Tire

Abstract

Provided is a tire capable of effectively suppressing a failure due to tire flexing and a failure due to friction between the tire and a flange of a rim, thereby improving durability. In a tire (10) having a cross-sectional height SH in the range of 50 mm to 150 mm, in a no-load state in which the tire (10) is fitted to a prescribed rim and filled with a prescribed internal pressure, when an opening distance between the tire (10) and the flange (22) of the rim on a vertical line drawn from a radially outermost point Tr of the flange (22) to an outer surface of the tire (10) is set as A, the opening distance A satisfies a relationship of 0.01 ≤ A / SH ≤ 0.16 with respect to the cross-sectional height SH, and when a projection amount equivalent to 1 / 2 of a difference between a total width TW of the tire (10) and a rim width DW of the prescribed rim (21) is set as W, the opening distance A satisfies a relationship of 0.03 ≤ A / W ≤ 1.60 with respect to the projection amount W.

Description

Technical Field

[0001] This invention relates to a tire suitable for applications requiring high load capacity, and more specifically, to a tire that can effectively suppress failures caused by tire flexing and failures caused by friction between the tire and the rim flange, thereby improving durability. Background Technology

[0002] With the increasing weight of vehicles due to electrification, there is a demand for tires with high load-bearing capacity. However, increasing the load can lead to the following problem: if the repeated deformation from the sidewall to the bead increases during tire rotation, the tire's durability will decrease.

[0003] To address this issue, a suggestion has been made 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, if the shape of the bead portion is defined only relative to the shape of the rim flange, the improvement in durability is insufficient, and failures due to tire flexing and friction between the tire and the flange may still occur.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 11-34619 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this invention is to provide a tire that can effectively suppress failures caused by tire flexing and failures caused by friction between the tire and the rim flange, thereby improving durability.

[0009] Technical means to solve the problem

[0010] The tire of the present invention for achieving the above-mentioned objectives has a cross-sectional height SH in the range of 50mm to 150mm. Its characteristic is that, under no-load conditions where the tire is mounted on a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point of the rim flange to the outer surface of the tire is set as A, the opening distance A satisfies the relationship 0.01 ≤ A / SH ≤ 0.16 relative to the cross-sectional height SH. When the protrusion amount, equivalent to half the difference between the total width TW of the tire and the rim width DW of the specified rim, is set as W, the opening distance A satisfies the relationship 0.03 ≤ A / W ≤ 1.60 relative to the protrusion amount W.

[0011] Invention Effects

[0012] The inventors have conducted in-depth research on the movement of the bead portion of passenger car tires with a cross-sectional height SH in the range of 50mm to 150mm. The results show that the tire's cross-sectional height SH and the protrusion W, which is equivalent to half the difference between the tire's total width TW and the specified rim width DW, have a significant impact on tire flexing. Therefore, by appropriately specifying the opening distance A between the tire and the rim flange relative to the cross-sectional height SH and the protrusion W, it is possible to effectively suppress failures caused by tire flexing and failures caused by friction between the tire and the flange, thus completing this invention.

[0013] That is, in this invention, under no-load conditions where the tire is mounted on a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point of the rim flange to the outer surface of the tire is set as A, the opening distance A is such that the relationship between the opening distance A and the section height SH is 0.01≤A / SH≤0.16. When the protrusion amount, which is equivalent to half of the difference between the total width TW of the tire and the rim width DW of the specified rim, is set as W, the relationship between the opening distance A and the protrusion amount W is such that the relationship between the opening distance A and the protrusion amount W is 0.03≤A / W≤1.60. This effectively suppresses failures caused by tire deflection and failures caused by friction between the tire and the flange, resulting in improved tire durability.

[0014] In this invention, when a tire is mounted on a specified rim and filled with a specified internal pressure while being subjected to a load of 100% of the specified load capacity, the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point of the rim flange to the outer surface of the tire is defined as A. 100 When the opening distance is A, it is preferable to have a distance between the openings. 100 The cross-sectional height SH satisfies 0.003 ≤ A. 100 The relationship is / SH≤0.100. The opening distance A is particularly preferred. 100 The convexity W satisfies 0.010 ≤ A 100 / W≤1.000. Furthermore, it is preferable that the opening distance A is related to the opening distance A'. 100 Satisfying 0.20≤A 100 The relationship is / A≤0.80. Therefore, it can improve the durability.

[0015] The chamfer distance A is preferably within the range of 1.5 mm ≤ A ≤ 8.0 mm. Furthermore, the chamfer distance A is preferably such that the radial height SDH of the tire at its maximum width position satisfies the relationship 0.01 ≤ A / SDH ≤ 0.50. This improves durability.

[0016] Furthermore, under no-load conditions with the tire mounted on a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point of the rim flange and the midpoint of the rim flange away from the tire's opening point to the outer surface of the tire is defined as A', it is preferable that the opening distance A' satisfies the relationship 0.006 ≤ A' / SH ≤ 0.150 with respect to the section height SH. Furthermore, the opening distance A and the opening distance A' preferably satisfy the relationship 0.50 ≤ A' / A ≤ 0.96. Moreover, the opening distance A' is preferably within the range of 1.0 mm ≤ A' ≤ 7.5 mm. This improves durability.

[0017] In this invention, the dimensions measured under no-load conditions are taken when the tire is mounted on a specified rim and filled with a specified internal pressure. Conversely, the dimensions measured under load conditions are taken when the tire is mounted on a specified rim and filled with a specified internal pressure, and the tire is placed vertically on a flat surface and subjected to a load of 100% of the specified load capacity. Each dimension is the average of the measured values ​​taken at four locations on the tire circumference. "Specified rim" refers to the rim specified for each tire within a specification system that includes the tire's specifications; for example, it is designated as a standard rim for JATMA, a "Design Rim" for TRA, or a "Measuring Rim" for ETRTO. "Specified internal pressure" refers to the air pressure corresponding to the maximum load capacity specified for each tire within a specification system that includes the tire's specifications. "Specified load capacity" refers to the maximum load capacity specified for each tire within a specification system that includes the tire's specifications. Attached Figure Description

[0018] Figure 1 This is a half-section view along the meridian of an inflatable tire (unloaded state) constructed according to an embodiment of the present invention.

[0019] Figure 2 It is to extract Figure 1 A cross-sectional view showing the bead portion of an inflatable tire (without load).

[0020] Figure 3 It is to extract Figure 1 A cross-sectional view showing the bead portion of an inflatable tire (100% load).

[0021] Figure 4 It is to extract Figure 1 Other cross-sectional views showing the bead portion of an inflatable tire (unloaded).

[0022] Figure 5 It is to extract Figure 1 A cross-sectional view showing the bead and sidewall of an inflatable tire (unloaded).

[0023] Figure 6 It is to extract Figure 1 Other cross-sectional views showing the bead portion of an inflatable tire (unloaded).

[0024] Figure 7 It is to extract Figure 1 Other cross-sectional views showing the bead portion of an inflatable tire (unloaded).

[0025] Figure 8 It is to extract Figure 1 Other cross-sectional views showing the bead portion of an inflatable tire (unloaded).

[0026] Figure 9 It is to extract Figure 1 Other cross-sectional views showing the bead and sidewall portions of an inflatable tire (unloaded).

[0027] Figure 10 It is to extract Figure 1 Other cross-sectional views showing the bead portion of an inflatable tire (unloaded).

[0028] Figure 11 It is to extract Figure 1 Other cross-sectional views showing the bead portion of an inflatable tire (unloaded).

[0029] Figure 12 This is a cross-sectional view showing an example of a variation in the bead portion (unloaded state). Detailed Implementation

[0030] Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings. Figures 1 to 12 This refers to an inflatable tire constructed according to an embodiment of the present invention. Figure 1 A side of an inflatable tire is depicted with the tire equator CL as its boundary, but the inflatable tire has a symmetrical or asymmetrical structure on both sides of the tire equator CL.

[0031] like Figure 1 As shown, the pneumatic tire 10 of this embodiment includes a tread portion 1 that extends in the circumferential direction of the tire and is annular, 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 radially inner side of these sidewall portions 2.

[0032] A carcass layer 4 is provided between a pair of bead portions 3, 3. This carcass layer 4 comprises multiple reinforcing cords extending radially along the tire and folded back from the inside to the outside of the tire around the bead core 5 disposed in each bead portion 3. A sidewall core 6 with a triangular cross-section, made of a rubber composition, is disposed on the outer periphery of the bead core 5. The carcass layer 4 has a main body portion 4A and an upper rolled portion 4B bounded by the bead core 5.

[0033] On the other hand, multiple belt layers 7 are embedded on the outer periphery of the carcass layer 4 on the tread portion 1. These belt layers 7 are configured to contain multiple reinforcing cords inclined relative to the tire circumference, and the reinforcing cords intersect each other between layers. In the belt layers 7, the inclination angle of the reinforcing cords relative to the tire circumference is set, for example, in the range of 10° to 40°. Steel cords are preferably used as the reinforcing cords of the belt layers 7. To improve high-speed durability, at least one belt cover layer 8 is disposed on the outer periphery of the belt layers 7, consisting of reinforcing cords arranged at an angle of, for example, 5° or less relative to the tire circumference. Organic fiber cords such as nylon and aramid are preferably used as the reinforcing cords of the belt cover layer 8.

[0034] It should be noted that the above description of the internal structure of a tire shows a representative example of a pneumatic tire 10, but is not limited thereto. Figure 1 In this tire, a tread rubber layer 11 is provided on the tread portion 1, a sidewall rubber layer 12 is provided on the sidewall portion 2, a rim buffer rubber layer 13 is provided on the bead portion 3, and an inner liner rubber layer 14 is provided on the inner surface of the tire 10 along the carcass layer 4. In addition, a rim protector 15 for protecting the rim flange 22 is formed on the sidewall portion 2 in a manner that protrudes outward in the tire width direction.

[0035] The section height SH of the aforementioned tire 10 is in the range of 50mm to 150mm, and it is mainly used for passenger cars. The following structure applies to this type of tire 10. That is, as follows... Figure 1 and Figure 2As shown, under no-load conditions where the tire 10 is mounted on 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 a vertical line drawn from the outermost radial point Tr of the rim flange 22 to the outer surface of the tire 10 is set as A (mm), the opening distance A satisfies the relationship 0.01 ≤ A / SH ≤ 0.16 relative to the section height SH (mm). When the protrusion amount, equivalent 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 set as W (mm), the opening distance A satisfies the relationship 0.03 ≤ A / W ≤ 1.60 relative to the protrusion amount W. It should be noted that when the rim flange 22 has a portion extending parallel to the tire width direction at the outermost radial position, the outermost radial point Tr of the rim flange 22 becomes the innermost point in the width direction of the rim flange 22 at the outermost radial position. The total width TW of the tire 10 is the total width of the tire 10 at the point where the carcass layer 4 is most bulging in the outermost direction of the tire width. That is, the total width TW excludes the rim guard 15 used to protect the rim flange 22.

[0036] In the tire 10 described above, by ensuring that the opening distance A between the tire 10 and the rim flange 22 in the unloaded state satisfies the relationship 0.01 ≤ A / SH ≤ 0.16 with respect to the section height SH, and by ensuring that the opening distance A satisfies the relationship 0.03 ≤ A / W ≤ 1.60 with respect to the protrusion W, which is equivalent 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 relative to the flexural deformation of the tire 10, thereby effectively suppressing failures caused by the flexural deformation of the tire 10 and failures caused by friction 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, although excellent durability is required, the improvement in durability can be maximized in this case.

[0037] If the ratio A / SH is less than 0.01, the opening distance A is insufficient. When the tire 10 flexes, the stress near the rim flange 22 will increase, potentially leading to malfunctions. Conversely, if it exceeds 0.16, the opening distance A is too large, making it prone to malfunctions due to friction between the tire 10 and the rim flange 22. This allows stones and other contaminants to easily enter, potentially significantly reducing durability. Ideally, the relationship 0.015 ≤ A / SH ≤ 0.14 should be satisfied, and even more ideally, the relationship 0.02 ≤ A / SH ≤ 0.12 should be satisfied.

[0038] Similarly, if the ratio A / W is less than 0.03, the chamfer distance A is insufficient. When the tire 10 flexes, the stress near the rim flange 22 will increase, potentially leading to malfunctions. Conversely, if it exceeds 1.60, the chamfer distance A is too large, making it prone to malfunctions due to friction between the tire 10 and the rim flange 22. This allows stones and other contaminants to easily enter, potentially significantly reducing durability. Ideally, the ratio should be 0.035 ≤ A / W ≤ 1.5, and even more ideally, 0.04 ≤ A / W ≤ 1.4.

[0039] In the aforementioned tire 10, such as Figure 3 As shown, when the tire 10 is mounted on a specified rim 21 and filled with a specified internal pressure while being loaded with a specified load capacity of 100%, the opening distance between the tire 10 and the rim flange 22 on a vertical line drawn from the outermost radial point Tr of the rim flange 22 to the outer surface of the tire 10 is defined as A. 100 When (mm), the opening distance A 100 The cross-sectional height SH (mm) satisfies 0.003 ≤ A. 100 A relationship where / SH≤0.100 is preferable. It should be noted that the opening distance A... 100 The measurement position is the same as the measurement position of the chamfer distance A. Thus, by optimizing the chamfer distance A during tire deformation... 100 This can improve durability.

[0040] Where, if the ratio A 100 If / SH is less than 0.003, then the opening distance A 100 The problem is that when tire 10 flexes, the stress near rim flange 12 increases, which can lead to malfunctions. Conversely, if it exceeds 0.100, the chamfer distance A... 100 If the value is too large, it can easily lead to failures due to friction between the tire 10 and the rim flange 22, which will reduce the improvement in durability in either case. Ideally, the value should be 0.005 ≤ A. 100 The relationship is SH≤0.070, and ideally, 0.007≤A is also satisfied. 100 The relationship is / SH≤0.065.

[0041] In the aforementioned tire 10, the chamfer distance A 100 The value (mm) relative to the protrusion W (mm) satisfies 0.010 ≤ A 100 A relationship of / W≤1.000 is ideal. This can improve the durability.

[0042] Where, if the ratio A 100 If / W is less than 0.010, then the opening distance A 100The problem is that when the tire 10 deflects, the stress near the rim flange 22 increases, which can lead to malfunctions. Conversely, if it exceeds 1.000, the chamfer distance A... 100 If the value is too large, it can easily lead to failures due to friction between the tire 10 and the rim flange 22, which will reduce the improvement in durability in either case. Ideally, the value should be 0.015 ≤ A. 100 The relationship is W ≤ 0.800, and ideally, it should satisfy 0.020 ≤ A. 100 The relationship is / W≤0.800.

[0043] In the tire 10 described above, the cuff distance A (mm) and the cuff distance A 100 (mm) satisfies 0.20≤A 100 A value of / A ≤ 0.80 is desirable. This helps to suppress stress caused by repeated deformation, thereby improving durability.

[0044] Where, if the ratio A 100 If A is less than 0.20, the deformation near the rim flange 22 will significantly increase when the tire 10 flexes, which may reduce the durability improvement effect. Conversely, if A exceeds 0.80, the deformation away from the rim flange 22 will significantly increase when the tire 10 flexes, which may also reduce the durability improvement effect. Ideally, A should be 0.23 ≤ 0.23. 100 The relationship is A ≤ 0.75, and ideally, it should satisfy 0.25 ≤ A. 100 The relationship is / A≤0.70.

[0045] In the aforementioned tire 10, the chamfer distance A is preferably within the range of 1.5mm ≤ A ≤ 8.0mm. This helps to suppress stress caused by repeated deformation, thereby improving durability.

[0046] If the chamfer distance A is less than 1.5 mm, it is insufficient, and the stress near the rim flange 12 will increase when the tire 10 flexes, potentially leading to malfunction. Conversely, if it exceeds 8.0 mm, the chamfer distance A is too large, making it prone to malfunctions caused by friction between the tire 10 and the rim flange 22. In either case, the durability improvement effect will be reduced. Ideally, the chamfer distance A should be within the range of 1.8 mm ≤ A ≤ 7.5 mm, and even more ideally, within the range of 2.0 mm ≤ A ≤ 7.0 mm.

[0047] In the tire 10 described above, it is preferable that the chamfer distance A (mm) relative to the radial height SDH (mm) of the tire at the position of maximum width of the tire 10 (the measurement position of the total width TW) satisfies the relationship 0.01≤A / SDH≤0.50. By specifying the chamfer distance A relative to the height SDH, which has a greater impact on the deformation of the bead portion 3, it is possible to suppress the stress generated by repeated deformation, thereby improving the durability.

[0048] If the ratio A / SDH is less than 0.01, the chamfer distance A is insufficient. When the tire 10 flexes, the stress near the rim flange 12 will increase, potentially leading to failure. Conversely, if it exceeds 0.50, the chamfer distance A is too large, making it prone to failure due to friction between the tire 10 and the rim flange 22. In either case, the durability improvement effect will be reduced. Ideally, the relationship 0.02 ≤ A / SDH ≤ 0.45 should be satisfied, and even more ideally, the relationship 0.03 ≤ A / SDH ≤ 0.40 should be satisfied.

[0049] In the aforementioned tire 10, such as Figure 2 As shown, under no-load conditions where the tire 10 is mounted on a specified rim 21 and filled with a specified internal pressure, the opening distance between the tire 10 and the rim flange 22 on a vertical line drawn from the outermost radial point Tr of the rim flange 22 and the midpoint Ur of the rim flange 22 away from the opening point S of the tire 10 to the outer surface of the tire 10 is set as A' (mm). It is preferable that the opening distance A' relative to the section height SH (mm) satisfies the relationship 0.006 ≤ A' / SH ≤ 0.150. This can suppress the stress generated by repeated deformation, thereby improving durability.

[0050] If the ratio A' / SH is less than 0.006, the chamfer distance A' is insufficient. When the tire 10 flexes, the stress near the rim flange 12 will increase, potentially leading to a malfunction. Conversely, if it exceeds 0.150, the chamfer distance A' is too large, making it prone to malfunctions due to friction between the tire 10 and the rim flange 22. In either case, the improvement in durability will be reduced. Ideally, the relationship 0.010 ≤ A' / SH ≤ 0.130 should be satisfied, and even more ideally, the relationship 0.014 ≤ A' / SH ≤ 0.110 should be satisfied.

[0051] In the tire 10 described above, it is preferable that the cuff distance A (mm) and cuff distance A' (mm) satisfy the relationship 0.50≤A' / A≤0.96. This can suppress the stress generated by repeated deformation, thereby improving durability.

[0052] If the ratio A' / A is less than 0.50, the opening distance A' is insufficient. When the tire 10 flexes, the stress near the rim flange 12 will increase, potentially leading to malfunctions. Conversely, if it exceeds 0.96, the opening distance A' is too large, making it prone to malfunctions caused by friction between the tire 10 and the rim flange 22. In either case, the improvement in durability will be reduced. Ideally, the relationship 0.53 ≤ A' / A ≤ 0.94 should be satisfied, and even more ideally, the relationship 0.56 ≤ A' / A ≤ 0.92 should be satisfied.

[0053] In the tire 10 described above, the chamfer distance A' is preferably within the range of 1.0 mm ≤ A' ≤ 7.5 mm. This helps to suppress stress caused by repeated deformation, thereby improving durability.

[0054] If the chamfer distance A' is less than 1.0 mm, it is insufficient, and the stress near the rim flange 12 will increase when the tire 10 flexes, potentially leading to malfunction. Conversely, if it exceeds 7.5 mm, the chamfer distance A' is too large, making it prone to malfunctions caused by friction between the tire 10 and the rim flange 22. In either case, the durability improvement effect will be reduced. Ideally, the chamfer distance A' should be within the range of 1.2 mm ≤ A' ≤ 7.0 mm, and even more ideally, within the range of 1.4 mm ≤ A' ≤ 6.5 mm.

[0055] In the aforementioned tire 10, such as Figure 4 As shown, under no-load conditions where the tire 10 is mounted on the specified rim 21 and filled with the specified internal pressure, the point where the horizontal line in the tire width direction passing through the outermost radial point Tr of the rim flange 22 intersects the outer surface of the tire 10 is set as P, and the point defining the rim width DW and rim diameter DO of the specified rim 21 is set as 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 within the range of 50°≤α≤80°.

[0056] Thus, by keeping the angle α, which corresponds to the tilt angle of the bead portion 3, within the range of 50°≤α≤80°, the chamfer distance A can be optimized relative to the flexural deformation of the tire 10, thereby effectively suppressing failures caused by the flexural deformation of the tire 10 and failures caused by friction between the tire 10 and the flange 22. This suppresses failures near the bead portion 3, thereby further improving the durability of the tire 10.

[0057] If the angle α is less than 50°, the opening distance A is insufficient. When the tire 10 flexes, the stress near the rim flange 22 will increase, potentially leading to malfunction. Conversely, if the angle exceeds 80°, the opening distance A is too large, making it prone to malfunctions due to friction between the tire 10 and the rim flange 22. This allows stones and other contaminants to easily enter, potentially significantly reducing durability. Ideally, the angle α should be within the range of 55° ≤ α ≤ 75°, and even more ideally, within the range of 60° ≤ α ≤ 70°.

[0058] In the aforementioned tire 10, such as Figure 1 and Figure 5 As shown, under no-load conditions where the tire 10 is mounted on a specified rim 21 and filled with a specified internal pressure, and the point defining the total width TW of the tire 10 is set as L, the angle θ formed by the straight line connecting points P and Q with respect to the straight line connecting points L and Q is preferably within the range of 2° ≤ θ ≤ 30°. This allows for optimization of the chamfer distance A relative to the amount of flexural deformation, thereby improving durability.

[0059] If the angle θ is less than 2°, the opening distance A is insufficient. When the tire 10 flexes, the stress near the rim flange 12 will increase, potentially leading to a malfunction. Conversely, if the angle exceeds 30°, the opening distance A is too large, making it prone to malfunctions caused by friction between the tire 10 and the rim flange 22. In either case, the improvement in durability will be reduced. Ideally, the angle should be within the range of 4° ≤ θ ≤ 25°, and even more ideally, it should be within the range of 6° ≤ θ ≤ 20°.

[0060] In the aforementioned tire 10, such as Figure 6 As shown, under no-load conditions, with the tire 10 mounted on a specified rim 21 and filled with a specified internal pressure, and with the starting point of the opening of the rim flange 22 away from the tire 10 designated as S, the outermost radial point of the rim flange 22 designated as Tr, and the point where the perpendicular line drawn from point Tr to the outer surface of the tire 10 intersects the outer surface of the tire designated as T, the angle β formed by the straight line connecting points S and T with respect to the straight line connecting points S and Tr is preferably within the range of 15° ≤ β ≤ 65°. This improves durability.

[0061] Specifically, if the angle β is less than 15°, the stress near the rim flange 22 will increase when the tire 10 flexes, which may lead to a malfunction. Conversely, if it exceeds 65°, a malfunction may easily occur due to friction between the tire 10 and the rim flange 22. Ideally, the angle β should be within the range of 20° ≤ β ≤ 60°, and even more ideally, it should be within the range of 25° ≤ β ≤ 55°.

[0062] In the aforementioned tire 10, such as Figure 7As shown, it is preferable that the horizontal distance B (mm) in the tire width direction between point Q and point S, relative to the section height SH (mm), satisfies the relationship 0.02≤B / SH≤0.18. This ensures that the stress generated by repeated deformation is within an appropriate range, thereby improving durability.

[0063] If the ratio B / SH is less than 0.02, malfunctions are more likely to occur due to friction between the tire 10 and the rim flange 22. Conversely, if it exceeds 0.18, the stress near the rim flange 22 will increase when the tire 10 flexes, thus leading to malfunctions. In either case, the improvement in durability will be reduced. Ideally, the relationship 0.03 ≤ B / SH ≤ 0.15 should be satisfied, and even more ideally, the relationship 0.04 ≤ B / SH ≤ 0.13 should be satisfied.

[0064] In the aforementioned tire 10, the horizontal distance B is preferably within the range of 3.0 mm ≤ B ≤ 9.0 mm. This ensures that the stress generated by repeated deformation is within an appropriate range, thereby improving durability.

[0065] If the horizontal distance B is less than 3.0 mm, malfunctions are more likely to occur due to friction between the tire 10 and the rim flange 22. Conversely, if it exceeds 9.0 mm, the stress near the rim flange 12 will increase when the tire 10 flexes, thus leading to malfunctions. In either case, the improvement in durability will be reduced. Ideally, the horizontal distance B should be within the range of 3.2 mm ≤ B ≤ 8.5 mm, and even more ideally, within the range of 3.4 mm ≤ B ≤ 8.0 mm.

[0066] In the aforementioned tire 10, such as Figure 8 As shown, when the point where the perpendicular line drawn from the outermost radial point Tr of the rim flange 22 intersects the outer surface of the tire 10 is designated as T, it is preferable that the center of the arc (radius of curvature Rb) of the tire 10 passing through points S, P, and T is located outside the tire width direction. This prevents compressive stress from being applied to the portion of the tire 10 in contact with the rim flange 22, thus improving durability.

[0067] In particular, such as Figure 8 As shown, when Pr is the point where the 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 preferable that the radius of curvature Rb (mm) of the arc of the tire 10 passing through points S, P, and T satisfies the relationship 1.2 ≤ Rb / Rr ≤ 14.5 relative to the radius of curvature Rr (mm) of the arc of the rim flange 22 passing through points S, Pr, and Tr. This prevents compressive stress from being applied to the portion of the tire 10 in contact with the rim flange 22, thus improving durability.

[0068] If the ratio Rb / Rr exceeds the above range, compressive stress is easily applied to the part of the tire 10 that contacts the rim flange 22, thus reducing the durability improvement effect. Ideally, the relationship 1.5 ≤ Rb / Rr ≤ 12.2 should be satisfied, and even more ideally, the relationship 2.0 ≤ Rb / Rr ≤ 10.0 should be satisfied.

[0069] In the aforementioned tire 10, such as Figure 9 As shown, under no-load conditions where the tire 10 is mounted on a specified rim 21 and filled with a specified internal pressure, when the point where the horizontal line in the tire width direction passing through the edge of the innermost radial layer 7 of the multi-layer belt layer 7 intersects with the outer surface of the tire 10 is designated as V, and the point defining the total width TW of the tire 10 is designated as L, the angle γ formed by the straight line connecting point L and point V with respect to the horizontal line in the tire width direction is preferably within the range of 45°≤γ≤80°. This ensures that the stress generated by repeated deformation is within an appropriate range, thereby improving durability.

[0070] If the angle γ exceeds the above range, the stress generated by repeated deformation will exceed the appropriate range, thus reducing the improvement in durability. Ideally, the range of 50°≤γ≤75° should be met, and even more ideally, the range of 55°≤γ≤70° should be met.

[0071] In the aforementioned tire 10, such as Figure 9 As shown, when the point W, located on the outer surface of tire 10, is the radial center of the tire between points L and V, it is preferable that the radius of curvature Rs of the arc of tire 10 passing through points V, W, and L satisfies the relationship 0.3 ≤ Rs / SH ≤ 2.5 relative to the section height SH. This ensures that the stress generated by repeated deformation is within an appropriate range, thereby improving durability.

[0072] If the ratio Rs / SH exceeds the above range, the stress generated by repeated deformation will exceed the appropriate range, thus reducing the improvement in durability. Ideally, the relationship 0.4 ≤ Rs / SH ≤ 2.3 should be satisfied, and even more ideally, the relationship 0.5 ≤ Rs / SH ≤ 2.0 should be satisfied.

[0073] In the aforementioned tire 10, such as Figure 10As shown, under no-load conditions with the tire 10 mounted on a specified rim 21 and filled with a specified internal pressure, the starting point of the opening of the rim flange 22 away from the tire 10 is defined as S. The point where the vertical line drawn from the outermost radial 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 T. When two vertical lines are drawn from points S and T to the upper rolled portion 4B of the carcass layer 4, the cross-sectional area Sr of the rubber portion R (oblique line portion) contained in the area enclosed by these two vertical lines and the upper rolled portion 4B of the carcass layer 4 is 12 mm. 2 ≤Sr≤101mm 2 It is best to keep it within the specified range. It should be noted that the cross-sectional area Sr of the rubber part R is the cross-sectional area of ​​the part that is further outward than the tire cords that make up the tire carcass layer 4.

[0074] Thus, by making the cross-sectional area Sr of the rubber portion R that bears the cushioning effect on the rim flange 22 12mm 2 ≤Sr≤101mm 2 Within a certain range, the chamfer distance A can be optimized relative to the flexural deformation of the tire 10, thereby effectively suppressing failures caused by the flexural deformation of the tire 10 and failures caused by friction between the tire 10 and the flange 22. This suppresses failures near the bead portion 3, further improving the durability of the tire 10.

[0075] Where the cross-sectional area Sr of the rubber portion R is less than 12 mm 2 When tire 10 flexes, compressive stress near the rim flange 22 is easily applied to the carcass layer 4, which can lead to malfunctions. Conversely, if the stress exceeds 101mm... 2 If the rim flange 22 is not sufficiently sturdy, it will be difficult to ensure the rim opening distance A. When the tire 10 flexes, the stress near the rim flange 22 will increase, potentially leading to malfunctions. Ideally, a 14mm opening distance should be maintained. 2 ≤Sr≤98mm 2 The range is ideally 16mm. 2 ≤Sr≤93mm 2 The range.

[0076] In the aforementioned tire 10, such as Figure 11 As shown, when the thickness of the rubber portion R on the vertical line drawn from point S to the upper rolled portion 4B of the carcass layer 4 is set to Gl (mm), and the thickness of the rubber portion R on the vertical line drawn from point T to the upper rolled portion 4B of the carcass layer 4 is set to Gu (mm), it is preferable that the thicknesses Gl and Gu satisfy the relationship 0.40≤Gl / Gu≤0.90. This ensures good cushioning and improves durability.

[0077] If the ratio Gl / Gu exceeds the above range, the cushioning effect will decrease, thus reducing the improvement in durability. Ideally, the relationship 0.45 ≤ Gl / Gu ≤ 0.85 should be satisfied, and even more ideally, 0.50 ≤ Gl / Gu ≤ 0.80 should be satisfied. Furthermore, the thickness Gl of the rubber portion R ideally satisfies the range of 0.5 mm ≤ Gl ≤ 4.0 mm, and even more ideally, the range of 1.5 mm ≤ Gl ≤ 3.0 mm should be satisfied. The thicknesses Gl and Gu of the rubber portion R can also be measured in a cut sample of the tire 10.

[0078] In the aforementioned tire 10, such as Figure 11 As shown, under no-load conditions with the tire 10 mounted on a specified rim 21 and filled with a specified internal pressure, the point where the vertical line drawn from point S to the upper rolled portion 4B of the carcass layer 4 intersects with the upper rolled portion 4B of the carcass layer 4 is designated as Sc; the point where the vertical line drawn from point T to the upper rolled portion 4B of the carcass layer 4 intersects with the upper rolled portion 4B of the carcass layer 4 is designated as Tc; and the midpoint between points Sc and Tc is designated as Uc, it is preferable that the center of the arc (radius of curvature Rc) of the carcass layer 4 passing through points Sc, Tc, and Uc is located outside the tire width direction. This prevents compressive stress from being applied to the carcass layer 4 during tire deformation, thus improving durability. It should be noted that, ideally, the center of the arc of the carcass layer 4 passing through points Sc, Tc, and Uc should be located outside the tire width direction, even when the tire 10 is in a single-unit state not mounted on the rim or under 100% load.

[0079] In particular, such as Figure 11 As shown, when Ur is set as the midpoint between points S and Tr, it is preferable that the radius of curvature Rc (mm) of the arc passing through points Sc, Tc, and Uc of the tire carcass layer 4 satisfies the relationship 1 ≤ Rc / Rr ≤ 55 relative to the radius of curvature Rr (mm) of the arc passing through points S, Tr, and Ur. This prevents compressive stress from being applied to the tire carcass layer 4 during tire deformation, thus improving durability.

[0080] If the ratio Rb / Rr exceeds the above range, the compressive stress during tire deformation is more likely to be applied to the carcass layer 4, thus reducing the improvement effect on durability. Ideally, the relationship 2 ≤ Rc / Rr ≤ 50 should be satisfied, and even more ideally, the relationship 3 ≤ Rc / Rr ≤ 45 should be satisfied.

[0081] Figure 12 An example of variation in the bead portion is shown. Figure 12In this configuration, the main body portion 4A and the rolled-up portion 4B of the carcass layer 4 do not contact each other via the sidewall core, thereby forming a closed area that includes the bead core 5. That is, the carcass layer 4 is configured such that the main body portion 4A and the rolled-up portion 4B are in close contact with each other at the upper end of the bead core 5, as the carcass layer 4 is rolled up from the inside to the outside of the tire around the bead core 5. By employing this rolled-up structure of the carcass layer 4, the carcass layer 4 can be moved away from the rim flange 22 at the contact point with the rim flange 22, thus significantly reducing the compressive stress applied to the carcass layer 4 and improving durability. It should be noted that the rubber content of the closed area 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 content referred to here is the percentage of the rubber portion (e.g., bead wire insulation rubber or small sidewall core) in the closed area formed by the carcass layer 4 in the tire radial cross-section.

[0082] In addition, Figure 12 In this structure, durability can be improved by placing an auxiliary sidewall core 9 or a thickened rim buffer rubber layer 13 on the outer side of the upper rolled portion 4B of the carcass layer 4 in the tire width direction. In this case, the cross-sectional area Sr of the rubber portion R can be set to 36 mm². 2 ≤Sr≤101mm 2 Within the range. Ideally, it should meet 42mm. 2 ≤Sr≤98mm 2 The range is ideally 48mm. 2 ≤Sr≤93mm 2 The range.

[0083] In the aforementioned tire 10, such as Figure 10 As shown, when the tire 10 has a rim buffer rubber layer 13 disposed in the area contacting the rim flange 22 and a sidewall rubber layer 12 disposed further radially outward of the tire than the rim buffer rubber layer 13, under no-load conditions where the tire 10 is mounted on a specified rim and filled with a specified internal pressure, it is preferable that the boundary point X of the rim buffer rubber layer 13 and the sidewall rubber layer 12 on the outer surface of the tire 10 is located further radially outward of the tire than point T. That is, the rim buffer rubber layer 13 preferably extends at least to point T from the underside of the bead core 5 towards the radially outward of the tire. As a result, compressive stress is less likely to be applied to the carcass layer 4 during tire deformation, thus improving durability.

[0084] The rim buffer rubber layer 13 should ideally have a hardness of 55 or higher and 80 or lower at 20°C. This improves the durability of the rim buffer rubber layer 13. However, if the hardness of the rim buffer rubber layer 13 exceeds this range, the improvement in durability will be reduced. The hardness is measured using a type A hardness tester according to JIS-K6253 at 20°C.

[0085] The rim buffer rubber layer 13 preferably has a 100% modulus of 2.0 MPa or higher and 9.5 MPa or lower at 20°C. This improves the durability of the rim buffer rubber layer 13. However, if the 100% modulus of the rim buffer rubber layer 13 exceeds this range, the improvement in durability will be reduced. The 100% modulus is the specified elongation tensile stress measured at 20°C according to JIS-K6251.

[0086] The loss tangent (tanδ) of the rim buffer rubber layer 13 at 20°C is preferably 0.05 or higher and 0.35 or lower. This allows for the suppression of increased rolling resistance while ensuring the thickness (durability) of the rim buffer rubber layer 13. If the loss tangent of the rim buffer rubber layer 13 exceeds 0.35, the rolling resistance will increase. The loss tangent (tanδ) is measured according to JIS-K6394 using a viscoelastic spectrometer (manufactured by Toyo Seiki Co., Ltd.) under the conditions of a frequency of 20Hz, initial strain of 10%, dynamic strain ±2%, and temperature of 60°C.

[0087] The intermediate elongation of the carcass cords constituting the carcass layer 4 is preferably 3.3% or more and 6.2% or less under a 1.5 cN / dtex load. This improves durability. However, if the intermediate elongation of the carcass cords constituting the carcass layer 4 exceeds this range under a 1.5 cN / dtex load, the improvement in durability will be reduced. Particularly ideally, the intermediate elongation of the carcass cords under a 1.5 cN / dtex load is 3.8% or more and 5.9% or less. Intermediate elongation refers to the data measured according to JIS-L1017 under a tensile test performed on the carcass cords taken from the sidewall of the tire 10 at a clamping interval of 250 mm and a tensile speed of 300 ± 20 mm / min.

[0088] The carcass cords constituting the carcass layer 4 are preferably organic fiber cords. For example, using high-modulus rayon cords as carcass cords will improve durability. The total thickness of the carcass layer 4 is preferably 0.8 mm or more and 1.5 mm or less. When using rayon cords, the cord diameter is preferably 0.6 mm or more and 1.1 mm or less, and the cord insertion density is preferably 43 cords / 50 mm or more and 59 cords / 50 mm or less. Furthermore, polyester cords, which have excellent fatigue resistance, are also suitable as carcass cords. When using polyester cords, the cord diameter is preferably 0.7 mm or more and 1.2 mm or less, and the cord insertion density is preferably 44 cords / 50 mm or more and 60 cords / 50 mm or less.

[0089] Furthermore, the angle between the carcass cords constituting the carcass layer 4 and the tire circumference can be set within a range of 75° to 90°. In particular, when the angle of the carcass cords is set to less than 88°, the tire rigidity increases, thus improving durability. Additionally, the upper roll portion 4B of the carcass layer 4 preferably extends beyond the maximum width of the tire to a position overlapping with the edge of the belt layer 7. By employing this upper roll structure, the tire rigidity is increased, thereby improving durability.

[0090] Example

[0091] Pneumatic tires of Comparative Examples 1 to 4 and Examples 1 to 8 were manufactured, wherein in tires with a tire size of 285 / 35R20 (SH = 95mm), the following parameters were considered: height SDH, total width TW, rim width DW of the specified rim, protrusion W, A / SH, A / W, and A. 100 / SH、A 100 / W、A 100 / A, Opening distance A, Opening distance A 100 The settings for A / SDH, A' / SH, A' / A, and the opening distance A' are as shown in Table 1.

[0092] For these test tires, strain resistance and friction resistance were evaluated using the following test methods, and the results are summarized in Table 1.

[0093] Strain resistance:

[0094] Each test tire was mounted on a 20×10J rimmed wheel and installed on a testing machine with a drum diameter of 1707mm. The tire pressure was set to 290kPa, the speed to 81km / h, and the initial load to 88% of the maximum load capacity. The load was increased by 13% every 2 hours, and the distance traveled before tire failure was measured. The evaluation results were expressed using an index of 100 for Comparative Example 2. A higher index value indicates better strain resistance.

[0095] Abrasion resistance:

[0096] Each test tire was mounted on a 20×10J rim wheel and installed on a testing machine with a drum diameter of 1707mm. The tire pressure was set to 290kPa, the speed to 81km / h, and the initial load to 88% of the maximum load capacity. The load was increased by 13% every 2 hours, and a 2500km driving test was conducted. The rubber thickness from the tire's outer surface to the carcass layer at the position corresponding to the outermost radial point of the rim flange was measured before and after the test, and the change in rubber thickness was calculated. The evaluation result was expressed as the reciprocal of the change in rubber thickness, with Comparative Example 1 set to an exponent of 100. A higher exponent value indicates better abrasion resistance.

[0097] [Table 1]

[0098]

[0099] As can be seen from Table 1, the tires of Examples 1 to 8 have improved strain resistance and friction resistance compared with Comparative Examples 1 to 4, and have excellent durability.

[0100] Explanation of reference numerals in the attached figures

[0101] 1: Fetal face

[0102] 2: Side wall portion

[0103] 3: Bead area

[0104] 4: Fetal body layer

[0105] 5: Tire bead core

[0106] 6: Tire sidewall core

[0107] 7: Belt layer

[0108] 8: Belt Covering Layer

[0109] 10: Tires

[0110] 11: Tread rubber layer

[0111] 12: Sidewall rubber layer

[0112] 13: Rim buffer rubber layer

[0113] 14: Inner Lining

[0114] 15: Wheel rim protection components

[0115] 21: Specified wheel rim

[0116] 22: Rim flange

Claims

1. A tire, wherein the cross-sectional height SH of the tire is in the range of 50mm to 150mm, characterized in that, Under no-load conditions, with the tire mounted on a specified rim and filled with a specified internal pressure, when the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point 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 relative to the cross-sectional height SH. When the protrusion amount equivalent 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 0.03 ≤ A / W ≤ 1.60 relative to the protrusion amount W. With the tire mounted on a specified rim and filled with a specified internal pressure while bearing a load of 100% of the specified load capacity, the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point of the rim flange to the outer surface of the tire is defined as A. 100 At that time, the opening distance A 100 The height SH of the cross section satisfies 0.003 ≤ A 100 The relationship between / SH≤0.

100.

2. The tire according to claim 1, characterized in that, The opening distance A 100 The protrusion W satisfies 0.010 ≤ A 100 The relationship is / W≤1.

000.

3. The tire according to claim 1 or 2, characterized in that, The opening distance A and the opening distance A 100 Satisfying 0.20≤A 100 The relationship is / A≤0.

80.

4. The tire according to claim 1 or 2, characterized in that, The opening distance A is in the range of 1.5mm ≤ A ≤ 8.0mm.

5. The tire according to claim 1 or 2, characterized in that, The opening distance A is such that the radial height SDH of the tire relative to the tire at the position of maximum tire width satisfies the relationship 0.01≤A / SDH≤0.

50.

6. The tire according to claim 1 or 2, characterized in that, When the tire is mounted on a specified rim and filled with a specified internal pressure under no-load conditions, and the opening distance between the tire and the rim flange on a vertical line drawn from the outermost radial point of the rim flange and the midpoint of the rim flange opening away from the tire's starting point to the outer surface of the tire is defined as A', the opening distance A' satisfies the relationship 0.006≤A' / SH≤0.150 relative to the cross-sectional height SH.

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

96.

8. The tire according to claim 6, characterized in that, The opening distance A' is within the range of 1.0mm ≤ A' ≤ 7.5mm.

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