JP2000085314A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain wondering of a pneumatic radial tire. SOLUTION: An inside reinforcement layer 26 is arranged in an inside of a tire width direction of a circumference-directional groove 24 in the outermost side of the tire width direction, an outer reinforcement layer 28 is arranged in an outside of the tire width direction, a tread 20 is made easily bendable around the groove 24 of the outermost side in the tire width direction (an outside end part A-point of the layer 24 for a carcass reinforcement layer 15) as a fulcrum, and wiping reaction gets easy to be generated in the vicinity of an end part in the width direction of the tread 20 when a pneumatic radial tire 10 climbs a rutted slope obliquely. Camber thrust acting in a direction to climb the slope is generated in the tire 10 by the wiping reaction when climbing the rutted slope obliquely, so as to enhance a wondering performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and relates to a complicated movement of a vehicle which cannot be predicted by a driver when traveling on a road surface having a changing gradient in a lateral direction, for example, a road surface having irregularities such as a rut. The present invention relates to a pneumatic radial tire in which so-called wandering is suppressed.

[0002]

2. Description of the Related Art In recent years, not only for passenger cars, but also for light trucks, trucks, buses, and other vehicles, so-called radial tires having carcass cords arranged in a direction substantially orthogonal to the tire equatorial plane have been developed. It is widely used because it is superior in wear resistance and steering stability as compared with tires.

[0003] In addition, the adoption of radial tires has been increasing with the speeding up of vehicles, and high-speed running of vehicles has become commonplace with the maintenance of road networks.

[0004]

By the way, wandering may occur when a vehicle travels on a road surface having irregularities such as a rut. However, this wandering tends to occur when traveling at high speed. There is a demand for suppression of wandering.

An object of the present invention is to provide a pneumatic radial tire capable of suppressing wandering in view of the above fact.

[0006]

In vehicles such as small trucks, wandering performance is one of the important performances.
In order to improve the wandering performance with the tire, as shown in FIG.
It is effective to increase the camber thrust CT in the direction opposite to the force FD for sliding down the cam.

[0008] When the tire 102 touches the road surface and bends as shown in FIG. 8, the tread in the contact surface receives a force,
It is known that the tread shrinks toward the center of contact as shown by the arrow f in FIG.

[0008] The tread during rolling is subjected to a forward force (arrow F direction) from the road surface in the first half of the contact with the road surface, and a rearward force (arrow B direction) in the second half. Further, the contact portion of the tire also contracts in the lateral direction. Then, the contraction at the center where the maximum bending occurs becomes the largest. Therefore, the tread rubber is also subjected to shear deformation in the lateral direction.

One of the forces that generate camber thrust is a wiping reaction force (a force that attempts to return the deformed tread in the contact patch) to the original. It was found that the wiping reaction force was not sufficiently exerted to improve the wandering performance.

Further, the wiping reaction force that generates camber thrust is affected by the bending rigidity of the tread in the vicinity of the end in the tire width direction, and the circumferential groove on the outermost side in the tire width direction as a fulcrum. It has been found that the wiping reaction force that generates camber thrust is easily generated by making the portion easy to bend.

The invention according to claim 1 has been made in view of the above fact, and has a carcass reinforcement comprising a plurality of layers on the outer periphery of a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores. In a pneumatic radial tire in which a layer and a tread are sequentially arranged, and in the tread, a plurality of circumferential grooves are arranged, the carcass reinforcing layer has a first portion facing a tire width direction outermost circumferential groove, The first portion is divided into a second portion adjacent to the inside in the tire axial direction and a third portion adjacent to the first portion outside in the tire axial direction, and the rigidity of the third portion is A. , The first
When the stiffness of the portion is B and the stiffness of the second portion is C, the B is not more than at least one of A and C.

The operation of the pneumatic radial tire according to the first aspect will be described.

[0013] When a pneumatic radial tire tries to obliquely climb over an inclined surface of a convex portion on a road surface such as a rutted road surface, the tread is bent near the outer side in the tire width direction by the inclined surface of the convex portion.

The rigidity B of the first portion facing the outermost circumferential groove in the tire width direction is determined by the rigidity A of the third portion adjacent to the first portion in the tire axial direction and the tire of the first portion. When the rigidity C of the second portion adjacent to the inner side in the axial direction is set to be equal to or less than at least one value, the tread becomes easy to bend with the circumferential groove on the outermost side in the tire width direction as a fulcrum. A wiping reaction force is likely to be generated at the widthwise end on the slope side, and a camber thrust acting on the slope in the direction of climbing the slope is generated in the tire by the wiping reaction force, thereby improving the wandering performance.

According to a second aspect of the present invention, in the pneumatic radial tire according to the first aspect, B <C and B <A
It is characterized by being.

The operation of the pneumatic radial tire according to claim 2 will be described.

By setting B <C and B <A, the tread is easily bent with the outermost circumferential groove in the tire width direction as a fulcrum, and the wandering performance is improved.

According to a third aspect of the present invention, in the pneumatic radial tire according to the first aspect, B <C and A = B
It is characterized by being.

The operation of the pneumatic radial tire according to claim 3 will be described.

By setting B <C and A = B, the tread is easy to bend with the outermost circumferential groove in the tire width direction as a fulcrum, and wandering performance is improved.

According to a fourth aspect of the present invention, there is provided a pneumatic radial tire according to the first aspect, wherein B <A and A = C.
It is characterized by being.

The operation of the pneumatic radial tire according to claim 4 will be described.

By setting B <A and A = C, the tread is easily bent with the outermost circumferential groove in the tire width direction as a fulcrum, and the wandering performance is improved.

According to a fifth aspect of the invention, there is provided the pneumatic radial tire according to the first aspect, wherein B <A <C.

The operation of the pneumatic radial tire according to claim 5 will be described.

By setting B <A <C, the tread is easily bent around the outermost circumferential groove in the tire width direction as a fulcrum, and the wandering performance is improved.

According to a sixth aspect of the present invention, in the pneumatic radial tire according to the first aspect, B <C <A.

The operation of the pneumatic radial tire according to claim 5 will be described.

By setting B <C <A, the tread becomes easy to bend with the outermost circumferential groove in the tire width direction as a fulcrum, and the wandering performance is improved.

According to a seventh aspect of the present invention, a carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged on the outer periphery of a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and the tread is provided on the tread. In a pneumatic radial tire in which a plurality of circumferential grooves are arranged, the carcass reinforcing layer, an inner portion adjacent to the tire width direction inner side bordering a portion facing the outermost circumferential groove in the tire width direction, When divided into outer parts adjacent to the outside in the tire width direction,
The inner part has a higher rigidity than the outer part.

The operation of the pneumatic radial tire according to claim 7 will be described.

When a pneumatic radial tire tries to obliquely climb over an inclined surface of a convex portion on a road surface such as a rutted road surface, the tread is bent near the outer side in the tire width direction by the inclined surface of the convex portion.

The carcass reinforcing layer is formed so that the rigidity of the outer portion adjacent to the outer side in the tire width direction is smaller than the rigidity of the inner portion adjacent to the inner side in the tire width direction with respect to the portion facing the outermost circumferential groove in the tire width direction. When it is higher, the tread is more likely to bend around the outermost circumferential groove in the tire width direction,
When crossing the slope diagonally, a wiping reaction force is likely to be generated at the widthwise end of the tread on the slope side, and this wiping reaction force generates camber thrust acting on the slope in the direction of climbing the tire, improving wandering performance I do.

According to an eighth aspect of the present invention, a carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged on the outer periphery of a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and the tread is provided on the tread. In a pneumatic radial tire in which a plurality of circumferential grooves are arranged, the carcass reinforcing layer has a belt layer composed of a plurality of plies having different cord directions, and at least one ply of the belt layer is a tire. It is characterized in that it is divided in the tire width direction at a portion facing the outermost circumferential groove in the width direction.

The operation of the pneumatic radial tire according to claim 8 will be described.

When a pneumatic radial tire tries to obliquely climb over an inclined surface of a convex portion on a road surface such as a rutted road surface, the tread is bent near the outer side in the tire width direction by the inclined surface of the convex portion.

When at least one ply of the belt layer is divided in the tire width direction at a portion opposed to the outermost circumferential groove in the tire width direction, the tread moves in the outermost circumferential groove in the tire width direction. It becomes easy to bend as a fulcrum, and when crossing the slope diagonally, a wiping reaction force is easily generated at the widthwise end of the tread on the slope side, and the tire generates a camber thrust acting in the direction of climbing the slope by the wiping reaction force. , Wandering performance is improved.

According to a ninth aspect of the present invention, a carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged on the outer periphery of a crown portion of a carcass layer straddling a pair of bead cores in a toroidal manner. In a pneumatic radial tire in which a plurality of circumferential grooves are arranged, the carcass reinforcing layer has a belt layer composed of a plurality of plies having different cord directions, and the belt layer is an outermost circumferential layer in the tire width direction. Between the outer portion and the inner portion in the tire width direction with respect to the direction groove, the inner portion has a larger number of plies than the outer portion.

The operation of the pneumatic radial tire according to claim 9 will be described.

When a pneumatic radial tire tries to obliquely climb over an inclined surface of a convex portion on a road surface such as a rutted road surface, the tread is bent near the outer side in the tire width direction by the inclined surface of the convex portion.

If the number of plies of the belt layer in the inner portion in the tire width direction is larger than that in the outer portion with respect to the outermost circumferential groove in the tire width direction, the tread is set with the outermost circumferential groove in the tire width direction as a fulcrum. It becomes easy to bend, and when crossing the slope diagonally, a wiping reaction force is easily generated at the widthwise end of the tread on the slope side, and the camber thrust acting on the slope in the direction of climbing the slope is generated on the tire by this wiping reaction, and wander is generated. Ring performance is improved.

According to a tenth aspect of the present invention, a carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged on the outer periphery of a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and the tread is provided on the tread. In a pneumatic radial tire in which a plurality of circumferential grooves are arranged, the carcass reinforcing layer is a belt layer composed of a plurality of plies having different cord directions from each other, and a reinforcing layer disposed outside the belt layer in the tire radial direction. Wherein the reinforcing layer is divided in the tire width direction at a portion facing the outermost circumferential groove in the tire width direction.

The operation of the pneumatic radial tire according to claim 10 will be described.

When a pneumatic radial tire tries to obliquely climb over an inclined surface of a convex portion on a road surface such as a rutted road surface, the tread is bent near the outer side in the tire width direction by the inclined surface of the convex portion.

When the reinforcing layer for reinforcing the belt layer is divided in the tire width direction at a portion facing the outermost circumferential groove in the tire width direction, the tread bends around the outermost circumferential groove in the tire width direction as a fulcrum. This makes it easy to generate a wiping reaction force at the widthwise end of the tread on the slope side when crossing the slope diagonally, and this wiping reaction force causes camber thrust acting on the slope in the direction of climbing the tire, and wandering Performance is improved.

According to an eleventh aspect of the present invention, a carcass reinforcing layer and a tread composed of a plurality of layers are sequentially arranged on the outer periphery of a crown portion of a carcass layer straddling a pair of bead cores in a toroidal manner. Is a pneumatic radial tire in which a plurality of circumferential grooves are arranged, wherein the carcass reinforcing layer is a belt layer composed of a plurality of plies having different cord directions from each other, and a plurality of plies arranged outside the belt layer in the tire radial direction. And a reinforcing layer, wherein the reinforcing layer has a portion adjacent to the outside in the tire width direction and a portion adjacent to the inside with respect to the outermost circumferential groove in the tire width direction. Is characterized in that the number of layers is larger than that of the portion adjacent to the outside.

The operation of the pneumatic radial tire according to the eleventh aspect will be described.

When a pneumatic radial tire tries to obliquely climb over an inclined surface of a convex portion on a road surface such as a rutted road surface, for example, the tread is bent near the outer side in the tire width direction by the inclined surface of the convex portion.

If the number of reinforcing layers in the portion adjacent to the inner side in the tire width direction is larger than that in the portion adjacent to the outer side in the tire width direction, the tread will become It becomes easy to bend around the circumferential groove,
When crossing the slope diagonally, a wiping reaction force is likely to be generated at the widthwise end of the tread on the slope side, and this wiping reaction force generates camber thrust acting on the slope in the direction of climbing the tire, improving wandering performance I do.

According to a twelfth aspect of the present invention, in the pneumatic radial tire according to the tenth or eleventh aspect, the reinforcing layer is a cord layer including a plurality of cords.

The operation of the pneumatic radial tire according to claim 12 will be described.

In the pneumatic radial tire according to the twelfth aspect, since the reinforcing layer is a cord layer including a plurality of cords, a difference in rigidity between a portion where the cords are arranged and a portion where the cords are not arranged is large. And the tread is easily bent with the outermost circumferential groove in the tire width direction as a fulcrum.

The cord is made of an organic fiber, a metal fiber or the like which has higher rigidity than rubber.

According to a thirteenth aspect of the present invention, in the pneumatic radial tire according to the twelfth aspect, the cord layer is a spiral belt spirally wound in the tire circumferential direction.

The operation according to claim 13 will be described.

The spiral belt is formed by winding a narrow ply having a fixed width including a cord on the outer peripheral surface of the carcass while shifting it in the tire width direction. Therefore, the number of parts is reduced.

According to a fourteenth aspect of the present invention, in the pneumatic radial tire according to the tenth or eleventh aspect, the reinforcing layer is a rubber layer made of only a rubber having a higher hardness than a rubber constituting the tread. It is characterized by:

The operation of the pneumatic radial tire according to claim 14 will be described.

In the pneumatic radial tire according to the fourteenth aspect, since the rubber layer is formed only of rubber having a higher hardness than the rubber constituting the tread, the rubber layer is disposed at the portion where the rubber layer is disposed. The rigidity difference between the tread portion and the non-existing portion can be increased, and the tread can be easily bent with the outermost circumferential groove in the tire width direction as a fulcrum.

According to a fifteenth aspect of the present invention, in the pneumatic radial tire according to the fourteenth aspect, the rubber constituting the rubber layer has a hardness higher than that of the coating rubber coating the cord of the belt layer. It is characterized by having. The operation of the pneumatic radial tire according to claim 15 will be described.

In the pneumatic radial tire according to the fifteenth aspect, the rubber constituting the rubber layer has a hardness higher than that of the coating rubber coating the cord of the belt layer. The difference in rigidity between the portion provided and the portion not disposed can be increased, and the tread can be easily bent with the outermost circumferential groove in the tire width direction as a fulcrum.

[0062]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a pneumatic radial tire according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, the pneumatic radial tire 10 according to the present embodiment includes a pair of bead cores 12 and a carcass layer 14 that extends over the pair of bead cores 12 in a toroidal manner.
have.

As shown in FIGS. 1 and 2, the carcass layer 1
The carcass reinforcement layer 15 is disposed on the outside of the tire No. 4 in the tire radial direction.

The carcass reinforcing layer 15 of this embodiment comprises a belt layer 18 disposed radially outside the carcass layer 14, an inner reinforcing layer 26 disposed outside the belt layer 18 in the tire radial direction, and an outer reinforcing layer. It is composed of a layer 28.

A tread rubber 22 constituting the tread 20 is disposed outside the carcass reinforcing layer 15 in the tire radial direction.

The belt layer 18 is composed of a plurality of (two in the present embodiment) belt plies 16. These belt plies 16 are generally formed by rubber coating with a plurality of steel cords arranged in parallel.

A plurality of (four in the present embodiment) circumferential grooves 24 extending along the tire circumferential direction are formed in the tread 20 at substantially equal intervals in the tire width direction.

As shown in FIG. 2, the inner reinforcing layer 26 is disposed inwardly in the tire width direction from the outermost circumferential groove 24 in the tire width direction, and the outer reinforcing layer 28 is disposed in the tire width direction more than the circumferential groove 24. It is located outside.

The inner reinforcing layer 26 and the outer reinforcing layer 28 of the present embodiment are a cord layer in which a plurality of cords made of organic fibers or the like are arranged in parallel and a rubber-coated ply is caused to make one round on the outer peripheral surface of the belt layer 18. is there.

The inner reinforcing layer 26 and the outer reinforcing layer 28 of the present embodiment have the same bending rigidity.

The inner reinforcing layer 26 and the outer reinforcing layer 28
May be a so-called spiral belt in which a plurality of cords made of organic fibers or the like are arranged in parallel and a rubber-coated narrow belt is spirally wound, or a rubber layer made of only rubber without cords may be used. good.

The inner reinforcing layer 26 and the outer reinforcing layer 28
Is a rubber layer made of only rubber, the rubber is preferably higher in hardness than the tread rubber 22, and has a hardness equal to or higher than the coating rubber coating the cord of the belt ply 16. More preferred.

Next, the operation of the pneumatic radial tire 10 of the present embodiment will be described.

The pneumatic radial tire 10 of the present embodiment
In the above, the inner reinforcing layer 26 is arranged inside the outer circumferential groove 24 in the tire width direction in the tire width direction, and the outer reinforcing layer 28 is arranged outside the tire width direction. The first portion 15B opposing the circumferential groove 24, the second portion 15C adjacent to the first portion 15B inside in the tire axial direction, and the third portion adjacent to the first portion 15B outside in the tire axial direction. When divided into the portion 15A, the first portion 15B has lower bending rigidity than the second portion 15C and the third portion 15A.

As a result, the tread 20 easily bends around the outermost circumferential groove 24 in the tire width direction as a fulcrum (the outer end of the inner reinforcing layer 26 as the carcass reinforcing layer 15 (point A in FIG. 2)). When the pneumatic radial tire 10 climbs obliquely on the slope of the rut, a wiping reaction force is likely to be generated near the widthwise end of the tread 20.

Therefore, when climbing the rut slope diagonally,
Due to the wiping reaction force, camber thrust acting in the direction of climbing the slope is generated in the pneumatic radial tire 10,
Wandering performance is improved.

In the above embodiment, neither the inner reinforcing layer 26 nor the outer reinforcing layer 28 is disposed on the first portion 15B of the carcass reinforcing layer 15. If it is easy to bend with the circumferential groove 24 as a fulcrum, for example, as shown in FIG.
Part of the inner reinforcing layer 26 and the outer reinforcing layer 28 may enter the first portion 15B.

In the above embodiment, the tire equatorial plane C
L, one inner reinforcing layer 26 and the other inner reinforcing layer 2
6, the inner reinforcing layer 26 may be a single wide one that covers the central portion of the belt layer 18, as shown in FIG.

In the above embodiment, the inner reinforcing layer 26
And the outer reinforcing layer 28 is one each. However, the number of the inner reinforcing layers 26 may be more than one, and the number of the inner reinforcing layers 26 may be larger than the number of the outer reinforcing layers 28. The number may be larger than the number of the inner reinforcing layers 26.

In the above embodiment, the inner reinforcing layer 26
In addition, the tread 20 can be easily bent with the outer circumferential groove 24 on the outermost side in the tire width direction as a fulcrum by providing the outer reinforcing layer 28 and the inner reinforcing layer 26 alone, as shown in FIG.

The pneumatic radial tire 10 may not have the inner reinforcing layer 26 and the outer reinforcing layer 28 in some cases.

In the case where the inner reinforcing layer 26 and the outer reinforcing layer 28 are not provided, the tread 20 is moved to the outermost circumferential groove 2 in the tire width direction.
For example, as shown in FIG. 6, at least one of the plurality of belt plies 16 may be divided in the tire width direction at a portion facing the circumferential groove 24, as shown in FIG. A method in which the number of plies on the inner side in the tire width direction is larger than the number of plies on the outer side in the tire width direction with respect to the outermost circumferential groove 24 in the tire direction (for example, from the outermost circumferential groove 24 in FIG. (There is no narrow belt ply 16 extending outward in the width direction). (Test Examples) In order to confirm the effects of the present invention, two types of conventional tires and three types of tires of the example to which the present invention was applied were prepared, and the camber thrust was measured by a drum tester. The result is represented by an index with the tire of Conventional Example 1 being 100, and the larger the numerical value, the larger the camber thrust and the better the wandering performance.

The tire size is LT 205/7
0R16 111L, the rim used the JATMA standard rim, and the internal pressure and load used the maximum value of the JATMA standard.

As shown in FIG. 10, the conventional tire 1
This is a tire in which only the outer reinforcing layer 28 is disposed outside the belt layer 18 in the tire radial direction.

As shown in FIG. 11, the conventional tire 2
The tire has a wide (40 mm wide) reinforcing layer 30 extending continuously on both sides of a circumferential groove 24 on the outermost side in the tire width direction.

As shown in FIG. 2, the tires of Examples 1 and 2 have an inner reinforcing layer 26 outside the belt layer 18 in the tire radial direction.
And the outer reinforcing layer 28 (the inner reinforcing layer 26 of the tire of Example 1 is a rubber layer, and the inner reinforcing layer 26 of the tire of Example 2 is a cord layer).

The tire according to the third embodiment is, as shown in FIG.
This is a tire in which only the inner reinforcing layer 26 is arranged outside the belt layer 18 in the tire radial direction.

The rubber layer uses the same rubber (rubber hardness: 75 to 85 degrees) as the belt coating rubber.

The cord layer is made of nylon cord (12
60d / 2) are lined up with 23.5 rubber pieces per inch.

[0091]

[Table 1] As a result of the test, the pneumatic radial tires of Examples 1 to 3 to which the present invention is applied have an increased camber thrust and an improved wandering performance as compared with the conventional tire. it is obvious.

Further, from a comparison between Example 1 and Example 2, it can be seen that the higher the rigidity of the reinforcing layer, the larger the camber thrust.

[0093]

As described above, the pneumatic radial tire of the present invention has the above-mentioned structure, and therefore has an excellent effect that wandering can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view along a tire rotation axis of a pneumatic radial tire according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a tread of the pneumatic radial tire shown in FIG.

FIG. 3 is a cross-sectional view of a tread of a pneumatic radial tire according to another embodiment.

FIG. 4 is a cross-sectional view of a tread of a pneumatic radial tire according to another embodiment.

FIG. 5 is a cross-sectional view of a tread of a pneumatic radial tire according to another embodiment.

FIG. 6 is a cross-sectional view of a tread of a pneumatic radial tire according to another embodiment.

FIG. 7 is an explanatory diagram showing a force acting on a tire climbing diagonally on an inclined road surface.

FIG. 8 is a cross-sectional view of a tire which is bent by touching a road surface.

FIG. 9 is an explanatory view showing a force acting on a tread contact surface.

FIG. 10 is a sectional view of a tread of a pneumatic radial tire of Conventional Example 1.

FIG. 11 is a sectional view of a tread of a pneumatic radial tire of Conventional Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pneumatic radial tire 12 Bead core 14 Carcass layer 15 Carcass reinforcement layer 15B First part 15C Second part 15A Third part 18 Belt layer 20 Tread 24 Circumferential groove 26 Inner reinforcement layer (reinforcement layer) 28 Outer reinforcement layer (Reinforcing layer)

Claims (15)

[Claims] 1. A carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged around a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and a plurality of circumferential grooves are provided in the tread. In the pneumatic radial tire in which the carcass reinforcement layer is disposed, a first portion facing the outermost circumferential groove in the tire width direction, a second portion adjacent to the first portion inward in the tire axial direction, And a third portion adjacent to the first portion outside in the tire axial direction, wherein the rigidity of the third portion is A, the rigidity of the first portion is B, and the rigidity of the second portion. , C is equal to or less than at least one of A and C. A pneumatic radial tire. 2. The pneumatic radial tire according to claim 1, wherein B <C and B <A. 3. The pneumatic radial tire according to claim 1, wherein B <C and A = B. 4. The pneumatic radial tire according to claim 1, wherein B <A and A = C. 5. The pneumatic radial tire according to claim 1, wherein B <A <C. 6. The pneumatic radial tire according to claim 1, wherein B <C <A. 7. A carcass reinforcement layer comprising a plurality of layers and a tread are sequentially arranged around a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and a plurality of circumferential grooves are provided in the tread. In the pneumatic radial tire in which the carcass reinforcing layer is arranged, an inner portion adjacent to the tire width direction inner side and a tire width direction outer side adjacent to the portion facing the outermost circumferential groove in the tire width direction are bordered. The pneumatic radial tire, wherein when divided into an outer portion, the inner portion has higher rigidity than the outer portion. 8. A carcass reinforcement layer comprising a plurality of layers and a tread are sequentially arranged around the crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and a plurality of circumferential grooves are provided in the tread. In the pneumatic radial tire in which the carcass reinforcing layer has a belt layer composed of a plurality of plies having different cord directions, at least one of the plies of the belt layer is arranged in the outermost circumferential direction in the tire width direction. A pneumatic radial tire, which is divided in a tire width direction at a portion facing a groove. 9. A carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged around the crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and a plurality of circumferential grooves are formed in the tread. In the pneumatic radial tire in which the carcass reinforcing layer has a belt layer composed of a plurality of plies having different cord directions from each other, the belt layer has a tire in a tire width direction outermost circumferential groove as a boundary. A pneumatic radial tire, wherein the number of plies is larger at the inner part than at the outer part in the width direction outer part and the inner part. 10. A carcass reinforcing layer comprising a plurality of layers and a tread are sequentially arranged around a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and a plurality of circumferential grooves are provided in the tread. In the pneumatic radial tire in which the carcass reinforcing layer is provided, the carcass reinforcing layer includes a belt layer including a plurality of plies having different cord directions from each other, and a reinforcing layer disposed outside the belt layer in the tire radial direction. A pneumatic radial tire, wherein a layer is divided in a tire width direction at a portion facing an outermost circumferential groove in a tire width direction. 11. A carcass reinforcement layer comprising a plurality of layers and a tread are sequentially arranged around a crown portion of a carcass layer straddling in a toroidal manner between a pair of bead cores, and a plurality of circumferential grooves are provided in the tread. In the pneumatic radial tire in which the carcass reinforcement layer has a belt layer composed of a plurality of plies having different cord directions, and a plurality of reinforcement layers disposed outside the belt layer in the tire radial direction. In the reinforcing layer, the portion adjacent to the outside in the tire width direction and the portion adjacent to the inside in the tire width direction outer circumferential groove at the outermost circumferential groove in the tire width direction, the portion adjacent to the inside is more than the portion adjacent to the outside. A pneumatic radial tire characterized by having a large number of layers. 12. The pneumatic radial tire according to claim 10, wherein the reinforcing layer is a cord layer including a plurality of cords. 13. The pneumatic radial tire according to claim 12, wherein the cord layer is a spiral belt spirally wound in a tire circumferential direction. 14. The pneumatic radial tire according to claim 10, wherein the reinforcing layer is a rubber layer made of only a rubber having a higher hardness than a rubber constituting the tread. 15. The pneumatic radial according to claim 14, wherein the rubber constituting the rubber layer has a hardness equal to or higher than the coating rubber coating the cord of the belt layer. tire.