JPH02185802A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve abrasion resistance, grip ability and the like by making reinforcement differ in structures of carcasses and a reinforcing layers on side parts of a tire for motor sports, while dividing a tread in two parts in lateral direction of the tire and providing different character of rubber substance to respective ones. CONSTITUTION:First and second reinforcing layers 21, 22 composed of steel cords both coated with rubber are provided on one side of a tire, and respective reinforcing layers 21, 22 are made to extend over the maximum width position S of the tire. Also, on the other side of the tire, a third reinforcing layer 23 composed of Kepler cord coated with rubber is similarly provided. The tread 16 is divided in two parts by making the division position 16a in lateral direction as boundary, rubber hardness of one side, the first tread 16A, is made lower than rubber hardness of the other side, the second tread 16B, in less than 6 deg., and still the value divided tangamma of rubber of the first tread 16A with tangamma of rubber of the second tread 16B is made to be in a range of 0.78-0.99.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a pneumatic radial tire, which is mounted on a vehicle that runs at high speed and safely on road surfaces including straight roads and curved roads, and which has wear resistance and heat resistance. This invention relates to a pneumatic radial tire for motorsports that has improved performance and grip.

(Prior Art) Generally, pneumatic radial tires, especially pneumatic radial tires for motorsports, are installed on vehicles that run at high speed on paved roads including straight roads and curved roads, and are used to prevent sudden braking and sudden acceleration on straight roads. For this reason, pneumatic radial tires with a radial structure that have high cornering power and cornering force are mainly used, and the tread is made of a single rubber layer to reduce the mileage. If the rubber is long, it has good abrasion resistance, and if the rubber is hard at room temperature or high temperature.
Use rubber that has low hardness at room temperature and high temperature.

As a conventional pneumatic radial tire for racing, there is, for example, one whose partial cross section is shown in FIG. In FIG. 6, a conventional pneumatic radial tire 1 includes two carcass 3 having a radial structure extending between a pair of bead cores 2 and folded back around the bead cores 2, and a side portion extending along the carcass 3. A reinforcing layer 4 of one steel cord to be reinforced, a belt 5 extending circumferentially outside the crown part 3a of the carcass 3, a tread 6 covering the outside of the belt 5, and a tread 6 covering the end of the belt 5. belt 5
and two layer layers 7 interposed between the tread 6 and the tread 6;
It has a sidewall 8 that covers the outside of the side part of the carcass 3, and has a symmetrical structure with respect to the equatorial plane E of the tire.

When this pneumatic radial tire for racing is mounted on a vehicle, in order to fully exhibit the tire characteristics of the radial structure, as shown in FIGS. 7 and 8 (a) and (b),
Compared to a tire with a bias structure, a larger camber angle in the negative direction (so-called reverse camber) -3″~
-6" (the figure shows a larger camber angle than the actual one for easy understanding. In addition, the inside and outside in the diagram indicate the inside and outside when the tire is installed on the vehicle, and the inside and outside of the tire The reason for this is that the belt 5 of a pneumatic radial tire has a high rigidity, so when it is mounted on a vehicle with a camber angle α of zero degrees, when driving straight, the belt 5 has a high rigidity. , the tread 6 is in contact with the road surface 9 over its entire width, but when cornering on a curved road at high speed, a large centrifugal force is applied to the center of gravity of the vehicle, causing the tread 6 to roll.
As schematically shown in Figure (b), the inside of the tire is on the road surface 9.
This is because the wheel lifts off the ground, making it impossible to obtain sufficient cornering performance. Therefore, by installing the tires on the vehicle in advance so that they have a large camber angle in the negative direction, the tread 6 can make wide contact with the road surface 9 during cornering, as shown in FIG. 8(b), and good cornering performance can be obtained. It is made so that it can be done.

(Problem to be Solved by the Invention) However, when tires are mounted on a vehicle with such a large camber angle in the negative direction, although the cornering performance of the tires is good, when driving straight, As shown in Figure (a), the ground contact pressure at the inner tread edge 6a of the tire increases, promoting wear near the tread edge, causing premature wear and increasing the temperature at the tread edge. There is a problem with it being too much.

Furthermore, the pneumatic radial tire 1 has a radial structure, and as shown in FIG. There is also a problem that it may cause peeling failure or bursting failure of the end portion 5a of 5.

To solve these problems, the rubber material of the tread is made of wear-resistant material.
Materials with good heat resistance are used. However, since racing tires run fast, they also require high grip on the road surface. The problem is that it is difficult to create a single layer of rubber that satisfactorily has both of these properties.

Therefore, in order to effectively utilize the characteristics of pneumatic radial tires for motorsports, the present invention aims to improve the wear resistance, heat resistance, and high grip of the tire tread even when the tire is mounted on a car at a large camber angle. An object of the present invention is to provide a pneumatic radial tire that can sufficiently maintain the following properties over a long period of time and exhibit cornering characteristics sufficiently.

(Means for Solving the Problems) The present inventors mounted a pneumatic radial tire for motorsports without a tread pattern on a vehicle with a large camber angle in the negative direction, and drove the vehicle at high speed on straight roads and curved roads. The relationship between the rigidity of the side part of the tire and the traction performance, braking performance, handling performance, etc., and the relationship between the rigidity of the side part of the tire and the tire structure, tread thickness, ground pressure, and inside of the tire. , the relationship between the outer tread rubber quality and physical properties, especially the compatibility of the tread's high grip, wear resistance, and heat resistance, hardness, and internal loss (tan).
Various tests and studies were conducted regarding the relationship with δ).

As a result, they focused on the fact that increasing the rigidity of the tire's side parts is necessary when cornering when driving on curved roads, and found that increasing the rigidity of the outer side part of the tire is effective during cornering. Ta.

Furthermore, it has been found that the rigidity of the inner side part of the tire is not increased in order to take advantage of the characteristics of a radial tire, so that traction performance and braking performance when traveling straight are not impaired.

In addition, the tread has a suitable thickness, and in addition to reinforcing the side parts of the tire, the tread is further divided in the lateral direction of the tire into an inner side and an outer side, each with a rubber material with different characteristics. It has been found that the overall performance of the tire can be further significantly improved by providing this.

The present inventors further conducted intensive studies and reached the present conclusion.

A pneumatic radial tire according to the present invention includes a carcass having a folded part extending between a pair of bead cores and folded back around the bead core, and a non-stretchable belt extending circumferentially outside the crown part of the carcass. a pneumatic radial tire comprising: a substantially cylindrical tread that covers the outside of the belt; and a sidewall that covers the outside of the side portion of the carcass; and providing at least one reinforcing layer for reinforcing the side portion of the tire,
One side part of the tire is reinforced more strongly than the other side part by combining the folded part of the carcass and the reinforcing layer, and the tread consists of two treads divided laterally, and The hardness of the rubber of the first tread is within 6' lower than the hardness of the rubber of the second tread on the other side, and the hardness of the rubber of the first trend is
The value obtained by dividing the tan δ of the second tread rubber by δ is 0.7
It is characterized by a range of 8 to 0.99.

Here, one side part of the tire is reinforced more strongly than the other side by combining the folded part of the tire and the reinforcing layer. This means that the reinforcing is done only by the folded part of the carcass or only by the reinforcing layer. It may be reinforced by either or both. This reinforcement means that the side portion on one side of the tire is reinforced more strongly than the side portion on the other side of the tire.

Further, the side portions of these tires may be reinforced by the respective structures, materials, materials, or combinations thereof of the folded portions and reinforcing layers. As a specific method, the following may be used.

(1) In order to differentiate the reinforcement depending on the structure of the carcass and reinforcing layer in the side portion of the tire, (1) the number of reinforcing layers may be greater on one side than on the other side.

■The height of the folded portion of the carcass from the bead core to the tread side may be higher on one side than on the other side.

(2) In order to differentiate the reinforcement depending on the material used for the reinforcing layer and the material used, (1) Use a material with higher rigidity on one side than on the other side. For example, an organic fiber cord on the other side,
Use steel cord on one side. Also, ■ Use a material that is more rigid on one side than on the other. For example, for cords made of the same material, a material with a larger number of cords or a material with a thicker cord diameter is used on one side than on the other side.

Further, the reason why the tread is divided into two parts in the horizontal direction is to use tread rubber having different characteristics for each part. In other words, the rubber of the first tread (hereinafter simply referred to as the first tread)
This is because the rubber of the second tread (hereinafter simply referred to as "second tread rubber") is made of rubber that emphasizes high grip properties, and the rubber of the second tread (hereinafter simply referred to as "second tread rubber") is made of rubber that emphasizes wear resistance and heat resistance. The most important and effective thing here is to connect the first tread rubber to the more strongly reinforced side parts. Considering the balance of the tire as a whole, the division ratio of the width of the tread in the lateral direction is, assuming that the widths of the first and second tread rubbers are TWl and TWt, respectively, the division ratio TW, /'Tw is 0. 5
-1 is preferred.

Further, the thickness of the central portion of the tread is preferably 7M or less. 7
This is because if it exceeds III11, heat generation increases and high-speed durability deteriorates.

Also, the reason why the hardness of the first tread rubber is lower than the hardness of the second tread rubber within 6 degrees is because if the hardness difference exceeds 6 degrees, the hardness difference will be too large and the performance during straight running and cornering will be affected. This is because the performance of one of them will deteriorate. The hardness here refers to a value measured based on the 6301 spring type according to the JIS standard.

Furthermore, the value tanδ2/lanδ, which is obtained by dividing tanδ2 of the second tread rubber by tanδ of the first tread rubber, is 0.
．． The reason for setting it to 78 to 0.99 is that even if it is less than 0.78, it is 0.
This is because even if it exceeds 99, the effects of the present invention cannot be fully exhibited. The tan δ (internal loss) of this tread rubber was measured under test conditions of a temperature of 70° C1, a dynamic strain of 13%, and a frequency of 30 Hz using a method of measuring tensile dynamic strain using a viscoelasticity measuring device.

When the pneumatic radial tire according to the present invention is mounted on a vehicle at a large camber angle in the negative direction, one side of the tire is positioned on the outside of the vehicle and the other side of the tire is positioned on the inside. That is, on the outside of the vehicle, there is a tire with strongly reinforced side parts, high rigidity, low hardness of the tread rubber, and high internal loss. When installing the tire on a vehicle with a large camber angle in the opposite positive direction, the other side of the tire should be located on the outside of the vehicle, and the one side of the tire should be located on the inside of the vehicle. That is, it is installed in accordance with the camber of the vehicle.

(Function) In the pneumatic radial tire of the present invention, one side portion of the tire is stronger (reinforced) than the other side portion, and the side portion of the tire has higher side rigidity.

In addition to the above-mentioned reinforcement, the tread is divided into two parts in the horizontal direction, each with specific characteristics. Tread rubber has low internal loss and generates little heat. Therefore, when such a pneumatic radial tire is mounted with one side on the outside of the vehicle and the other side on the inside of the vehicle with a large camber angle in the negative direction and runs at high speed, as shown in Figure 7.8, When driving on a straight road, the rigidity of the side part of the tire on the inside of the vehicle is low, and the tire deflects significantly. For this reason, the ground contact area becomes large and the surface pressure is significantly reduced. Furthermore, the tread generates less heat and its durability is significantly increased.

Also, when driving on a curved road, the load shift (roll) of the vehicle
However, since the rigidity of the one (outside) side portion of the tire is sufficiently large, the tire deflects little, and the tire has a sufficient ground contact width in the width direction. In addition, the tread rubber on one side (outside) of the tire is soft and has good grip on the road surface, so the tire generates sufficient cornering power and force, and fully demonstrates the traction performance and braking performance of a radial structure. can.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partial sectional view showing a first embodiment of a pneumatic radial tire according to the present invention. In this embodiment, a tire is mounted on a vehicle so that it has a large camber angle in the negative direction, and one side of the tire is located on the outside of the vehicle, and the other side of the tire is located on the inside of the vehicle.

First, the configuration will be explained. In Figure 1, 11 is a pneumatic radial tire, and the tire size is 240.
/655 R17. Pneumatic radial tire 11
extends substantially in the radial direction between the bead cores 12A at the center of the pair of beads 12, and extends in the circumferential direction outside the carcass 13 having a folded part folded back around the bead core 12A and the crown part 13a of the carcass 13. The carcass 13 has a non-stretchable belt 15, a substantially cylindrical tread 16 that covers the outside of the belt 15 in the radial direction, and a sidewall 17 that covers the outside of the side portion 13b of the carcass 13. The tread 16 is divided into two parts, a first tread 16A and a second tread, which are divided in the lateral direction of the tire at the center and extend in the circumferential direction.
It has a tread 16B. The carcass 13 is made of nylon cord of cord type 1260 d/2, and the inner first carcass ply 13A (number of strokes 62.8/5
cm ) and a second carcass ply 13B on the outside thereof. When the pneumatic radial tire 11 is mounted on the vehicle, on one side of the tire that is on the outside of the vehicle (the right side in the figure, the same applies hereinafter), the folded part 13AaO of the first carcass ply 13A is folded back around the bead core 12A from the inside to the outside. It reaches the inside of the belt end portion 15a and ends. The second carcass ply 13B is disposed outside the folded portion 13Aao of the first carcass ply 13A, and the folded portion 13Bao is folded back from the outside of the bead core 12A to the inside and ends near the bead 12.

For this reason, the folded portion 13A of the first carcass ply 13A
ao is fixed in the vicinity of the bead 12 by a bead core 12A, and the terminal end 13c of the folded part 13Aao is connected to the first and second carcass plies 13A, 13B and the end 1 of the belt 15.
5a, and provides a so-called anchor effect to strongly reinforce the side portion 13b.

When the pneumatic radial tire 11 is mounted on the vehicle, on the other side of the tire (the left side in the figure, the same applies hereinafter), the folded part 13Aai of the first carcass ply 13A is folded back around the bead core 12A from the inside to the outside. , ends on the bead 12 side from the maximum width position S of the tire. The second carcass ply 13B is the first carcass ply 1
3A, this folded portion 13Bai is folded back from the outside of the bead core 12A to the inside, and ends near the bead 12. That is, the end position of the folded portion 13Aao of the first carcass ply 13A on one side is the same as the folded portion 13 on the other side.
It is folded back from the bead 12 to a higher position (at the top of the figure) compared to the final position of Aai (hereinafter referred to as high).

Further, on one side of the tire, 21 is a first reinforcing layer;
2 is a second reinforcing layer, both of which are made of rubber-coated steel cord (cord type 1x5); the first reinforcing layer 21 is the folded portion 1 of the first carcass ply 13A;
3Aao, extending radially outward from the vicinity of the bead core 12A and beyond the maximum width position S of the tire. The second reinforcement N22 is the second carcass ply 13
B and the folded portion 13Aao of the first carcass ply 13A, from the vicinity of the mid-bead core 12 to the outside in the radial direction. Moreover, it extends beyond the maximum width position S of the tire. The positions of these radially outer ends are such that the second reinforcement layer 22 is located at the first reinforcement N.
21 so that it is closer to the tread 16. Further, on the other side of the tire, 23 is a third reinforcing layer,
The third reinforcement JiW23 is a rubber-coated Kevlar cord (
The code type is 1500d/2), and extends from the inside of the folded part 13Aai of the first carcass ply 13A to the inside of the second carcass ply 13B, from the vicinity of the bead core 12A to the outside in the radial direction, and at the maximum width position S of the tire. extends beyond. The steel cord layer of the 1.2 reinforcing layer had 38 wires and a length of 75 cm, and was inserted at an angle of about 20'' with respect to the tire circumferential direction.

Hereinafter, when representing the 1.2.3 reinforcing layer 21.22.23, it will be referred to as the reinforcing layer 20.

The combined reinforcement of the folded part of the carcass 13 and the reinforcing layer 20 is such that the side part on one side of the tire has two high folded parts 13Aao and 2 in addition to the main body part of the carcass 13.
The tire is reinforced with the first and second reinforcing layers 21 and 22 consisting of two steel cord layers, while the other side of the tire is reinforced with two steel cord layers, in addition to the main body of the two carcass 13. It is reinforced with only one reinforcing layer. For this reason, the reinforcement of the side portions of the tire has an asymmetric structure in which one side portion is reinforced more strongly than the other side portion, and the one side portion has greater rigidity.

The belt 15 has two belts disposed between a pair of shoulders.
belt plies 15A and 15B, and belt ends 15a of belt plies 15A and 15B.
It has a pair of two layer layers 15C covering the outside. The belt plies 15A and 15B are made of rubber-coated steel cords of 1×5 cord type and are arranged so as to be inclined in opposite directions at an angle of 22° (38 strokes 15C11) with respect to the circumferential direction of the tire. Layer layer 15C
is made of a steel cord of cord type 1260 d/2, and suppresses movement of the belt end 15a. Here, the entire width of the belt 15 outside the bell stitch 5 may be covered with one camp ply made of nylon cord, and the outside of the belt end 15a may be further covered with a layer layer 15C.

The tread 16 is located at a horizontal division position 16a of the tread 16.
The first tread 16A is arranged on one side of the tire, and the second tread 16B is arranged on the other side of the tire, and the widths of the respective treads TW and TW are the division ratio T W
I/T W z is 0.85. Also, tread 1
The thickness DI6 of 6 is 5 mm. 1.2 tread 1
The hardness HA and H7 of the 1.2 tread rubbers of 6A and 16B are 44646°, respectively, and the hardness difference H is 2''.In addition, the internal losses tan δ and tan δ of the 1.2 tread rubbers are respectively 44646° and the hardness difference H is 2″. are 0.53 and 0.47, respectively, and the loss rate ratio tan δ11 / tan δ, which is the value obtained by dividing the tan δ of the second trend rubber by the tan δ of the first tread rubber,
is 0.89. That is, the second tread rubber on the other side (in) has high hardness, excellent wear resistance, and generates little heat. The first tread rubber on one side has low hardness and excellent grip on the road surface.

In the pneumatic radial tire of the present invention, one side of the tire is strongly reinforced, and the first trend rubber with low hardness and good grip is used on the - side trend, so when cornering, the load is Even if movement occurs, the deflection of the side part flb is small, and the lateral ground contact width of the Trend 16 is wide, demonstrating high grip.

In addition, the reinforcement of the side part on the other side is small, and the second trend rubber with high hardness, wear resistance, and low heat generation is used for the trend on the other side, so when traveling straight, the side part lie is largely deflected, and the tread contacts the ground. The area becomes larger, and the ground contact pressure of the other tread end 16c decreases as shown in FIG. 10(b), resulting in good wear resistance and significantly improved durability.

Figures 2(b) and 2(a) show the case where a pneumatic radial tire is filled with the normal internal pressure, the camber angle is -66, and the normal load is applied (corresponding to Fig. 8(a)). FIG. 2 is a diagram showing surface pressure distributions of the ground contact surfaces of a pneumatic radial tire with an asymmetric side structure and a conventional pneumatic radial tire with a side symmetric structure, corresponding to the present invention. The pneumatic radial tire of the present invention has a portion F on the inside of the tire where the contact pressure is higher than that of conventional tires.

has become smaller in both the tire width direction and the circumferential direction, and the area F2 with low surface pressure has expanded, and the surface pressure on the inside of the tire has decreased significantly.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a diagram showing a second embodiment of the pneumatic radial tire according to the present invention, and the same components as in the first embodiment are given the same reference numerals.

In the pneumatic radial tire 31 of the second embodiment,
The height of the folded part of the carcass 13 is set to be the same or higher (higher in this embodiment) than the side part llb on one side (the right side in the figure) of the tire and the side part 11c on the other side (the left side in the figure). , the material of the reinforcing layer 20 is strengthened, the number of layers is increased, and the height is increased for strong reinforcement, and the same two specific types of tread rubber as in the first embodiment are used for the tread.

That is, the height of the folded part 13A ao of the first carcass ply 13A on one side is the same as that of the folded part 13Aai on the other side.
higher than the height of Also, while the reinforcing layer 20 on the other side (in) is made of one steel cord, the reinforcing layer 20 on the one side
0 is made of two pieces of steel cord and is reinforced by increasing the height. Further, in accordance with the trend, as in the first embodiment, the first tread rubber is soft and has high grip properties on one side, and the second tread rubber is hard, has good friction resistance, and generates little heat on the other side.

Next, a third embodiment of the present invention will be described.

FIG. 4 is a diagram showing a third embodiment of the present invention, and the same components as in the first embodiment are given the same reference numerals.

In the pneumatic radial tire 41 of the third embodiment,
The folded portion of the first carcass ply 13A is raised in height so that the side portion 11b on one side (the right side in the figure) of the tire is higher than the side portion 11c on the other side (the left side in the figure) to provide an anchor effect. The material and height of the reinforcement 120 are increased to provide strong reinforcement, and the tread uses the same two types of specific tread rubber as in the first embodiment.

Next, a fourth embodiment of the present invention will be described.

FIG. 5 is a diagram showing a fourth embodiment of the present invention, and the same components as in the first embodiment are given the same reference numerals.

In the pneumatic radial tire 51 of the fourth embodiment,
The height of the folded portion of the first carcass ply 13A is the same between the side portion 11b on one side (right side in the figure) of the tire and the side portion 11c on the other side (left side in the figure) so that both have an anchor effect, The reinforcing layer 20 is strongly reinforced by inserting only the first reinforcing layer N21, which is a single sheet of steel cord, and the tread uses the same two types of specific tread rubber as in the first embodiment.

Next, test tires were prepared in two different tire sizes, and when the test tires were run at high speed on a lap course, a feeling test was conducted to measure controllability, brake traction, and side rigidity, which are the difficulties in controlling the vehicle. Comparative tests were conducted to determine the best lap times, occurrence of failures, etc.

The first test tire was tire size 240/655 R1
7, the tire of the present invention is the same as the first embodiment shown in FIG. 1 described above, and the conventional tire is the same as that shown in FIG. In the test, the test tires were attached to the front and rear wheels of a Gr-A specification vehicle (FR vehicle) at camber angles of -6'' and -6'', respectively.
I installed it at 4 and 5@, drove around a lap course at high speed, and compared it. The circuit was inspected every 10 laps to determine whether there were any malfunctions. The test results are shown in the following table as an index with the conventional tire set as 100. The larger the value, the better.

(This page, blank space below) Table 1 The test results show that, as shown in the previous table, the tires of the present invention had no failures, significantly improved controllability and brake traction, and also significantly improved best ramp time. did.

The second test tire had a tire size of 1801 for the front wheel.
580 R15, which is the tire of the present invention. This is because in the first embodiment shown in FIG.
The entire width of the belt is covered with one cap ply made of nylon cord, and the outside of the belt end 15a is further covered with one layer [15C].

Also, the tire size for the rear wheel is 1551580 R15.
This is a conventional tire shown in FIG. The comparative example is a conventional tire having a belt structure compatible with the tire of the present invention for both the front wheel and the rear wheel. The test is a GrA specification car (FF car)
The test was carried out in the same manner as the first test tire described above. The test results are shown in Table 2.

The numerical value shows that the larger modulus is better.

Table 2 As shown in the above table, the test results showed that the tires of the present invention had no failures, had significantly improved controllability and brake trough silane properties, and also had significantly improved best lap times.

(Effects) As explained above, according to the present invention, in order to effectively exhibit the characteristics of a pneumatic radial tire for motorsports, even if the tire is mounted on a car at a large camber angle in the negative direction, the tire The wear resistance, heat resistance, and high grip of the tread can be sufficiently maintained over a long period of time, and the cornering characteristics can be fully demonstrated.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a pneumatic radial tire according to the present invention. Figure 2 (a) and (b) show camber angle -6°
FIG. 2(a) is a diagram showing the surface pressure distribution of the contact surface at the time of the test, FIG. 2(a) is a diagram showing the surface pressure distribution corresponding to the conventional tire, and FIG. 2(b) is a diagram showing the surface pressure distribution of the tire of the present invention. 3 to 5 are partial cross-sectional views showing second to fourth embodiments of the pneumatic radial tire according to the present invention, respectively. FIG. 6 is a partial sectional view of a conventional tire. FIG. 7 is a schematic view of the vehicle as seen from the front when the tire is mounted on the vehicle at a large camber angle in the negative direction. Figures 8(a) and (b) are schematic diagrams showing the ground contact shape during straight driving and cornering when tires are mounted on a vehicle with a large negative camber angle, respectively, and Figures 9(a) and (b) are shown in Figures 8(a) and (b), respectively.
) is a schematic diagram showing the ground contact shape during straight travel and cornering when the camber angle is zero. Figure 10 (a
) and (b) are graphs showing the ground pressure at the tread end of the conventional tire and the tire of the present invention, respectively, corresponding to FIG. 8(a). 11.31.41.51...Pneumatic radial tire, 12...Bead, 13...Carcass, 15...Belt, 16... ...Tread, 16A...First trend, 16B...Second tread, 17...Side wall, 20...Reinforcement layer, 21... ...First reinforcing layer, 22... Second reinforcing layer, 23... Third reinforcing layer. Agent Patent Attorney Yugagun Part Figure 2 (a) Conventional tire (b) Tire of the present invention (a) Figure 8 Camber angle (minus) (b) Straight cornering Figure 8 Straight cornering Figure 10 (a) (b) + 6C Tread surface position

Claims (1)

[Claims] A carcass that extends between a pair of bead cores and has a folded part that is folded back around the bead core, a non-stretchable belt that extends circumferentially outside the crown part of the carcass, and a substantially cylindrical shape that covers the outside of the belt. with a tread of
In a pneumatic radial tire comprising a sidewall that covers the outside of the side portion of the carcass, at least one reinforcing layer extends radially outward from the vicinity of at least one of the bead cores and reinforces the side portion of the tire. one side part of the tire is reinforced more strongly than the other side part by combining the folded part of the carcass and the reinforcing layer; The hardness of the rubber of the first tread on one side is within 6 degrees lower than the hardness of the rubber of the second tread on the other side, and the value obtained by dividing the tan δ of the rubber of the second tread by the tan δ of the rubber of the first tread. 1. A pneumatic radial tire characterized in that: is in the range of 0.78 to 0.99.