JPH06183216A - Set snow tire for motorcycle - Google Patents

Abstract

PURPOSE:To provide a set snow tire for a motorcycle by which driving force and braking force can be improved on the ice or on the snow and a side slip can be prevented when riding across a rut. CONSTITUTION:A ratio Ra/Wa of a radius of curvature Ra on a surface of a tread 1a to tread width Wa of a front wheel tire Ta is set in 0.6-0.7, and a longitudinal sipe 5a extending in a circumferential direction of a tire is arranged in the block 4a, and a rate of this longitudinal sipe 5a to the whole sipes is set not less than 70%. In addition to it, a ratio Rb/Wb of a radius of curvature Rb on a surface of a tread 1b to tread width Wb of a rear wheel tire Tb is set not less than 1.1, and a lateral sipe 5b extending in a tire width direction is arranged in the block 4b, and length of this lateral sipe 5b is set not less than 70%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle snow tire suitable for traveling on ice or snow.
More specifically, while improving the driving force and the braking force,
The present invention relates to a pair of snow tires for a motorcycle, which prevent skid when riding over a rut.

[0002]

2. Description of the Related Art Conventionally, in a snow tire for a motorcycle having a block-based tread pattern, a large number of sipes are provided in the block. Among these sipes, the lateral sipes extending in the tire width direction mainly contribute to driving force and braking force on ice or snow, and the longitudinal sipes extending in the tire circumferential direction mainly contribute to skid prevention.

However, it is difficult to achieve both improvement of driving force and braking force and improvement of skid prevention performance at the same time by providing the above-mentioned sipes, and abrupt driving or braking is performed on ice or snow. There is a problem that the rear tires tend to slip, and the front tires tend to skid when overcoming a rut.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the driving force and braking force on ice or snow by skillfully combining the functions of the front tires and the rear tires, and at the same time, to skid when crossing a rut. It is to provide a combined snow tire for a motorcycle capable of preventing the above.

[0005]

A combined snow tire for a motorcycle according to the present invention for achieving the above object has a block-based tread pattern, and includes a pair of front tires and rear tires. In the combined snow tire, the ratio Ra / Wa of the radius of curvature Ra of the tread surface to the tread width Wa of the front wheel tire is 0.6 to
The vertical sipe that extends in the tire circumferential direction is installed in the block to 0.7, and the ratio of this vertical sipe to all the sipe is 7
0% or more, and the tread width W of the rear tire
Ratio of radius of curvature Rb of tread surface to b Rb / Wb
Is set to 1.1 or more, a lateral sipe extending in the tire width direction is provided in the block, and the length of the lateral sipe is set to 7 of the actual ground contact width.
It is characterized by being set to 0% or more.

In this way, the ratio Ra / Wa of the radius of curvature Ra of the tread surface to the tread width Wa of the front tire is set to 0.6 to 0.7 to round the tread surface and the block extends mainly in the tire circumferential direction. A vertical sipe is provided, and the ratio of this vertical sipe to all the sipe is 7
By setting it to 0% or more, it is possible to prevent the front tires from skidding when overcoming a rut. On the other hand, the ratio Rb / Wb of the curvature radius Rb of the tread surface to the tread width Wb of the rear wheel tire is set to 1.1 or more to flatten the tread surface, and the block is provided with a lateral sipe extending mainly in the tire width direction. By setting the length of the lateral sipe to 70% or more of the actual ground contact width, the driving force and braking force of the rear tires on ice or snow are improved, and the rear tires are prevented from slipping during driving or braking. .

In the present invention, the vertical sipe is defined as a narrow groove whose angle to the tire circumferential direction is within ± 15 °,
The lateral sipe has an angle of 75 ° to 10 with respect to the tire circumferential direction.
It is defined as a narrow groove in the range of 5 °. The actual ground contact width is the total width of the blocks on the tread. Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 4 show a combined snow tire for a motorcycle including a front tire and a rear tire according to an embodiment of the present invention. FIG. 1 is a schematic sectional view of the front tire, and FIG. 2 is a front wheel. FIG. 3 is a development view of a tire tread, FIG. 3 is a schematic cross-sectional view of a rear tire, and FIG. 4 is a development view of a rear tire tread.

In the front tire Ta, the ratio Ra of the radius of curvature Ra of the surface of the tread 1a to the tread width Wa thereof is Ra.
/ Wa is set in the range of 0.6 to 0.7, and the surface is rounded. The tread 1a is provided with a plurality of main grooves 2a extending in the tire circumferential direction and a lug groove 3a extending in the tire width direction, and a plurality of blocks 4a are formed by the main groove 2a and the lug groove 3a. ing. The blocks 4a are provided with vertical sipes 5a that mainly extend in the tire circumferential direction. The sipes provided in the block 4a may include some horizontal sipes, but the ratio of the vertical sipes 5a to all sipes is set to 70% or more.

On the other hand, in the rear tire Tb, the ratio Rb / Wb of the radius of curvature Rb of the surface of the tread 1b to the tread width Wb is set to 1.1 or more, and the surface is flat. The tread 1b is provided with a plurality of main grooves 2b extending in the tire circumferential direction and a lug groove 3b extending in the tire width direction. The main groove 2b and the lug groove 3b form a plurality of blocks 4b in a divided manner. ing. The blocks 4b are provided with lateral sipes 5b that mainly extend in the tire width direction. The length of the lateral sipe 5b is 70% or more of the actual ground contact width, that is, the block 4
It is set to be 70% or more of the total width of b.

According to the present invention, the surface of the tread 1a of the front tire Ta is rounded by the radius of curvature Ra, and the block 4a is provided mainly with the vertical sipes 5a, so that the front tire Ta is not caught by a rut. Sip 5a when riding over a vehicle
Can be prevented by. On the other hand, the rear tire Tb
Since the surface of the tread 1b is flattened by the radius of curvature Rb and the block 4b is mainly provided with a lateral sipe, the driving force and the braking force of the rear wheel tire Tb are improved. It is possible to prevent the rear tire Tb from slipping.

That is, in a combined snow tire for a motorcycle having a front tire Ta and a rear tire Tb as one set, the front tire Ta emphasizes rut-riding performance and skid prevention performance, and the rear tire Tb emphasizes traction performance. By placing importance on these tires Tb and Ta and combining them in different configurations, it is possible to improve the driving force and braking force on ice and snow, and to prevent skidding during rut crossing.

In the present invention, the tread surfaces of the front tire Ta and the rear tire Tb can each be formed with a plurality of radii of curvature. When the radius of curvature is changed on the same tread surface in this manner, the above-mentioned is at least in a region of (3/5) wa, (3/5) wb centered on the tire equator with respect to the tread development widths wa, wb. The tread surface may be formed according to the radii of curvature Ra and Rb.

[0013]

[Example] Tire size of front wheels 2.75-14 4P
R, rear tire size 2.75-14 6PR,
In one set of snow tires for motorcycles having a block pattern, only the radius of curvature of the tread surface and the sipes provided on the blocks were changed as described below.
I made various types of tires. Inventive Tire As shown in FIGS. 1 to 4, the ratio Ra / Wa of the radius of curvature Ra of the tread surface to the tread width Wa of the front wheel tire is 0.
7, all the blocks were provided with longitudinal sipes, the ratio Rb / Wb of the radius of curvature Rb of the tread surface to the tread width Wb of the rear tire was set to 1.1, and the transverse sipes were provided in all the blocks. Conventional tire The ratio Ra / Wa of the radius of curvature Ra of the tread surface to the tread width Wa of the front tire is set to 0.9, a lateral sipe is provided in the block on the center side of the tread, and a longitudinal sipe is provided in the block on the shoulder side. Ratio Rb of radius of curvature Rb of tread surface to tread width Wb of wheel tire
/ Wb was set to 0.9, the block on the center side of the tread was provided with horizontal sipes, and the block on the shoulder side was provided with vertical sipes.

With respect to these two types of tires, the braking distance and the starting time were measured by the following methods, and their rudder crossing performances were evaluated. The results are shown in Table 1. Braking distance: Attach test tires to the front and rear wheels of the motorcycle,
The braking distance when the rear brake was applied to stop the vehicle while traveling on ice at a speed of 15 km / h was measured.

Start-up time: Test tires were attached to the front and rear wheels of a motorcycle, and the start-up time from the standstill on ice to the start of moving 1.2 mm was measured. Rut-riding performance: Test tires were attached to the front and rear wheels of a motorcycle, run on ice with a rut, and rut-riding performance was evaluated by the feeling of 10 test drivers. The evaluation results are indicated by x when the steering wheel was taken over the rudder and frequently skid, and by ○ when the rudder could be crossed with almost no skid.

[0016] As is clear from Table 1, the tire of the present invention has improved driving force and braking force as compared with the conventional tire, and has excellent rudder riding performance.

[0017]

As described above, according to the present invention, in a combined snow tire for a motorcycle having a block-based tread pattern, the ratio Ra / W of the radius of curvature Ra of the tread surface to the tread width Wa of the front tire is Ra / W.
a is set to 0.6 to 0.7, a vertical sipe extending in the tire circumferential direction is provided in the block, and the ratio of the vertical sipe to the total sipe is 70% or more, and the tread surface with respect to the tread width Wb of the rear tire. R of curvature radius Rb of
b / Wb is set to 1.1 or more, a lateral sipe that extends in the tire width direction is provided in the block, and the length of this lateral sipe is set to 70% or more of the actual ground contact width. By combining both tires, on ice or snow It is possible to improve the driving force and the braking force of the vehicle and to prevent the skid from slipping over the rut.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a front tire of a motorcycle combined snow tire according to an embodiment of the present invention.

FIG. 2 is a development view showing the tread of the front tire of the assembled snow tire for motorcycle according to the embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a rear wheel tire of the assembled snow tire for motorcycle according to the embodiment of the present invention.

FIG. 4 is a development view showing a tread of a rear wheel tire of a motorcycle snow tire according to an embodiment of the present invention.

[Explanation of sign]

 1a, 1b Tread 2a, 2b Main groove 3a, 3b Lug groove 4a, 4b Block 5a Vertical sipe 5b Horizontal sipe Ta Front wheel tire Tb Rear wheel tire

Claims (1)

[Claims] 1. A combined snow tire for a motorcycle, which has a block-based tread pattern and includes a front tire and a rear tire as one set, and a ratio of a radius of curvature Ra of a tread surface to a tread width Wa of the front tire. Ra / Wa is set to 0.6 to 0.7, a vertical sipe extending in the tire circumferential direction is provided in the block, and the ratio of the vertical sipe to the total sipe is 70% or more, and the tread width Wb of the rear wheel tire is set. The ratio Rb / Wb of the curvature radius Rb of the tread surface to 1.1 or more is set to 1.1 or more, a lateral sipe extending in the tire width direction is provided in the block, and the length of the lateral sipe is set to 70% or more of the actual ground contact width. Working snow tires.