JPH10181313A - Pneumatic tire for two-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide large traction in a sandy place. SOLUTION: When the angle of tire circumferential wall surface 26 of blocks 16A, 16B to normal line 24 raised on a grounding surface 22 is θ, space of the blocks 16A, 16B of tire circumferential direction is S and the height of the blocks 16A, 16B is h, 15 deg.<θ<30 deg., 0.5<(S-2h.tanθ)/S<0.8 in a central area of the tread, the height h is 10mm<h<14mm for a front wheel, 12mm<h<17mm for a rear wheel, length W of tire circumferential direction of the blocks 16A, 16B is 15mm<W<20mm for the front wheel, 20mm<W<28mm for the rear wheel and ratio W/S is 0.6<W/S<0.8. Whereby, excess removing of sand is prevented when traveling in a sandy place and large traction may be provided by pressing the sand.

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 a motorcycle mounted on a motorcycle and, more particularly, to a pneumatic tire for a motorcycle suitable for running mainly on sandy land.

[0002]

2. Description of the Related Art Pneumatic tires for motorcycles having a block pattern are mounted on motorcycles running mainly on sandy ground.

Hitherto, pneumatic tires for motorcycles having this type of block pattern have been considered mainly for scratching the road surface (sandy ground), thereby drawing out effective traction performance.

For this reason, the angle of the wall in the tire circumferential direction of the block with respect to the normal to the ground contact surface is set relatively small,
In many cases, the patterns are arranged such that the interval between the blocks in the tire circumferential direction is relatively large.

[0005]

However, the conventional pneumatic tire for a motorcycle having a block pattern, especially when traveling mainly on sand or the like, excessively discharges sand backward by so-called scratching. It has been found that traction is reduced.

An object of the present invention is to provide a pneumatic tire for a motorcycle capable of obtaining a large traction in a sandy ground in consideration of the above fact.

[0007]

As a result of repeated experiments and studies, it has been found that in sandy road running, how the sand is pressed down without scratching the sand and flotation running (sandy ground running) is obtained. It has been found that improvement can be achieved.

The invention according to claim 1 is a motorcycle pneumatic tire in which a plurality of blocks are formed on a tread, wherein an angle of a tire circumferential wall surface of the block with respect to a normal to a ground contact surface is θ, When the interval measured at the block contact level between adjacent blocks in the tire circumferential direction is S, and the height of the block is h, in the tread central region, the angle θ is 15 ° <θ <30 °, The relationship between the interval S, the height h, and the angle θ is 0.5 <(S−2h ·
tan θ) / S <0.8.

In the pneumatic tire for a motorcycle according to the first aspect, in the central region of the tread, the angle θ of the wall in the tire circumferential direction is set to 15 ° <θ <30 °, and the block contact level between blocks adjacent to each other in the tire circumferential direction is set. Since the relationship between the measured interval S, the height h of the block, and the angle θ of the wall in the tire circumferential direction was set to 0.5 <(S−2h · tan θ) / S <0.8, when running on sandy ground, Can prevent excessive scraping, and can provide great traction by holding down the sand.

[0010] The tread central region is defined as the inside of the tread periphery (the length from one tread end to the other tread end measured along the tread surface) when the tread perimeter is equally divided into four parts. It refers to two regions (regions inside the 1/4 point), and particularly relates to traction in traveling on sand.

Note that the angle θ of the circumferential wall surface of the tire is a biting angle when the block comes into contact with the road surface. Therefore, if the angle is too low, the road surface will be scraped too much, and if it is too large, it will be difficult to obtain effective traction.

When the angle θ of the circumferential wall surface of the tire is less than 15 °, it leads to excessive scraping of sand as in the case of the conventional tire, and the traction level cannot be improved. On the other hand, if the angle θ of the wall in the tire circumferential direction exceeds 30 °, the block slips and it becomes difficult to obtain effective traction.

In the circumferential arrangement of the blocks, the positional relationship and the size between the blocks and the block in front of the block (stepping side) when the block comes into contact with the road surface leads to excessive scraping of the sand.

For this reason, the relationship between the interval S measured at the block contact level between adjacent blocks in the tire circumferential direction, the height h of the blocks, and the angle θ of the wall in the tire circumferential direction is set to 0.
5 <(S−2h · tan θ) / S <0.8.

Here, if the value of (S−2h · tan θ) / S is 0.5 or less, the sand is scraped too much as in the conventional tire, and the traction level cannot be improved.
On the other hand, if the value of (S−2h · tan θ) / S exceeds 0.8, the block slips and it becomes difficult to obtain effective traction.

According to a second aspect of the present invention, in the pneumatic tire for a motorcycle according to the first aspect, the angle θ is 18
° <θ <25 °, and the relationship between the interval S, the height h, and the angle θ is 0.55 <(S−2h · tan θ) / S <0.
75.

In the pneumatic tire for a motorcycle according to the second aspect, the angle θ of the wall in the tire circumferential direction is set to 18 ° <θ <25.
The relationship between the distance S measured between the blocks adjacent to each other in the tire circumferential direction and the height h of the blocks and the angle θ of the wall surface in the tire circumferential direction is 0.55 <(S−2h · tan).
θ) / S <0.75, the ability to prevent excessive scraping of sand during traveling on sand can be maintained at the highest level, and the ability to hold down sand can also be maintained at the highest level. Thereby, a large traction can be surely obtained.

According to a third aspect of the present invention, in the pneumatic tire for a motorcycle according to the first or second aspect, the height h is 10 mm <h <14 mm for front wheels and 12 mm for rear wheels.
mm <h <17 mm, and the circumferential length W of the block measured on the ground contact surface is 15 mm <W <20 mm for the front wheels and 20 mm <W <28 mm for the rear wheels. The ratio W / S to the length W in the direction is 0.6 <W / S <0.
8 is characterized.

In the pneumatic tire for a motorcycle according to the third aspect, the height h of the block is 10 mm <h <14 m for the front wheels.
m, 12 mm <h <17 mm for the rear wheels, and the tire circumferential length W measured on the ground contact surface of the block is 15 mm <W for the front wheels.
<20mm, 20mm <W <28mm for rear wheels, and
The ratio W / S of the interval S to the tire circumferential length W is 0.6 <W
Since /S<0.8, a larger traction level can be obtained, and the durability of the block when traveling on sandy ground can be ensured.

As described above, the circumferential arrangement of the blocks is such that the positional relationship and the size of the blocks and the blocks before (stepping on) the blocks when they contact the road surface are as follows.
The block height h,
It is important to define the tire circumferential length W and the ratio W / S between the interval S and the tire circumferential length W as described above.

Here, if the length W of the block in the tire circumferential direction is smaller than the above range, the durability of the block may be reduced and the block may be chipped. On the other hand, if the length W of the block in the tire circumferential direction is larger than the above range, it becomes difficult for the block to bite into the sandy ground, and it becomes difficult to obtain traction.

If the height h of the block is smaller than the above range, the size of the block that digs into the sand becomes short, and it becomes difficult to obtain traction. On the other hand, if the height h of the block is higher than the above range, the sand is scraped too much, and the traction level cannot be improved.

The absolute value of the length W of the block in the tire circumferential direction is 15 to 20 mm for the front wheels and 20 to 2 for the rear wheels (drive wheels) because it contributes to biting into sand and contributes to durability.
8mm is required.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a pneumatic tire for a motorcycle according to the present invention will be described with reference to FIGS. The internal structure of the tire is the same as that of a general and well-known motorcycle pneumatic tire, and a description thereof will be omitted.

FIG. 1 is a developed view of a tread 12 of a pneumatic tire 10 for a motorcycle (tire size: 140 / 80-18).

The tread 12 has a tread central region 14
Are provided with blocks 16A, 16B and 16C having different shapes, respectively. Blocks 16D and 16E having different shapes are provided so as to straddle the tread central region 14 and the tread end side region 18, respectively. A block 16F, a block 16G, and a block 16H having different shapes are provided in the area 18.

Here, the tread central region 14 is the two regions on the tire equatorial plane CL side when the distance between one tread end 20A and the other tread end 20B is divided into four equal parts, and the tread end side region Reference numerals 18 are regions on both sides of the tread central region 14 in the tire width direction.

In the block 16 formed in the tread central region 14, as shown in FIG. 2, the wall angle θ of the tire circumferential wall surface 26 with respect to the normal line 24 raised to the ground contact surface 22 is determined for the front wheels and the rear wheels. In both cases, 15 ° <θ <30 °.

The block height h is 10 mm <h <for front wheels.
14 mm. On the other hand, for rear wheels, the block height h is 12 mm <h <17 mm.

The tire circumferential block length W is 15 mm <W <20 mm for the front wheels. On the other hand, for rear wheels,
The tire circumferential direction block length W is 20 mm <W <28 mm.

The relationship between the block interval S measured at the block contact level between adjacent blocks in the tire circumferential direction, the block height h, and the wall angle θ is 0.5 <(S−2h ·
tan θ) / S <0.8, and 0.55 <(S−2h)
Tan θ) / S <0.75 is more preferable.

The relationship between the block interval S and the tire circumferential block length W is 0.6 <W / S <0.8.

The absolute value of the tire circumferential block length W is
It is 15 to 20 mm for the front wheels to contribute to biting into the sand and contribute to durability. On the other hand, for rear wheels (drive wheels), the absolute value of the tire circumferential block length W is 20 to 28 mm.

By defining the relationship between the respective portions of the tread central region 14 as described above, it is possible to prevent excessive scraping of the sand during traveling on sandy ground, to obtain large traction by pressing the sand, and to improve the durability of the block. Nature can be secured.

It is needless to say that the above-mentioned rule may be applied to the tread end side area 18 as well. (Test Example) One type of tire to which the present invention was applied and one type of conventional tire were used for off-road motorcycles (displacement 400c
c) It was mounted on the rear wheel and a sandy road running test was performed to compare traction levels.

The tire size is 140 / 80-18 for both the example tire and the conventional tire.

Test course, test method and evaluation method: A 400cc off-road motorcycle was used to run a real vehicle on a special course on the Oigawa riverbed, and the feeling was evaluated by two riders.

Main specifications and test results of the test tire are as shown in Table 1 below. The evaluation is expressed as an index with the conventional tire 1 as 100, and the larger the numerical value, the higher the traction level.

[0039]

[Table 1]

As shown in the above test results, the tires of the examples to which the present invention is applied have significantly improved sand traction levels as compared with the conventional tires 1 and 2.

[0041]

As described above, the pneumatic tire for a motorcycle according to the first aspect of the present invention has the above-described configuration, and thus has an excellent effect that large traction can be obtained on sandy ground.

The pneumatic tire for a motorcycle according to the second aspect has the above-described configuration, and thus has an excellent effect that large traction can be reliably obtained.

Further, since the pneumatic tire for a motorcycle according to the third aspect has the above-described structure, it has an excellent effect that greater traction can be obtained and durability of the block can be ensured.

[Brief description of the drawings]

FIG. 1 is a development view of a tread of a pneumatic tire for a motorcycle according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of the motorcycle pneumatic tire shown in FIG.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire for motorcycle 12 Tread 16A block 16B block 16C block 16D block 16E block 16F block 16G block 16H block

Claims (3)

[Claims] 1. A pneumatic tire for a motorcycle having a plurality of blocks formed on a tread, wherein an angle of a wall surface in a tire circumferential direction of the block with respect to a normal to a ground contact surface is θ, and a block adjacent in a tire circumferential direction. Assuming that the interval measured at the block ground level between the two is S and the height of the block is h, in the tread central region, the angle θ is 15 ° <θ <30 °, and the interval S and the height h Is 0.5 <(S−2h · t).
anθ) / S <0.8. A pneumatic tire for a motorcycle. 2. The angle θ is 18 ° <θ <25 °, and the relationship between the interval S, the height h, and the angle θ is 0.55 <
The pneumatic tire for a motorcycle according to claim 1, wherein (S-2htan tan) / S <0.75. 3. The height h for front wheels is 10 mm <h <14.
mm, 12 mm <h <17 mm for the rear wheel, and the tire circumferential length W measured on the ground contact surface is 15 mm <W <20 mm for the front wheel and 20 mm <W <28 mm for the rear wheel
The ratio W / S of the interval S and the tire circumferential length W is
The pneumatic tire for a motorcycle according to claim 1 or 2, wherein 0.6 <W / S <0.8.