Tire

Abstract

To provide a tire configured to effectively suppress a failure due to deflection of the tire and a failure due to flection between the tire and a rim flange to improve durability.SOLUTION: In a tire 10, whose cross section height SH is in a range of 50 mm-150 mm, under an unloaded condition that the tire 10 is assembled to a specific rim and is filled with a specific inner pressure, when an opening distance between the tire 10 and a rim flange 22 on a perpendicular line drawn on an outer surface of the tire 10 from an outermost point Tr in a radial direction of the rim flange 22 is defined as A, the opening distance A with respect to the cross section height SH satisfies a relational expression of 0.01≤A / SH≤0.16, and when an ejection amount corresponding to a half of a difference between total widths TW of the tire 10 and a rim width DW of the specific rim 21 is defined as W, the opening distance A with respect to the ejection amount W satisfies a relational expression of 0.03≤A / W≤1.60.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire that is suitable for situations where high load capacity is required, and more specifically, to a tire that effectively suppresses failures caused by tire bending and failures caused by rubbing between the tire and rim flange, thereby improving durability. [Background technology]

[0002] With the increase in vehicle weight due to the electrification of automobiles, etc., there is a demand for tires with high load capacity. However, if the deformation that occurs repeatedly from the sidewall to the bead when the tire rolls due to the increase in load increases, there is a problem that the durability of the tire deteriorates.

[0003] In response to this, it has been proposed to improve durability in heavy-duty tires by defining the shape of the bead portion relative to the shape of the rim flange (see, for example, Patent Document 1). However, simply defining the shape of the bead portion relative to the shape of the rim flange is not effective enough to improve durability, and there are still concerns that failures due to tire bending or rubbing between the tire and the flange may occur. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-34619 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a tire which effectively suppresses failures caused by tire bending and failures caused by rubbing between the tire and the rim flange, thereby improving durability. [Means for solving the problem]

[0006] The tire of the present invention for achieving the above object is a tire having a cross-sectional height SH in the range of 50 mm to 150 mm, in a no-load state where the tire is assembled on a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on the perpendicular line drawn from the radially outermost point of the rim flange to the outer surface of the tire is defined as A, the opening distance A satisfies the relationship of 0.01 ≦ A / SH ≦ 0.16 with respect to the cross-sectional height SH, and when the protruding amount corresponding to half of the difference between the total width TW of the tire and the rim width DW of the specified rim is defined as W, the opening distance A satisfies the relationship of 0.03 ≦ A / W ≦ 1.60 and with the tire assembled on a specified rim, filled with a specified internal pressure, and loaded with a load of 100% of the specified load capacity, the opening distance between the tire and the rim flange on the perpendicular line drawn from the radially outermost point of the rim flange to the outer surface of the tire is A 100 when 100 the opening distance A 100 satisfies the relationship of 0.003 ≦ A which is characterized by the above.

Effect of the Invention

[0007] As a result of intensive research on the behavior of the bead portion in a passenger car tire having a cross-sectional height SH in the range of 50 mm to 150 mm, the present inventor has found that the cross-sectional height SH of the tire and the protruding amount W corresponding to half of the difference between the total width TW of the tire and the rim width DW of the specified rim greatly affect the deflection of the tire. Therefore, by appropriately defining the opening distance A between the tire and the rim flange with respect to the cross-sectional height SH and the protruding amount W, failures caused by tire deflection and failures caused by rubbing between the tire and the flange can be effectively suppressed, and thus the present invention has been achieved.

[0008] That is, in the present invention, in the unloaded state where the tire is assembled to the specified rim and filled with the specified internal pressure, when the opening distance between the tire and the rim flange on the perpendicular line drawn from the radially outermost point of the rim flange to the outer surface of the tire is defined as A, the opening distance A satisfies the relationship of 0.01 ≦ A / SH ≦ 0.16 with respect to the section height SH. When the protrusion amount corresponding to half of the difference between the total width TW of the tire and the rim width DW of the specified rim is defined as W, by satisfying the relationship of 0.03 ≦ A / W ≦ 1.60 for the opening distance A with respect to the protrusion amount W, failures caused by tire deflection and failures caused by rubbing between the tire and the flange can be effectively suppressed. As a result, the durability of the tire can be improved.

[0009] In the present invention, in the state where the tire is assembled to the specified rim, filled with the specified internal pressure, and loaded with a load of 100% of the specified load capacity, the opening distance between the tire and the rim flange on the perpendicular line drawn from the radially outermost point of the rim flange to the outer surface of the tire is A 100 When this is the case, the opening distance A 100 Preferably satisfies the relationship of 0.003 ≦ A 100 / SH ≦ 0.100 with respect to the section height SH. In particular, the opening distance A 100 Preferably satisfies the relationship of 0.010 ≦ A 100 / W ≦ 1.000 with respect to the protrusion amount W. Also, it is preferable that the opening distance A and the opening distance A 100 Satisfy the relationship of 0.20 ≦ A 100 / A ≦ 0.80. Thereby, the effect of improving durability can be enhanced.

[0010] The opening distance A is preferably in the range of 1.5 mm ≦ A ≦ 8.0 mm. Also, it is preferable that the opening distance A satisfies the relationship of 0.01 ≦ A / SDH ≦ 0.50 with respect to the height SDH in the tire radial direction up to the maximum width position of the tire. Thereby, the effect of improving durability can be enhanced.

[0011] Further, in a no-load state where the tire is assembled to a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on the perpendicular line drawn from the midpoint between the radially outermost point of the rim flange and the opening start point where the rim flange separates from the tire to the outer surface of the tire is defined as A', it is preferable that the opening distance A' satisfies the relationship of 0.006 ≦ A' / SH ≦ 0.150 with respect to the sectional height SH. Also, it is preferable that the opening distance A and the opening distance A' satisfy the relationship of 0.50 ≦ A' / A ≦ 0.96. And it is preferable that the opening distance A' is in the range of 1.0 mm ≦ A' ≦ 7.5 mm. Thereby, the effect of improving durability can be enhanced.

[0012] In the present invention, the dimensions measured in the no-load state are measured in a no-load state where the tire is assembled to a specified rim and filled with a specified internal pressure. On the other hand, the dimensions measured in the load-bearing state are measured in a state where the tire is assembled to a specified rim, filled with a specified internal pressure, placed vertically on a plane, and loaded with a 100% load of the specified load capacity. Each dimension is the average value of the measured values measured at four locations on the tire circumference. The "specified rim" is the rim defined for each tire in the standard system including the standard based on which the tire is based. For example, in the case of JATMA, it is the standard rim; in the case of TRA, it is the "Design Rim"; or in the case of ETRTO, it is the "Measuring Rim". The "specified internal pressure" is the air pressure corresponding to the maximum load capacity defined for each tire in the standard system including the standard based on which the tire is based. The "specified load capacity" is the maximum load capacity defined for each tire in the standard system including the standard based on which the tire is based.

Brief Description of the Drawings

[0013] / SH ≦ 0.100 with respect to the section height SH It is a meridian half-sectional view showing a pneumatic tire (no-load state) according to an embodiment of the present invention.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Best Mode for Carrying Out the Invention

[0014] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 to 12 show a pneumatic tire according to an embodiment of the present invention. FIG. 1 depicts one side of the pneumatic tire with the tire equator CL as a boundary, and this pneumatic tire has a symmetric or asymmetric structure on both sides of the tire equator CL.

[0015] As shown in FIG. 1, the pneumatic tire 10 of the present embodiment includes a tread portion 1 that extends in the tire circumferential direction and forms an annular shape, a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3, 3 disposed on the inner side in the tire radial direction of these sidewall portions 2.

[0016] A carcass layer 4 is mounted between a pair of bead portions 3, 3. This carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inner side to the outer side of the tire around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is disposed on the outer periphery of the bead core 5. The carcass layer 4 has a main body portion 4A and a turned-up portion 4B with the bead core 5 as a boundary.

[0017] On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged such that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of, for example, 10° to 40°. As the reinforcing cord of the belt layer 7, a steel cord is preferably used. On the outer peripheral side of the belt layer 7, at least one belt cover layer 8 formed by arranging reinforcing cords at an angle of, for example, 5° or less with respect to the tire circumferential direction is disposed for the purpose of improving high-speed durability. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

[0018] Note that the above-described tire internal structure shows a typical example in the pneumatic tire 10, but is not limited thereto. In FIG. 1, a tread rubber layer 11 is disposed in the tread portion 1, a sidewall rubber layer 12 is disposed in the sidewall portion 2, a rim cushion rubber layer 13 is disposed in the bead portion 3, and an inner liner rubber layer 14 is disposed along the carcass layer 4 on the inner surface of the tire 10. Further, in the sidewall portion 2, a rim protector 15 for protecting the rim flange 22 is formed so as to project outward in the tire width direction.

[0019] The above-described tire 10 has a cross-sectional height SH in the range of 50 mm to 150 mm and is mainly a tire for passenger cars. For such a tire 10, the following configuration is applied. That is, as shown in FIGS. 1 and 2, in a no-load state where the tire 10 is assembled to a specified rim 21 and filled with a specified internal pressure, when the opening distance between the tire 10 and the rim flange 22 on the perpendicular line drawn from the radially outermost point Tr of the rim flange 22 to the outer surface of the tire 10 is A (mm), the opening distance A satisfies the relationship of 0.01 ≦ A / SH ≦ 0.16 with respect to the cross-sectional height SH, and when the protruding amount corresponding to half of the difference between the total width TW of the tire 10 and the rim width DW of the specified rim 21 is W (mm), the opening distance A satisfies the relationship of 0.03 ≦ A / W ≦ 1.60. When the rim flange 22 has a portion extending parallel to the tire width direction at the radially outermost position, the radially outermost point Tr of the rim flange 22 is the innermost point in the width direction of the rim flange 22 at the radially outermost position. The total width TW of the tire 10 is the total width of the tire 10 at the position where the carcass layer 4 bulges most outward in the tire width direction. That is, the rim protector 15 for protecting the rim flange 22 is excluded from the total width TW.

[0020] In the above-described tire 10, the opening distance A between the tire 10 and the rim flange 22 in the no-load state satisfies the relationship of 0.01 ≦ A / SH ≦ 0.16 with respect to the cross-sectional height SH, and the opening distance A satisfies the relationship of 0.03 ≦ A / W ≦ 1.60 with respect to the protruding amount W corresponding to half of the difference between the total width TW of the tire 10 and the rim width DW of the specified rim 21. By doing so, the opening distance A can be optimized with respect to the deflection deformation amount of the tire 10, and failures caused by the deflection of the tire 10 and failures caused by the rubbing between the tire 10 and the flange 22 can be effectively suppressed. Thereby, failures in the vicinity of the bead portion 3 can be suppressed, and the durability of the tire 10 can be improved. In particular, when the aspect ratio of the tire 10 is 55% or less, excellent durability is required, and in such a case, the effect of improving durability can be maximally enjoyed.

[0021] Here, if the ratio A / SH is less than 0.01, the opening distance A becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 22 increases, leading to failure. Conversely, if it exceeds 0.16, the opening distance A is too large, making it easy for failures due to rubbing between the tire 10 and the rim flange 22 to occur. Furthermore, it becomes easy for small stones, etc. to enter, which may cause a significant deterioration in durability. In particular, it is desirable to satisfy the relationship of 0.015 ≤ A / SH ≤ 0.14, and more preferably, the relationship of 0.02 ≤ A / SH ≤ 0.12.

[0022] Similarly, if the ratio A / W is less than 0.03, the opening distance A becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 22 increases, leading to failure. Conversely, if it exceeds 1.60, the opening distance A is too large, making it easy for failures due to rubbing between the tire 10 and the rim flange 22 to occur. Furthermore, it becomes easy for small stones, etc. to enter, which may cause a significant deterioration in durability. In particular, it is desirable to satisfy the relationship of 0.035 ≤ A / W ≤ 1.5, and more preferably, the relationship of 0.04 ≤ A / W ≤ 1.4.

[0023] In the above tire 10, as shown in FIG. 3, when the tire 10 is assembled to the specified rim 21 and filled with the specified internal pressure while a load of 100% of the specified load capacity is applied, the opening distance between the tire 10 and the rim flange 22 on the perpendicular line drawn from the radially outermost point Tr of the rim flange 22 to the outer surface of the tire 10 is A 100 (mm), when the opening distance A 100 satisfies the relationship of 0.003 ≤ A 100 / SH ≤ 0.100 with respect to the section height SH (mm), it is good. Note that the measurement position of the opening distance A 100 is the same as the measurement position of the opening distance A. By optimizing the opening distance A 100 when the tire 10 is deformed in this way, the effect of improving durability can be enhanced.

[0024] Here, if the ratio A 100 / SH is less than 0.003, the opening distance A 100becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to failure. Conversely, if it exceeds 0.100, the opening distance A 100 is too large, making it easy for failures due to rubbing between the tire 10 and the rim flange 22 to occur. In either case, the effect of improving durability decreases. In particular, it is desirable that 0.005 ≦ A 100 / SH ≦ 0.070, and furthermore, it is desirable that 0.007 ≦ A 100 / SH ≦ 0.065 is satisfied.

[0025] In the above tire 10, the opening distance A 100 (mm) preferably satisfies the relationship of 0.010 ≦ A 100 / W ≦ 1.000 with respect to the protrusion amount W (mm). This can enhance the effect of improving durability.

[0026] Here, if the ratio A 100 / W is less than 0.010, the opening distance A 100 becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 22 increases, leading to failure. Conversely, if it exceeds 1.000, the opening distance A 100 is too large, making it easy for failures due to rubbing between the tire 10 and the rim flange 22 to occur. In either case, the effect of improving durability decreases. In particular, it is desirable that 0.015 ≦ A 100 / W ≦ 0.800, and furthermore, it is desirable that 0.020 ≦ A 100 / W ≦ 0.800 is satisfied.

[0027] In the above tire 10, the opening distance A (mm) and the opening distance A 100 (mm) preferably satisfy the relationship of 0.20 ≦ A 100 / A ≦ 0.80. This can suppress the stress generated by repeated deformation and enhance the effect of improving durability.

[0028] Here, the ratio A 100If / A is less than 0.20, when the tire 10 deflects, the deformation near the rim flange 22 becomes significantly large, so the durability improvement effect may decrease. Conversely, if it is more than 0.80, when the tire 10 deflects, the deformation at a position deviated from the rim flange 22 becomes significantly large, so the durability improvement effect may decrease. In particular, 0.23 ≦ A 100 / A satisfies the relationship of 0.23 ≦ A 100 / A ≦ 0.75, and furthermore, it is desirable that 0.25 ≦ A

[0029] In the above tire 10, it is preferable that the opening distance A is in the range of 1.5 mm ≦ A ≦ 8.0 mm. Thereby, the stress generated by repeated deformation can be suppressed, and the durability improvement effect can be enhanced.

[0030] Here, if the opening distance A is less than 1.5 mm, the opening distance A becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to a failure. Conversely, if it is more than 8.0 mm, the opening distance A is too large, so a failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. In either case, the durability improvement effect decreases. In particular, the opening distance A is in the range of 1.8 mm ≦ A ≦ 7.5 mm, and furthermore, it is desirable that it is in the range of 2.0 mm ≦ A ≦ 7.0 mm.

[0031] In the above tire 10, it is preferable that the opening distance A (mm) satisfies the relationship of 0.01 ≦ A / SDH ≦ 0.50 with respect to the height SDH (mm) in the tire radial direction up to the maximum width position (the measurement position of the total width TW) of the tire 10. By defining the opening distance A with respect to the height SDH that has a great influence on the deformation of the bead portion 3, the stress generated by repeated deformation can be suppressed, and the durability improvement effect can be enhanced.

[0032] Here, when the ratio A / SDH is less than 0.01, the opening distance A becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to failure. Conversely, when it exceeds 0.50, the opening distance A is too large, and failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. In either case, the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 0.02 ≦ A / SDH ≦ 0.45, and further, the relationship of 0.03 ≦ A / SDH ≦ 0.40.

[0033] In the above tire 10, as shown in FIG. 2, in the unloaded state where the tire 10 is assembled to the specified rim 21 and filled with the specified internal pressure, when the opening distance between the tire 10 and the rim flange 22 on the perpendicular line drawn from the intermediate point Ur between the radially outermost point Tr of the rim flange 22 and the opening start point S where the rim flange 22 separates from the tire 10 to the outer surface of the tire 10 is defined as A' (mm), it is preferable that the opening distance A' satisfies the relationship of 0.006 ≦ A' / SH ≦ 0.150 with respect to the section height SH (mm). Thereby, the stress generated by repeated deformation can be suppressed, and the effect of improving durability can be enhanced.

[0034] Here, when the ratio A' / SH is less than 0.006, the opening distance A' becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to failure. Conversely, when it exceeds 0.150, the opening distance A' is too large, and failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. In either case, the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 0.010 ≦ A' / SH ≦ 0.130, and further, the relationship of 0.014 ≦ A' / SH ≦ 0.110.

[0035] In the above tire 10, it is preferable that the opening distance A (mm) and the opening distance A' (mm) satisfy the relationship of 0.50 ≦ A' / A ≦ 0.96. Thereby, the stress generated by repeated deformation can be suppressed, and the effect of improving durability can be enhanced.

[0036] Here, if the ratio A' / A is less than 0.50, the opening distance A' is insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to failure. Conversely, if it exceeds 0.96, the opening distance A' is too large, and failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. In either case, the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 0.53 ≦ A' / A ≦ 0.94, and further, to satisfy the relationship of 0.56 ≦ A' / A ≦ 0.92.

[0037] In the above tire 10, it is preferable that the opening distance A' is in the range of 1.0 mm ≦ A' ≦ 7.5 mm. Thereby, the stress generated by repeated deformation can be suppressed, and the effect of improving durability can be enhanced.

[0038] Here, if the opening distance A' is less than 1.0 mm, the opening distance A' is insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to failure. Conversely, if it exceeds 7.5 mm, the opening distance A' is too large, and failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. In either case, the effect of improving durability decreases. In particular, the opening distance A' is in the range of 1.2 mm ≦ A' ≦ 7.0 mm, and further, it is desirable that it is in the range of 1.4 mm ≦ A' ≦ 6.5 mm.

[0039] In the above tire 10, as shown in FIG. 4, in the unloaded state where the tire 10 is assembled to the specified rim 21 and filled with the specified internal pressure, when the point where the horizontal line in the tire width direction passing through the outermost point Tr in the radial direction of the rim flange 22 intersects the outer surface of the tire 10 is defined as point P, and the point defining the rim width DW and the rim diameter DO of the specified rim 21 is defined as point Q, it is preferable that the angle α formed by the straight line connecting point P and point Q with respect to the horizontal line in the tire width direction is in the range of 50° ≦ α ≦ 80°.

[0040] When the angle α corresponding to the inclination angle of the bead portion 3 is in the range of 50° ≤ α ≤ 80° in this way, the opening distance A is optimized with respect to the deflection deformation amount of the tire 10, and failures caused by the deflection of the tire 10 and failures caused by the rubbing between the tire 10 and the flange 22 can be effectively suppressed. Thereby, failures in the vicinity of the bead portion 3 can be suppressed, and the effect of improving the durability of the tire 10 can be further enhanced.

[0041] Here, when the angle α is less than 50°, the opening distance A becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 22 increases, leading to failure. Conversely, when it exceeds 80°, the opening distance A is too large, so failures due to rubbing between the tire 10 and the rim flange 22 are likely to occur. Furthermore, small stones and the like are likely to enter, and as a result, the durability may be significantly deteriorated. In particular, it is desirable to satisfy the range of 55° ≤ α ≤ 75°, and further, to satisfy the range of 60° ≤ α ≤ 70°.

[0042] In the above tire 10, as shown in FIGS. 1 and 5, in the unloaded state where the tire 10 is assembled to the specified rim 21 and filled with the specified internal pressure, when the point L that defines the total width TW of the tire 10 is set, the angle θ formed by the straight line connecting the point P and the point Q with respect to the straight line connecting the point L and the point Q is preferably in the range of 2° ≤ θ ≤ 30°. Thereby, the opening distance A is optimized with respect to the deflection deformation amount, and the effect of improving the durability can be enhanced.

[0043] Here, when the angle θ is less than 2°, the opening distance A becomes insufficient, and when the tire 10 deflects, the stress near the rim flange 12 increases, leading to failure. Conversely, when it exceeds 30°, the opening distance A is too large, so failures due to rubbing between the tire 10 and the rim flange 22 are likely to occur. In either case, the effect of improving the durability decreases. In particular, it is desirable to satisfy the range of 4° ≤ θ ≤ 25°, and further, to satisfy 6° ≤ θ ≤ 20°.

[0044] In the above tire 10, as shown in FIG. 6, in the unloaded state where the tire 10 is assembled to the specified rim 21 and filled with the specified internal pressure, with the opening start point S where the rim flange 22 separates from the tire 10, the radially outermost point Tr of the rim flange 22, and the point T where the perpendicular line drawn from the point Tr to the outer surface of the tire 10 intersects the outer surface of the tire, it is preferable that the angle β formed by the straight line connecting the point S and the point T with respect to the straight line connecting the point S and the point Tr is in the range of 15° ≤ β ≤ 65°. Thereby, the effect of improving durability can be enhanced.

[0045] Here, if the angle β is less than 15°, the stress near the rim flange 22 increases when the tire 10 deflects, leading to a failure. Conversely, if it exceeds 65°, a failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. In particular, it is desirable to satisfy the range of 20° ≤ β ≤ 60°, and further, the range of 25° ≤ β ≤ 55°.

[0046] In the above tire 10, as shown in FIG. 7, it is preferable that the horizontal distance B (mm) in the tire width direction between the point Q and the point S satisfies the relationship of 0.02 ≤ B / SH ≤ 0.18 with respect to the section height SH (mm). Thereby, the stress due to repeated deformation is within an appropriate range, and the effect of improving durability can be enhanced.

[0047] Here, if the ratio B / SH is less than 0.02, a failure due to rubbing between the tire 10 and the rim flange 22 is likely to occur. Conversely, if it exceeds 0.18, the stress near the rim flange 22 increases when the tire 10 deflects, leading to a failure. In either case, the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 0.03 ≤ B / SH ≤ 0.15, and further, the relationship of 0.04 ≤ B / SH ≤ 0.13.

[0048] In the above tire 10, it is preferable that the horizontal distance B is in the range of 3.0 mm ≤ B ≤ 9.0 mm. Thereby, the stress due to repeated deformation is within an appropriate range, and the effect of improving durability can be enhanced.

[0049] Here, if the horizontal distance B is less than 3.0 mm, it is likely to cause a failure due to rubbing between the tire 10 and the rim flange 22. Conversely, if it is more than 9.0 mm, when the tire 10 deflects, the stress near the rim flange 12 increases, leading to a failure, and in either case, the effect of improving durability decreases. In particular, the horizontal distance B is in the range of 3.2 mm ≤ B ≤ 8.5 mm, and more preferably, it is in the range of 3.4 mm ≤ B ≤ 8.0 mm.

[0050] In the above tire 10, as shown in FIG. 8, when the point where the perpendicular line drawn from the radially outermost point Tr of the rim flange 22 to the outer surface of the tire 10 intersects the outer surface of the tire 10 is defined as point T, it is preferable that the arc (curvature radius Rb) of the tire 10 passing through points S, P, and T has a center on the outer side in the tire width direction. Thereby, it becomes difficult for compressive stress to be applied to the portion of the tire 10 that contacts the rim flange 22, so that the effect of improving durability can be enhanced.

[0051] In particular, as shown in FIG. 8, when the point where the perpendicular line drawn from point P to the outer surface of the tire 10 intersects the outer surface of the rim flange 22 is defined as point Pr, it is preferable that the curvature radius Rb (mm) of the arc of the tire 10 passing through points S, P, and T satisfies the relationship of 1.2 ≤ Rb / Rr ≤ 14.5 with respect to the curvature radius Rr (mm) of the arc of the rim flange 22 passing through points S, Pr, and Tr. Thereby, it becomes difficult for compressive stress to be applied to the portion of the tire 10 that contacts the rim flange 22, so that the effect of improving durability can be enhanced.

[0052] Here, if the ratio Rb / Rr is out of the above range, compressive stress is likely to be applied to the portion of the tire 10 that contacts the rim flange 22, so that the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 1.5 ≤ Rb / Rr ≤ 12.2, and more preferably, to satisfy the relationship of 2.0 ≤ Rb / Rr ≤ 10.0.

[0053] In the above tire 10, as shown in FIG. 9, in a no-load state where the tire 10 is assembled to a specified rim 21 and filled with a specified internal pressure, when a horizontal line in the tire width direction passing through the edge portion of the belt layer 7 located innermost in the tire radial direction among the plurality of belt layers 7 intersects the outer surface of the tire 10 at a point V, and a point that defines the total width TW of the tire 10 is L, it is preferable that the angle γ formed by the straight line connecting the point L and the point V with respect to the horizontal line in the tire width direction is in the range of 45° ≤ γ ≤ 80°. Thereby, the stress due to repeated deformation is within an appropriate range, and the effect of improving durability can be enhanced.

[0054] Here, when the angle γ is out of the above range, the stress due to repeated deformation is out of the appropriate range, so the effect of improving durability decreases. In particular, it is desirable to satisfy the range of 50° ≤ γ ≤ 75°, and further, to satisfy the range of 55° ≤ γ ≤ 70°.

[0055] In the above tire 10, as shown in FIG. 9, when a point on the outer surface of the tire 10 at the central position in the tire radial direction between the point L and the point V is W, it is preferable that the radius of curvature Rs of the arc of the tire 10 passing through the point V, the point W, and the point L satisfies the relationship of 0.3 ≤ Rs / SH ≤ 2.5 with respect to the section height SH. Thereby, the stress due to repeated deformation is within an appropriate range, and the effect of improving durability can be enhanced.

[0056] Here, when the ratio Rs / SH is out of the above range, the stress due to repeated deformation is out of the appropriate range, so the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 0.4 ≤ Rs / SH ≤ 2.3, and further, to satisfy the relationship of 0.5 ≤ Rs / SH ≤ 2.0.

[0057] In the above tire 10, as shown in FIG. 10, in a no-load state where the tire 10 is assembled to a specified rim 21 and filled with a specified internal pressure, with the opening start point S where the rim flange 22 separates from the tire 10, and the point T where the perpendicular line drawn from the radially outermost point Tr of the rim flange 22 intersects the outer surface of the tire 10, when two perpendicular lines are drawn from the point S and the point T to the turned-up portion 4B of the carcass layer 4, the cross-sectional area Sr of the rubber portion R (hatched portion) included in the region surrounded by these two perpendicular lines and the turned-up portion 4B of the carcass layer 4 is 12 mm 2 ≦ Sr ≦ 101 mm 2 is preferably in the range. Note that the cross-sectional area Sr of the rubber portion R is the cross-sectional area of the portion outside the carcass cords constituting the carcass layer 4.

[0058] In this way, since the cross-sectional area Sr of the rubber portion R that bears the buffering action against the rim flange 22 is in the range of 12 mm 2 ≦ Sr ≦ 101 mm 2 the opening distance A can be optimized with respect to the amount of deflection deformation of the tire 10, and failures caused by the deflection of the tire 10 and failures caused by rubbing between the tire 10 and the flange 22 can be effectively suppressed. Thereby, failures in the vicinity of the bead portion 3 can be suppressed, and the effect of improving the durability of the tire 10 can be further enhanced.

[0059] Here, if the cross-sectional area Sr of the rubber portion R is less than 12 mm 2 compressive stress is likely to be applied to the carcass layer 4 in the vicinity of the rim flange 22 when the tire 10 is deflected, leading to failure. Conversely, if it exceeds 101 mm 2 it becomes difficult to ensure a sufficient opening distance A, and the stress in the vicinity of the rim flange 22 increases when the tire 10 is deflected, leading to failure. In particular, it is desirable to satisfy the range of 14 mm 2 ≦ Sr ≦ 98 mm 2 and further, to satisfy the range of 16 mm 2 ≦ Sr ≦ 93 mm 2

[0060] ​In the above tire 10, as shown in FIG. 11, when the thickness of the rubber portion R on the perpendicular line drawn from the point S to the winding-up portion 4B of the carcass layer 4 is Gl (mm), and the thickness of the rubber portion R on the perpendicular line drawn from the point T to the winding-up portion 4B of the carcass layer 4 is Gu (mm), it is preferable that the thicknesses Gl and Gu satisfy the relationship of 0.40 ≦ Gl / Gu ≦ 0.90. Thereby, a good buffering action can be ensured and the effect of improving durability can be enhanced.

[0061] Here, when the ratio Gl / Gu deviates from the above range, the buffering action decreases and the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 0.45 ≦ Gl / Gu ≦ 0.85, and further, to satisfy the relationship of 0.50 ≦ Gl / Gu ≦ 0.80. Also, the thickness Gl of the rubber portion R preferably satisfies the range of 0.5 mm ≦ Gl ≦ 4.0 mm, and further, preferably satisfies the range of 1.5 mm ≦ Gl ≦ 3.0 mm. The thicknesses Gl and Gu of the rubber portion R can also be measured in the cut sample of the tire 10.

[0062] In the above tire 10, as shown in FIG. 11, in the unloaded state where the tire 10 is assembled to the specified rim 21 and filled with the specified internal pressure, the point where the perpendicular line drawn from the point S to the winding-up portion 4B of the carcass layer 4 intersects the winding-up portion 4B of the carcass layer 4 is defined as Sc, the point where the perpendicular line drawn from the point T to the winding-up portion 4B of the carcass layer 4 intersects the winding-up portion 4B of the carcass layer 4 is defined as Tc, and when the midpoint between the point Sc and the point Tc is defined as Uc, it is preferable that the arc (curvature radius Rc) of the carcass layer 4 passing through the point Sc, the point Tc, and the point Uc has a center on the outer side in the tire width direction. Thereby, it becomes difficult for compressive stress to be applied to the carcass layer 4 when the tire is deformed, so that the effect of improving durability can be enhanced. Note that the arc of the carcass layer 4 passing through the point Sc, the point Tc, and the point Uc preferably has a center on the outer side in the tire width direction even in the state where the tire 10 is not assembled to the rim or in the state where 100% load is applied.

[0063] In particular, as shown in FIG. 11, when the intermediate point between point S and point Tr is Ur, it is preferable that the radius of curvature Rc (mm) of the arc of the carcass layer 4 passing through point Sc, point Tc, and point Uc satisfies the relationship of 1 ≦ Rc / Rr ≦ 55 with respect to the radius of curvature Rr (mm) of the arc of the rim flange 22 passing through point S, point Tr, and point Ur. Thereby, it becomes difficult for compressive stress to be applied to the carcass layer 4 during tire deformation, so that the effect of improving durability can be enhanced.

[0064] Here, if the ratio Rc / Rr is out of the above range, compressive stress is likely to be applied to the carcass layer 4 during tire deformation, so that the effect of improving durability decreases. In particular, it is desirable to satisfy the relationship of 2 ≦ Rc / Rr ≦ 50, and further, it is desirable to satisfy the relationship of 3 ≦ Rc / Rr ≦ 45.

[0065] FIG. 12 shows a modified example of the bead portion. In FIG. 12, the main body portion 4A and the winding-up portion 4B of the carcass layer 4 are in contact with each other without passing through the bead filler to form a closed region that encloses the bead core 5. That is, the carcass layer 4 is wound up from the inner side to the outer side of the tire around the bead core 5, and the main body portion 4A and the winding-up portion 4B are arranged to be in close contact with each other at the upper end position of the bead core 5. By adopting such a winding-up structure of the carcass layer 4, it is possible to move the carcass layer 4 away from the rim flange 22 at the contact portion with the rim flange 22, so that the compressive stress applied to the carcass layer 4 can be significantly reduced, and the effect of improving durability can be enhanced. In addition, the rubber occupancy rate of the closed region formed by the carcass layer 4 is preferably 15% or less, more preferably 10% or less, and still more preferably 5% or less. The rubber occupancy rate referred to here is the percentage of the rubber portion (for example, the insulation rubber of the bead wire or the small bead filler) in the closed region formed by the carcass layer 4 in the tire meridian cross section.

[0066] Also, in the structure of FIG. 12, durability can be improved by arranging a secondary bead filler 9 or thickening the rim cushion rubber layer 13 on the outer side in the tire width direction of the winding-up portion 4B of the carcass layer 4. In this case, the cross-sectional area Sr of the rubber portion R is 36 mm 2 ≦Sr≦101 mm 2 can be set within the range. In particular, 42 mm 2 ≦Sr≦98 mm 2 satisfies the range, and furthermore, it is desirable to satisfy the range of 48 mm 2 ≦Sr≦93 mm 2 .

[0067] In the tire 10, as shown in FIG. 10, when having a rim cushion rubber layer 13 disposed in a region in contact with the rim flange 22 and a sidewall rubber layer 12 disposed radially outside the tire diameter of the rim cushion rubber layer 13, in a no-load state where the tire 10 is assembled to a specified rim and filled with a specified internal pressure, it is preferable that the boundary point X between the rim cushion rubber layer 13 and the sidewall rubber layer 12 on the outer surface of the tire 10 is located radially outside the tire diameter of the point T. That is, it is desirable that the rim cushion rubber layer 13 extends at least to the position of the point T from the lower side of the bead core 5 toward the outside in the tire diameter direction. Thereby, it becomes difficult for compressive stress to be applied to the carcass layer 4 during tire deformation, and thus the effect of improving durability can be enhanced.

[0068] The hardness of the rim cushion rubber layer 13 at 20°C is preferably 55 or more and 80 or less. Thereby, the durability of the rim cushion rubber layer 13 can be improved. Here, when the hardness of the rim cushion rubber layer 13 is out of the above range, the effect of improving durability decreases. The hardness is the durometer hardness measured under the condition of a temperature of 20°C using a type A durometer in accordance with JIS-K6253.

[0069] It is preferable that the 100% modulus of the rim cushion rubber layer 13 at 20°C is 2.0 MPa or more and 9.5 MPa or less. Thereby, the durability of the rim cushion rubber layer 13 can be improved. Here, if the 100% modulus of the rim cushion rubber layer 13 is out of the above range, the improvement effect of durability will decrease. The 100% modulus is a predetermined elongation tensile stress measured under the condition of a temperature of 20°C in accordance with JIS-K6251.

[0070] It is preferable that the loss tangent (tanδ) of the rim cushion rubber layer 13 at 20°C is 0.05 or more and 0.35 or less. Thereby, it is possible to suppress an increase in rolling resistance while ensuring the thickness (durability) of the rim cushion rubber layer 13. Here, if the loss tangent of the rim cushion rubber layer 13 exceeds 0.35, the rolling resistance will increase. The loss tangent (tanδ) is measured under the conditions of a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 60°C using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) in accordance with JIS-K6394.

[0071] It is preferable that the intermediate elongation of the carcass cord constituting the carcass layer 4 under a load of 1.5 cN / dtex is 3.3% or more and 6.2% or less. Thereby, the improvement effect of durability can be enhanced. Here, if the intermediate elongation of the carcass cord constituting the carcass layer 4 under a load of 1.5 cN / dtex is out of the above range, the improvement effect of durability will decrease. In particular, it is desirable that the intermediate elongation of the carcass cord under a load of 1.5 cN / dtex is 3.8% or more and 5.9% or less. The intermediate elongation is measured by conducting a tensile test on the carcass cord taken out from the sidewall portion of the tire 10 under the conditions of complying with JIS-L1017, a gripping interval of 250 mm, and a tensile speed of 300 ± 20 mm / min.

[0072] The carcass cords constituting the carcass layer 4 are preferably organic fiber cords. When, for example, high-modulus rayon cords are employed as the carcass cords, the durability is improved. The total thickness of the carcass layer 4 is preferably 0.8 mm or more and 1.5 mm or less. In the case of rayon cords, the cord diameter is preferably 0.6 mm or more and 1.1 mm or less, and the cord driving density is preferably 43 cords / 50 mm or more and 59 cords / 50 mm or less. Also, as the carcass cords, polyester cords having excellent fatigue resistance are also suitable. In the case of polyester cords, the cord diameter is preferably 0.7 mm or more and 1.2 mm or less, and the cord driving density is preferably 44 cords / 50 mm or more and 60 cords / 50 mm or less.

[0073] Also, the angle of the carcass cords constituting the carcass layer 4 with respect to the tire circumferential direction can be set in the range of 75° or more and 90° or less. In particular, when the angle of the carcass cords is set to less than 88°, the tire rigidity increases and the durability is improved. Also, the turned-up portion 4B of the carcass layer 4 preferably extends to a position overlapping the edge portion of the belt layer 7 beyond the tire maximum width position. By adopting such a turned-up structure, the tire rigidity increases and the durability is improved.

Example

[0074] For a tire of tire size 285 / 35R20 (SH = 95 mm), the height SDH, the total width TW, the rim width DW of the specified rim, the protrusion amount W, A / SH, A / W, A 100 / SH, A 100 / W, A 100 / A, the opening distance A, the opening distance A 100 Inflated tires of Comparative Examples 1 to 4 and Examples 1 to 8 were manufactured with the height SDH, the total width TW, the rim width DW of the specified rim, the protrusion amount W, A / SH, A / W, A / A, the opening distance A, A / SDH, A' / SH, A' / A, and the opening distance A' set as shown in Table 1.

Figure 12

[0075] For these test tires, the strain resistance performance and the abrasion resistance performance were evaluated by the following test methods, and the results are also shown in Table 1.

[0076] Strain resistance performance: Each test tire was assembled onto a wheel with a rim size of 20×10J and mounted on a testing machine with a drum diameter of 1707 mm. The air pressure was set at 290 kPa, the speed was set at 81 km / h, the initial load was set at 88% of the maximum load capacity, and the load was increased by 13% every two hours. The running distance until a failure occurred in the tire was measured. The evaluation results were shown as an index with Comparative Example 2 set to 100. A larger value of this index means better strain resistance performance.

[0077] Abrasion resistance performance: Each test tire was assembled onto a wheel with a rim size of 20×10J and mounted on a testing machine with a drum diameter of 1707 mm. The air pressure was set at 290 kPa, the speed was set at 81 km / h, the initial load was set at 88% of the maximum load capacity, and the load was increased by 13% every two hours. A running test of 2500 km was carried out. The rubber thickness from the outer surface of the tire to the carcass layer at the position corresponding to the outermost point in the radial direction of the rim flange was measured before and after the test, and the change amount of the rubber thickness was obtained. The evaluation results were shown as an index using the reciprocal of the change amount of the rubber thickness with Comparative Example 1 set to 100. A larger value of this index means better abrasion resistance performance.

[0078]

Table 1

[0079] As can be seen from Table 1, the tires of Examples 1 to 8 had improved strain resistance performance and abrasion resistance performance in comparison with Comparative Examples 1 to 4, and had excellent durability.

Explanation of symbols

[0080] 1 Tread part 2 Sidewall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 10 Tire 11 Tread rubber layer 12 Sidewall rubber layer 13 Rim cushion rubber layer 14 Inner liner layer 15 Rim protector 21 Specified rim 22 Rim flange

Claims

1. In a tire having a cross-sectional height SH in the range of 50 mm to 150 mm, in a no-load state where the tire is assembled to a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on the perpendicular line drawn from the radially outermost point of the rim flange to the outer surface of the tire is defined as A, the opening distance A satisfies the relationship of 0.01 ≦ A / SH ≦ 0.16 with respect to the cross-sectional height SH, and when the protrusion amount corresponding to half of the difference between the total width TW of the tire and the rim width DW of the specified rim is defined as W, the opening distance A satisfies the relationship of 0.03 ≦ A / W ≦ 1.60 with respect to the protrusion amount W, in a state where the tire is assembled to a specified rim, filled with a specified internal pressure, and loaded with a 100% load of the specified load capacity, when the opening distance between the tire and the rim flange on the perpendicular line drawn from the radially outermost point of the rim flange to the outer surface of the tire is defined as A100, the opening distance A100 satisfies the relationship of 0.003 ≦ A100 / SH ≦ 0.100 with respect to the cross-sectional height SH. A tire characterized by this.

2. the opening distance A 100 satisfies the relationship of 0.010 ≦ A 100 / W ≦ 1.000, and the tire according to claim 1 is characterized by this.

3. The opening distance A and the opening distance A 100 satisfy the relationship of 0.20 ≦ A 100 / A ≦ 0.80, and the tire according to claim 1 or 2 is characterized in that.

4. The tire according to any one of Claims 1 to 3, characterized in that the opening distance A is in the range of 1.5 mm ≦ A ≦ 8.0 mm.

5. The tire according to any one of Claims 1 to 4, characterized in that the opening distance A satisfies the relationship of 0.01 ≦ A / SDH ≦ 0.50 with respect to the height SDH in the tire radial direction up to the maximum width position of the tire.

6. In a no-load state where the tire is assembled to a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on the perpendicular line drawn from the intermediate point between the radially outermost point of the rim flange and the opening start point where the rim flange separates from the tire to the outer surface of the tire is defined as A', the opening distance A' satisfies the relationship of 0.006 ≦ A' / SH ≦ 0.150 with respect to the cross-sectional height SH. A tire characterized by this according to any one of Claims 1 to 5.

7. The tire according to Claim 6, characterized in that the opening distance A and the opening distance A' satisfy the relationship of 0.50 ≦ A' / A ≦ 0.

96.

8. The tire according to Claim 6 or 7, characterized in that the opening distance A' is in the range of 1.0 mm ≦ A' ≦ 7.5 mm.

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