JPH04274905A - Pneumatic tire for heavy load - Google Patents

Abstract

PURPOSE:To retain compatibly the low maintenance of the average rib pattern in travel on an asphalt road surface while retaining the prior average snow tire running performance on snow, in a heavy load pneumatic tire, especially in a snow tire. CONSTITUTION:At one or both shoulder portions of a block pattern in the tread center portion of a heavy load pneumatic tire, a rib pattern divided with tire peripheral grooves is formed within the range of 0.1T<=t<=0.2T where (t) and T represent a rib width and a tread width, respectively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for heavy loads, and particularly to a snow tire intended for driving on snow-covered and icy roads.

0002

2. Description of the Related Art In conventional snow tires, the tread is divided into a plurality of blocks by grooves and sipes to increase the coefficient of friction between the snow surface and the tread. However, when such snow tires are actually used and are installed before snowfall and continued operation, they are susceptible to wear due to sipes, etc., and various uneven wear occurs on the tread shoulders during initial driving at the beginning of winter after installation. This tendency is particularly noticeable in tires mounted on the front wheels. To deal with this, we perform frequent tire rotations, such as replacing the left and right tires.

0003

[Problem to be solved by the invention] However, when actually wearing and driving tires, frequent tire rotation is not only troublesome but also uneconomical. In terms of performance, it is preferable to have a plurality of blocks and lugs on the entire surface of the tread, and there has been a demand for improved performance when driving on dry roads before snowfall.

In view of the above-mentioned circumstances, the present invention focuses on the occurrence of uneven shoulder wear on the outside side when a snow tire is mounted on the front wheel, and by finding a combination of the arrangement of rib elements, it is possible to make the snow tire comparable to a general snow tire. The purpose of this design is to maintain snow running performance of at least 100% or better, and to achieve low maintenance comparable to that of a general rib pattern when running on asphalt roads, and to make the effect more effective especially when mounted on the front wheel.

[0005]

[Means for Solving the Problems] That is, the present invention is characterized in that the tread center portion has a block pattern divided by circumferential grooves and widthwise grooves intersecting the grooves, and This is a heavy-duty pneumatic tire, particularly a snow tire, intended for driving on snowy roads and icy roads, and is provided with a rib pattern divided in the width direction by circumferential grooves in at least one shoulder portion of the tire. The present invention particularly provides a rib width in the above rib pattern that is 0.1 T≦, where t is the shoulder rib width and T is the tread width when viewed in the cross-sectional width direction of the tire.
It is within the range of t≦0.2T.

[0006]

[Function] The snow tire according to the present invention has the block pattern of the tread center part to ensure on-snow running performance comparable to that of conventional general snow tires, and the rib elements provided on the sides of the snow tire ensure wear resistance on general dry roads. It achieves low maintenance comparable to a high rib pattern, and improves turning performance on icy roads. In particular, the shoulder rib width (t) is 0.1 T relative to the tread width (T).
≦t≦0.2 When T is within the range, the on-snow performance of the tire is not reduced, and the turning performance on ice is improved, and when the shoulder rib is arranged only on one side, the on-snow running performance is improved. Improve.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with further reference to the accompanying drawings.

FIGS. 1 and 2 show examples according to the present invention,
In these figures, (1) is the tire tread part, (2) is the tread center part, and (3) is the shoulder part. Although the width of the tire tread (1) is not particularly restricted, it is usually a standard rim. When filled to the specified internal pressure, it is 82% or more of the maximum total width of the tire, and the tread center (3) has circumferential grooves (4) extending in the circumferential direction of the tire.
) and a large number of blocks (6) divided by grooves (5) in the width direction that intersect with the grooves (4).
Ribs (8), which are divided in the width direction by grooves (7) extending in the circumferential direction of the tire, are provided in the shape of ridges in the circumferential direction of the tire.

The ribs (8) may be provided symmetrically in the shoulder portions (3) on both sides of the tread center portion (2) as shown in FIG. 1, or may be provided asymmetrically on one side as shown in FIG. good. However, when provided on one side, it is preferable to provide the rib (8) so that it is located on the outside when the front wheel is mounted.

Furthermore, the width of the rib (8) must be determined as much as possible to prevent the width of the rib (8) from decreasing as much as possible since the block pattern of the tread of a snow tire maintains performance on snow as described above. The rib width must be set so that the rib width (t) is within the range of 0.1 T≦t≦0.2 T, where t is the partial rib width and T is the tire tread width. If the torque is too small, the effect of the careful rib arrangement will be small, and on the other hand, if it exceeds 0.2 T, there is a risk that performance on snow will deteriorate.

[0011] The rib width (t) mentioned above is the rib width (t) on one side when the ribs (8) are on both sides. In addition, the rubber used for the tread in the above tread configuration is generally standard rubber, for example, one with a hardness of about 70 degrees, but the main body of the block is made of soft rubber (hardness of about 50 to 65 degrees).
And, the entire surface is made of hard rubber (hardness 75-8
It is also possible to form an epidermal layer of about 0°.

Next, a comparison of the turning performance on ice and the amount of shoulder wear between the above-mentioned invention tire and a conventional snow tire will be explained. (1) Turning performance on ice Tires with a tire size of 10.00 R 20 and 14PR were used, and ribs were provided on the shoulder portions on both sides of the tread center portion with varying rib widths to obtain the test tires shown by the black circles in the figure. A general snow tire of the same size as above, but also having a block in the shoulder part and without studs, was used as a comparison tire. Then, each of the above tires was turned five times along a designated figure-eight circle to measure the limit speed at which steady turning could be performed, and the performance of each test tire was detected, with a general snow tire set as 100. The results are shown in Figure 3, and the test tire is better than the general snow tire shown by the dotted line when the shoulder rib width occupancy (t/T) is between 0.1 and 0.2; It was observed that performance deteriorated when outside the range. From this result, shoulder rib width occupancy (t
/T) is found to be effective in the range of 0.1 to 0.2. (2) Wear test Next, the tire of the present invention with a shoulder rib width occupancy ratio (t/T) of 0.1 was selected, and this was compared to the general snow tire prepared for comparison, and the studless tire and tire of the same tire size. A test run was conducted on a general dry road with a general ribbed tire, and the amount of shoulder wear corresponding to each mileage was measured. The results are shown in Figure 4. Although the tire of the present invention had a slightly higher amount of wear than a summer tire, which is a general ribbed tire, it had extremely good wear resistance compared to a normal snow tire or a studless tire. It was recognized that there was.

[0013]

Effects of the Invention As described above, the present invention has a block pattern in the tread center portion, a rib pattern in at least one shoulder portion, and the width of the shoulder rib when viewed in the cross-sectional width direction of the tire is the same as that of the rib. When the width is t, the tread width T is 0.1 T≦t≦0.2
This is a snow tire in the T range, and the block pattern in the tread center ensures on-snow performance comparable to that of a regular snow tire, while the rib pattern in the shoulder area provides wear resistance comparable to that of a regular ribbed tire on asphalt roads. It also improves turning performance on icy roads and prevents the uneven wear seen on the tread shoulders of conventional snow tires.Therefore, the tire rotation interval can be extended compared to conventional methods, improving economic efficiency and making it easier to install snow tires at the beginning of winter. After that, it is extremely effective even during the initial run, and is expected to be effective in improving practical performance as a snow tire.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view showing one example of a main part of a tire according to the present invention.

FIG. 2 is a partial perspective view showing another embodiment of a tire essential part according to the present invention.

FIG. 3 is a chart showing the relationship between shoulder rib width occupancy and turning performance on ice.

FIG. 4 is a chart showing the results of a wear test.

[Explanation of symbols]

(1) Tire tread section (2) Tread center part (3) Shoulder part (4) Groove (5) Groove (6) Block (7) Groove (8) Rib

Claims (1)

[Claims] Claim 1: A heavy-duty pneumatic tire intended for driving on snow-covered roads and icy roads, the tread of which has a block pattern divided by grooves in the tire circumferential direction and grooves intersecting the grooves in the tread center part of the tread. and has a rib pattern divided by grooves in the circumferential direction of the tire in at least one shoulder portion thereof, and the shoulder rib width in the rib pattern is such that the rib width when viewed in the cross-sectional width direction of the tire is t, and that A pneumatic tire for heavy loads, characterized in that the tread width is within the range of 0.1 T≦t≦0.2 T, where T is the tread width.