JPS60179304A - Pneumatic tire for heavy load - Google Patents

Abstract

PURPOSE:To improve the eccentric-abrasion suppressing performance of a tread part by setting the radius of curvature of the contours of the tread part on the sectional surface of a tire including the axis of revolution of the tire larger on the outside than the inside with repsect to the equatorial plane. CONSTITUTION:The radius of curvature R2 of the contours of the tread part outside a wheel is set larger by 70mm. or more than the radius of curvature R3 on the inside. Since the radius of curvature of a tread inside in less, the ground contact pressure inside reduces. Therefore, the ground contact pressure at the edge part of the outside tread increases in comparison with that of the symmetrical tread, and the eccentric abrasion accompanied with reduced shoulder can be suppressed.

Description

[Detailed Description of the Invention] (Technical Field) This invention relates to the radius of curvature of the outline of the trend part of a pneumatic tire for heavy loads,
'PS also belongs to those related to wear prevention.

(Prior art and its problems) In heavy-duty pneumatic tires, especially radial tires, uneven shoulder drop wear often occurs on a portion of the outer shoulder of the front wheel.

In conventional heavy-duty pneumatic tires, the radius of curvature of the tread profile is bilaterally symmetrical, and a method is used to greatly increase the ground contact pressure at the end of the tire trend in a symmetrical state to prevent uneven shoulder wear. However, in order to increase the radius of curvature, a method of increasing the trend volume has usually been used, but this method is disadvantageous in terms of Goss I.

(Aim of the invention) This invention minimizes the trend volume increase.

The objective is to improve the performance against uneven wear of the tread edges.

(Structure of the invention) Uneven wear that occurs at the tread edges is caused by uneven wear that occurs not at both ends of the tread.
It mainly occurs at the outer trend end of the vehicle. this is,
This is due to the fact that roads have not only straight sections but also curved sections. When a vehicle turns around a curve, centrifugal force causes the vehicle to roll. An increase in load and a concentration of lateral force occur at the trend end of the trend section of the tire mounted on the outside of the turn, which tends to cause uneven wear at the end of the tire on the outside of the tire.

Therefore, one inventor discovered that since the radius of curvature of the contour of the trend section that appears in the cross section of the tire including the axis of rotation of the tire is asymmetric with respect to the tire equatorial plane because the side with the larger radius of curvature is mounted on the outside of the wheel, the radius of curvature A heavy-duty pneumatic tire characterized by a difference of 70 mm or more has been found.

FIG. 1 shows a tire according to the prior art, and FIG. 2 shows a tire according to the present invention. The radius of curvature (R1) of the tread contour of the tire in Figure 1 is 485 mm, and the radius of curvature (R2) of the tread contour on the outside of the vehicle in Figure 2 is 535 mm.
IIn, the inner one (R3) is 435■,
The difference in the radius of curvature is 100 = l.

Since the asymmetric tread tire of the present invention has a small inner tread radius of curvature, the positive and negative ground contact 4j4 there decreases, resulting in higher ground contact pressure at the outer tread end than in a symmetrical I red tire, which prevents uneven shoulder drop wear. Progress is extremely slow.

In conventional symmetric tread tires, the radius of curvature was increased by increasing the tread volume, but in the asymmetric tread tire of this invention, the radius of curvature of the tread contour on the outside of the vehicle is made larger than that on the inside, thereby increasing the tread volume. Suppression of uneven wear can be achieved without increasing.

(Effects of the Invention) The tires shown in Figures 1 and 2 were subjected to actual running tests to compare uneven wear performance at the trend end.

The tire size is lQ, 00 R20, and there is no difference in tread volume between the tire in Figure 1 and the tire in Figure 2, and the tire size is 3.
A comparison of cross-sections of uneven wear that occurred on the outer tread edge of the vehicle after traveling 10,000 km revealed that the tires shown in Fig.
The tire shown in FIG. 2 was also found to have an improved uneven wear resistance of 10 mm.

[Brief explanation of drawings]

FIG. 1 shows a tire according to the prior art, and FIG. 2 shows a tire according to the present invention. l...Trend, R1, R2, R3...Tren IS
゛The radius of curvature of the contour. Patent applicant Brideston Tire Co., Ltd. Figure 1

Claims (1)

[Claims] The radius of curvature of the tread profile that appears in the cross section of the tire including the tire rotation axis is 4. Because the side with the larger radius of curvature is mounted on the outside of the wheel, the tire becomes asymmetrical with respect to the equatorial plane and the difference in radius of curvature is 70'ms or more. A pneumatic tire for heavy loads.