Motorcycle tires

Abstract

To provide a tire 2 for a two-wheel automobile which can enhance rigid feeling while restraining ground-contact feeling from being deteriorated.SOLUTION: A bead part TB of a tire 2 contains a core 18. An external surface of the bead part TB comprises a seat surface 24, a flange surface 26 and a heel surface 28. An inner diameter dw of the core 18, a rim diameter D, an inner diameter dA of the tire 2 in a heel reference point PH and an inner diameter dB of the tire 2 in a seat reference point PS satisfy equations as follows: dw / D≥1.0041, dA / D≤0.9966, and dA-1.72≤dB≤dA-0.73.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a tire for a two-wheeled vehicle.

Background Art

[0002] A tire is assembled to a rim and used, for example, by filling air inside. The tire includes a carcass that spans between a pair of beads. The tire expands by filling air. As a result, a certain tension is generated in the carcass.

[0003] Conventionally, by adjusting the ratio dw / D of the inner diameter dw of the core to the heel diameter D of the rim and the ratio dt / D of the heel diameter dt of the bead portion to the heel diameter D of the rim defined in the public standard, a pneumatic tire has been proposed that improves rim assembly workability while maintaining good rim detachment resistance (for example, Patent Document 1 below).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] If importance is attached to rim detachment resistance and rim assembly workability as in the tire disclosed in Patent Document 1 described above, there is a concern that the clamping force of the bead may decrease. When the clamping force of the bead is low, when a load acts on the tire, the bead moves with respect to the rim. Such a tire is inferior in rigidity.

[0006] Increasing the bead tightening force improves rigidity. The increased carcass tension also increases the rigidity of the tire's sidewall. Higher sidewall rigidity reduces flex, thus decreasing the tire's contact with the road surface. The tread surface of motorcycle tires has a smaller radius of curvature compared to four-wheeled vehicle tires such as those for passenger cars and go-karts, resulting in localized contact between the tread and the road surface. Motorcycle tires have a high sensitivity to road contact, making it difficult to increase rigidity while maintaining that contact feel.

[0007] This invention has been made in view of these circumstances. The object of this invention is to provide a motorcycle tire that can increase rigidity while suppressing a decrease in ground contact feel. [Means for solving the problem]

[0008] A two-wheeled vehicle tire according to one aspect of the present invention comprises a bead portion fitted onto a rim, the bead portion including a core extending in the circumferential direction. The outer surface of the bead portion includes the toe of the tire and comprises a seat surface that contacts the seat of the rim, a flange surface that contacts the flange of the rim, and a heel surface located between the seat surface and the flange surface. The rim is a regular rim. In the meridional cross-section of the tire, the heel reference point is the intersection of the seat extension line of the seat surface, which extends outward from the axial outer end of the seat surface, and the flange reference line, which extends radially inward from the radial inner end of the flange surface, and the seat reference point is the position on the seat surface at an axial distance of 7 mm from the flange reference line. The inner diameter dw of the core, the rim diameter D of the rim, the inner diameter dA of the tire at the heel reference point, and the inner diameter dB of the tire at the seat reference point satisfy the following equation. dw / D≧1.0041 dA / D ≤ 0.9966 dA-1.72 ≤ dB ≤ dA-0.73 However, the units for dw, D, dA, and dB are mm.

[0009] Preferably, in this motorcycle tire, the axial distance H from the heel reference point to the toe exceeds 7 mm, and the axial distance H, the inner diameter dC of the tire at the toe, and the inner diameter dB of the tire at the seat reference point satisfy the following equation. dB-1.16(H-7)≦dC≦dB-0.61(H-7) However, the units for dB, H, and dC are mm.

[0010] Preferably, in this motorcycle tire, the rim diameter D of the rim and the inner diameter dA of the tire at the heel reference point satisfy the following equation. 0.9884 ≤ dA / D ≤ 0.9931 More preferably, in this motorcycle tire, the inner diameter dw of the core and the rim diameter D of the rim satisfy the following equation. 1.0064 ≤ dw / D ≤ 1.0111

[0011] Preferably, in this motorcycle tire, the contour line of the heel surface in the meridional cross-section of the tire is represented by a circular arc. The radius of the circular arc is 2.5 mm or more and 7.5 mm or less.

[0012] Preferably, in this motorcycle tire, the axial distance H from the heel reference point to the toe is 10.0 mm or more and 13.5 mm or less.

[0013] Preferably, the motorcycle tire further comprises a chafer in which the bead portion contacts the seat and flange of the rim. The chafer is made of canvas. [Effects of the Invention]

[0014] According to the present invention, a motorcycle tire can be obtained that can increase rigidity while suppressing a decrease in ground contact feel. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view showing a part of a tire according to the first embodiment of the present invention. [Figure 2] It is a cross-sectional view for explaining a rim. [Figure 3] It is a cross-sectional view for explaining the contour of a bead part.

Mode for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described in detail based on preferred embodiments while appropriately referring to the drawings.

[0017] FIG. 1 shows a part of a tire 2 according to a first embodiment of the present invention. This tire 2 is a tire for a two-wheeled vehicle. This tire 2 is a rear tire mounted on the rear wheel of a two-wheeled vehicle. FIG. 1 shows a part of a cross-section (hereinafter, a meridian cross-section) of this tire 2 along a plane including the rotation axis of the tire 2. In FIG. 1, the left-right direction is the axial direction of the tire 2, and the up-down direction is the radial direction of the tire 2. The direction perpendicular to the paper surface of FIG. 1 is the circumferential direction of the tire 2. The one-dot chain line CL represents the equatorial plane of the tire 2.

[0018] The tire 2 includes, as components, a tread 4, a pair of sidewalls 6, a pair of beads 8, a carcass 10, an inner liner 12, and a reinforcing layer 14. The tread 4 has a tread surface 16 that contacts the road surface. The tread surface 16 forms a part of the outer surface G of the tire 2. Each sidewall 6 is continuous with the tread 4. Each bead 8 is located radially inward of the sidewall 6. The carcass 10 spans between the pair of beads 8. The inner liner 12 is located inside the carcass 10. The inner liner 12 constitutes the inner surface N of the tire 2. The reinforcing layer 14 is laminated with the carcass 10 inside the tread 4 in the radial direction.

[0019] The bead 8 includes a core 18 and an apex 20. The core 18 extends in the circumferential direction. Although not shown, the core 18 includes a metal wire. In this tire 2, the cross-sectional shape of the core 18 is rectangular. The cross-sectional shape may be circular or hexagonal.

[0020] The carcass 10 comprises carcass plies 22. The carcass plies 22 are folded axially from the inside outwards around each core 18. Although not shown, the carcass plies 22 contain a number of parallel cords.

[0021] The reinforcing layer 14 includes a spirally wound cord. This reinforcing layer 14 is also referred to as a band. This reinforcing layer 14 may also be a belt containing a number of parallel cords.

[0022] In Figure 1, the position indicated by the symbol PT is the toe of tire 2. The toe PT is the boundary between the outer surface G and the inner surface N of tire 2. Although not described in detail, tire 2 is obtained by pressurizing and heating the uncrosslinked tire 2 in a cavity formed between the mold and the bladder (or rigid core). The outer surface G of tire 2 is shaped by a mold (not shown). The inner surface of tire 2 is shaped by a bladder.

[0023] The tire 2 comprises a tread portion TT, a pair of bead portions TB, and a pair of sidewall portions TS. The tread portion TT is the portion of the tire 2 that contacts the road surface and includes, for example, the tread 4. The bead portion TB is the portion of the tire 2 that is fitted onto the rim R, which will be described later, and includes, for example, the bead 8. The sidewall portion TS is the portion of the tire 2 that bridges the gap between the tread portion TT and the bead portion TB, and includes, for example, the sidewall 6. In this disclosure, the side portion is the portion consisting of the sidewall portion TS and the bead portion TB.

[0024] Figure 2 shows a part of the rim R. The bead portion TB is fitted into the rim R. This mounts the tire 2 onto the rim R. Air is then filled inside the tire 2, for example, and the internal pressure of the tire 2 is adjusted. The tire 2 mounted on the rim R is also called a tire-rim assembly. The tire-rim assembly comprises the rim R and the tire 2 mounted on this rim R.

[0025] Rim R is a standard rim. A standard rim refers to a rim defined in the standard on which the tire is based. The "Standard Rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are standard rims.

[0026] The rim R comprises a seat S and a flange F. The seat S supports the bead portion TB from the radially inner side. The flange F supports the bead portion TB from the axially outer side. The boundary between the seat S and the flange F is also called the heel H. In Figure 2, the solid line BBL extending in the axial direction is the bead baseline. The bead baseline is the line that defines the rim diameter of the rim R (see JATMA, etc.). In Figure 2, the length indicated by the symbol D is the rim diameter.

[0027] Figure 3 shows a portion of the meridian cross-section of tire 2 shown in Figure 1. Figure 3 shows a cross-section of the bead portion TB. The configuration of the outer surface of the bead portion TB described below also applies to the outer surface of the bead portion of a front tire (not shown) mounted on the front wheel of a two-wheeled vehicle.

[0028] The bead portion TB includes the core 18 of the bead 8. In tire 2, the core 18 forms a ring. In Figure 3, the arrow indicated by the symbol dw represents the inner diameter of the core 18. The solid line CBL extending axially is the line that defines the inner diameter dw of the core 18 (hereinafter referred to as the core reference line).

[0029] The outer surface of the bead portion TB forms part of the outer surface G of the tire 2. The outer surface of the bead portion TB includes a seat surface 24, a flange surface 26, and a heel surface 28. The seat surface 24 contacts the seat S of the rim R. The axial outer end 24g of the seat surface 24 is also the boundary with the heel surface 28. The axial inner end 24n of the seat surface 24 is the toe PT of the tire 2. This seat surface 24 includes the toe PT of the tire 2. The flange surface 26 contacts the flange F of the rim R. The radial inner end 26n of the flange surface 26 is the boundary with the heel surface 28. The heel surface 28 is located between the seat surface 24 and the flange surface 26. In the meridian cross-section, the contour of the heel surface 28 is represented by an arc. In Figure 3, the arrow indicated by the symbol Rh represents the radius of the arc that defines the contour of the heel surface 28.

[0030] In Figure 3, the solid line indicated by the symbol BS is the sheet extension line of the sheet surface 24, extending outward from the axial outer end 24g of the sheet surface 24. The sheet extension line BS is tangent to the contour line of the sheet surface 24 at the axial outer end 24g. The sheet extension line BS is also tangent to the contour line of the heel surface 28 at the axial outer end 24g. In Figure 3, the solid line indicated by the symbol BF is the flange reference line extending radially inward from the radially inner end 26n of the flange surface 26. In this tire 2, the flange reference line BF is tangent to the contour line of the flange surface 26 at the radially inner end 26n. The flange reference line BF is also tangent to the contour line of the heel surface 28 at the radially inner end 26n. In Figure 3, the symbol PH represents the intersection of the sheet extension line BS and the flange reference line BF. In this disclosure, this intersection PH is the heel reference point.

[0031] In Figure 3, the arrow denoted by dA represents the inner diameter of the tire at the heel reference point PH. This inner diameter dA is expressed by the following equation, using the radial distance hA from the core reference line CBL to the heel reference point PH and the inner diameter dW of the core 18. dA = dW - 2 × hA

[0032] In Figure 3, the position indicated by the symbol PS is a position on the seat surface 24. The length indicated by the double arrow SH is the axial distance from the flange reference line BF to position PS. In this disclosure, this axial distance SH is 7 mm. Therefore, position PS is a position on the seat surface 24 where the axial distance SH from the flange reference line BF is 7 mm. In this disclosure, this position PS is the seat reference point. In this tire 2, the seat reference point PS is located radially inward of the core 18.

[0033] In Figure 3, the arrow indicated by the sign dB represents the inner diameter of the tire at the sheet reference point PS. This inner diameter dB is expressed by the following equation, using the radial distance hB from the core reference line CBL to the sheet reference point PS and the inner diameter dW of the core 18. dB = dW - 2 × hB

[0034] In Figure 3, the length indicated by the double arrow H is the axial distance from the heel reference point PH to the toe PT. In this tire 2, the axial distance H exceeds 7 mm.

[0035] In Figure 3, the arrow denoted by dC represents the inner diameter of the tire at toe point PT. This inner diameter dC is expressed by the following equation, using the radial distance hC from the core reference line CBL to toe point PT and the inner diameter dW of the core 18. dC = dW - 2 × hC

[0036] The inventors diligently studied how to increase rigidity while suppressing a decrease in tire contact feel, and as a result found that it is important to increase the inner diameter dw of the core 18 and decrease the inner diameter dA of the tire 2 at the heel reference point PH. Specifically, it was found that the inner diameter dw of the core 18, the rim diameter D of the rim R, and the inner diameter dA of the tire 2 at the heel reference point PH satisfy the following equation. dw / D≧1.0041 dA / D ≤ 0.9966 However, the units for dw, D, and dA are mm.

[0037] This allows the tire 2 to increase the tightening force of the bead 8 while properly maintaining the tension generated in the carcass 10. The tire 2 achieves increased rigidity while minimizing the decrease in contact with the road.

[0038] By increasing the inner diameter dw of core 18 and decreasing the inner diameter dA of tire 2 at heel reference point PH, it is possible to increase rigidity while suppressing a decrease in contact feel. However, there are concerns that the fitting pressure will increase and the rim assembly performance will decrease.

[0039] Regarding this point, as a result of intensive studies focusing on the contact pressure with the rim R in the inner part of the core 18 of the bead 8, the inventors have found that in order to reduce the contact pressure with the rim R, it is important that the inner diameter dA of the tire 2 at the heel reference point PH and the inner diameter dB of the tire at the seat reference point PS satisfy the following formula. dA - 1.72 ≤ dB ≤ dA - 0.73 However, the units of dA and dB are mm.

[0040] Thereby, even if the inner diameter dw of the core 18 is increased and the inner diameter dA of the tire 2 at the heel reference point PH is decreased, this tire 2 can reduce the contact pressure with the rim R at the inner part of the core 18. As a result, in this tire 2, the increase in the fitting pressure is suppressed and good rim compatibility is maintained.

[0041] The reason is that when dB < dA - 1.72, the contact pressure with the rim R increases, and there is a drawback that the increase in the fitting pressure cannot be suppressed and the rim compatibility deteriorates. When dB > dA - 0.73, although the fitting pressure decreases, the contact pressure with the rim R decreases, and the bead part TB becomes more likely to move with respect to the rim R.

[0042] In this tire 2, it is preferable that the axial distance H from the heel reference point PH to the toe PT, the inner diameter dC of the tire at the toe PT, and the aforementioned inner diameter dB of the tire satisfy the following formula. dB - 1.16(H - 7) ≤ dC ≤ dB - 0.61(H - 7) However, the units of dB, H, and dC are mm.

[0043] Thereby, the contact pressure with the rim R at the toe PT of the tire 2 is increased. In this tire 2, the adhesion with the rim R is enhanced and the rigidity feeling is further improved.

[0044] The reason is that when dC < dB - 1.16(H - 7), the contact pressure with the rim R increases too much, and the increase in the fitting pressure cannot be suppressed, resulting in a drawback of deteriorated rim assembly property. When dC > dB - 0.61(H - 7), although the fitting pressure decreases, the contact pressure with the rim R decreases, and the bead portion TB becomes more likely to move with respect to the rim R.

[0045] In this tire 2, from the viewpoint of further enhancing the rigidity, the ratio (dA / D) of the inner diameter dA to the rim diameter D preferably satisfies the following formula. 0.9884 ≦ dA / D ≦ 0.9931 In this case, there is a concern that the fitting pressure increases and the rim assembly property deteriorates. Therefore, from the viewpoint of suppressing the increase in the fitting pressure and improving the grounding feeling, the ratio (dw / D) of the inner diameter dw to the rim diameter D more preferably satisfies the following formula. 1.0064 ≦ dw / D ≦ 1.0111

[0046] When dA < 0.9884, the fitting pressure increases too much and the rim assembly property deteriorates. When dw / D > 1.0111, when a load acts on the tire 2, the bead portion TB deflects, and this tire cannot ensure the rigidity.

[0047] As described above, in the meridian cross-section of the tire 2, the contour line of the heel surface 28 is represented by an arc. In this tire 2, the radius Rh of this arc is preferably 2.5 mm or more and 7.5 mm or less. By setting the radius Rh to 2.5 mm or more, the increase in the fitting pressure can be effectively suppressed, and good rim assembly property can be obtained. From this viewpoint, the radius Rh is more preferably 3.5 mm or more. By setting the radius Rh to 7.5 mm or less, the contact pressure with the rim R on the heel surface 28 is appropriately maintained. This heel surface 28 can contribute to enhancing the rigidity. From this viewpoint, this radius Rh is more preferably 6.5 mm or less.

[0048] In this tire 2, the axial distance H from the heel reference point PH to the toe PT is preferably 10.0 mm or more and 13.5 mm or less. By setting the axial distance H to 10.0 mm or more, the contact pressure with the rim R at the toe point (PT) is increased, improving the adhesion with the rim R. This further improves the rigidity of tire 2. From this perspective, an axial distance H of 10.5 mm or more is more preferable. By setting the axial distance H to 13.5 mm or less, the increase in fitting pressure is effectively suppressed, resulting in good rim assembly performance. From this viewpoint, it is more preferable that the axial distance H be 12.0 mm or less.

[0049] The seat surface 24 of this tire 2 comprises two surfaces: a first seat surface 30 and a second seat surface 32, with the boundary being the seat reference point PS. The first sheet surface 30 spans the space between the axial outer end 24g of the sheet surface 24 and the sheet reference point PS. The second sheet surface 32 spans the space between the sheet reference point PS and the toe PT. In Figure 3, the dashed line denoted by VS is a virtual contour line of the first sheet surface 30, which is an extension of the contour line of the first sheet surface 30 inward from the sheet reference point PS. As shown in Figure 3, in the meridional cross-section of this tire 2, the toe PT is located radially inward from the virtual contour line VS. Therefore, the contact pressure between the toe PT and the rim R is increased, and the adhesion with the rim R is improved. This further improves the rigidity of the tire 2. From this viewpoint, it is preferable that the sheet surface 24 comprises a first sheet surface 30 that spans between the axial outer end 24g of the sheet surface 24 and the sheet reference point PS, and a second sheet surface 32 that spans between the sheet reference point PS and the toe PT, and that in the meridional cross-section of the tire 2, the toe PT is located radially inward from the virtual contour line VS of the first sheet surface 30, which is an extension of the contour line of the first sheet surface 30 inward from the sheet reference point PS.

[0050] The tire 2 may further be equipped with a chafer 34 in its bead portion TB. In other words, the bead portion TB may be equipped with a chafer 34. As shown in Figure 1, the chafer 34 is located radially inward of the bead 8. The chafer 34 comprises an inner portion 36, an outer portion 38, and a bottom portion 40 located between the inner portion 36 and the inner portion 36. The inner portion 36 constitutes a part of the inner surface N of the tire 2. The outer portion 38 contacts the flange F of the rim R. The outer end 38e of the outer portion 38 is located between the sidewall 6 and the carcass 10 and is located radially outward from the outer end 36e of the inner portion 36. The bottom portion 40 contacts the seat S. The bottom portion 40 spans between the inner portion 36 and the outer portion 38. The chafer 34 constitutes the aforementioned seat surface 24, flange surface 26, and heel surface 28.

[0051] The Chafer 34 is made of canvas. In other words, the Chafer 34 contains cloth. Specifically, the Chafer 34 consists of cloth and rubber impregnated into this cloth. Nylon is one example of the material used for the cloth.

[0052] As mentioned above, in this tire 2, the inner diameter dw of the core 18 is increased, and the inner diameter dA of the tire 2 at the heel reference point PH is decreased, thereby increasing rigidity while suppressing a decrease in contact feel. Preferably, by controlling the inner diameter dC of the tire at the toe PT, the contact pressure with the rim R at the toe PT is increased, further improving rigidity. In this tire 2, the volume of rubber in the toe PT area is greater than in conventional tires. Therefore, there is a concern that the bead portion TB may be easily damaged when mounting this tire 2 onto the rim R.

[0053] However, as mentioned above, the bead portion TB of this tire 2 is equipped with a chafer 34 that contacts the seat S and flange F of the rim R, and this chafer 34 is made of canvas. The chafer 34 has excellent wear resistance. The chafer 34 suppresses wear caused by contact with the rim R. Since this chafer 34 effectively reinforces the bead portion TB, the occurrence of damage to the bead portion TB is suppressed. This tire 2 improves rim mounting. From this viewpoint, it is preferable that this tire 2 is equipped with a chafer 34 that contacts the seat S and flange F of the rim R, and that this chafer 34 is made of canvas.

[0054] As described above, the present invention provides a motorcycle tire that can increase rigidity while suppressing a decrease in ground contact feel. [Examples]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0056] A prototype rear tire for a motorcycle (tire size = 200 / 60R17) with the basic configuration shown in Figure 1 was manufactured based on the specifications shown in Table 1 below. The specifications of Comparative Example 1 correspond to the specifications of conventional tires that prioritize fitting pressure and rim assembly ease. Example 14 does not have a chafer. This is indicated by "N" in the "Chafer" column of Table 4. "Y" indicates that a chafer is provided. Using commercially available tires (tire size = 120 / 70R17) for the front tires, performance evaluations were conducted on each prototype tire regarding contact feel and rigidity.

[0057] [Performance evaluation] The prototype tire was mounted on a standard rim, inflated, and the internal pressure was adjusted to 290 kPa. This tire was then mounted on the rear wheel of a motorcycle equipped with a 1000cc four-stroke engine. The internal pressure of the front tire was adjusted to 250 kPa. This motorcycle was driven on an asphalt circuit course, and riders were given subjective evaluations regarding road contact and rigidity. The results are shown as indices in Table 1-4 below. A higher number is preferable.

[0058] [comprehensive evaluation] The sum of the indices obtained from each evaluation was calculated. The results are shown in the "Overall Score" column of Table 1-4 below. A higher number is preferable.

[0059] [Table 1]

[0060] [Table 2]

[0061] [Table 3]

[0062] [Table 4]

[0063] As shown in Table 1-4, improvements in ground contact feel and rigidity feel were confirmed in the embodiments. The advantages of the present invention are clear from these evaluation results. [Industrial applicability]

[0064] The technology described above, which can enhance rigidity while minimizing the decrease in ground contact feel, can be applied to various motorcycle tires. [Explanation of Symbols]

[0065] 2... Tires 4. Tread 6. Sidewall 8...bead 10.. Carcass 12..Inner Liner 14. Reinforcement layer 16...Tread surface 18 cores 24..Seat surface 26..Flange surface 28. Heel surface 30...First sheet surface 32...Second sheet surface 34... Chafer TT...Tread section TB...Bead section TS... Sidewall section

Claims

1. A tire for a two-wheeled vehicle, having a bead portion that fits onto a rim, The bead portion includes a core that extends in the circumferential direction, The outer surface of the bead portion includes the toe of the tire and comprises a seat surface that contacts the seat of the rim, a flange surface that contacts the flange of the rim, and a heel surface located between the seat surface and the flange surface. The aforementioned rim is a standard rim, In the meridional cross-section of the aforementioned tire, The heel reference point is the intersection of the sheet extension line of the seat surface, which extends outward from the axial outer end of the seat surface, and the flange reference line, which extends radially inward from the radial inner end of the flange surface. The position on the seat surface where the axial distance from the flange reference line is 7 mm is the seat reference point. The inner diameter dw of the core, the rim diameter D of the rim, the inner diameter dA of the tire at the heel reference point, and the inner diameter dB of the tire at the seat reference point satisfy the following equation: Tires for motorcycles. dw / D≧1.0041 dA / D≦0.9966 dA-1.72≦dB≦dA-0.73 However, the units for dw, D, dA, and dB are mm.

2. The axial distance H from the heel reference point to the toe exceeds 7 mm. The axial distance H, the inner diameter dC of the tire at the toe, and the inner diameter dB of the tire satisfy the following equation: A tire for a two-wheeled vehicle according to claim 1. dB-1.16 (H-7)≦dC≦dB-0.61 (H-7) However, the units for dB, H, and dC are mm.

3. The rim diameter D of the rim and the inner diameter dA of the tire at the heel reference point satisfy the following equation: A tire for a two-wheeled vehicle according to claim 1 or 2. 0.9884 ≤ dA / D ≤ 0.9931

4. The inner diameter dw of the core and the rim diameter D of the rim satisfy the following equation: A tire for a two-wheeled vehicle according to claim 3. 1.0064 ≤ dw / D ≤ 1.0111

5. In the meridional cross-section of the tire, the contour line of the heel surface is represented by an arc. The radius of the aforementioned arc is 2.5 mm or more and 7.5 mm or less. A tire for a two-wheeled vehicle according to any one of claims 1 to 4.

6. The axial distance H from the heel reference point to the toe is 10.0 mm or more and 13.5 mm or less. A tire for a two-wheeled vehicle according to any one of claims 1 to 5.

7. The bead portion further comprises a chafer in which it contacts the seat and flange of the rim, The chafer is made of canvas. A tire for a two-wheeled vehicle according to any one of claims 2 to 6.

Images