a tire 11 can reduce the possibility of cracks occurring along the interface 12 even when a load is repeatedly applied near the interface 12, and can improve durability.

[0057] The interface 12 of the second embodiment is curved convexly outward in the tire radial direction. Such an interface 12 has a large ratio of the sidewall rubber 8 near the end 7a of the tread rubber 7, so that the ride comfort of the tire 11 can be improved when turning with a large camber angle.

[0058] Figure 3 1 is a tire meridian cross-sectional view of a standard state of a bias tire 21 for a two-wheeled vehicle (hereinafter sometimes simply referred to as "tire 21") according to a third embodiment. Elements having the same functions as those in the above embodiment are denoted by the same reference numerals and their description is omitted.

[0059] like Figure 3 As shown, the tire 21 of the third embodiment includes: a tread portion 2; a pair of sidewall portions 3 extending radially inward from both ends of the tread portion 2; and a pair of bead portions 4 located radially inward of the sidewall portions 3. For example, bead cores 5 are respectively embedded in the pair of bead portions 4. Preferably, the tire 21 includes a carcass 6 of a bias structure and a reinforcing layer 10 arranged radially outward of the carcass 6 and inside the tread portion 2, similarly to the above-mentioned tire 1.

[0060] The tire 21 of the third embodiment includes a tread rubber 7 forming a tread portion 2 and a sidewall rubber 22 disposed on the inner side of the tread rubber 7 in the tire radial direction. The tread rubber 7 of the third embodiment is connected to the sidewall rubber 22 via an interface 23. That is, the tread rubber 7 and the sidewall rubber 22 of the third embodiment are formed of different rubbers.

[0061] Such a tire 21 can use rubber having excellent grip performance as the tread rubber 7 and rubber having excellent absorption performance as the sidewall rubber 22. Therefore, the tire 21 of the third embodiment can improve the steering stability during cornering.

[0062] The sidewall rubber 22 of the third embodiment includes a sidewall main body 22a forming a pair of sidewall portions 3 and a connecting portion 22b connecting the pair of sidewall main body portions 22a. Such a tire 21 can suppress the heat generated by the deformation of the tread rubber 7 during high-speed driving by the presence of the sidewall rubber 22 between the tread rubber 7 and the carcass 6, and can improve the durability performance during high-speed driving. In addition, the tire 21 can reduce the energy loss of the tread portion 2, thereby reducing the rolling resistance and improving the low fuel consumption performance.

[0063] The outer end 23a of the interface 23 in the third embodiment is located radially inward of the tread end Te of the tread portion 2 in the tread radial direction and is located on the outer surface of the tire. As with the tire 1, even when turning with a large camber angle, the tread rubber 7 of such a tire 21 always contacts the ground, and there is no possibility that the sidewall rubber 22 contacts the ground. Therefore, the sidewall rubber 22 of the tire 21 in the third embodiment does not contact the ground when turning, and the grip performance does not change drastically, which can improve the handling stability.

[0064] The distance L3 in the tire radial direction between the outer end 23a of the interface 23 and the tread end Te is preferably 20 mm or less. By making the distance L3 20 mm or less, the outer end 23a of the interface 23 can be located on the outer surface of the tire that is less deformed during cornering, and the durability of the tire 21 can be improved. From this point of view, the distance L3 is more preferably 15 mm or less.

[0065] The height H of the outer end 23a of the interface 23 from the bead base line BL in the tire radial direction is preferably 60% or more, and more preferably 70% or more, of the height HS of the tread end Te from the bead base line BL in the tire radial direction. Such a tire 21 can make the outer end 23a of the interface 23 located on the tire outer surface where deformation is small during cornering, thereby improving durability. Here, the bead base line BL is equivalent to a line that specifies the rim diameter of a standard rim on which the tire 21 is mounted.

[0066] The height H of the outer end 23a of the interface 23 is preferably 98% or less, and more preferably 95% or less of the height HS of the tread end Te. Such a tire 21 does not have the possibility of the sidewall rubber 22 contacting the ground even when turning with a large camber angle, which can improve the steering stability of the tire 21 when turning.

[0067] Figure 4 It is a development view of the tread portion 2 according to the third embodiment. Figure 3 yes Figure 4 The cross-sectional view of the AA line. Figure 3 and Figure 4 As shown, the tread portion 2 of the third embodiment includes a plurality of grooves 24. The shape of the grooves 24 is not limited to the shape shown in the figure, and for example, a circumferential groove extending in the tire circumferential direction may be included.

[0068] The groove 24 is provided with a plurality of slide marks 25 for indicating the wear state of the tread portion 2. Here, the slide mark 25 is a portion protruding from the groove bottom of the groove 24 to the outer side in the tire radial direction, and the slide mark 25 is exposed on the tread 2s due to the wear of the tread portion 2, thereby becoming a reference for tire replacement.

[0069] like Figure 3 As shown, the connection portion 22b of the third embodiment is located radially inward of the tire relative to the surface 25s of the slip mark 25 closest to the tire equator C. Such a connection portion 22b will not be exposed on the tread 2s even if it is worn to the slip mark 25 near the tire equator C where the wear is most serious. Therefore, the connection portion 22b of the tire 21 of the third embodiment will not touch the ground even if the wear is increased, and the grip performance will not change drastically, which can improve the steering stability performance.

[0070] The thickness t of the connecting portion 22b is preferably 0.5 mm or more, more preferably 0.8 mm or more. The thickness t of the connecting portion 22b is preferably 2.0 mm or less, more preferably 1.8 mm or less. Such a connecting portion 22b is suitable for suppressing heat generation caused by deformation of the tread rubber 7 during high-speed driving.

[0071] The interface 23 of this embodiment has an axial end 23b that curves convexly inward in the tire radial direction. Since the interface 23 has a small ratio of the sidewall rubber 22 near the end 23b, the steering stability of the tire 21 can be improved when turning with a large camber angle.

[0072] Like the above-mentioned side rubber 8, the side rubber 22 of this embodiment has a loss tangent tanδS at 70°C smaller than the loss tangent tanδT of the tread rubber 7 at 70°C. Such side rubber 22 has excellent absorption performance and can improve the ride comfort of the tire 21.

[0073] Similar to the above-mentioned sidewall rubber 8, the ratio of natural rubber to 100 parts by mass of the rubber component in the sidewall rubber 22 is preferably 30 parts by mass or more, more preferably 40 parts by mass or more. Such sidewall rubber 22 can suppress the occurrence of cracks and improve the durability of the tire 21.

[0074] As mentioned above, although the particularly preferred embodiment of the present invention has been described in detail, the present invention is not limited to the above-mentioned embodiment, and can be implemented in various modified forms.

[0075] [Example]

[0076] As a first embodiment, a prototype was produced according to the specifications in Table 1. Figure 1 and Figure 2Bias tires for two-wheeled vehicles with the basic structure shown in FIG. In addition, as a comparative example, bias tires for two-wheeled vehicles with tread rubber and sidewall rubber formed integrally were trial-produced. Using these trial tires, the steering stability performance, ride comfort performance and durability performance were tested. The common specifications and test methods of each trial tire are as follows.

[0077] <General Specifications>

[0078] Tire size: 130 / 70-13M / C

[0079] Rim size: 13×3.50MT

[0080] Air pressure: 225kPa

[0081] <Handling stability performance>

[0082] The test tires were mounted on the rear wheels of a mid-sized scooter, and the test driver's grip performance, ground contact feel, and transition characteristics when turning were comprehensively evaluated by the test driver's senses. The results were indexed with the comparative example as 100, and the larger the value, the better the steering stability.

[0083] <Ride Comfort Performance>

[0084] The test driver's sense of ride comfort was evaluated by using a mid-sized scooter with a trial tire mounted on the rear wheel. The result was an index with the comparative example as 100, and a larger value indicated a better ride comfort.

[0085] <Durability>

[0086] As an ozone degradation treatment, the trial tires that were placed in an ozone chamber with a concentration of 50 pphm for 3 weeks were mounted on a drum tester, and the durability performance was evaluated by the incidence of cracks on the tire side when a load of 3.29 kN was applied and the tires were driven for 10,000 km. The results were indexed with the comparative example as 100, and the larger the value, the fewer cracks and the better the durability performance.

[0087] The test results are shown in Table 1.

[0088]

Table 1

[0089]

[0090] Next, as a second example, a prototype having Figure 3Bias tires for two-wheeled vehicles with the basic structure shown in FIG. 1 are used as a comparative example. In addition, bias tires for two-wheeled vehicles with tread rubber and sidewall rubber formed integrally are trial-produced in the same manner as in the first embodiment. These trial tires are used to test high-speed durability, handling stability, ride comfort and durability. The common specifications and test methods of each trial tire are as follows.

[0091] <General Specifications>

[0092] Tire size: 130 / 70-13M / C

[0093] Rim size: 13×3.50MT

[0094] <High-speed durability performance>

[0095] The trial tire with air pressure adjusted to 250 kPa was mounted on a drum tester, a load of 1.99 kN was applied, and the tire was driven at a speed of 81 km / h for 2 hours. After cooling to room temperature, the driving speed was increased stepwise every 30 minutes to evaluate the high-speed durability performance until the tire broke. The results were indexed with the comparative example as 100, and the larger the value, the better the high-speed durability performance.

[0096] <Handling stability performance>

[0097] A test driver drove a mid-sized scooter around the test route using a prototype tire with an air pressure of 225 kPa mounted on the rear wheel. The driver's senses were used to comprehensively evaluate the handling stability of the prototype tire during cornering based on the grip performance, ground contact feel, and transition characteristics during cornering. The results were indexed with the comparative example as 100, and the larger the value, the better the handling stability.

[0098] <Ride Comfort Performance>

[0099] A mid-sized scooter with a trial tire adjusted to 225 kPa air pressure mounted on the rear wheel was used to evaluate the ride comfort of the test driver while driving around the test course using the test driver's senses. The results were indexed with the comparative example as 100, and a larger value indicated a better ride comfort.

[0100] <Durability>

[0101] As an ozone degradation treatment, the trial tires were placed in an ozone chamber with a concentration of 50 pphm for 3 weeks, adjusted to an air pressure of 225 kPa, and mounted on a drum tester. Then, the durability performance was evaluated based on the incidence of cracks on the sidewalls when a load of 3.29 kN was applied to the trial tires and the tires were driven for 10,000 km. The results were an index with the comparative example set to 100, and the larger the value, the fewer cracks and the better the durability performance.

[0102] The test results are shown in Table 2.

[0103]

Table 2

[0104]

[0105] The test results show that the bias tires for two-wheeled vehicles of the embodiments have excellent steering stability performance compared to the comparative examples, and the overall performance evaluated by the sum of various performances is also good. Therefore, it is confirmed that the bias tires for two-wheeled vehicles of the embodiments have improved steering stability performance during cornering.

Claims

1. A bias tire for a two-wheeled vehicle, comprising a carcass with a bias structure, wherein: The bias tire for two-wheeled vehicles includes a tread rubber forming a tread portion and a sidewall rubber forming a sidewall portion, the tread rubber is connected to the sidewall rubber via an interface, a reinforcing layer is arranged on the tire radially outer side of the carcass and inside the tread portion, and in a standard state of the bias tire for two-wheeled vehicles, an axially outer end of the interface is closer to the tire radially inner side than the axially outermost end of the tread portion, i.e., the tread end, and is located on the tire outer surface, an axially end of the tread rubber is directly connected to the sidewall rubber via the interface, and an axially inner end of the interface is closer to the tire radially outer side than the tread end and is located on the reinforcing layer and is located on the tire radially outer side of the reinforcing layer.

2. The bias tire for a two-wheeled vehicle according to claim 1, wherein: A distance in the tire radial direction between the outer end of the interface and the tread end is 20 mm or less.

3. The bias tire for a two-wheeled vehicle according to claim 1 or 2, wherein: A height of the outer end of the interface from the bead base line in the tire radial direction is greater than or equal to 60% of a height of the tread end from the bead base line in the tire radial direction.

4. The bias tire for a two-wheeled vehicle according to claim 1 or 2, wherein: The loss tangent tanδS of the sidewall rubber at 70°C is smaller than the loss tangent tanδT of the tread rubber at 70°C.

5. The bias tire for a two-wheeled vehicle according to claim 1 or 2, wherein: In the side wall rubber, the ratio of the natural rubber to 100 parts by mass of the rubber component is 30 parts by mass or more.

6. The bias tire for a two-wheeled vehicle according to claim 1 or 2, wherein: An inner end of the interface in the tire axial direction is located farther outward in the tire radial direction than the outer end of the interface.

7. The bias tire for a two-wheeled vehicle according to claim 1 or 2, wherein: The interface is curved convexly toward the inner side in the tire radial direction.

8. The bias tire for a two-wheeled vehicle according to claim 1 or 2, wherein: The interface is curved convexly toward the outer side in the tire radial direction.

Images