pneumatic tires

Abstract

To provide a pneumatic tire that improves ride comfort while suppressing deterioration in low rolling resistance performance. [Solution] A pneumatic tire 1 includes a cap rubber 2C with rubber hardness B. In a meridian cross section of the tire in a normal state, a rim protector 10 is formed on the outer surface 4s of the first bead portion 4A, with an apex 11 that protrudes outward from the tire. The rim protector 10 extends radially inward from the apex 11 and includes an inner arc surface 12 with a curvature radius C (mm) that has a center 12c outside the tire. When the axial distance H in the tire is between the apex 11 and a tire radial line RL that defines the rim width of the normal rim R, the following formula (1) is satisfied: 12.8≦H×B / C≦93.5 …(1)

Description

Technical Field

[0001] The present invention relates to a pneumatic tire.

Background Art

[0002] Patent Document 1 below describes a pneumatic tire provided with a protrusion protruding outward in the tire axial direction in the bead portion. The protrusion is provided at a position where at least a part thereof contacts an arc surface at the outer end of a rim flange of the regular rim in a loaded state where the regular rim is rim-mounted, filled with the regular internal pressure, and loaded with the regular load.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, it has been desired to improve the riding comfort performance. The riding comfort performance is favorably evaluated by reducing vibrations when crossing protrusions provided on the road surface, for example, single protrusions. As a method for enhancing such riding comfort performance, for example, reducing the rigidity of the tread portion is known. However, simply reducing the rigidity of the tread portion has a problem that the frictional resistance during running tends to increase and the low rolling performance tends to deteriorate.

[0005] The present invention has been devised in view of the above actual situation, and the main object is to provide a pneumatic tire capable of improving the riding comfort performance while suppressing a decrease in low rolling performance.

Means for Solving the Problems

[0006] The present invention relates to a pneumatic tire comprising a tread portion, a first bead portion in which a bead core is embedded, and a cap rubber that forms the contact surface of the tread portion and has a rubber hardness B (degrees), wherein, in a tire meridian cross-section in an unloaded, normal state when the pneumatic tire is mounted on a normal rim and adjusted to the normal internal pressure, the outer surface of the first bead portion has a rim protector formed thereon having a top portion that protrudes outward from the tire and extending in the circumferential direction of the tire, the rim protector includes an inner circular arc surface with a radius of curvature C (mm) that extends radially inward from the top portion and has its center outward from the tire, and the following equation (1) is satisfied when the axial distance H between the top portion and the tire radial line that defines the rim width of the normal rim is given by the pneumatic tire: 12.8 ≤ H × B / C ≤ 93.5 …(1) [Effects of the Invention]

[0007] By adopting the above configuration, the pneumatic tire of the present invention can improve ride comfort while suppressing a decrease in low rolling performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is a meridional cross-sectional view of a pneumatic tire showing one embodiment of the present invention. [Figure 2] This is an enlarged view of the first sidewall and first bead portion of Figure 1. [Figure 3] (A) is a perspective cross-sectional view of a pneumatic tire according to this embodiment, and (B) is a perspective cross-sectional view of a pneumatic tire according to another embodiment. [Figure 4] This is a meridian cross-sectional view of the tire's first sidewall and first bead portion in another embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The drawings contain exaggerations and representations that differ from the actual structural dimensional ratios in order to aid in understanding the present invention. Furthermore, where there are multiple embodiments, the same or common elements are denoted by the same reference numerals throughout the specification, and redundant descriptions are omitted.

[0010] Figure 1 is a meridional cross-sectional view of a pneumatic tire 1 (hereinafter sometimes simply referred to as "tire 1"), including the tire rotation axis (not shown), which represents one embodiment of the present invention. The tire 1 of this embodiment is suitably used, for example, as a tire for a passenger car. However, the present invention may also be applied, for example, to a tire for heavy loads. Figure 1 shows tire 1 in a normal state.

[0011] The aforementioned "normal state" refers to the unloaded state in the case of pneumatic tires for which various standards are defined, where the tire is mounted on a standard rim R (hereinafter sometimes referred to as "rim R") and adjusted to the standard internal pressure. In the case of tires for which various standards are not defined, the aforementioned normal state means the standard usage state according to the intended use of the tire, where it is not mounted on a vehicle and is unloaded. In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the aforementioned normal state. Furthermore, for components that cannot be measured in the aforementioned normal state (for example, the internal material of tire 1), the values ​​are measured with tire 1 in a state that approximates the aforementioned normal state as closely as possible.

[0012] The "standard rim R" is the rim defined for each tire in the standard system on which the tire is based, including the standard on which the tire is based. For example, it is the "standard rim" in JATMA, the "design rim" in TRA, and the "measuring rim" in ETRTO. The rim R has a rim flange Rf. In this specification, the rim flange Rf is the portion of the rim R located radially outward from the bead baseline BL. The bead baseline BL is a hypothetical straight line extending parallel to the tire axis that defines the rim diameter Rr of the rim R (see JATMA, etc.).

[0013] "Regular internal pressure" refers to the air pressure specified for each tire by each standard within the tire standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0014] The tire 1 includes a tread portion 2 and a first bead portion 4A in which a bead core 5 is embedded. The tire 1 also includes a cap rubber 2C that forms the contact surface 2s of the tread portion 2 and has a rubber hardness B (degrees). Furthermore, the tire 1 includes a first sidewall portion 3A that is connected to the tread portion 2 and the first bead portion 4A.

[0015] Furthermore, in the tire meridian cross-section in the normal state, the outer surface 4s of the first bead portion 4A has a top portion 11 (shown in Figure 2) that protrudes outward from the tire, and a rim protector 10 extending in the circumferential direction of the tire is formed thereon.

[0016] Figure 2 is an enlarged view of the first sidewall portion 3A and the first bead portion 4A of the tire 1 in Figure 1. For convenience, the rim R has been removed from Figure 2. As shown in Figure 2, the rim protector 10 includes an inner arc surface 12. The inner arc surface 12 is an arc that extends radially inward from the top portion 11 of the tire and has its center 12c on the outer side of the tire. The inner arc surface 12 is formed with a radius of curvature C (mm). Such a rim protector 10 comes into contact with the rim flange Rf (shown in Figure 1) of the regular rim R during driving. This suppresses the deformation of the first bead portion 4A starting from the rim flange Rf. Therefore, heat generation (energy loss) due to rubber deformation in the first bead portion 4A during driving is reduced, and consequently, rolling resistance is reduced. Furthermore, the radius of curvature C is determined by the average of the maximum and minimum radii of curvature of each arc when the inner arc surface 12 is formed from multiple arcs. Also, the apex 11 is the outer end of the inner arc surface 12 in the tire axial direction.

[0017] The separation distance H of the rim protector 10 is one of the indices for ensuring the contact area F (not shown) between the rim flange Rf and the rim protector 10, and its value has a great influence on the contact area F. Also, the radius of curvature C of the inner arc surface 12 is one of the indices for ensuring the contact area F, and its value has a great influence on the contact area F. From this, it can be said that the rolling performance can be evaluated using the ratio (H / C) of the separation distance H to the radius of curvature C. Further, the rubber hardness B of the cap rubber 2C is one of the indices for damping the vibration during running, and its value has a great influence on the vibration damping effect. The cap rubber 2C is, for example, the portion that first contacts a protrusion (single protrusion) provided on the road surface, and the vibration caused by this single protrusion is transmitted to the vehicle through the cap rubber 2C, the first sidewall portion 3A, the first bead portion 4A, and the rim R. Therefore, it can be said that the rigidity of the cap rubber 2C has a great influence on the vibration damping effect. From the above, it can be said that (H×B / C) obtained by applying the rubber hardness B to the ratio (H / C) can evaluate the rolling performance and the riding comfort performance. And the inventor has found the upper limit value and the lower limit value of (H×B / C) from various experimental results, and in the present invention, it is set as 12.8≦A×B / C≦93.5. Thereby, the riding comfort performance can be improved while suppressing the deterioration of the rolling performance. The separation distance H is the length in the tire axial direction between the top 11 and the tire radial direction line RL (refer to JATMA) that defines the rim width Rw of the rim R. The tire radial direction line RL is a virtual straight line extending parallel to the tire radial direction.

[0018] In order to further suppress the deterioration of the rolling performance, it is desirable to satisfy the formula (2). 25.0≦H×B / C≦93.5 …(2) Especially, in order to improve the riding comfort performance, it is desirable to satisfy the formula (3). 25.0≦H×B / C≦61.0 …(3) By setting the lower limit value to 25.0, the deterioration of the rolling performance can be further suppressed. By setting the upper limit value to 61.0, the riding comfort performance can be further improved.

[0019] The separation distance H is preferably 4.0 to 12.0 mm. When the separation distance H is 4.0 mm or more, the contact area F between the rim flange Rf and the rim protector 10 is secured in the normal state, and deformation of the first bead portion 4A is suppressed. To increase the contact area F, the separation distance H is more preferably 6.0 mm or more, more preferably 8.0 mm or more, and even more preferably 9.0 mm or more. When the separation distance H is 12.0 mm or less, an excessive increase in the mass of the rim protector 10 is suppressed, and its heat generation is reduced. To keep the mass of the rim protector 10 small, the separation distance H is more preferably 11.5 mm or less, more preferably 11.0 mm or less, and even more preferably 10.5 mm or less. For example, the separation distance H is preferably 6.0 to 11.5 mm, even better 8.0 to 11.0 mm, and even better 9.0 to 10.5 mm.

[0020] The rubber hardness B is preferably between 48 and 74 degrees. Since the rubber hardness B is 74 degrees or less, the damping effect of the cap rubber 2C (shown in Figure 1) on vibrations during driving, especially vibrations that occur when driving over single protrusions, can be highly effective. To improve ride comfort, the rubber hardness B is more preferably 72 degrees or less, more preferably 70 degrees or less, and even more preferably 68 degrees or less. Since the rubber hardness B is 48 degrees or more, excessive deformation of the tread section 2 is suppressed, and basic low rolling performance can be maintained. To maintain high low rolling performance, the rubber hardness B is more preferably 50 degrees or more, more preferably 52 degrees or more, and even more preferably 54 degrees or more. As an example, the rubber hardness B is preferably between 50 and 72 degrees, even more preferably 52 and 70 degrees, and even more preferably 54 and 68 degrees.

[0021] "Rubber hardness" is measured as Shore hardness (Hs) using a durometer type A under conditions of 23°C, in accordance with JIS K 6253-3:2012. The Shore hardness measurement sample is prepared by cutting it from the tread section 2 so that the tire radius direction is the thickness direction. The measurement is performed by pressing the measuring instrument against the sample from the contact surface side of the hardness measurement sample.

[0022] The radius of curvature C is preferably 9.5 to 15.0 (mm). Since the radius of curvature C is 15.0 (mm) or less, in the normal state, the contact area F between the rim flange Rf and the rim protector 10 is ensured, and the deformation of the first bead portion 4A is suppressed. In order to increase the contact area F, the radius of curvature C is more preferably 13.5 (mm) or less, still more preferably 12.0 (mm) or less, and even more preferably 10.5 (mm) or less. In a preferred embodiment, the radius of curvature C is 9.5 (mm).

[0023] As shown in FIG. 1, the tire 1 includes a second sidewall portion 3B and a second bead portion 4B that is continuous with the second sidewall portion 3B on the inner side in the tire radial direction and in which the bead core 5 is embedded. The second sidewall portion 3B and the second bead portion 4B of the present embodiment have the same shape as the first sidewall portion 3A and the first bead portion 4A, respectively, and thus the description thereof is omitted. The second sidewall portion 3B and the second bead portion 4B may have a different shape from the first sidewall portion 3A and the first bead portion 4A, for example.

[0024] The tire 1 of the present embodiment includes a carcass 6 that extends in a toroidal shape. Further, the tire 1 includes, in the tread portion 2, for example, a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6, and a base rubber 2B disposed between the belt layer 7 and the cap rubber 2C. The tire 1 further includes a sidewall rubber 3G that forms the first sidewall portion 3A and a clinch rubber 4G that forms the first bead portion 4A.

[0025] The carcass 6 is composed of, for example, one carcass ply 6A. The carcass ply 6A includes, for example, a main body portion 6a and a pair of folded portions 6b. The main body portion 6a extends, for example, between the first bead portion 4A and the second bead portion 4B. Each folded portion 6b is connected to the main body portion 6a and is folded back from the inside to the outside in the tire axial direction around the bead core 5. In this embodiment, each folded portion 6b extends radially outward from the tire maximum width position M. The carcass 6 may be composed of, for example, multiple carcass plies. The tire maximum width position M is determined by the outer end of the carcass ply 6A in the tire axial direction.

[0026] The carcass ply 6A includes multiple carcass cords and a topping rubber covering them (not shown). The carcass cords may be organic fiber cords such as aramid or rayon. Preferably, the carcass cords are arranged at an angle of 70 to 90° with respect to the circumferential direction of the tire.

[0027] As shown in Figure 1, the belt layer 7 is adjacent to the carcass 6 on the radially outer side of the tread portion 2. The belt layer 7 includes an outer belt ply 7A and an inner belt ply 7B located radially inside the outer belt ply 7A. The belt layer 7 may consist of, for example, three or more belt plies. Each of the outer belt ply 7A and the inner belt ply 7B extends, for example, outward in the tire axial direction beyond the contact edges Te on both sides.

[0028] In this specification, the contact end Te is the contact point on the axial side of the tire that contacts the plane when the tire 1 in its normal state is subjected to 80% of its normal load and the camber angle is 0°. The axial distance between the two contact ends Te is the contact width TW. The axial center of the contact width TW is the tire equator Co. The contact surface 2s includes the tire equator Co and extends to at least both contact ends Te.

[0029] "Regular load" refers to the load specified for each tire within the standard system, including the standard on which the tire is based, in the case of pneumatic tires for which various standards are defined. For example, it is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. For tires for which no various standards are defined, "regular load" refers to the maximum load that can be applied when using the tire, in accordance with the above standards.

[0030] Each of the outer belt ply 7A and the inner belt ply 7B includes multiple belt cords arranged at an angle of 15 to 45° with respect to the circumferential direction of the tire, and a topping rubber covering them (not shown). As the belt cords, for example, steel cords or organic fiber cords such as aramid or rayon are used.

[0031] While not particularly limited, the rubber thickness d1 of the cap rubber 2C is set to be greater than the rubber thickness d2 of the base rubber 2B. This significantly improves ride comfort. If the rubber thickness d1 of the cap rubber 2C is excessively large, the low rolling performance may deteriorate. For this reason, the rubber thickness d1 of the cap rubber 2C is preferably 150% or more of the rubber thickness d2 of the base rubber 2B, more preferably 200% or more, preferably 900% or less, and more preferably 400% or less. In this specification, the rubber thickness d1 of the cap rubber 2C corresponds to the value obtained by dividing the cross-sectional area of ​​the cap rubber 2C between the contact points Te in a tire meridian cross-section by the contact width TW. The rubber thickness d2 of the base rubber 2B is also defined in the same way as the rubber thickness d1 of the cap rubber 2C. Note that the base rubber 2B may not be provided on the outer side of the belt layer 7 in the tire radial direction, and only the cap rubber 2C may be provided (not shown).

[0032] For example, the inner end 3i of the sidewall rubber 3G is located radially outward from the outer end Re of the rim flange Rf. For example, the outer end 4e of the clinch rubber 4G is located radially outward from the outer end Re of the rim flange Rf.

[0033] The rubber hardness G of the clinch rubber 4G is set to be greater than the rubber hardness I of the sidewall rubber 3G. Such a clinch rubber 4G can effectively suppress deformation of the first bead portion 4A during driving. In addition, the sidewall rubber 3G helps to improve ride comfort. Furthermore, the rubber hardness G of the clinch rubber 4G is set to be greater than the rubber hardness B of the cap rubber 2C. Although not particularly limited, the rubber hardness G of the clinch rubber 4G is preferably 60 degrees or higher, more preferably 65 degrees or higher, preferably 75 degrees or lower, and more preferably 70 degrees or lower.

[0034] As shown in Figure 2, the rim protector 10 includes, for example, an outer surface 13 extending outward in the radial direction of the tire from the top portion 11. In this embodiment, the outer surface 13 is formed by an arc having its center 13c on the outside of the tire. The radius of curvature L of the outer surface 13 is preferably greater than or equal to the radius of curvature C of the inner arc surface 12, and more preferably greater than the radius of curvature C of the inner arc surface 12. Such an outer surface 13 can further suppress the deformation of the first bead portion 4A during driving. In order to effectively exert this effect, the difference (LC) between the radius of curvature L of the outer surface 13 and the radius of curvature C of the inner arc surface 12 is preferably, for example, 5 (mm) or more, and more preferably 10 (mm) or more.

[0035] In a tire 1 in a normal state, the radial distance D from the bead baseline BL to the inner end 12i of the inner arc surface 12 in the tire radial direction is preferably 11.5 to 14.5 mm. Since the distance D is 11.5 mm or more and 14.5 mm or less, a large contact area F can be secured. In order to secure a large contact area F, the distance D is more preferably 12.0 mm or more, even more preferably 12.5 mm or more, even more preferably 14.0 mm or less, and even more preferably 13.5 mm or less. In this specification, the inner end 12i of the inner arc surface 12 is identified as the position where the angle α of the tangent t of the outer surface 4s of the first bead portion 4A with respect to the tire radial line is 10 degrees. Angle α is considered positive when the tangent t is inclined inward in the tire axial direction toward the inner side in the tire radial direction.

[0036] The rim protector 10 in this embodiment is formed of clinch rubber 4G. Such a rim protector 10 effectively suppresses deformation of the first bead portion 4A, thereby further suppressing the decrease in low rolling performance. The rim protector 10 is not limited to this embodiment, and may be formed of sidewall rubber 3G, or it may be formed by including both sidewall rubber 3G and clinch rubber 4G.

[0037] In a properly inflated tire 1, it is desirable that 50% or more of the length of the inner arcuate surface 12 of the rim protector 10 is in contact with the rim flange Rf (shown in Figure 1) of the regular rim R. In this embodiment, in a properly inflated tire 1, the entire inner arcuate surface 12 (including the top portion 11) is in contact with the rim flange Rf.

[0038] Figure 3(A) is a cross-sectional perspective view of the right half of tire 1. As shown in Figure 3(A), in this embodiment, the rim protector 10 extends continuously without interruption in the circumferential direction of the tire. Figure 3(B) is a cross-sectional perspective view of the right half of tire 1 in another embodiment. As shown in Figure 3(B), the rim protector 10 may be provided, for example, with interruptions in the circumferential direction of the tire. In this case, the total length La of the rim protector 10 in the circumferential direction of the tire is preferably 50% or more, more preferably 70% or more, and more preferably 90% or more, of the circumference at the position where the top portion 11 is provided.

[0039] Figure 4 is a cross-sectional view of the first sidewall portion 3A and the first bead portion 4A of another embodiment. As shown in Figure 4, in this embodiment, the outer surface 13 is formed to have a center 13c inward of the tire. Even in such a tire 1, in the normal state tire meridian cross-section, the top portion 11 of the rim protector 10 and the inner arc surface 12 satisfy the above formula (1) when the separation distance H, radius of curvature C, and rubber hardness B are defined. Furthermore, it is desirable that the radius of curvature L of the outer surface 13 is the same as the radius of curvature L of the outer surface 13 shown in Figure 2. Note that the outer surface 13 is not limited to this embodiment and may be formed as a straight line, for example.

[0040] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be implemented in various modified forms. [Examples]

[0041] A pneumatic tire with the basic structure shown in Figure 1 was prototyped based on the specifications in Table 1. The low rolling resistance and ride comfort of the test tire were then tested. The test methods and common specifications for each test tire are as follows. Tire size: 215 / 55R17 Rim size: 17×7J Internal pressure: 200kPa

[0042] <Low rolling performance> Low rolling performance was evaluated in accordance with ECE R117-02 (ECE Regulation No. 117 Revision 2). Low rolling performance was evaluated by running the test tire on a simulated road surface in an indoor drum testing machine and measuring the rolling resistance value at that time. The evaluation was expressed as an index with the reciprocal of the rolling resistance value of Comparative Example 1 set to 100. The result was such that a higher number indicates better performance, and 95 or higher was considered a passing grade. Vertical load: 4.6kN Speed: 80km / h

[0043] <Ride comfort performance> Test tires were fitted to all wheels of the following vehicle, and a test driver drove it on a test course with a dry asphalt surface marked with small bumps. The magnitude of the shock when going over the bumps and the amount of vibration during driving were evaluated subjectively by the test driver. The results are shown on a scale where Comparative Example 1 is rated at 100. A higher number indicates better ride comfort. Vehicle: Domestic front-wheel-drive car with a 2000cc engine displacement. The test results are shown in Tables 1 and 2.

[0044] [Table 1]

[0045] [Table 2]

[0046] The test results show that, compared to the tire in Comparative Example 1, the tire in the Example shows a slight decrease in low-rolling performance in some cases, but the ride comfort performance is significantly improved in all cases. Furthermore, compared to the tire in Comparative Example 2, the tire in the Example shows a significant improvement in low-rolling performance. Therefore, overall, the tire in the Example shows a suppression of the decrease in low-rolling performance and a significant improvement in ride comfort performance.

[0047] [Note] The present invention includes the following embodiments.

[0048] [Invention 1] It is a pneumatic tire, The tread section and The first bead section in which the bead core is embedded, The tread portion includes a cap rubber that forms the contact surface and has a rubber hardness of B (degrees), In the meridian cross-section of the tire in an unloaded, normal state, with the aforementioned pneumatic tire mounted on a normal rim and adjusted to the normal internal pressure, The outer surface of the first bead portion has a rim protector formed thereon, which has a top portion that protrudes outward from the tire and extends in the circumferential direction of the tire. The rim protector is, It includes an inner arc surface with a radius of curvature C (mm) that extends radially inward from the top of the tire and has its center on the outer side of the tire, When the distance H in the tire axial direction between the top and the tire radial line defining the rim width of the regular rim is taken as, The following equation (1) is satisfied: Pneumatic tires. 12.8 ≤ H × B / C ≤ 93.5 …(1) [Invention 2] Furthermore, the pneumatic tire according to the present invention 1 satisfies the following formula (2). 25.0 ≤ H × B / C ≤ 93.5 …(2) [Invention 3] Furthermore, the pneumatic tire according to the present invention 2 satisfies the following formula (3). 25.0 ≤ H × B / C ≤ 61.0 …(3) [4th Invention] The pneumatic tire according to any one of inventions 1 to 3, wherein the radius of curvature C is 9.5 to 15.0 (mm). [5th ​​Invention] The pneumatic tire according to any one of inventions 1 to 4, wherein the rubber hardness B is 48 to 74 degrees. [Invention 6] The pneumatic tire according to any one of inventions 1 to 5, wherein the separation distance H is 4.0 to 12.0 (mm). [7th Invention] In the above-mentioned pneumatic tire in a normal state, the tire radial distance D from the bead baseline to the inner end of the inner arc surface in the tire radial direction is 11.5 to 14.5 mm, as described in any one of invention 1 to 6. [8th Invention] The pneumatic tire according to any one of invention 1 to 7, wherein, in the standard state of the pneumatic tire, 50% or more of the length of the inner arc surface of the rim protector is in contact with the rim flange of the standard rim. [Explanation of symbols]

[0049] 1. Pneumatic tire 2C Cap Rubber 4A First Bead Section 4s external surface 10 Rim Protectors 11 Top 12 Inner arc surface 12c center R Regular Rim RL Tire Radius Direction Line

Claims

1. It is a pneumatic tire, The tread section and The first bead section in which the bead core is embedded, The tread portion includes a cap rubber that forms the contact surface and has a rubber hardness of B (degrees), In the meridian cross-section of the tire in an unloaded, normal state, with the aforementioned pneumatic tire mounted on a normal rim and adjusted to the normal internal pressure, The outer surface of the first bead portion has a rim protector formed thereon, which has a top portion that protrudes outward from the tire and extends in the circumferential direction of the tire. The rim protector is, It includes an inner arc surface with a radius of curvature C (mm) that extends radially inward from the top of the tire and has its center on the outer side of the tire, When the distance H in the tire axial direction between the top and the tire radial line defining the rim width of the regular rim is taken as, The following equation (1) is satisfied, In the aforementioned pneumatic tire in a normal state, the radial distance D from the bead baseline to the inner edge of the inner arc surface in the tire radial direction is 11.5 to 14.5 mm. Pneumatic tires. 12.8 ≤ H × B / C ≤ 93.5 …(1)

2. It is a pneumatic tire, The tread section and The first bead section in which the bead core is embedded, The tread portion includes a cap rubber that forms the contact surface and has a rubber hardness of B (degrees), In the meridian cross-section of the tire in an unloaded, normal state, with the aforementioned pneumatic tire mounted on a normal rim and adjusted to the normal internal pressure, The outer surface of the first bead portion has a rim protector formed thereon, which has a top portion that protrudes outward from the tire and extends in the circumferential direction of the tire. The rim protector is, It includes an inner arc surface with a radius of curvature C (mm) that extends radially inward from the top of the tire and has its center on the outer side of the tire, When the distance H in the tire axial direction between the top and the tire radial line defining the rim width of the regular rim is taken as, The following equation (1) is satisfied, In the aforementioned standard pneumatic tire, the length of 50% or more of the inner arc surface of the rim protector is in contact with the rim flange of the standard rim. Pneumatic tires. 12.8 ≤ H × B / C ≤ 93.5 …(1)

3. It is a pneumatic tire, The tread section and The first bead section in which the bead core is embedded, The tread portion includes a cap rubber that forms the contact surface and has a rubber hardness of B (degrees), In the meridian cross-section of the tire in an unloaded, normal state, with the aforementioned pneumatic tire mounted on a normal rim and adjusted to the normal internal pressure, The outer surface of the first bead portion has a rim protector formed thereon, which has a top portion that protrudes outward from the tire and extends in the circumferential direction of the tire. The rim protector is, It includes an inner arc surface with a radius of curvature C (mm) that extends radially inward from the top of the tire and has its center on the outer side of the tire, When the distance H in the tire axial direction between the top and the tire radial line defining the rim width of the regular rim is taken as, The following equation (1) is satisfied, The aforementioned separation distance H is 4.0 to 11.5 (mm). The radius of curvature C is 9.5 to 13.5 mm. Pneumatic tires. 12.8 ≤ H × B / C ≤ 93.5 …(1)

4. A pneumatic tire, The tread section and The first bead section in which the bead core is embedded, The tread portion includes a cap rubber that forms the contact surface and has a rubber hardness of B (degrees), In the meridian cross-section of the tire in an unloaded, normal state, with the aforementioned pneumatic tire mounted on a normal rim and adjusted to the normal internal pressure, The outer surface of the first bead portion has a rim protector formed thereon, which has a top portion that protrudes outward from the tire and extends in the circumferential direction of the tire. The rim protector is, It includes an inner arc surface with a radius of curvature C (mm) that extends radially inward from the top of the tire and has its center on the outer side of the tire, When the distance H in the tire axial direction between the top and the tire radial line defining the rim width of the regular rim is taken as, The following equation (1) is satisfied, The rim protector includes an outer surface extending outward from the top in the radial direction of the tire, The outer surface is formed by an arc with a radius of curvature L having its center on the outside of the tire. The difference between the radius of curvature L and the radius of curvature C (L-C) is 10 mm or more. Pneumatic tires. 12.8 ≤ H × B / C ≤ 93.5 …(1)

5. A pneumatic tire according to any one of claims 1 to 4, further satisfying the following formula (2). 25.0 ≤ H × B / C ≤ 93.5 …(2)

6. The pneumatic tire according to claim 5, further satisfying the following formula (3). 25.0 ≤ H × B / C ≤ 61.0 …(3)

7. The pneumatic tire according to any one of claims 1, 2, or 4, wherein the radius of curvature C is 9.5 to 15.0 (mm).

8. The pneumatic tire according to any one of claims 1 to 4, wherein the rubber hardness B is 48 to 74 degrees.

9. The pneumatic tire according to any one of claims 1, 2, or 4, wherein the separation distance H is 4.0 to 12.0 (mm).

10. The pneumatic tire according to any one of claims 2 to 4, wherein in the normal state of the pneumatic tire, the radial distance D from the bead baseline to the inner end of the inner arc surface in the tire radial direction is 11.5 to 14.5 (mm).

11. The pneumatic tire according to any one of claims 1, 3, or 4, wherein in the normal state of the pneumatic tire, 50% or more of the length of the inner arc surface of the rim protector is in contact with the rim flange of the normal rim.