JPS63159108A - Pnfumatic tire - Google Patents

Abstract

PURPOSE:To enhance the grip characteristic of a tire during running on a dry road surface, by gradually increasing the ground contact area of the tread surface of the tire from the widthwise inside to the outside of the tire upon installation, and by specifically setting the ground contact area rate of the tread surface. CONSTITUTION:The ground contact area of the tread surface of a tire is increased steppedly and gradually in the order of the inside shoulder section A, the center section B, the center section C and the outer shoulder section D, that is, from the widthwise inside to the outside of the tire upon installation. For example, the ground contact rate of the section D is set to be around 90 %, that of the section C around 60 %, that of the section B around 60 % and that of the A around 40 %. Further, the ground contact area ratio of the tread surface is set to 70 to 80 % with the provision of such an asymmetric pattern as mentioned above, it is possible to enhance the grip characteristic of the tire during running on a dry road surface and to make the abrasion of the tire uniform. Further, the tire is used inside out during running on a wet road surface so as to obtain a characteristic similar to that of a symmetric pattern tire running on a wet road surface.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a pneumatic tire having a tread pattern with an asymmetrical design on the tread surface (tire tread), which improves grip (road surface grip) when driving on dry roads. Regarding.

[Prior art]

BACKGROUND ART Conventionally, as the performance and horsepower of vehicles have increased, there has been an increasing demand for improved grip limits. When the grip limit is exceeded while driving, the grip force suddenly decreases, which is dangerous because an unexpected spin condition may occur.

In addition, when cornering, the load is concentrated on the outer tread surface of the vehicle due to cornering force, so the ground pressure distribution exhibits a deviation with a peak on the outer tread surface, resulting in problems such as impaired handling stability. .

Therefore, as shown in FIG. 3, a tire has been proposed that has a tread pattern 1 with an asymmetrical design in which the outer tread surface in the width direction is designed to be close to a slick when mounted on a vehicle. However, even this tire cannot sufficiently improve the grip limit. In Figure 3, the tread surface has three main grooves 2 arranged annularly in the tire circumferential direction.
are formed, and a plurality of sub grooves 3 are arranged in the tire width direction.

4 represents a rib, 5 represents a block, and T represents a tread development width.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire with improved grip when driving on dry roads, particularly when cornering.

[Structure of the invention]

For this reason, the present invention provides a tire having a trend pattern on its trend surface, in which the ground contact area of the tread surface is gradually increased from the inside to the outside in the width direction when mounted on a vehicle, and furthermore, the ground contact area of the tread surface is The gist of this invention is a pneumatic tire characterized by an area ratio of 70 to 80%.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing a tread pattern of an example of a pneumatic tire of the present invention. Note that the same parts as in FIG. 3 are indicated by the same numbers.

+11 In the present invention, the ground contact area of the trend surface is gradually increased from the inner side to the outer side in the width direction when mounted on a vehicle. That is, in FIG. 1, the ground contact area of the tread surface is gradually increased in steps from inner shoulder part A to center part B to center part C to outer shoulder part. This relationship is shown in FIG. Figure 2 shows the relationship between the parts of the tread surface and the ground contact ratio. D), around 60% (
Center part C), around 50% (center part B), 40%
Front and rear (inner shoulder part A).

The ratio of the total area of each divided portion is not necessarily 1/4, and is different from other portions. From this second figure,
It can be seen that the contact area of the tread surface gradually increases from the inside to the outside.

By gradually increasing the ground contact area of the trend surface in this way, it is possible to equalize the surface pressure during cornering. In FIG. 1, the outer ribs 4 are not separated by grooves, kerfs, etc., but are continuously connected.

<2) Furthermore, in the present invention, the ground contact area ratio of the tread surface is set to 70 to 80%.

If the ground contact area ratio is less than 70%, it is difficult to obtain an effective grip force. This is because if it exceeds 80%, a hydroplaning phenomenon will occur in rainy weather, making safe driving difficult.

Next, the results of comparing the grip performance of the tire of the present invention and the conventional tire when running on a dry road are shown in Table 1 below as an index.

(a) Tire of the present invention.

Tire size 185/60 R14゜Figures 1 and 2
It has the tread pattern shown in the figure.

(b) Conventional tires.

Tire size: 185/60 R14° with tread pattern shown in Figure 3. The tire structure is the same as the tire according to the invention described above.

Evaluation of Grip Performance: Using a Toyota Corolla Levin as a test vehicle, a test was conducted at the Tsukuba Circuit with 6 JJ x 14 rims and an air pressure of 2.1 kg/cnl.

Topsoil Inventive Tire Conventional Tire Grip Performance 110 100 From Table 1, it can be seen that the inventive tire is superior in grip/knob performance G.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be achieved.

- Since the surface pressure during cornering is evened out, high grip can be obtained when driving on dry roads, and wear can progress evenly.

■ The ground contact area ratio of the tread surface is set to 70-80%, so the inner groove increases compared to a symmetrical design.
When driving on wet roads, by installing the tires upside down on the vehicle, it is possible to obtain wet road driving performance equivalent to or better than that of a symmetrical design.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a tread pattern of an example of a pneumatic tire of the present invention, Fig. 2 is a diagram showing the relationship between tread surface parts and ground contact ratio, and Fig. 3 is a trend pattern of an example of a conventional pneumatic tire. FIG. 1... Tread pattern, 2... Main groove, 3... Minor groove, 4... Rib, 5... Block, T... Tread development width.

Claims (1)

[Scope of Claims] A tire having a tread pattern on the tread surface, wherein the ground contact area of the tread surface is gradually increased from the inner side to the outer side in the width direction when mounted on a vehicle, and the ground contact area of the tread surface is further provided. Ratio 70~
A pneumatic tire characterized by a pneumatic tire of 80%.