tire

Abstract

To provide a tire than can be improved in durability.SOLUTION: In a tire 0, whose cross section height SH is in a range of 50 mm-150 mm, under an unloaded condition that the tire is assembled to a specific rim and is filled with a specific inner pressure, when an opening distance between the tire and a rim flange 22 on a perpendicular line drawn on an outer surface of the tire 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 opening starting point at which the rim flange 22 separates away from the tire is defined as S and a point at which the perpendicular line drawn on the outer surface of the tire from the outermost point Tr in the radial direction of the rim flange 22 crosses the outer surface of the tire is defined as T, and when two perpendicular lines are drawn on a wound-up part of a carcass layer 4 from the point S and the point T, cross sectional areas Sr of a rubber portion R included in a region surrounded by the two perpendicular lines and the wound-up part of the carcass layer 4 are in a range of 12 mm2≤Sr≤101 mm2.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 flexure and failures caused by rubbing between the tire and rim flange, thereby improving durability. [Background technology]

[0002] As vehicle weight increases due to factors such as the electrification of automobiles, there is a demand for tires with high load capacity. However, if the increased load causes repeated deformation from the sidewall to the bead during tire rolling, this increases the problem of reduced tire durability.

[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 may occur due to tire flexing or rubbing between the tire and the flange. [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 that can effectively suppress failures caused by tire flexure and failures caused by rubbing between the tire and the rim flange, thereby improving durability. [Means for solving the problem]

[0006] In order to achieve the above object, the tire of the present invention has a carcass layer mounted between a pair of bead portions, the carcass layer having a structure in which the carcass layer is wound up around a bead core from the inside to the outside of the tire, and a cross-sectional height SH in the range of 50 mm to 150 mm, When the tire is mounted on a specified rim and inflated to a specified internal pressure in an unloaded state, the opening distance between the tire and the rim flange on a perpendicular line drawn from the radially outermost point Tr of the rim flange to the outer surface of the tire is defined as A, and the opening distance A satisfies the relationship of 0.01≦A / SH≦0.16 with respect to the cross-sectional height SH, and the opening start point where the rim flange separates from the tire is defined as S, and the point where the perpendicular line drawn from the radially outermost point Tr of the rim flange to the outer surface of the tire intersects with the outer surface of the tire is defined as T, and when two perpendicular lines are drawn from the point S and the point T to the turned-up portion of the carcass layer, the cross-sectional area Sr of the rubber portion included in the area surrounded by the two perpendicular lines and the turned-up portion of the carcass layer is 12 mm 2 ≦Sr≦101mm 2 It is characterized in that the range is [Effects of the Invention]

[0007] As a result of extensive research by the inventors into the behavior of the bead portion of passenger car tires with a cross-sectional height SH in the range of 50 mm to 150 mm, they discovered that because the cross-sectional height SH of the tire has a significant effect on the deflection of the tire, by appropriately specifying the opening distance A between the tire and the rim flange in relation to the cross-sectional height SH, and by appropriately specifying the cross-sectional area Sr of the rubber portion that provides a cushioning effect for the rim flange, failures caused by the deflection of the tire and failures caused by rubbing between the tire and the flange can be effectively suppressed, which led to the present invention.

[0008] That is, in the present invention, when a tire is mounted on a specified rim and inflated to a specified internal pressure in an unloaded state, if the opening distance between the tire and the rim flange on a perpendicular line drawn from the radially outermost point Tr of the rim flange to the outer surface of the tire is defined as A, the opening distance A satisfies the relationship 0.01≦A / SH≦0.16 with respect to the cross-sectional height SH, the opening start point where the rim flange separates from the tire is defined as S, and the point where the perpendicular line drawn from the radially outermost point Tr of the rim flange to the outer surface of the tire intersects with the outer surface of the tire, and two perpendicular lines are drawn from points S and T to the turned-up part of the carcass layer, the cross-sectional area Sr of the rubber portion included in the area surrounded by these two perpendicular lines and the turned-up part of the carcass layer is 12 mm 2 ≦Sr≦101mm 2 By keeping the value within this range, failures caused by tire flexure and failures caused by rubbing between the tire and the flange can be effectively suppressed, thereby improving the durability of the tire.

[0009] In the present invention, when the thickness of the cushioning rubber portion on the perpendicular line drawn from point S to the turned-up portion of the carcass layer is defined as Gl, and the thickness of the cushioning rubber portion on the perpendicular line drawn from point T to the turned-up portion of the carcass layer is defined as Gu, it is preferable that the thicknesses Gl and Gu satisfy the relationship 0.40≦Gl / Gu≦0.90. This ensures good cushioning action and enhances the effect of improving durability.

[0010] In an unloaded state with the tire mounted on a specified rim and inflated to a specified internal pressure, when the point where a perpendicular line drawn from point S to the turned-up portion of the carcass layer intersects with the turned-up portion of the carcass layer is defined as Sc, the point where a perpendicular line drawn from point T to the turned-up portion of the carcass layer intersects with the turned-up portion of the carcass layer is defined as Tc, and the midpoint between points Sc and Tc is defined as Uc, it is preferable that the arc of the carcass layer passing through points Sc, Tc, and Uc has its center on the outer side in the tire width direction. This makes it difficult for compressive stress to be applied to the carcass layer when the tire deforms, thereby enhancing the effect of improving durability.

[0011] When the tire is mounted on a specified rim and inflated to a specified internal pressure in an unloaded state, and Ur is the midpoint between points S and Tr, it is preferable that the radius of curvature Rr of the rim flange arc passing through points S, Tr, and Ur, and the radius of curvature Rc of the carcass layer arc passing through points Sc, Tc, and Uc, satisfy the relationship 1≦Rc / Rr≦55. This makes it difficult for compressive stress to be applied to the carcass layer when the tire deforms, thereby enhancing the effect of improving durability.

[0012] It is preferable that the main body and the turned-up portion of the carcass layer contact each other without a bead filler in between to form a closed region that encloses the bead core. By adopting such a turned-up structure of the carcass layer, it is possible to move the carcass layer away from the rim flange at the contact area with the rim flange, which significantly reduces the compressive stress applied to the carcass layer and enhances the effect of improving durability.

[0013] When a tire has a rim cushion rubber layer positioned in the region that contacts the rim flange and a sidewall rubber layer positioned radially outward of the rim cushion rubber layer, it is preferable that when the tire is mounted on a specified rim and inflated to a specified internal pressure and in an unloaded state, boundary point X between the rim cushion rubber layer and the sidewall rubber layer on the outer surface of the tire be located radially outward of point T. This makes it less likely that compressive stress will be applied to the carcass layer when the tire deforms, thereby further improving durability.

[0014] The hardness of the rim cushion rubber layer at 20° C. is preferably 55 or more and 80 or less, thereby improving the durability of the rim cushion rubber layer.

[0015] The intermediate elongation of the carcass cords constituting the carcass layer under a load of 1.5 cN / dtex is preferably 3.3% or more and 6.2% or less, which can enhance the effect of improving durability.

[0016] In the present invention, the dimensions measured under no load are those measured under an unloaded condition when the tire is mounted on a specified rim and inflated to the specified internal pressure. On the other hand, the dimensions measured under a load are those measured under a loaded condition when the tire is mounted on a specified rim, inflated to the specified internal pressure, and placed vertically on a flat surface with a load of 100% of the specified load capacity. Each dimension is the average of measurements taken at four points around the tire. A "specified rim" is a rim specified for each tire in a standard system, including the standard to which the tire is based. For example, it is a standard rim for JATMA, a "Design Rim" for TRA, or a "Measuring Rim" for ETRTO. A "specified internal pressure" is the air pressure corresponding to the maximum load capacity specified for each tire in a standard system, including the standard to which the tire is based. A "specified load capacity" is the maximum load capacity specified for each tire in a standard system, including the standard to which the tire is based. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a meridian half cross-sectional view showing a pneumatic tire (unloaded state) according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view showing a bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 3] 2 is another cross-sectional view showing the bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 4] FIG. 10 is a cross-sectional view showing a modified example of the bead portion (in an unloaded state). [Figure 5] 2 is another cross-sectional view showing the bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 6] 2 is a cross-sectional view showing a bead portion of the pneumatic tire (under 100% load) in FIG. 1. FIG. [Figure 7] 2 is another cross-sectional view showing the bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 8] 2 is a cross-sectional view showing a bead portion and a sidewall portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 9] 2 is another cross-sectional view showing the bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 10] 2 is another cross-sectional view showing the bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 11] 2 is another cross-sectional view showing the bead portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. [Figure 12] 2 is another cross-sectional view showing the bead portion and the sidewall portion of the pneumatic tire (in an unloaded state) of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] The configuration of the present invention will be described in detail below with reference to the accompanying drawings. Figures 1 to 12 show a pneumatic tire according to an embodiment of the present invention. Figure 1 depicts one side of the pneumatic tire, separated by the tire equator CL, but the pneumatic tire has a symmetrical or asymmetrical structure on both sides of the tire equator CL.

[0019] As shown in FIG. 1, the pneumatic tire 10 of this embodiment includes a tread portion 1 extending circumferentially in a ring shape, a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3, 3 arranged radially inward of the sidewall portions 2.

[0020] 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 inside to the outside of the tire around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition and having a triangular cross section is disposed on the outer periphery of the bead core 5. The carcass layer 4 has a main portion 4A and a turned-up portion 4B, with the bead core 5 as the boundary.

[0021] On the other hand, multiple 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 multiple reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to a range of 10° to 40°, for example. Steel cords are preferably used as the reinforcing cords of the belt layers 7. At least one belt cover layer 8 is arranged on the outer peripheral side of the belt layer 7, with the aim of improving high-speed durability, and the reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. As the reinforcing cords of the belt cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0022] The above-described tire internal structure shows a typical example of a pneumatic tire 10, but is not limited to this. In Fig. 1, a tread rubber layer 11 is arranged in the tread portion 1, a sidewall rubber layer 12 is arranged in the sidewall portion 2, a rim cushion rubber layer 13 is arranged in the bead portion 3, and an inner liner rubber layer 14 is arranged along a carcass layer 4 on the inner surface of the tire 10. In addition, a rim protector 15 for protecting a rim flange 22 is formed in the sidewall portion 2 so as to protrude outward in the tire width direction.

[0023] The above-described tire 10 has a cross-sectional height SH in the range of 50 mm to 150 mm and is primarily a tire for passenger cars. The following configuration is applied to such a tire 10. That is, as shown in Figures 1 and 2, when the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure in an unloaded state, when the opening distance between the tire 10 and the rim flange 22 on a 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 and the cross-sectional height SH (mm) satisfy the relationship 0.01 ≦ A / SH ≦ 0.16. Furthermore, when the opening start point where the rim flange 22 separates from the tire 10 is defined as S, and the point where a perpendicular line drawn from the radially outermost point Tr of the rim flange 22 to the outer surface of the tire 10 intersects with the outer surface of the tire 10 is defined as T, and when two perpendicular lines are drawn from point S and point T to the turned-up portion 4B of the carcass layer 4, the cross-sectional area Sr of the rubber portion R (shaded portion) included in the area surrounded by these two perpendicular lines and the turned-up portion 4B of the carcass layer 4 is 12 mm 2 ≦Sr≦101mm 2 In the case where the rim flange 22 has a portion that extends parallel to the tire width direction at its radially outermost position, the radially outermost point Tr of the rim flange 22 is the point that is the innermost in the width direction of the rim flange 22 at the radially outermost position of the rim flange 22. In addition, the cross-sectional area Sr of the rubber portion R is the cross-sectional area of ​​the portion outside the carcass cords that make up the carcass layer 4.

[0024] In the tire 10 described above, the opening distance A between the tire 10 and the rim flange 22 in an unloaded state satisfies the relationship 0.01≦A / SH≦0.16 with respect to the cross-sectional height SH, and the cross-sectional area Sr of the rubber portion R that provides a buffering effect for the rim flange 22 is 12 mm 2 ≦Sr≦101mm 2By keeping the opening distance A within this range, it is possible to optimize the opening distance A relative to the amount of flexural deformation of the tire 10, and effectively suppress failures caused by flexure of the tire 10 and failures caused by rubbing between the tire 10 and the flange 22. This suppresses failures near the bead portion 3 and improves the durability of the tire 10. In particular, when the aspect ratio of the tire 10 is 55% or less, excellent durability is required, and in such cases, the effect of improving durability can be maximized.

[0025] If the ratio A / SH is less than 0.01, the opening distance A will be insufficient, and when the tire 10 flexes, the stress near the rim flange 22 will be large, leading to failure, while if it exceeds 0.16, the opening distance A will be too large, making the tire 10 more susceptible to failure due to rubbing between the rim flange 22 and the tire, and furthermore making it easier for small stones and the like to get in, which could result in a significant deterioration in durability. In particular, it is desirable to satisfy the relationship 0.015≦A / SH≦0.14, and furthermore to satisfy the relationship 0.02≦A / SH≦0.12.

[0026] On the other hand, the cross-sectional area Sr of the rubber part R is 12 mm 2 If the tire 10 is less than 101 mm, compressive stress is likely to be applied to the carcass layer 4 near the rim flange 22 when the tire 10 is bent, which may lead to failure. 2 If the distance exceeds 14 mm, it becomes difficult to ensure a sufficient opening distance A, and when the tire 10 is bent, the stress in the vicinity of the rim flange 22 increases, leading to failure. 2 ≦Sr≦98mm 2 and furthermore, 16mm 2 ≦Sr≦93mm 2 It is desirable to satisfy the range of

[0027] In the tire 10, as shown in Fig. 3, when the thickness of the rubber portion R on a perpendicular line drawn from point S to the turned-up portion 4B of the carcass layer 4 is Gl (mm) and the thickness of the rubber portion R on a perpendicular line drawn from point T to the turned-up portion 4B of the carcass layer 4 is Gu (mm), it is preferable that the thicknesses Gl and Gu satisfy the relationship 0.40 ≤ Gl / Gu ≤ 0.90. This ensures a good cushioning effect and enhances the effect of improving durability.

[0028] If the ratio Gl / Gu is outside the above range, the cushioning effect decreases and the durability improvement effect decreases. In particular, it is desirable to satisfy the relationship 0.45≦Gl / Gu≦0.85, and more desirably the relationship 0.50≦Gl / Gu≦0.80. Furthermore, it is desirable that the thickness Gl of the rubber portion R satisfy the range 0.5 mm≦Gl≦4.0 mm, and more desirably the range 1.5 mm≦Gl≦3.0 mm. The thicknesses Gl and Gu of the rubber portion R can also be measured on a cut sample of the tire 10.

[0029] In the tire 10 described above, as shown in FIG. 3 , when the tire 10 is mounted on a standard rim 21 and inflated to a standard internal pressure, and in an unloaded state, the point where a perpendicular line drawn from point S to the turned-up portion 4B of the carcass layer 4 intersects with the turned-up portion 4B of the carcass layer 4 is defined as Sc, the point where a perpendicular line drawn from point T to the turned-up portion 4B of the carcass layer 4 intersects with the turned-up portion 4B of the carcass layer 4 is defined as Tc, and the midpoint between points Sc and Tc is defined as Uc. It is preferable that the center of the arc of the carcass layer 4 (having a curvature radius Rc) passing through points Sc, Tc, and Uc is on the outer side in the tire width direction. This makes it difficult for compressive stress to be applied to the carcass layer 4 during tire deformation, thereby improving durability. It is also preferable that the center of the arc of the carcass layer 4 passing through points Sc, Tc, and Uc is on the outer side in the tire width direction, even when the tire 10 is not mounted on a rim alone or when a 100% load is applied.

[0030] In particular, as shown in Figure 3, when the midpoint between points S and Tr is defined as Ur, it is preferable that the radius of curvature Rr (mm) of the arc of the rim flange 22 passing through points S, Tr, and Ur, and the radius of curvature Rc (mm) of the arc of the carcass layer 4 passing through points Sc, Tc, and Uc, satisfy the relationship 1 ≤ Rc / Rr ≤ 55. This makes it difficult for compressive stress to be applied to the carcass layer 4 when the tire deforms, thereby enhancing the effect of improving durability.

[0031] If the ratio Rc / Rr is outside the above range, compressive stress is likely to be applied to the carcass layer 4 when the tire deforms, thereby reducing the effect of improving durability. In particular, it is desirable to satisfy the relationship 2≦Rc / Rr≦50, and more preferably the relationship 3≦Rc / Rr≦45.

[0032] FIG. 4 shows a modified example of a bead portion. In FIG. 4, the main body portion 4A and the turned-up portion 4B of the carcass layer 4 contact each other without a bead filler, forming a closed region that encloses the bead core 5. In other words, the carcass layer 4 is turned up around the bead core 5 from the inside to the outside of the tire, and is arranged so that the main body portion 4A and the turned-up portion 4B are in close contact with each other at the upper end of the bead core 5. By adopting such a turned-up structure for the carcass layer 4, it is possible to distance the carcass layer 4 from the rim flange 22 at the contact portion with the rim flange 22, thereby significantly reducing the compressive stress applied to the carcass layer 4 and improving durability. 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 even more preferably 5% or less. The rubber occupancy rate here refers to the percentage of the rubber portion (e.g., bead wire insulation rubber or small bead fillers) that occupies the closed region formed by the carcass layer 4 in the tire meridian cross section.

[0033] In the structure of Figure 4, durability can be improved by arranging a secondary bead filler 9 on the outer side of the turned-up portion 4B of the carcass layer 4 in the tire width direction or by thickening the rim cushion rubber layer 13. In this case, the cross-sectional area Sr of the rubber portion R is 36 mm 2 ≦Sr≦101mm 2 In particular, it can be set in the range of 42mm 2 ≦Sr≦98mm 2 Satisfies the range of 48mm 2 ≦Sr≦93mm 2 It is desirable to satisfy the range of

[0034] When the tire 10 has a rim cushion rubber layer 13 arranged in a region that contacts the rim flange 22 and a sidewall rubber layer 12 arranged radially outward of the rim cushion rubber layer 13, as shown in Figure 2, it is preferable that, in an unloaded state where the tire 10 is mounted on a standard rim and inflated to a standard internal pressure, 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 be located radially outward of point T. In other words, it is preferable that the rim cushion rubber layer 13 extend from below the bead core 5 radially outward to at least the position of point T. This makes it less likely that compressive stress will be applied to the carcass layer 4 when the tire deforms, thereby enhancing the effect of improving durability.

[0035] The hardness of the rim cushion rubber layer 13 at 20°C is preferably 55 or more and 80 or less. This improves the durability of the rim cushion rubber layer 13. If the hardness of the rim cushion rubber layer 13 is outside this range, the effect of improving durability decreases. The hardness is a durometer hardness measured at a temperature of 20°C using a type A durometer in accordance with JIS-K6253.

[0036] The 100% modulus of the rim cushion rubber layer 13 at 20°C is preferably 2.0 MPa or more and 9.5 MPa or less. This improves the durability of the rim cushion rubber layer 13. If the 100% modulus of the rim cushion rubber layer 13 is outside this range, the effect of improving durability decreases. The 100% modulus is the tensile stress at a specified elongation measured at a temperature of 20°C in accordance with JIS-K6251.

[0037] The loss tangent (tanδ) of the rim cushion rubber layer 13 at 20°C is preferably 0.05 or more and 0.35 or less. This makes it 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, rolling resistance will increase. The loss tangent (tanδ) is measured in accordance with JIS-K6394 using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisakusho) under conditions of a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 60°C.

[0038] The intermediate elongation of the carcass cords constituting the carcass layer 4 under a load of 1.5 cN / dtex is preferably 3.3% or more and 6.2% or less. This can enhance the effect of improving durability. If the intermediate elongation of the carcass cords constituting the carcass layer 4 under a load of 1.5 cN / dtex is outside the above range, the effect of improving durability decreases. In particular, the intermediate elongation of the carcass cords under a load of 1.5 cN / dtex is preferably 3.8% or more and 5.9% or less. The intermediate elongation is measured by conducting a tensile test on the carcass cords taken out from the sidewall portion of the tire 10 in accordance with JIS-L1017 under conditions of a grip interval of 250 mm and a tensile speed of 300±20 mm / min.

[0039] The carcass cords constituting the carcass layer 4 are preferably organic fiber cords. For example, if high-modulus rayon cords are used as the carcass cords, durability will be 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 count density is preferably 43 / 50 mm or more and 59 / 50 mm or less. Polyester cords, which have excellent fatigue resistance, are also suitable as carcass cords. 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 count density is preferably 44 / 50 mm or more and 60 / 50 mm or less.

[0040] The angle of the carcass cords constituting the carcass layer 4 relative to the tire circumferential direction can be set within a range of 75° to 90°. In particular, when the carcass cord angle is set to less than 88°, tire rigidity increases, improving durability. Furthermore, it is preferable that the turned-up portion 4B of the carcass layer 4 extends beyond the maximum tire width position to a position where it overlaps with the edge portion of the belt layer 7. By adopting such a turned-up structure, tire rigidity increases, improving durability.

[0041] 1 and 5, in the tire 10 described above, when the tire 10 is mounted on a specified rim 21, inflated to a specified internal pressure, and in an unloaded state, the opening distance A preferably satisfies the relationship 0.03≦A / W≦1.60 with respect to the protrusion amount W, where W (mm) is half the difference between the total width TW of the tire 10 and the rim width DW of the specified rim 21. 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 outward most in the tire width direction. In other words, the rim protector 15 for protecting the rim flange 22 is excluded from the total width TW.

[0042] In this way, by having the opening distance A between the tire 10 and the rim flange 22 in an unloaded state satisfy the relationship 0.03≦A / W≦1.60 with respect to the protrusion amount W, which corresponds to half the difference between the total width TW of the tire 10 and the rim width DW of the specified rim 21, the opening distance A can be optimized with respect to the amount of flexural deformation of the tire 10, and failures caused by flexure of the tire 10 and failures caused by rubbing between the tire 10 and the flange 22 can be effectively suppressed. This suppresses failures near the bead portion 3, and further enhances the effect of improving the durability of the tire 10.

[0043] If the ratio A / W is less than 0.03, the opening distance A will be insufficient, and when the tire 10 flexes, the stress near the rim flange 22 will be large, leading to failure, while if it exceeds 1.60, the opening distance A will be too large, making the tire 10 more susceptible to failure due to rubbing between the rim flange 22 and the tire, and furthermore making it easier for small stones and the like to get in, which could result in a significant deterioration in durability. In particular, it is desirable to satisfy the relationship 0.035≦A / W≦1.5, and furthermore to satisfy the relationship 0.04≦A / W≦1.4.

[0044] In the above tire 10, as shown in FIG. 6, when the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure while being subjected to a load of 100% of the specified load capacity, the opening distance between the tire 10 and the rim flange 22 on a perpendicular line drawn from the radially outermost point Tr of the rim flange 22 to the outer surface of the tire 10 is defined as A. 100 (mm), the opening distance A 100 is 0.003≦A for cross-sectional height SH (mm) 100 It is advisable to satisfy the relationship / SH≦0.100. 100 The measurement position of the opening distance A is the same as the measurement position of the opening distance A. 100 By optimizing the above, the effect of improving durability can be enhanced.

[0045] Here, the ratio A 100 When / SH is less than 0.003, the opening distance A 100If the opening distance A is insufficient, the stress in the vicinity of the rim flange 12 increases when the tire 10 is bent, leading to failure. 100 Since A is too large, the tire 10 is more likely to be damaged by rubbing against the rim flange 22, and in either case, the effect of improving durability is reduced. 100 / SH≦0.070, and furthermore, 0.007≦A 100 It is desirable to satisfy the relationship / SH≦0.065.

[0046] In the tire 10, the opening distance A 100 (mm) is 0.010≦A for protrusion amount W (mm) 100 It is preferable to satisfy the relationship of / W≦1.000, which can enhance the effect of improving durability.

[0047] Here, the ratio A 100 When / W is less than 0.010, the opening distance A 100 If the opening distance A is insufficient, the stress in the vicinity of the rim flange 22 increases when the tire 10 is bent, leading to failure. 100 Since A is too large, the tire 10 is more likely to be damaged by rubbing against the rim flange 22, and in either case, the effect of improving durability is reduced. 100 / W≦0.800 and 0.020≦A 100 It is desirable to satisfy the relationship of / W≦0.800.

[0048] In the tire 10, the opening distance A (mm) and the opening distance A 100 (mm) means 0.20≦A 100 It is preferable that the relationship of / A≦0.80 is satisfied, which can suppress the stress generated by repeated deformation and enhance the effect of improving durability.

[0049] Here, the ratio A 100If / A is less than 0.20, deformation in the vicinity of the rim flange 22 becomes significantly large when the tire 10 is bent, which may reduce the effect of improving durability. Conversely, if it exceeds 0.80, deformation at a position away from the rim flange 22 becomes significantly large when the tire 10 is bent, which may reduce the effect of improving durability. In particular, if 0.23≦A 100 / A≦0.75, and furthermore, 0.25≦A 100 It is desirable to satisfy the relationship of / A≦0.70.

[0050] In the tire 10, the opening distance A is preferably in the range of 1.5 mm≦A≦8.0 mm, which can suppress stress caused by repeated deformation and enhance the effect of improving durability.

[0051] If the opening distance A is less than 1.5 mm, the opening distance A will be insufficient, and when the tire 10 flexes, the stress near the rim flange 12 will be large, leading to failure, while if it exceeds 8.0 mm, the opening distance A will be too large, making the tire 10 more susceptible to failure due to rubbing between the tire 10 and the rim flange 22. In either case, the improvement in durability will be reduced. In particular, it is desirable that the opening distance A be in the range of 1.8 mm≦A≦7.5 mm, and more preferably in the range of 2.0 mm≦A≦7.0 mm.

[0052] In the tire 10, it is preferable that the opening distance A (mm) satisfies the relationship 0.01≦A / SDH≦0.50 with respect to the height SDH (mm) in the tire radial direction up to the maximum width position (measurement position of the total width TW) of the tire 10. By specifying the opening distance A with respect to the height SDH, which has a large effect on deformation of the bead portion 3, it is possible to suppress stress caused by repeated deformation and enhance the effect of improving durability.

[0053] If the ratio A / SDH is less than 0.01, the opening distance A will be insufficient, and when the tire 10 flexes, the stress near the rim flange 12 will be large, leading to failure, while if it exceeds 0.50, the opening distance A will be too large, making failure more likely to occur due to rubbing between the tire 10 and the rim flange 22. In either case, the improvement in durability will be reduced. In particular, it is desirable to satisfy the relationship 0.02≦A / SDH≦0.45, and furthermore, to satisfy the relationship 0.03≦A / SDH≦0.40.

[0054] 5, in the tire 10 described above, when the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure in an unloaded state, when the opening distance A' (mm) between the tire 10 and the rim flange 22 on a perpendicular line drawn from a midpoint Ur between the radially outermost point Tr of the rim flange 22 and an opening start point S where the rim flange 22 separates from the tire 10 to the outer surface of the tire 10, it is preferable that the opening distance A' and the cross-sectional height SH (mm) satisfy the relationship 0.006≦A' / SH≦0.150. This suppresses stress caused by repeated deformation and enhances the effect of improving durability.

[0055] If the ratio A' / SH is less than 0.006, the opening distance A' will be insufficient, and when the tire 10 flexes, the stress near the rim flange 12 will be large, leading to failure, while if it exceeds 0.150, the opening distance A' will be too large, making the tire 10 more susceptible to failure due to rubbing between the rim flange 22. In either case, the improvement in durability will be reduced. In particular, it is desirable to satisfy the relationship 0.010≦A' / SH≦0.130, and furthermore, to satisfy the relationship 0.014≦A' / SH≦0.110.

[0056] In the tire 10, it is preferable that the opening distance A (mm) and the opening distance A' (mm) satisfy the relationship 0.50≦A' / A≦0.96. This can suppress stress caused by repeated deformation and enhance the effect of improving durability.

[0057] If the ratio A' / A is less than 0.50, the opening distance A' will be insufficient, and when the tire 10 flexes, the stress near the rim flange 12 will be large, leading to failure, while if it exceeds 0.96, the opening distance A' will be too large, making the tire 10 more susceptible to failure due to rubbing between the rim flange 22. In either case, the effect of improving durability will be reduced. It is particularly desirable to satisfy the relationship 0.53≦A' / A≦0.94, and furthermore, to satisfy the relationship 0.56≦A' / A≦0.92.

[0058] In the tire 10, the opening distance A' is preferably in the range of 1.0 mm≦A'≦7.5 mm, which can suppress stress caused by repeated deformation and enhance the effect of improving durability.

[0059] If the opening distance A' is less than 1.0 mm, the opening distance A' will be insufficient, and when the tire 10 flexes, the stress near the rim flange 12 will be large, leading to failure, while if it exceeds 7.5 mm, the opening distance A' will be too large, making the tire 10 more susceptible to failure due to rubbing between the rim flange 22. In either case, the improvement in durability will be reduced. In particular, it is desirable for the opening distance A' to be in the range of 1.2 mm≦A'≦7.0 mm, and even more desirably, 1.4 mm≦A'≦6.5 mm.

[0060] In the above tire 10, as shown in Figure 7, when the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure in an unloaded state, the point where a horizontal line in the tire width direction passing through the radially outermost point Tr of the rim flange 22 intersects with the outer surface of the tire 10 is defined as P, and the point that defines the rim width DW and rim diameter DO of the specified rim 21 is defined as Q. It is preferable that the angle α that the line connecting points P and Q makes with the horizontal line in the tire width direction is in the range of 50°≦α≦80°.

[0061] In this way, by setting the angle α corresponding to the inclination angle of the bead portion 3 within the range of 50°≦α≦80°, the opening distance A can be optimized with respect to the amount of flexural deformation of the tire 10, and failures caused by flexure of the tire 10 and failures caused by rubbing between the tire 10 and the flange 22 can be effectively suppressed. This can suppress failures near the bead portion 3 and further enhance the effect of improving the durability of the tire 10.

[0062] If the angle α is less than 50°, the opening distance A will be insufficient, and when the tire 10 flexes, the stress near the rim flange 22 will be large, leading to failure, while if it exceeds 80°, the opening distance A will be too large, making the tire 10 more susceptible to failure due to rubbing between the rim flange 22 and the tire, and furthermore making it easier for small stones and the like to get in, which could significantly reduce durability. In particular, it is desirable to satisfy the range of 55°≦α≦75°, and furthermore to satisfy the range of 60°≦α≦70°.

[0063] 1 and 8, in the tire 10, when the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure in an unloaded state, when a point defining the total width TW of the tire 10 is defined as L, the angle θ formed by the line connecting points P and Q with the line connecting points L and Q is preferably in the range of 2°≦θ≦30°. This allows the opening distance A to be optimized with respect to the amount of deflection deformation, thereby enhancing the effect of improving durability.

[0064] If the angle θ is less than 2°, the opening distance A will be insufficient, and when the tire 10 flexes, the stress near the rim flange 12 will be large, leading to failure, while if it exceeds 30°, the opening distance A will be too large, making it more likely to fail due to rubbing between the tire 10 and the rim flange 22. In either case, the improvement in durability will be reduced. It is particularly desirable to satisfy the range of 4°≦θ≦25°, and even more preferably 6°≦θ≦20°.

[0065] 9, in the tire 10 described above, when the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure in an unloaded state, if the opening start point where the rim flange 22 separates from the tire 10 is defined as S, the radially outermost point of the rim flange 22 is defined as Tr, and the point where a perpendicular line drawn from point Tr to the outer surface of the tire 10 intersects with the outer surface of the tire is defined as T, then the angle β formed by the line connecting points S and T and the line connecting points S and Tr should be in the range of 15°≦β≦65°. This can enhance the effect of improving durability.

[0066] If the angle β is less than 15°, stress near the rim flange 22 increases when the tire 10 flexes, leading to failure, while if it exceeds 65°, failure is more likely to occur due to rubbing between the tire 10 and the rim flange 22. It is particularly desirable that the range of 20°≦β≦60° is satisfied, and more preferably that the range of 25°≦β≦55° is satisfied.

[0067] In the tire 10, it is preferable that the horizontal distance B (mm) in the tire width direction between points Q and S and the cross-sectional height SH (mm) satisfy the relationship 0.02≦B / SH≦0.18, as shown in Fig. 10. This brings the stress due to repeated deformation into an appropriate range, thereby enhancing the effect of improving durability.

[0068] If the ratio B / SH is less than 0.02, the tire 10 is more likely to break down due to rubbing against the rim flange 22, whereas if it exceeds 0.18, the stress in the vicinity of the rim flange 22 increases when the tire 10 flexes, leading to a breakdown. In either case, the improvement in durability is reduced. It is particularly desirable to satisfy the relationship 0.03≦B / SH≦0.15, and more preferably 0.04≦B / SH≦0.13.

[0069] In the tire 10, the horizontal distance B is preferably in the range of 3.0 mm≦B≦9.0 mm, which brings the stress due to repeated deformation into an appropriate range, thereby enhancing the effect of improving durability.

[0070] If the horizontal distance B is less than 3.0 mm, the tire 10 is more likely to break down due to rubbing against the rim flange 22, while if it exceeds 9.0 mm, the stress near the rim flange 12 increases when the tire 10 flexes, leading to a breakdown. In either case, the improvement in durability is reduced. In particular, it is desirable that the horizontal distance B be in the range of 3.2 mm≦B≦8.5 mm, and more preferably in the range of 3.4 mm≦B≦8.0 mm.

[0071] 11, in the tire 10, when a point T is defined as the intersection of a perpendicular line drawn from the radially outermost point Tr of the rim flange 22 to the outer surface of the tire 10 and the outer surface of the tire 10, an arc (with a curvature radius Rb) of the tire 10 passing through points S, P, and T preferably has its center on the outer side in the tire width direction. This makes it difficult for compressive stress to be applied to the portion of the tire 10 that comes into contact with the rim flange 22, thereby enhancing the effect of improving durability.

[0072] 11, when the point Pr is the point where a perpendicular line drawn from point P to the outer surface of the tire 10 intersects with the outer surface of the rim flange 22, it is desirable that the radius of curvature Rr (mm) of the arc of the rim flange 22 passing through points S, Pr, and Tr and the radius of curvature Rb (mm) of the arc of the tire 10 passing through points S, P, and T satisfy the relationship 1.2≦Rb / Rr≦14.5. This makes it less likely that compressive stress will be applied to the portion of the tire 10 that comes into contact with the rim flange 22, thereby enhancing the effect of improving durability.

[0073] If the ratio Rb / Rr is outside the above range, compressive stress is likely to be applied to the portion of the tire 10 that comes into contact with the rim flange 22, thereby reducing the effect of improving durability. In particular, it is desirable to satisfy the relationship 1.5≦Rb / Rr≦12.2, and more preferably the relationship 2.0≦Rb / Rr≦10.0.

[0074] 12, in the tire 10, in an unloaded state after the tire 10 is mounted on a specified rim 21 and inflated to a specified internal pressure, when the point where a horizontal line in the tire width direction passing through an edge portion of the belt layer 7 located radially innermost among the multiple belt layers 7 intersects with the outer surface of the tire 10 is defined as V, and a point defining the total width TW of the tire 10 is defined as L, the angle γ that a line connecting points L and V makes with the horizontal line in the tire width direction is preferably in the range of 45°≦γ≦80°. This brings the stress due to repeated deformation into an appropriate range, thereby enhancing the effect of improving durability.

[0075] If the angle γ is outside the above range, the stress due to repeated deformation will fall outside the appropriate range, and the effect of improving durability will be reduced. In particular, it is desirable to satisfy the range of 50°≦γ≦75°, and more preferably the range of 55°≦γ≦70°.

[0076] 12, when a point W is defined as a point on the outer surface of the tire 10 at a central position in the tire radial direction between points L and V, the radius of curvature Rs of the arc of the tire 10 that passes through points V, W, and L preferably satisfies the relationship 0.3≦Rs / SH≦2.5 with respect to the cross-sectional height SH. This brings the stress due to repeated deformation into an appropriate range, thereby enhancing the effect of improving durability.

[0077] If the ratio Rs / SH is outside the above range, the stress due to repeated deformation will fall outside the appropriate range, and the durability improvement effect will be reduced. In particular, it is desirable to satisfy the relationship 0.4≦Rs / SH≦2.3, and more preferably 0.5≦Rs / SH≦2.0. [Example]

[0078] Pneumatic tires of Comparative Examples 1 and 2 and Examples 1 to 9 were manufactured for a tire size of 285 / 35R20 (SH=95 mm) with A / SH, cross-sectional area Sr, Gl / Gu, thickness Gl, thickness Gu, opening distance A, the center position of the tire's arc (Rc) passing through points Sc, Tc, and Uc, Rc / Rr, radius of curvature Rc, radius of curvature Rr, the presence or absence of a bead filler in the closed region, the position of boundary point X between the rim cushion rubber layer and the sidewall rubber layer, the hardness of the rim cushion rubber layer at 20°C, and the intermediate elongation of the carcass cords constituting the carcass layer at a load of 1.5 cN / dtex as shown in Table 1. Regarding the center position of the arc (Rc), when the center position of the arc is on the inner side in the tire width direction it is referred to as "inner side," and when the center position of the arc is on the outer side in the tire width direction it is referred to as "outer side." Furthermore, with regard to the position of boundary point X between the rim cushion rubber layer and the sidewall rubber layer, when boundary point X is located radially inward of point T, it is indicated as "inside," and when boundary point X is located radially outward of point T, it is indicated as "outside."

[0079] The strain resistance and abrasion resistance of these test tires were evaluated by the following test methods, and the results are shown in Table 1.

[0080] Strain resistance: Each test tire was mounted on a wheel with a rim size of 20 x 10J and attached to a testing machine with a drum diameter of 1707 mm. The tire was inflated to 290 kPa, the speed was 81 km / h, the initial load was 88% of the maximum load capacity, and the load was increased by 13% every two hours, and the distance traveled until the tire failed was measured. The evaluation results were expressed as an index, with Comparative Example 2 being 100. The higher the index value, the better the strain resistance performance.

[0081] Scratch resistance: Each test tire was mounted on a wheel with a rim size of 20x10J and attached to a testing machine with a drum diameter of 1707mm. A 2500km running test was conducted at an air pressure of 290kPa, a speed of 81km / h, an initial load of 88% of the maximum load capacity, and a load increase of 13% every two hours. The rubber thickness from the tire outer surface to the carcass layer at a position corresponding to the radially outermost point of the rim flange was measured before and after the test, and the amount of change in rubber thickness was determined. The evaluation results were expressed as an index using the reciprocal of the amount of change in rubber thickness, with Comparative Example 1 being set to 100. A higher index value indicates better abrasion resistance.

[0082] [Table 1]

[0083] As can be seen from Table 1, in comparison with Comparative Examples 1 and 2, the tires of Examples 1 to 9 were improved in both strain resistance and abrasion resistance, and had excellent durability. [Explanation of symbols]

[0084] 1 Tread section 2 Sidewall 3 Bead section 4 carcass layers 5 bead core 6 Bead filler 7 Belt Layer 8 Belt cover layer 10 Tires 11 Tread rubber layer 12 Sidewall rubber layer 13 Rim cushion rubber layer 14 Inner liner layer 15 Rim Protector 21 regulation rim 22 rim flange

Claims

1. A tire having a carcass layer mounted between a pair of bead portions, the carcass layer having a structure in which the carcass layer is wound up around a bead core from the inside to the outside of the tire, and a cross-sectional height SH in the range of 50 mm to 150 mm, In an unloaded state in which the tire is mounted on a specified rim and inflated to a specified internal pressure, when an opening distance between the tire and the rim flange on a perpendicular line drawn from the radially outermost point Tr 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, the opening start point where the rim flange separates from the tire is defined as S, and the point where a perpendicular line drawn from the radially outermost point Tr of the rim flange to the outer surface of the tire intersects with the outer surface of the tire, and when two perpendicular lines are drawn from the point S and the point T to the turned-up portion of the carcass layer, a cross-sectional area Sr of the rubber portion included in the region surrounded by the two perpendicular lines and the turned-up portion of the carcass layer is 12 mm 2 ≦Sr≦101mm 2 A tire characterized in that

2. 2. The tire according to claim 1, characterized in that when a thickness of the rubber portion on a perpendicular line drawn from the point S to the turned-up portion of the carcass layer is Gl and a thickness of the rubber portion on a perpendicular line drawn from the point T to the turned-up portion of the carcass layer is Gu, the thicknesses Gl and Gu satisfy the relationship 0.40≦Gl / Gu≦0.

90.

3. 3. The tire according to claim 1 or 2, characterized in that in an unloaded state in which the tire is mounted on a specified rim and inflated to a specified internal pressure, when a point where a perpendicular line drawn from the point S to the turned-up portion of the carcass layer intersects with the turned-up portion of the carcass layer is defined as Sc, a point where a perpendicular line drawn from the point T to the turned-up portion of the carcass layer intersects with the turned-up portion of the carcass layer is defined as Tc, and a midpoint between the points Sc and Tc is defined as Uc, an arc of the carcass layer passing through the points Sc, Tc, and Uc has a center on the outer side in the tire width direction.

4. 4. The tire according to claim 3, characterized in that in an unloaded state in which the tire is mounted on a specified rim and inflated to a specified internal pressure, when the midpoint between the points S and Tr is defined as Ur, the radius of curvature Rr (mm) of the arc of the rim flange passing through the points S, Tr, and Ur, and the radius of curvature Rc (mm) of the arc of the carcass layer passing through the points Sc, Tc, and Uc satisfy the relationship 1≦Rc / Rr≦55.

5. The tire according to any one of claims 1 to 4, characterized in that the main body portion and the turned-up portion of the carcass layer are in contact with each other without a bead filler therebetween to form a closed region that encloses the bead core.

6. a rim cushion rubber layer disposed in an area in contact with the rim flange, and a sidewall rubber layer disposed radially outward of the rim cushion rubber layer, 6. The tire according to claim 1, wherein in an unloaded state in which the tire is mounted on a specified rim and inflated to a specified internal pressure, a boundary point X between the rim cushion rubber layer and the sidewall rubber layer on an outer surface of the tire is located radially outward of the point T.

7. The tire according to claim 6, wherein the hardness of the rim cushion rubber layer at 20°C is 55 or more and 80 or less.

8. The tire according to any one of claims 1 to 7, characterized in that the intermediate elongation of the carcass cord constituting the carcass layer under a load of 1.5 cN / dtex is 3.3% or more and 6.2% or less.

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