JPH03153402A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To concurrently improve abrasion resistance and wet performance by arranging three straight main grooves on a tread surface, arranging straight sub-grooves on ribs divided by main grooves, and connecting these grooves with width direction auxiliary grooves. CONSTITUTION:Three straight main grooves 1 are circularly formed along the tire peripheral direction EE' on a tread surface. Ribs 2 are formed on the tread surface. Straight sub-grooves 3 are circularly formed along the tire peripheral direction EE' at the center in the width direction of ribs 2. Straight main grooves 1 and straight sub-grooves 3 are connected by width direction auxiliary grooves 4. The width B of straight main grooves 1 is set within the range 0.04-0.07 of the tire ground width A. The pitch C in the tire peripheral direction EE' of width direction auxiliary grooves 4, i.e., the distance between width direction auxiliary grooves 4 in the tire peripheral direction EE', is set within the range 0.20-0.30 of the tire ground width A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic radial tire that has both wear resistance and wet performance.

[Conventional technology]

In recent years, pneumatic radial tires, especially 13 inch and 14 inch
There is a strong demand for improved wear resistance for inch-sized radial tires for small trucks, especially among delivery service users.

In order to improve wear resistance, current technology includes constructing the trend portion with a trend compound having excellent wear resistance and reducing the groove area ratio on the tread surface. However, when the wear resistance is improved in this way, there is a problem in that wet performance (wet road running performance, particularly wet braking performance and wet circular turning performance) is reduced.

[Problem to be solved by the invention]

The present invention has been made in order to solve the above-mentioned problem of the trade-off between improving wear resistance and decreasing wet performance. The purpose of the present invention is to provide a pneumatic radial tire that satisfies both of these requirements.

[Means to solve the problem]

In the pneumatic radial tire of the present invention, three straight ribs are provided on the tread surface in an annular manner in the tire circumferential direction, and three straight ribs are provided in an annular manner in the tire circumferential direction at approximately the center in the width direction of each rib formed by the arrangement of these straight leaders. A straight sub-groove is provided, and the straight main groove and the straight sub-groove are connected by a g+I groove in the width direction, and the width B of the straight main groove is set to B/A=0 with respect to the tire ground contact width A.
04 to 0.07, and the pitch C of the width direction minor groove in the tire circumferential direction is C/A=0 with respect to the tire ground contact width A.
．． 20 to 0.30.

This means will be explained in detail below with reference to the drawings.

FIG. 1 is an explanatory plan view showing an example of a trend pattern of the pneumatic radial tire of the present invention. In Fig. 1, three straight main grooves 1 are provided in an annular manner in the tire circumferential direction EE'' on the trend surface.The reason why there are three straight main grooves 1 is to obtain an appropriate groove area ratio. be.

In other words, if there are four or more straight main grooves 1, the groove area ratio becomes large and the wear resistance decreases, while if there are less than two, the groove area ratio decreases too much and the drainage performance and wet performance deteriorate. This is because you end up doing it. Here, the groove area ratio is the ratio of the conductive ground surface to the total ground contact area (ground contact width x circumferential length) of the trend surface.

The arrangement of these three straight main grooves 1 forms ribs 2 on the tread surface. Approximately at the center in the width direction of each rib 2, a straight sub tl is provided annularly in the tire circumferential direction EE'.
A fee of $3 will be provided. The straight sub-groove 3 was provided because
This is to improve drainage performance and enhance the edge effect in the tire lateral direction (width direction). The width of straight sub-groove 3 is
It should be less than 1.5 mm.1. It is preferably less than or equal to oIllII+. If it exceeds 1.5 ate, the ribs 2 tend to move easily, which may reduce the wear resistance.

The straight main groove I and the straight sub-groove 3 are connected by a width direction sub-groove 4. The reason why the width direction minor grooves 4 are arranged in this manner is to improve drainage performance and to enhance the edge effect in the tire circumferential direction EE'. The width of the width direction minor groove 4 is also
It is preferably 1.5 mm or less, and preferably 1.0 mm or less. This is because if it exceeds 1.5 mm, the ribs 2 may move easily and wear resistance may decrease.

Furthermore, in the present invention, the width B of the straight main groove 1 is set to B/A=0.04 to 0.07 with respect to the tire ground contact width A.

If it is less than 0.04, the groove area ratio will decrease too much and the wet performance will deteriorate, while if it exceeds 0.07, the groove area ratio will become too large and the wear resistance will deteriorate.

Further, in the present invention, the tire circumferential direction EE' of the width direction minor groove 4 is
Pitch C1, that is, the distance between the width direction minor grooves 4 in the tire circumferential direction EE', with respect to the tire ground contact width A, is C/A=
It is set at 0.20 to 0.30. If it is less than 0.20, the number of width direction minor grooves 4 becomes too large, the ribs 2 tend to move easily, and the wear resistance decreases. This is because if it exceeds 0.30, the effect of providing the width direction minor grooves 4 will be difficult to produce. In addition, in FIG. 1, l represents the tire equator line.

An example of a trend pattern of conventional pneumatic radial tires is shown in FIG. 2 and FIG. 3, respectively. Fig. 2 shows a case where there are three straight main grooves 1, and Fig. 3 shows a case where there are four straight main grooves 1.
The straight sub-groove 3 as shown in FIG. 1 is not provided.

Examples are shown below.

Examples The following pneumatic radial tires (inventive tires, conventional tires, and comparative tires 1 to 5) were evaluated for wear resistance, wet braking performance, and wet turning performance using the following methods. The results are shown in Table 1 as an index. The higher the number, the better.

■ Tire of the present invention.

Tire size 175 R14 (for rear wheels of 2-car class). It has a tread pattern shown in FIG. A = 1
34 mm, B = 8.0 ll1m5C = 33.5
mm.

B/A=0.06, C/A=0.25° Straight main groove 1 depth -9.0mm, straight sub groove 3 depth = 1
．． 4 mm, depth of width direction minor groove 4 -7.4 mm, width of straight sub groove 3 -0.8 mm, width of width direction minor groove 4 -0,
8mm.

■ Conventional tires.

Tire size 175 R14 (for rear wheels of 2-car class). It has a tread pattern shown in FIG. A =
128 n+m, B = 9.0 mm, B/A
= 0.07゜■ Comparison tie - 1.1゜tire size 175 R14 (2) for the rear wheel of a car class). It has a trend pattern shown in FIG. 4(a). FIG. 4(a) is the same as FIG. 1 except that the width direction minor groove 4 is not provided. B/A=0.06゜■ Comparison tire 2゜tire size 175 R1,4 (for rear wheels of 2-ton vehicle class). It has a tread pattern shown in FIG. 4(b).

FIG. 4(b) is the same as FIG. 1 except that the straight sub-groove 3 is not present. B/A=0.06゜■ Comparison tire 3゜tire size 175 R14 (for rear wheels of 2-ton vehicle class). It has a tread pattern consisting of three straights 1-main a1 as shown in FIG. 4(c). A=134mm,
B=8. Ova, B/A =0.06゜■
Comparison tire 4° tire size 175 R14 (2) for the rear wheel of a car class). It has a trend pattern consisting of four straight main grooves 1 as shown in FIG. 4(d). A-134mm, B
=8. On+m, B/A=0.06゜■ Comparison tire 5
゜Tire size 175 R14 (2) for the rear wheel of a car class). It has a tread pattern consisting of three zigzag main grooves 1'' as shown in FIG. 4(e). A-134mm, B
= 8.0 mIn, B / A = 0.06゜ Star-resistant hpE version: 10,000 on a dry road surface in a loaded actual vehicle state (attached to the rear wheels (double wheels) of a 2-ton vehicle. Carrying load: 2 tons) After driving for km, compare the amount of wear on each wheel.

A braking test was carried out by driving on the Uesoto road surface with an actual loaded vehicle (attached to the rear wheels (double wheels) of a 2-ton vehicle. Carrying load: 2 tons). , compare braking distance.

Wet circle method: Compare the time required for one lap by driving an empty vehicle (no load) on the Wend road surface (circular course with radius = 30 m).

(Margins below this page) From Table 1, it can be seen that the tires of the present invention are excellent in all of abrasion resistance, wet braking performance, and wet circular turning performance.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be achieved because the arrangement of the grooves on the tread surface is devised so as not to reduce the groove area ratio as much as possible.

(1) By arranging three straight main grooves, high drainage performance can be ensured with the smallest groove area ratio.

(2) By arranging straight sub-grooves on each rib, it is possible to enhance the lateral edge effect in wet conditions and ensure high lateral grip performance.

(3) By arranging the widthwise minor groove that connects the straight main groove and the straight sub-groove, it is possible to enhance the longitudinal (circumferential) edge effect and ensure high wet braking performance.

(4) Even when the trend portion is made of a trend compound with excellent wear resistance, it is possible to achieve both wear resistance and wet performance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory plan view showing an example of a tread pattern of a pneumatic radial tire of the present invention, FIGS. 2 and 3 are plan view explanatory views showing an example of a tread pattern of a conventional pneumatic radial tire, respectively, Figures 4(a) to (e)
) are plan view explanatory diagrams each showing an example of a trend pattern for comparison. 1... Straight leading, 2... Rib, 3... Straight sub groove, 4... Width direction minor groove.

Claims (1)

[Claims] Three straight main grooves are provided on the tread surface in an annular manner in the tire circumferential direction, and a straight sub-groove is provided in an annular manner in the tire circumferential direction at approximately the center in the width direction of each rib formed by the arrangement of these straight main grooves. The straight main groove and the straight sub-groove are connected by a width direction minor groove, and the width B of the straight main groove is set to B/A=0.04 to 0.07 with respect to the tire ground contact width A, A pneumatic radial tire characterized in that the pitch C of the width direction minor grooves in the tire circumferential direction is C/A=0.20 to 0.30 with respect to the tire ground contact width A.