JPH1159128A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent partial abrasion by arranging the maximum outside diameter position on the side inward from the tire center line in mounting to a vehicle, setting the distance between the tire center line and the maximum outside diameter position in the specified range in relation to the tire sectional width, and constituting a tread by a single radius of curvature in the specified range in relation to the maximum outside diameter. SOLUTION: The maximum outside diameter position P is offset to the side inward from the tire center line CL in mounting to a vehicle. At this time, the distance L between the tire center line CL and the maximum outside diameter position P is so set as to satisfy the relationship of 0.05W<=L<=0.12W in relation to the tire sectional width W. A tread 4 is constituted with a single radius of curvature (r), and the radius of curvature (r) is set in relation to the maximum outside diameter R so as to satisfy the relationship of 0.4R<=r<=0.6R. Therefore, the whole tread is uniformly worn from the start of mounting to the vehicle, and the life can be lengthened by preventing partial abrasion in which the tread 4 is early worn on the outer side in mounting to the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire used for heavy-duty vehicles such as trucks and buses, and more particularly, to a pneumatic radial pneumatic tire for preventing uneven wear and extending the life. Related to radial tires.

[0002]

2. Description of the Related Art A pneumatic radial tire mounted on the front of a heavy-duty vehicle such as a truck or a bus wears the outer side of the tread more quickly than the inner side when the vehicle is mounted on the tread. Nevertheless, the service life may be shortened because the outer grooves reach the wear limit.

In order to solve the above problem, for example, as disclosed in Japanese Patent Application Laid-Open No. Sho 60-179304, the outer tread radius is set to be larger than the inner tread radius when the vehicle is mounted. As disclosed in Japanese Patent No. 41204, means for offsetting the maximum outer diameter position outside the tire center line when the vehicle is mounted on the vehicle has been proposed.

[0004] However, in the above-described means, the contact area on the outside of the tread is increased when the vehicle is mounted on the vehicle, so that the contact pressure on the outside can be reduced. As a result, the effect of suppressing early wear on the outside when the vehicle is mounted cannot be sufficiently obtained.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire for heavy loads which can prevent uneven wear and extend the life.

[0006]

According to the present invention, there is provided a heavy-duty pneumatic radial tire according to the present invention, wherein a maximum outer diameter position is located inside a tire center line when mounted on a vehicle,
The distance L from the tire center line to the maximum outer diameter position has a relationship of 0.05 W ≦ L ≦ 0.12 W with respect to the tire cross-sectional width W, and the tread has a single radius of curvature r. The radius of curvature r is 0.4R ≦ r ≦ with respect to the maximum outer diameter R.
It is characterized by having a relation of 0.6R.

The inventor of the present invention has proposed that when a tire used in a similar operation is run and the wear progresses, the cross-sectional shape of the tread gradually changes, and when the tread finally reaches a specific shape, the tire is used. Thereafter, it was confirmed by experiments that the wear of the entire tread progressed uniformly while maintaining the shape. In particular, the tire mounted on the front of a heavy-duty vehicle has a large outer tread drop compared to the inside because the outer wear is fast when the vehicle is mounted.

In this wear process, the radius of curvature r of the tread becomes substantially equal between the crown portion and the right and left shoulder portions, and changes to a range of 0.4R ≦ r ≦ 0.6R with respect to the maximum outer diameter R. In addition, the maximum outer diameter position shifts inward from the tire center line when the vehicle is mounted, and the distance L from the tire center line is 0.05 W ≦ L ≦ 0.1 with respect to the tire sectional width W.
It changes to the range of 2W.

Therefore, as described above, when the vehicle is new, the maximum outer diameter position is offset from the center line of the tire by the above-described specific distance to the inside when the vehicle is mounted, and the crown portion and the shoulder portion of the tread have the above-mentioned specific radius of curvature r. With this configuration, the entire tread is uniformly worn from the time of mounting on the vehicle. Therefore, uneven wear, in which the tread is worn early on the outer side when the vehicle is mounted, can be prevented, and the life can be extended.

In the present invention, when a plurality of main grooves extending in the tire circumferential direction are provided on the tread, it is preferable that the depths of these main grooves are equal between the inside and the outside when the vehicle is mounted. When narrow grooves extending in the tire circumferential direction are provided in the non-ground areas of the shoulder portions on the left and right sides, respectively, the depths of these narrow grooves are equal between the inside and outside when the vehicle is mounted, and the narrow grooves are opened from the shoulder edges. It is preferable to make the radial distance to the portion equal between the inside and the outside when the vehicle is mounted.

Further, when the present invention is applied to a pneumatic radial tire for heavy loads having an aspect ratio of 90% or more, a remarkable effect can be obtained. The dimensions in the present invention are determined by mounting the tire on a JATMA standard rim,
In the air pressure-load capacity correspondence table specified in MA (1997 version), the air pressure corresponding to the maximum load capacity is 10
This is a value measured when 0% is filled.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic radial tire for heavy loads having an aspect ratio of 90% or more according to an embodiment of the present invention. In the figure, a carcass layer 2 in which a plurality of reinforcing cords are oriented in a tire radial direction is mounted between a pair of right and left bead portions 1 and 1,
Both ends of the carcass layer 2 in the tire width direction are wound up from the inside of the bead core 3 to the outside of the tire.

Between the tread 4 and the carcass layer 2, a plurality of belt layers 5 in which a plurality of reinforcing cords are inclined with respect to the tire circumferential direction are arranged so that the cords cross each other between the layers. . The tread 4 is provided with a plurality of main grooves 6 extending in the tire circumferential direction. The depths D of these main grooves 6 are equal between the inside and the outside when the vehicle is mounted.

In the pneumatic radial tire, the maximum outer diameter position P is offset inward from the tire center line CL when the vehicle is mounted, and the distance L from the tire center line CL to the maximum outer diameter position P is the tire sectional width. 0.0 for W
It is set so as to satisfy the relationship of 5W ≦ L ≦ 0.12W. The tread 4 has a single radius of curvature r.
It is set so as to satisfy the relationship of R ≦ r ≦ 0.6R.

As described above, when the vehicle is new, the maximum outer diameter position P is offset inward from the tire center line CL when the vehicle is mounted, and the tread 4 has a single radius of curvature r. Since the entire tread is uniformly worn, uneven wear, in which the tread 4 is worn early on the outside when the vehicle is mounted, can be prevented, and the life can be extended.

The distance L from the tire center line CL to the maximum outer diameter position P is 0.05W ≦ L ≦
It must be in the range of 0.12W. If this distance L is 0.
If it is less than 05 W or more than 0.12 W, the effect of preventing uneven wear will be insufficient. Further, the radius of curvature r of the tread 4 is set in a range of 0.4R ≦ r ≦ 0.6R with respect to the maximum outer diameter R.
When the radius of curvature r is less than 0.4R or more than 0.6R, the effect of preventing uneven wear becomes insufficient.

When the tread 4 is provided with a plurality of main grooves 6 extending in the tire circumferential direction, the depth D of the main grooves 6
Is preferably equal between the inside and the outside when the vehicle is mounted. That is, in the above tires, the height of the tread 4 in the tire radial direction is different between the inside and the outside when the vehicle is mounted, but the entire tread is uniformly worn when the vehicle is mounted. By making the inside and outside equal, the remaining groove of the main groove 6 can be made uniform over the entire tread, and desired tire performance can be exhibited.

FIG. 2 illustrates a pneumatic radial tire for heavy loads having a flatness of 90% or more according to another embodiment of the present invention. In this embodiment, a thin groove is added to the shoulder portion in the embodiment of FIG. That is, narrow grooves 7 extending in the tire circumferential direction are provided in the non-ground areas near the tire rotation axis from the shoulder edge E in the shoulder portions on both the left and right sides. And the narrow groove 7
Is equal between the inside and the outside when the vehicle is mounted, and the radial distance δ from the shoulder edge E to the opening of the narrow groove 7 is equal between the inside and the outside when the vehicle is mounted.

When the narrow grooves 7 extending in the circumferential direction of the tire are respectively provided in the non-ground areas of the shoulder portions on the left and right sides as described above, the depth d of these narrow grooves 7 is made equal between the inside and outside when the vehicle is mounted. In addition, it is preferable that the radial distance δ from the shoulder edge E to the opening of the narrow groove 7 is equal between the inside and the outside when the vehicle is mounted. That is, in the above-mentioned tire, the heights of the shoulder portions on the right and left sides in the radial direction of the tire are different between the inside and the outside when the vehicle is mounted, but the entire tread is uniformly worn when the vehicle is mounted. By setting the distance δ to the opening at the inside and outside when the vehicle is mounted, the narrow grooves 7 on both the left and right sides are simultaneously exposed to the ground contact surface after the middle period of wear, and only one side engages with the narrow groove 7 Does not easily occur. In addition, the narrow groove 7
By making the depth d equal between the inside and the outside when the vehicle is mounted, the remaining groove of the narrow groove 7 can be made uniform on both the left and right sides, and the function of the narrow groove 7 can be exhibited uniformly.

Further, according to the pneumatic radial tire, as in the embodiment of FIG. 1, since the entire tread wears even when the vehicle is mounted, the tread 4 wears out early when the vehicle is mounted. Uneven wear can be prevented and the life can be extended. In each of the embodiments described above, the case where the tread is provided with the main groove extending in the tire circumferential direction is described. However, in the present invention, the tread is provided with a lug groove or the like extending in the tire width direction in addition to the circumferential main groove. It may be.

[0021]

[Example] The tire size is made common to 11R22.5,
As shown in FIG. 1, the maximum outer diameter position is arranged on the inner side of the tire center line when the vehicle is mounted, and the distance L from the tire center line to the maximum outer diameter position is 0.10 W with respect to the tire sectional width W.
In addition, the tire of the present invention in which the radius of curvature r of the tread is set to 0.5R with respect to the maximum outer diameter R, the maximum outer diameter position is matched with the tire center line, and the radius of curvature of the tread is r
Was made 0.5R with respect to the maximum outer diameter R to produce a conventional tire.

These test tires were mounted on the front wheels of a truck at an air pressure of 700 kPa, and were moved straight forward, left turning,
After running 2,000 km each in the right-turn state, the amount of tread wear of the tire mounted on the right side in the traveling direction was measured. The relationship between the position in the tread width direction and the amount of wear based on the measurement results is shown in FIGS. as a result,
As shown in FIGS. 3 to 5, the tire of the present invention has a larger amount of inner wear when mounted on the vehicle and a smaller amount of outer wear when mounted on the vehicle than the conventional tire in each running state, as shown in FIGS. The amount of wear was uniform throughout the tread.

[0023]

As described above, according to the present invention, the maximum outer diameter position is located inside the tire center line when the vehicle is mounted, and the distance L from the tire center line to the maximum outer diameter position is determined by the tire. 0.05W ≦ L ≦ 0.12 with respect to sectional width W
W, and the tread is configured with a single radius of curvature r, and the radius of curvature r is set to 0.4R ≦ maximum outer diameter R.
Since the relation of r ≦ 0.6R is applied, the entire tread is uniformly worn from the time of mounting the vehicle, so that uneven wear, in which the tread is worn early on the outside when the vehicle is mounted, is prevented and the life is extended. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a pneumatic radial tire for heavy loads according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a pneumatic radial tire for heavy loads according to another embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a position in a tread width direction and a wear amount at a time when the vehicle travels straight.

FIG. 4 is a diagram illustrating a relationship between a position in a tread width direction and a wear amount when turning left.

FIG. 5 is a diagram showing a relationship between a position in a tread width direction and a wear amount at the time of turning right.

FIG. 6 is a diagram showing a relationship between a position in a tread width direction and a total wear amount.

[Explanation of symbols]

 4 Tread 6 Main groove 7 Narrow groove CL Tire center line L Distance from tire center line to maximum outer diameter position P Maximum outer diameter position r Tread radius of curvature R Maximum outer diameter W Tire section width

Claims (3)

[Claims] 1. A maximum outer diameter position is arranged on the inner side of a tire center line when mounted on a vehicle, and a distance L from the tire center line to the maximum outer diameter position is set to 0.05 with respect to a tire sectional width W.
In addition to the relationship of W ≦ L ≦ 0.12W, the tread was configured with a single radius of curvature r, and the radius of curvature r was set to a relationship of 0.4R ≦ r ≦ 0.6R with respect to the maximum outer diameter R. Pneumatic radial tire for heavy loads. 2. The pneumatic radial tire for heavy load according to claim 1, wherein a plurality of main grooves extending in a tire circumferential direction are provided on the tread, and the depths of the main grooves are equal between inside and outside when the vehicle is mounted. . 3. A thin groove extending in the tire circumferential direction is provided in each of the non-ground areas of the shoulder portions on the left and right sides, the depth of the narrow groove is made equal between the inside and the outside when the vehicle is mounted, and the narrow groove is formed from the shoulder edge. The pneumatic radial tire for heavy loads according to claim 1 or 2, wherein a radial distance to the opening is equal between the inside and the outside when the vehicle is mounted.