JPH09136514A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy-load tire which enhances traction when running on bad roads, up to the end of its wear, as well as wet performance when running at high speed. SOLUTION: This tire has on its tread at least one circumferentially extending groove and a number of transverse grooves joined to the circumferential groove and placed on both sides of the circumferential groove at intervals along the circumferential direction. In this case, the circumferential groove extends circumferentially within the center area of the tread which corresponds to 50% of tread width, the depth of the circumferential groove is 5% or more of tread width, and of the transverse grooves at least those provided on both sides of the tread have a groove depth that is 109% or more of that of the circumferential groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tread pattern of a heavy-duty pneumatic tire, and more particularly to ensuring traction performance even when the tire reaches the end of wear.

[0002]

2. Description of the Related Art Conventionally, in a so-called block pattern having a circumferential main groove and a lateral groove connected thereto, the circumferential main groove and the lateral groove have the same groove depth or the lateral groove is shallower. It was normal.

[0003]

On the other hand, heavy-duty pneumatic tires, especially tires running on bad roads and highways, require traction performance on bad roads and wet performance at high speeds. There is. In the conventional tread pattern for heavy duty pneumatic tires, the circumferential main groove ensures wet performance (drainability) at high speeds, but at the end of wear, the lateral groove disappears or becomes too shallow, causing bad roads. There was a problem that traction performance during running was not sufficiently obtained.

The present invention has been made as a result of studies aimed at solving the above-mentioned problems, and improves both the traction performance on rough roads until the end of wear and the wet performance at high speeds. It is to provide a pneumatic tire for heavy loads.

[0005]

In order to achieve the above-mentioned object, a pneumatic tire according to the present invention has at least one circumferential groove extending in the circumferential direction and a circumferential groove connected to both sides of the circumferential groove. A pneumatic tire having a tread with a large number of lateral grooves arranged at intervals in the circumferential direction, comprising: (1)
The circumferential groove extends in the circumferential direction in the tread central region corresponding to 70% of the tread width, and (2) the groove depth of the circumferential groove is 5% or more of the tread width, and (3) the lateral groove Among them, a configuration is adopted in which the groove depth of the lateral groove provided on at least both sides of the tread is 109% or more of the groove depth of the circumferential groove.

Since the pneumatic tire of the present invention employs the above-mentioned structure, the pneumatic tire of the present invention has a final wear stage (about 70,000 to 80,000 km).
In conventional tires, the lateral grooves almost disappear when running, and even when the traction performance on bad roads is significantly reduced, the lateral grooves are 109 times larger than the circumferential grooves.
Since it is deeper than 10%, there are plenty of lateral grooves remaining, so traction performance on rough roads is ensured as well as wet performance, and balanced performance can be achieved even at the end of wear. The reason why the groove depth is 109% or more deeper than the circumferential groove is that the lateral groove still wears earlier than 109%. The upper limit of the groove depth depends on the tire structure and shape, but is about 150%.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a partially enlarged front view of a tread pattern of a heavy duty pneumatic tire according to an embodiment of the present invention. The size is 10.00R20. Although not shown, the tire according to the present invention has a non-stretchable belt layer arranged and reinforced on the circumference of the crown portion of the toroidal radial carcass, and has a cylindrical tread 8 thereon. The tread 8 has four main grooves extending in a zigzag or linear shape in the circumferential direction in the tread central area corresponding to 70% of the tread width, and has blocks divided by the lateral grooves connected to the main area. ing. The groove depth of the lateral groove provided on at least both sides of the tread is 12 of the main groove depth extending in the circumferential direction provided in the tread central region corresponding to 70% of the tread width.
It is set to 0%.

Next, in order to confirm the effect of the tire of the present invention, a tire conforming to the specifications shown in Table 1 was prototyped. These tires have exactly the same structure except for the groove depth of the tread lateral groove. These tires have an internal pressure of 7.25 kgf
Table 1 shows the results of comparison between the wet performance index at the time of new installation and the traction performance index at the end of wear by mounting it on the rear of a 10-ton dump truck by incorporating it into a 7.50V rim at 1 / cm ²
It is shown in

[0009]

[Table 1]

From the above table, it is clear that the tire of the present invention has excellent traction performance at the end of wear.

[0011]

As is clear from the above description, according to the present invention, there is provided a heavy duty pneumatic tire which improves both traction performance on rough roads and wet performance at high speeds until the end of wear. can do.

[Brief description of the drawings]

FIG. 1 is a partially enlarged front view and groove sectional view of a tread pattern of a pneumatic tire according to the present invention.

[Explanation of symbols]

1, 2 Circumferential groove 3, 4, 5 Lateral groove 6, 7, 8 Block 9 Tread E Tire equatorial line (tread pattern center) H Groove depth

Claims (1)

[Claims] 1. A tread comprising at least one circumferential groove extending in the circumferential direction and a plurality of lateral grooves connected to the circumferential groove and circumferentially spaced on both sides of the circumferential groove. (1) The circumferential groove extends in the circumferential direction within a tread central region corresponding to 70% of the tread width, and (2) the groove depth of the circumferential groove is equal to the tread width. 5% or more, and (3) the lateral groove is provided on at least both sides of the tread, and the groove depth of the lateral groove is 109% or more of the groove depth of the circumferential groove. Pneumatic tire for heavy loads.