JP2001071711A - Pneumatic tire for two-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for a two-wheeled vehicle capable of reducing noise in running on a paved road without sacrificing running performance on an unleveled road significantly. SOLUTION: A lug groove 14 is inclined to a tire axial direction so that an edge 18A of a block 18 on a treading side along a whole length does not strike a road surface at a time in rolling and contacting the road surface, and noise is reduced. A plurality of the blocks 18 are not in line in the tire axial direction, and do not strike the road surface simultaneously, also resulting in reduced noise. Noise can be reduced without degrading running performance on an unleveled road by setting a negative rate of a tread 12 within 30-60% and setting an arranging pitch P of the lug groove 14 in a circumferential direction in a standard ground contacting surface 20 within 50-100% of a maximum length L0 of the standard ground contacting surface 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called on / off two-wheeled pneumatic tire for both good road and rough terrain, and in particular, to remarkably sacrifice off-road traveling performance. The present invention relates to a pneumatic tire for a motorcycle capable of reducing noise when traveling on a good road.

[0002]

2. Description of the Related Art Conventionally, on / off roads for both good roads and rough terrain are used.
In pneumatic tires for off-road use, the noise during running on a good road such as a pavement road has been neglected because the running performance on rough terrain is rather emphasized.

[0003]

[Problems to be solved by the invention]
Although it is a pneumatic tire for on / off motorcycles that can also be used on uneven terrain, it does not always run on uneven terrain. There have been many opportunities for (on-road) driving, and the noise has been gradually becoming a problem in recent years.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a two-wheeled pneumatic tire capable of reducing noise when traveling on a good road without significantly sacrificing the terrain running performance. is there.

[0005]

According to the present invention, there is provided a pneumatic tire for a motorcycle having a plurality of blocks on a tread defined by a plurality of circumferential grooves and a plurality of lug grooves. The lug grooves are inclined with respect to the tire axial direction, so that the negative rate of the tread is 30 to 60%.
And the circumferential arrangement pitch of the lug grooves in the standard ground plane should be at least 50 mm of the maximum length of the standard ground plane.
It is characterized in that it is set within the range of １００100%.

In the pneumatic tire for a motorcycle according to the first aspect, the lug grooves are inclined with respect to the tire axial direction.
At the time of rolling contact, the block edge portion on the stepping side does not hit the road surface all at once over the entire length, so that noise can be reduced. Further, since the plurality of blocks are not arranged in a line in the tire axial direction, the plurality of blocks do not hit the road surface at the same time, so that noise can be reduced.

In addition, the negative rate of the tread is 30 to 6
By setting it within the range of 0%, it is possible to reduce noise without sacrificing the terrain running performance.

If the negative rate of the tread is less than 30%, the area of the groove portion becomes too small (the area of the block is too large), and the function of the block edge which is effective when traveling on uneven terrain is suppressed. As a result, a sufficient grip required for traveling cannot be obtained.

On the other hand, if the negative rate of the tread exceeds 60%, the number of grooves is too large (the area of the block is too small), and an effective contact area on a good road cannot be obtained. The head drop is large, and the blow sound becomes loud.

If the pitch of the lug grooves in the circumferential direction is less than 50% of the maximum length of the standard ground contact surface, at least the circumferential length of the block is too short, and the rigidity of the block against braking force and driving force is insufficient. And poor durability.

On the other hand, when the circumferential pitch of the lug grooves is longer than 100% of the maximum length of the standard ground plane, the edge component in the width direction of the block in the ground plane becomes too small, and the edge effect on the braking force and the driving force is reduced. And especially poor on rough terrain.

In the present invention, the standard ground contact surface means that the tire is mounted on a standard rim conforming to the JATMA standard and the air pressure and the load are 80% of the maximum air pressure and the maximum air pressure specified in the air pressure-load capacity correspondence table. It is defined as the footprint when the camber angle is 0 ° with a load of 70% of the load capacity.

Further, the circumferential groove in the present invention means a groove of less than 45 ° with respect to the tire equatorial plane, and the lug groove means a groove having an inclination angle of 45 ° or less with respect to the tire axial direction.

According to a second aspect of the present invention, in the pneumatic tire for a motorcycle according to the first aspect, the width of the lug groove in the standard ground plane is 5 to 50% of the maximum length of the standard ground plane.
Is set within the range.

The width of the lug groove is 5 times the maximum length of the standard ground plane.
%, The groove width is too narrow, and the drainage property of drainage and the soil removal property such as mud when traveling on uneven terrain are inferior.

On the other hand, if the width of the lug groove is greater than 50% of the maximum length of the standard ground plane, at least the circumferential length of the block in the ground plane becomes too short, and the block rigidity against the braking force and the driving force is insufficient. And inferior in durability.

Therefore, it is preferable that the width of the lug groove is set within a range of 5 to 50% of the maximum length of the standard ground plane.

According to a third aspect of the present invention, there is provided the pneumatic tire for a motorcycle according to the first or second aspect, wherein the lug groove is provided in a range of at least 50% or more of the entire length of the lug groove in a standard ground contact surface. The angle of the width center line with respect to the tire equatorial plane is set within a range of 60 to 70 °.

When the angle of the lug groove width center line with respect to the tire equatorial plane is less than 60 ° in the range of at least 50% or more of the entire length of the lug groove in the standard ground contact surface, the edge component in the width direction of the lug groove becomes too short. As a result, it is inferior to the edge effect on the braking force and the driving force, and particularly inferior to rough terrain.

On the other hand, if the angle of the lug groove width center line with respect to the tire equatorial plane exceeds 70 °, the widthwise edge component of the block that hits the road surface during rolling contact with the ground becomes too large, resulting in poor noise reduction.

[0021] In the pneumatic tire for a motorcycle according to the invention described in claim 4, the number of appearances of the lug grooves in a standard ground contact surface is 0.5.
It is characterized in that it is set within the range of ~ 2.

The number of lug grooves appearing in the standard ground plane is equal to 0.
If the number is less than 5, the drainage performance, the braking performance when traveling on uneven terrain, the driving performance, the earth discharging performance, and the like are inferior.

On the other hand, if the number of lug grooves appearing in the standard ground plane exceeds two, block rigidity, low noise resistance and the like are inferior, and their performance cannot be comprehensively improved.

Therefore, it is preferable to set the number of lug grooves appearing in the standard ground plane within the range of 0.5 to 2.

The number of appearances of the lug grooves in the present invention is counted as follows.

Number of appearances: One when the lug groove completely crosses the standard ground contact surface in the standard ground contact surface, and two groove ends (same as block edges) on the tread side of the lug groove appear (See FIGS. 7A and 7B. Note that FIG. 7A
Reference numeral 20 denotes a standard ground plane, and 14 denotes a lug groove. ).

Number of appearance 0.5: When the lug groove completely crosses the standard ground surface in the standard ground surface, one groove end (same as the block edge) on the tread side of the lug groove appears. (See FIG. 7C).

As shown in FIG. 7D, when the lug groove does not completely cross the standard ground plane, the lug groove crosses the outline of the standard ground plane by 0.5. (In the case of FIG. 7D, the number is counted as 1.5).

According to a fifth aspect of the present invention, there is provided a pneumatic tire for a motorcycle including a plurality of blocks on a tread defined by a plurality of circumferential grooves and a plurality of lug grooves,
At least a part of the stepping-side edge of the block is inclined with respect to the tire axial direction, the negative rate of the tread is set in a range of 30 to 60%, and at least the circumference of the lug groove in the standard ground contact surface is set. The directional arrangement pitch is set within a range of 50% to 100% of the maximum length of the standard ground plane.

[0030] In the pneumatic tire for a motorcycle according to the fifth aspect, at least a part (preferably all) of the stepping-side edge of the block is inclined with respect to the tire axial direction. The block edge portion does not hit the road surface at one time over the entire length, so that noise can be reduced. Further, since the plurality of blocks are not arranged in a line in the tire axial direction, the plurality of blocks do not hit the road surface at the same time, and the noise can be reduced.

The negative rate of the tread is 30 to 6
By setting it within the range of 0%, it is possible to reduce noise without sacrificing the terrain running performance.

The edge shape on the stepping side of the block may be a linear shape or a shape other than a linear shape, for example, a V-shape, a bent shape, a curved shape, or the like.

If the negative rate of the tread is less than 30%, the area of the groove portion becomes too small (the area of the block is too large), and the function of the block edge which is effective when traveling on uneven terrain is suppressed. As a result, a sufficient grip required for traveling cannot be obtained.

On the other hand, if the negative rate of the tread exceeds 60%, the number of grooves is too large (the area of the block is too small), so that an effective contact area on a good road cannot be obtained, and at the same time, the road surface of each block is not obtained. The head drop is large, and the blow sound becomes loud.

When the circumferential pitch of the lug grooves is less than 50% of the maximum length of the standard ground contact surface, at least the circumferential length of the block is too short, and the rigidity of the block against braking force and driving force is insufficient. And poor durability.

On the other hand, when the circumferential pitch of the lug grooves is longer than 100% of the maximum length of the standard ground plane, the edge component in the width direction of the block in the ground plane becomes too small, and the edge effect on the braking force and the driving force is reduced. And especially poor on rough terrain.

According to a sixth aspect of the present invention, in the pneumatic tire for a motorcycle according to the fifth aspect, the width of the lug groove is set within a range of 5 to 50% of the maximum length of the standard tread. It is characterized by:

The width of the lug groove is 5 times the maximum length of the standard ground plane.
%, The groove width is too narrow, and the drainage property and the soil discharging property such as mud when traveling on uneven terrain are inferior.

On the other hand, if the width of the lug groove is wider than 50% of the maximum length of the standard ground plane, at least the circumferential length of the block in the ground plane becomes too short, and the block rigidity against the braking force and the driving force is insufficient. And inferior in durability.

Therefore, it is preferable to set the width of the lug groove within the range of 5 to 50% of the maximum length of the standard ground contact surface.

According to a seventh aspect of the present invention, in the pneumatic tire for a motorcycle according to the fifth or sixth aspect, the number of the lug grooves in the standard ground contact surface is in the range of 0.5 to 2. It is characterized by having been set within.

The number of lug grooves appearing within the standard ground contact surface is equal to 0.
If the number is less than 5, the drainage performance, the braking performance when traveling on uneven terrain, the driving performance, the earth discharging performance, and the like are inferior.

On the other hand, if the number of the lug grooves in the standard ground contact surface is more than two, the block rigidity, the noise resistance and the like are inferior, and it is impossible to improve the overall performance of the lugs.

Therefore, it is preferable to set the number of lug grooves appearing in the standard ground plane within the range of 0.5 to 2.

[0045]

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.

FIG. 1 is a plan view (exploded view) of a tread 12 of a two-wheeled pneumatic tire 10 (tire size: 130 / 80-18) for a front wheel.

The internal structure of the pneumatic tire 10 for a motorcycle according to the present embodiment is the same as that of a normal pneumatic tire for a motorcycle, so that the description of the internal structure will be omitted.

As shown in FIG. 1, the tread 12 is provided with a plurality of blocks 18 divided by a plurality of lug grooves 14 and a circumferential groove 16.

The lug grooves 14 are inclined upward to the right from the left tread end 12L toward the tire equatorial plane CL, and are inclined downward to the right from the tire equatorial plane CL to the right tread end 12R. .

The lug groove 14 is formed so that the groove width gradually increases from the tire equatorial plane CL toward the tread ends 12L and 12R.

The width W1 of the lug groove 14 is about 7 mm near the equatorial plane CL of the narrowest tire, and the widest tread end 12L, 1
It is about 19 mm near 2R.

When the length of the standard grounding surface 20 of the motorcycle pneumatic tire 10 is L0, the circumferential pitch P of the lug grooves 14 in the standard grounding surface 20 (the distance between the lug groove width center lines 14C). ) Is the maximum length L of the standard ground plane 20
It is preferable to set within the range of 50 to 100% of 0. In the present embodiment, the circumferential arrangement pitch P / the maximum length L0 of the standard ground plane 20 is set to 60%.

The width W1 of the lug groove 14 in the standard ground plane 20 is preferably set within a range of 5 to 50% of the maximum length L0 of the standard ground plane 20. In this embodiment, the width W1 of the lug groove 14 / the maximum length L0 of the standard ground plane 20 is set to 8% in the standard ground plane 20.

In the range of at least 50% or more of the entire length of the lug groove 14 (the peripheral length of the lug groove width center line 14C) within the standard ground plane 20, the lug groove width center line 14C
Of the tire with respect to the tire equatorial plane CL (measured on the acute angle side) is 6
It is preferable to set the angle in the range of 0 to 70 ° and to set the number of the lug grooves 14 appearing in the standard ground plane 20 in the range of 0.5 to 2.

In the present embodiment, the angle θ 1 of the lug groove width center line 14C with respect to the tire equatorial plane CL is set to 62 ° on average in a range of at least 50% or more of the entire length of the lug groove 14 in the standard ground plane 20. The lug groove 14
Are 1 to 2 (1 to 2 depending on the rotational position).
Increase and decrease between books. ).

The depth of the lug groove 14 of this embodiment is 6
mm.

In this embodiment, four circumferential grooves 16 are formed between the lug grooves 14.

In the present embodiment, the circumferential groove 16 disposed on the left side of the tire equatorial plane CL is inclined upward and leftward.
The circumferential groove 16 disposed on the left side of the tire equatorial plane CL is inclined upward to the right.

In this embodiment, the angle θ 2 of the center line in the width direction of the circumferential groove 16 with respect to the tire equatorial plane CL is 62 on average.
° is set.

In the present embodiment, the circumferential groove 16 includes a slightly narrower groove and a slightly wider circumferential groove.
On average, the groove width W2 is set to 8 mm for the whole 2
The groove depth is 3.5 mm and they are arranged at substantially equal intervals.

The negative rate of the tread 12 is 30.
It is preferably set within the range of 〜60%, and in the present embodiment, it is set to 31%.

FIG. 2 is a plan view (exploded view) of a tread 12 of a pneumatic tire 30 for a rear wheel (tire size: 180 / 80-14) for a motorcycle. The same components as those of the pneumatic tire 10 for a front wheel are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 2, the pneumatic tire 30 for a rear motorcycle also has a tread pattern substantially equivalent to that of the pneumatic tire 10 for a front wheel.

The differences between the two-wheeled pneumatic tire 30 for the rear wheel and the two-wheeled pneumatic tire 10 for the front wheel will be described below.

The negative rate of the tread 12 is 34%.

The width W1 of the lug groove 14 in the standard ground plane 20 is set to 7% of the maximum length L0 of the standard ground plane 20.

In the range of at least 50% or more of the entire length of the lug groove 14 in the standard ground contact surface 20, the angle θ1 of the lug groove width center line 14C with respect to the tire equatorial plane CL is 6 on average.
It is set to 5 °.

Incidentally, the pneumatic tire 30 for the rear wheel is similar to the pneumatic tire 10 for the front wheel, and the circumferential arrangement pitch P /
The maximum length L0 of the standard ground plane 20 is set to 60%, and the number of the lug grooves 14 is one or two. (Operation) In the pneumatic tire 10 for a motorcycle and the pneumatic tire 30 for a motorcycle according to the present embodiment, a plurality of blocks 18 are provided.
Are not arranged in a line in the tire axial direction, and the lug grooves 14 are inclined within a range of 60 to 70 ° with respect to the tire equatorial plane. Since the edge 18A on the stepping side of the block 18 does not hit the road surface at one time over the entire length at the time of touchdown, the noise is reduced.

The negative rate of the tread 12 is 30
Since it is set within the range of ６０60%, low noise can be achieved without sacrificing rough terrain running performance.

The negative rate of the tread 12 is 30
%, The area of the groove portion becomes too small (the area of the block 18 is too large), and the function of the block edge that is effective when traveling on uneven terrain is suppressed, and as a result, the grip required for traveling is sufficiently obtained. I can't.

On the other hand, the negative rate of the tread 12 is 60
%, The groove portion is too large (the area of the block 18 is too small), so that an effective contact area on a good road cannot be obtained, and at the same time, the drop of each block 18 to the road surface is large, and the impact sound is reduced. Make it bigger.

When the pitch P in the circumferential direction of the lug grooves 14 is less than 50% of the maximum length L0 of the standard ground plane 20,
At least the circumferential length of the block 18 becomes too short, and the block rigidity against the braking force and the driving force is insufficient, and the durability is reduced.

On the other hand, if the circumferential pitch P of the lug grooves 14 is longer than 100% of the maximum length L0 of the standard ground plane 20, the width direction edge component of the block 18 in the ground plane becomes too small, and the braking force and The edge effect on the driving force is reduced, and especially the terrain running performance is reduced.

When the width W1 of the lug groove 14 is less than 5% of the maximum length L0 of the standard grounding surface 20, the groove width is too narrow, and the drainage property and the soil discharging property such as mud when traveling on uneven terrain are deteriorated. .

On the other hand, the width W 1 of the lug groove 14 is
If the maximum length L0 is larger than 50% of the maximum length L0, at least the circumferential length of the block 18 in the ground contact surface becomes too short, and the rigidity of the block against the braking force and the driving force is insufficient, and the durability is reduced.

In the range of at least 50% or more of the entire length of the lug groove 14 in the standard ground plane 20, the lug groove width center line 1
When the angle .theta.1 of the 4C with respect to the tire equatorial plane CL is less than 60 DEG, the width direction edge component of the lug groove 14 becomes too short, and the edge effect on the braking force and the driving force is inferior.

On the other hand, if the angle θ1 of the lug groove width center line 14C with respect to the tire equatorial plane CL exceeds 70 °, the width direction edge component of the block 18 that hits the road surface during rolling contact becomes too large, resulting in low noise. Inferior.

If the number of the lug grooves in the standard ground contact surface 20 is less than 0.5, the drainage performance, the braking performance when traveling on uneven terrain, the driving performance, the earth discharging performance, and the like are inferior.

On the other hand, if the number of the lug grooves 14 appearing in the standard ground plane 20 is more than two, the rigidity of the block, the noise-reducing property, etc. are inferior, and it is impossible to improve the overall performance of the lugs 14 in parallel. .

Here, the above-mentioned driving will be described with respect to the pneumatic tire 30 for a two-wheeled vehicle for the rear wheel which is a driving wheel.

The above embodiment is an example of the present invention, and the shape, arrangement, angle, width, etc. of each of the lug groove 14 and the circumferential groove 16 are not deviated from the scope of the present invention.
The shape, arrangement, and the like of the block 18 can be appropriately changed. (Test Examples) In order to confirm the effect of the present invention, a total of four types of tires (two types before and after the tire of the embodiment described above) to which the present invention was applied and a conventional tire (two types before and after the tire) were used. Tires were prepared, and a noise test was performed on these four types of tires using an indoor drum tester.

In the test, the test tires were assembled on a rim (the front wheel tire was mounted on a size 2.50 × 18 rim, and the rear wheel tire was mounted on a size 4.50 × 14 rim). An internal pressure of 1.5 kgf / cm ² was charged, and a predetermined load (82 kg for front wheels and 160 kg for rear wheels) was applied to measure the noise level of pattern noise (45 km / h).

As shown in FIG. 3, a tread 102 of a conventional pneumatic tire 100 for a front wheel for a front wheel has a plurality of circumferential grooves 104 extending linearly along the circumferential direction and a plurality of circumferential grooves 104 along the tire axial direction. A plurality of blocks 108 defined by the linearly extending lug grooves 106 are provided.

In the standard ground plane 20, the groove width W1 of the lug groove 106 is 40 (average) mm, the circumferential pitch P of the lug groove 106 is 40 (average) mm, and the negative ratio is 7
0%, the number of appearance of the lug grooves 106 is two. Incidentally, the groove width W2 of the circumferential groove 104 is 12 (average) mm on average in the entire tread 102.

As shown in FIG. 4, a plurality of circumferential grooves 112 extending substantially linearly along the circumferential direction are formed in a tread 102 of a conventional pneumatic tire 110 for a rear wheel.
And a lug groove 1 extending substantially linearly along the tire axial direction
14 and a narrow lug groove 115 crossing the tire equatorial plane CL
(But shallower than the lug groove 114), a plurality of blocks 116 are provided. Incidentally, in the two-wheeled pneumatic tire 110 for a rear wheel, there is no clear distinction between the circumferential groove 112 and the lug groove 114, and the circumferential groove 112 and the lug groove 114 are integrated grooves.

The negative rate of the tread 102 is 7
0%, in the standard ground plane 20, the groove width W1 of the lug groove 106 is 40 (average) mm, the circumferential pitch P of the lug groove 106 is 40 (average) mm, and the number of appearance of the lug groove 106 is 1.
5 or 2.

The groove width W2 of the circumferential groove 104 is 12 (average) mm on average in the entire tread 102.

The test results for the front wheel tires are as shown in the graph of FIG. 5, and the test results for the rear wheel tires are as shown in the graph of FIG.

It can be seen that the tire of the example to which the present invention is applied has a lower peak noise value and lower noise than the conventional tire.

[0090]

As described above, since the pneumatic tire for a motorcycle according to the first aspect has the above-described structure, it is possible to reduce noise when traveling on a rough road without significantly sacrificing the performance on uneven terrain. , Which is an excellent effect.

Since the pneumatic tire for a motorcycle according to the second aspect has the above-described configuration, it is possible to obtain the same level of drainage properties and the ability to discharge soil such as mud when traveling on uneven terrain, and to achieve the same level of durability as before. It has an excellent effect that the property can be obtained.

Since the pneumatic tire for a motorcycle according to the third aspect has the above-described structure, it has an excellent effect that it can surely obtain rough road running performance and low noise.

The pneumatic tire for a motorcycle according to the fourth aspect has the above-described structure, so that the braking performance, the driving performance, the drainage performance, and the soil removal performance can be obtained at the same level as the conventional ones. It is possible to improve the noise level comprehensively.
It has an excellent effect.

Since the pneumatic tire for a motorcycle according to the fifth aspect has the above-described configuration, it has an excellent effect that noise on a rough road can be reduced without significantly sacrificing the terrain running performance.

Since the pneumatic tire for a motorcycle according to the sixth aspect has the above-described configuration, it is possible to obtain the same level of drainage properties and the ability to discharge soil such as mud when traveling on uneven terrain, and to achieve the same level of durability as before. It has an excellent effect that the property can be obtained.

Further, the pneumatic tire for a motorcycle according to the seventh aspect has the above-described structure, so that the braking performance, the driving performance, the drainage performance, and the soil removal performance can be obtained at the same level as the conventional one, and the block rigidity and the rigidity can be improved. It has an excellent effect that the low noise level can be improved at the same time.

[Brief description of the drawings]

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

FIG. 2 is a development view of a tread of a pneumatic tire for a rear wheel motorcycle according to an embodiment of the present invention.

FIG. 3 is a development view of a tread of a conventional pneumatic tire for a motorcycle for a front wheel.

FIG. 4 is a development view of a tread of a conventional pneumatic tire for a rear wheel motorcycle.

FIG. 5 is a graph showing the results of a front wheel noise test.

FIG. 6 is a graph showing the result of a rear wheel noise test.

FIGS. 7A to 7D are explanatory diagrams illustrating the number of appearance of lug grooves. FIGS.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire for motorcycle 12 Tread 14 Lug groove 16 Circumferential groove 18 Block 20 Standard tread

Claims (7)

[Claims] 1. A pneumatic tire for a motorcycle having a plurality of blocks on a tread defined by a plurality of circumferential grooves and a plurality of lug grooves, wherein the lug grooves are inclined with respect to a tire axial direction. The negative rate of the tread is set in the range of 30 to 60%, and the circumferential pitch of the lug grooves in the standard ground plane is at least 50 to 100% of the maximum length of the standard ground plane. A pneumatic tire for a motorcycle, wherein the tire is set to: 2. The air for a motorcycle according to claim 1, wherein the width of the lug groove in the standard ground plane is set within a range of 5 to 50% of the maximum length of the standard ground plane. Containing tires. 3. An angle of a lug groove width center line with respect to a tire equatorial plane within a range of 60 to 70 ° in a range of at least 50% or more of a total length of the lug groove in a standard ground contact surface. The pneumatic tire for a motorcycle according to claim 1 or 2, wherein: 4. The method according to claim 1, wherein the number of the lug grooves appearing in a standard ground plane is set within a range of 0.5 to 2. Pneumatic tire for motorcycles. 5. A pneumatic tire for a motorcycle having a plurality of blocks defined by a plurality of circumferential grooves and a plurality of lug grooves on a tread, wherein at least a part of an edge on a stepping side of the block. Is tilted with respect to the tire axial direction, the negative rate of the tread is set in the range of 30 to 60%, and the circumferential pitch of the lug grooves in the standard ground plane is at least the maximum length of the standard ground plane. A pneumatic tire for a motorcycle, wherein the pneumatic tire is set within a range of 50 to 100% of the above. 6. The pneumatic tire for a motorcycle according to claim 5, wherein a width of the lug groove is set within a range of 5 to 50% of a maximum length of a standard ground contact surface. 7. The pneumatic tire for a motorcycle according to claim 5, wherein the number of the lug grooves appearing in a standard ground contact surface is set within a range of 0.5 to 2. .