WO2010119959A1

WO2010119959A1 - Pneumatic tire for two-wheeled motor vehicle

Info

Publication number: WO2010119959A1
Application number: PCT/JP2010/056866
Authority: WO
Inventors: 辰作片山
Original assignee: 株式会社ブリヂストン
Priority date: 2009-04-17
Filing date: 2010-04-16
Publication date: 2010-10-21

Abstract

A pneumatic tire for a two-wheeled motor vehicle, having enhanced driving stability performance during high-speed running, improved traction performance when the vehicle (motorcycle) is accelerated from the speed of running along a sharp curve during which the vehicle is largely tilted, and improves stability when the vehicle is tilted. A pneumatic tire for a two-wheeled motor vehicle, comprising: bead cores respectively embedded in a left and right pair of bead sections (14); a carcass layer consisting of at least one sheet of a carcass (2) toroidally extending between the pair of bead sections (14); a belt layer (3) consisting at least one sheet of a belt disposed on the outer side of the carcass layer in the radial direction of the tire; and a tread section (11) disposed on the outer side of the belt layer (3) in the radial direction of the tire. Buttress sections (12), side wall sections (13), and the bead sections (14) are provided in sequence to both sides of the tread section (11). Rubber members harder than a rubber member of the tread section (11) and rubber members of the side wall sections (13) are provided to the buttress sections (12).

Description

Pneumatic tires for motorcycles

The present invention relates to a pneumatic tire for a motorcycle (hereinafter, also simply referred to as “tire”), and more specifically, improves the steering stability performance at high speed, and particularly when accelerating from deep cornering that greatly depresses a vehicle (motorcycle). The present invention relates to a pneumatic tire for a motorcycle that can improve traction performance and stability when the vehicle body is collapsed.

In high-performance motorcycle tires, since the rotational speed of the tire is high, the influence of centrifugal force is large, and the tread portion of the tire expands outward, which may impair steering stability performance. Therefore, a tire structure has been developed in which a reinforcing member (spiral member) made of organic fiber or steel is wound around the tread portion of the tire so as to be substantially parallel to the tire equatorial plane.

Examples of the spiral member used for the spiral belt layer include nylon fiber, aromatic polyamide (trade name: Kevlar), and steel. Among them, aromatic polyamide and steel have recently been attracting attention because they can suppress expansion of the tread portion without stretching even at high temperatures. When such a spiral member is wound around the crown portion of the tire, a so-called “tangle” effect (the tire crown portion is restrained by the spiral member so that the tire is inflated by centrifugal force even when the tire rotates at a high speed. A number of techniques for improving these spiral members have been proposed so far (for example, Patent Documents 1 to 5). .

It is known that tires wound with these spiral members have excellent steering stability performance at high speeds and very high traction. However, with regard to the turning performance when the vehicle (motorcycle) is largely tilted, the steering stability performance is not dramatically improved even when the spiral member is wound. For this reason, consumers and riders who are racing may be required to improve grip performance when the motorcycle is greatly defeated.

JP 2004-067059 A JP 2004-067058 A JP 2003-011614 A JP 2002-316512 A JP 09-226319 A

In a pneumatic tire for a motorcycle, since the motorcycle turns while tilting the vehicle body, the place where the tire tread portion is in contact with the ground is different between when going straight and when turning. That is, the center portion of the tread portion is used when going straight, and the end portion of the tread portion is used when turning. Therefore, the shape of the tire is very round compared to the tire for passenger cars. This round crown shape (the shape of the tread portion of the tire is called a crown shape) has the following unique characteristics, particularly during turning.

In the case of motorcycle tires, particularly when the vehicle body is greatly tilted, the end of one side of the tread of the tire comes into contact with the grip to generate a grip. When turning the vehicle body greatly, the grounding state as shown in FIG. 8 is obtained. Considering the ground contact shape at this time, as shown in the drawing, the deformation state of the tread differs between the ground shape near the center and the ground shape near the tread end. Looking at the deformation of the tread in the tire rotation direction (also referred to as the tire equator direction or the tire front-rear direction), it is in the driving state near the center of the tire and in the braking state near the tread end of the tire.

Here, the driving state means that when the wheel is cut along the tire equator direction, the deformation of the tread is caused by the lower surface of the tread (the surface in contact with the skeleton member inside the tire) being sheared rearward in the tire traveling direction. This is a shearing state in which the tread surface that is in contact with the ground is deformed forward in the tire traveling direction, which is a deformation that occurs when a driving force is applied to the tire. On the other hand, the braking state is the reverse of the driving state, and the deformation of the tread is a sheared state in which the tire inner side (belt) is sheared forward, and the tread surface that is in contact with the road surface is deformed rearward, This is the movement of the tire when braking.

As shown in FIG. 8, when turning with a large camber angle (CA) such as 50 degrees, the ground contact area near the tread center even when the tire is rotated without driving force or braking force. The driving state appears at the front and the braking state appears near the tread edge. This is due to the difference in the radius of the belt portion of the tire (diameter difference). In a motorcycle tire, since the tire crown portion is rounded, the distance from the rotating shaft to the belt is greatly different between the tread center portion and the tread end portion. In the case of FIG. 8, the radius R1 near the center of the ground contact shape is obviously larger than the radius R2 near the tread edge of the ground shape. Since the angular speed at which the tire rotates is the same, the speed of the belt (when the tire is in contact with the road surface, it means the speed in the tire equator direction along the road surface; the belt radius multiplied by the tire angular speed) is The portion of R1 having a larger radius is faster. The tread surface of the tire is not sheared in the front-rear direction at the moment of contact with the road surface, but proceeds with the rotation of the tire while in contact with the road surface, and undergoes shear deformation in the front-rear direction when leaving the road surface. At this time, the tread near the tire center where the belt speed is fast becomes shearing deformation in the driving state, and at the tread end portion of the tire, the belt speed is low, so that the braking state occurs. This is a modification of the tread in the front-rear direction.

Such extra deformation during turning causes the tread to undergo forward and backward reverse shear deformation, which includes useless behavior and wasteful tire grip force during turning. Ideally, if all the deformations of the tread that are in contact with the ground are the same, the gripping force will be maximum, but the excessive deformation as described above will occur, and depending on the grounding location, the gripping force may be It may not occur. For example, when considering acceleration when the tire is tilted, the driving force is applied to the tire, but the tread near the center already in the driving state exhibits the driving grip as soon as the driving force is applied to the tire. On the other hand, the tread at the tread end already in the braking state cannot easily contribute to the driving force because the braking deformation once returns to neutral and then shifts to the deformation on the driving side. A large traction force is required to bring the tread end into the driving state. When the accelerator is opened and a driving force is applied to the tire to apply such a traction force, the tire center side in the driving state is originally The tread slips easily and falls into an idle state.

For such problems, it is considered that if the tread deformation of the tire shoulder portion (tread end portion) on the braking side is set to the driving side as much as possible, the traction force can be exerted greatly at the tread end portion. One solution is to increase the belt speed at the tread edge. However, the belt speed is determined by the belt radius as described above, and if the belt radius is increased, the belt cannot be used as a tire for a motorcycle. Therefore, it is conceivable to increase the belt speed by making the belt easily extend in the equator direction at the end of the tread after being grounded. In other words, when turning at a large CA, if the center half of the grounding shape has a structure in which the belt does not extend in the equator direction, and if the belt is extended in the equator direction for the half on the tread end side, then the tread after grounding. By extending the belt on the side, the belt speed on the tread end side is increased, and braking deformation on the tread end side can be reduced. As a result, the traction (acceleration from a turn with a large tilt of the motorcycle) at the time of large CA is improved.

In conventional motorcycle tires, the spiral belt layer is usually wound around the entire tread area. With such a tire, the belt of the shoulder portion of the tread cannot be extended in the equator direction. Therefore, if the spiral belt layer is arranged only on the center side without being wound around the tread edge, the belt speed at the tread edge increases at the time of large CA, that is, at the time of turning with a large camber angle. Thus, the traction grip can be improved. In addition, when the belt speed of the tread shoulder portion increases at the time of large CA, it means that the belt speed of the tread shoulder portion approaches the belt speed on the tread center side, and this causes an extra movement of the tread that is grounded. It is suppressed. That is, the tread that has been sheared in the reverse direction until now has the shear in the same direction, and unnecessary movement is eliminated, and the occurrence of uneven wear can be suppressed. In addition, since the spiral belt layer is disposed in the tread center portion, it is possible to suppress the expansion due to the centrifugal force of the tire during high speed running (high speed = the motorcycle is upright). Steering stability at high speeds can be maintained at the same level as a tire with a full width spiral belt layer.

However, if the spiral belt layer is not wound around the end of the tread, the region where there is no spiral belt layer suddenly touches the ground when the vehicle is tilted down, which is a cause of sudden grip changes (changes in rigidity steps). Also, there may be a problem that the rider feels the difference in level of the tires and cannot defeat the car body.

Accordingly, an object of the present invention is to improve the steering stability performance at high speed, and at the same time, improve the traction performance especially when accelerating from deep cornering that greatly defeats the vehicle (bike) and the stability when the vehicle body is collapsed. The object is to provide a pneumatic tire for a motorcycle.

From the above viewpoint, as a result of further studies, the present inventor can solve the above-mentioned problems by reducing the rigidity of the tread portion of the portion wound with the spiral belt layer and increasing the rigidity of the buttress portion to eliminate the rigidity step portion. As a result, the present invention has been completed.

That is, the pneumatic tire for a motorcycle of the present invention includes a bead core embedded in each of the pair of left and right bead portions, and a carcass layer including at least one carcass extending across the toroid between the pair of bead portions. A belt layer composed of at least one belt disposed on the outer side in the tire radial direction of the carcass layer, and a tread portion disposed on the outer side in the tire radial direction of the belt layer, In a pneumatic tire for a motorcycle that sequentially includes a buttress portion, a sidewall portion, and the bead portion on both sides,
A rubber member harder than the rubber member of the tread portion and the rubber member of the sidewall portion is disposed in the buttress portion.

In the present invention, the belt layer is provided with a spiral belt layer on the outer side in the tire radial direction of the carcass layer and having an arrangement width wound substantially in the width direction that is 0.5 to 0.8 times the entire tread width. Preferably, the spiral belt layer is divided into three in the width direction, and the tensile elastic modulus of the cord constituting the end region of the spiral belt layer divided into three is the cord constituting the central region. It is preferable that it is lower than the tensile elastic modulus. Further, the rubber gauge outside the tire radial direction of the carcass layer in the bead portion side region of the sidewall portion is thinner than the rubber gauge outside the tire radial direction of the carcass layer in the tread portion side region of the sidewall portion, In addition, it is preferable that an average value of the rubber gauge on the outer side in the tire radial direction of the carcass layer in the bead portion side region in the sidewall portion is 0.2 to 2.0 mm. Further, adjacent to the spiral belt layer, a belt crossing layer made of an organic fiber cord that is wider than the spiral belt layer and has an angle with respect to the tire equator direction of 30 degrees or more and less than 85 degrees is disposed. It is preferable that Further, a belt reinforcing layer made of an organic fiber cord having an angle of 85 degrees to 90 degrees with respect to the tire equator direction is in contact with the tread layer between the tread layer of the tread portion and the spiral belt layer. The width is preferably 90% or more and 110% or less, and further, a thickness of 0.3 to 1.5 mm is provided on the inner side in the tire radial direction of the belt reinforcement layer and adjacent to the belt reinforcement layer. It is preferable that a buffer rubber is provided.

According to the present invention, the above configuration enhances the steering stability performance at high speeds, and particularly improves the traction performance when accelerating from the deep cornering that greatly defeats the vehicle (bike) and the stability when the vehicle body is collapsed. It becomes possible to provide a pneumatic tire for a motorcycle that can be improved.

1 is a cross-sectional view in a width direction showing a pneumatic tire for a motorcycle according to a preferred example of the present invention. FIG. 6 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to another preferred embodiment of the present invention. FIG. 6 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. FIG. 6 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. FIG. 6 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. FIG. 6 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. FIG. 6 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to a conventional example. It is sectional drawing which shows the tire just under a load when a two-wheeled vehicle is turning by big CA (CA50 degree | times). It is a graph which shows the friction ellipse which shows the relationship between Fx and Fy.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire for a motorcycle according to a preferred embodiment of the present invention. As shown in the figure, the pneumatic tire for a motorcycle of the present invention includes at least one bead core 1 embedded in a pair of left and right bead portions 14 and at least one piece extending in a toroidal shape between the pair of bead portions 14. A carcass layer made of the carcass 2, a belt layer 3 made of at least one belt disposed on the outer side in the tire radial direction of the carcass layer, and a tread portion 11 arranged on the outer side in the tire radial direction of the belt layer 3. In the illustrated example, the bead core 1 is made of a bead wire 1, the belt layer 3 is made of a spiral belt layer 3, and the carcass layer has two carcass 2. The pneumatic tire for a motorcycle according to the present invention includes a buttress portion 12, a sidewall portion 13, and a bead portion 14 in order on both sides of the tread portion 11.

In the tire of the present invention, the rubber member of the tread portion 11 and the sidewall portion 13 are formed on the buttress portion 12 that is in the region closer to the sidewall portion 13 than the end of the tread portion 11 and closer to the end portion of the tread portion 11. A rubber member 4 that is harder than the rubber member is disposed. The buttress portion 12, which is the boundary between the tread portion 11 having the belt layer 3 and the sidewall portion 13, which generally has the belt layer 3 less than the tread portion 11, has a rigid step portion due to the difference in the number of belt layers 3. Become. For this reason, a sudden grip change at the end of the vehicle body in the buttress portion 12 occurs, and there is a problem that the rider feels the level difference of the tire and cannot collapse the vehicle body. In order to relieve this steep rigidity step, a hard rubber member 4 is disposed at the step portion. By disposing the hard rubber member 4, the compression rigidity is greatly increased due to the incompressibility of the rubber, and the bending rigidity due to the deformation of the stepped portion can be increased. As a result, by using such a configuration, the grip changes gently, and the rider can tilt the vehicle body without feeling uncomfortable.

In the present invention, the arrangement width W of the hard rubber member 4 is preferably 0.01 L ≦ W ≦ 0.1 L, where L is the total width of the tread. The purpose of the hard rubber member 4 is to alleviate the rigidity step, so that an effect cannot be obtained when the arrangement is made with a very narrow width, and the arrangement width of 0.01 L can provide a certain desired effect of the present invention. This is the lower limit. As for the upper limit value, if it exceeds 0.1L, the effect of increasing the bending rigidity of the side portion is increased, and a decrease in ride comfort due to an increase in spring is induced. did.

Furthermore, in the present invention, the hardness of the hard rubber member 4 is preferably 2 to 20 times the hardness of the rubber member of the sidewall portion 13. The purpose of the hard rubber member 4 is to relieve the rigidity step, so that the effect is not obtained with a soft rubber, and the double hardness is a lower limit value that is known to be effective to some extent. Moreover, about the upper limit value, if it is harder than 20 times, the effect of increasing the bending rigidity of the sidewall portion 13 is increased, and the ride comfort is lowered due to the increase in spring. . Further, the hard rubber member 4 is not limited to a single type of rubber, and may be composed of a plurality of types as long as the average hardness of the hard rubber member 4 is within a specified range. . In the present invention, Shore A hardness is used as an index of the hardness of the rubber member 4. Such Shore A hardness can be measured using a commercially available hardness meter. For example, after tread rubber is cut out and stored in a high temperature chamber kept at 50 ° C. for 30 minutes to bring the rubber temperature to 50 ° C., the hardness meter Can measure the hardness.

In the present invention, the belt layer 3 is provided with a spiral belt layer 3 on the outer side in the tire radial direction of the carcass layer and having a wound arrangement width of approximately 0.5 to 0.8 times the entire tread width. Preferably it is. Here, the full width of the tread is a distance of a curved surface from one end portion of the tread portion 11 to the end portion of the tread portion 11 on the opposite side along the tire surface. The basis for setting this width is based on the ground contact portion where the CA (Camber angle) at which the motorcycle falls most greatly is around 50 degrees and the ground contact portion where the motorcycle is slightly raised.

When turning at a CA of 50 degrees, only the tread shoulder portion with a width of 0.2 to 0.25 times the entire width of the tread is grounded (FIG. 8). This is about 1/4 of the total width. As described above, a spiral belt is wound around the tread center portion at the time of large CA to prevent the skeletal member from extending in the tire equator direction in the ground contact range, and conversely, the spiral belt is attached to the end portion side of the tread portion 11. There is a demand for positively extending the skeleton member in the tire equator direction without winding. Half of the grounding part at the time of large CA is 0.1 times the entire width of the tread, and if the spiral belt is not wound around this width, there is no spiral belt in the 0.1 times wide part at both ends. The total width of the spiral belt layer 3 is 0.8 times the tread width.

The above upper limit is an ideal value for grounding when the bike is most collapsed. However, when the motorcycle accelerates, the acceleration starts from the time when the motorcycle falls most, and the vehicle body is gradually raised, that is, the ground contact portion of the tire gradually moves from the center. Further, the motorcycle accelerates most in the range of 30 to 45 degrees CA than when the bike fell most at 50 degrees CA. In consideration of maximizing the traction performance at this time, it is preferable that the spiral belt width is narrower than the above 0.8 times width. Therefore, 0.5 times is set as the lower limit of the spiral belt width. When the spiral belt layer width is 0.5 times the tread width, the end portion of the spiral belt layer is located at the center in the width direction of the ground contact portion at CA 30 to 40 degrees. If the spiral belt width is less than 0.5 times, the position is shifted from the center in the width direction of the ground contact shape of CA 30 to 40 degrees, which is not preferable. That is, the spiral belt layer 3 is too narrow.

From the above, when the arrangement width of the spiral belt layer 3 is 0.8 times the upper limit of the tread width, the end of the spiral belt layer is positioned at the center of the ground contact shape near the CA of 50 degrees where the motorcycle is most tilted. The grip improvement effect becomes high in the early stage of acceleration. In addition, the effect is high at a low-speed corner where a motorcycle is greatly defeated (it is possible to greatly defeat a motorcycle at a low-speed corner). On the other hand, when the arrangement width of the spiral belt layer 3 is 0.5 times the tread width which is the lower limit, the end of the spiral belt layer can be arranged at the center of the ground shape when the motorcycle is slightly raised (CA30). From ~ 40 degrees), the grip improvement effect can be demonstrated in the middle of the acceleration when the vehicle body is slightly raised. In addition, it demonstrates the effect of increasing the grip at high-speed corners that do not overwhelm the bike. In the present invention, the spiral belt layer is arranged so that the center in the width direction coincides with the tire equator. This makes it possible to match the left and right reinforcement directions when the vehicle body is folded down.

The cord constituting the spiral belt layer 3 may be an organic fiber cord or a steel cord. In the case of organic fiber cords, for example, twisted cords such as aromatic polyamide (trade name: Kevlar), nylon, and aromatic polyketone can be used. In the case of a steel cord, for example, five steel single wires having a wire diameter of 0.2 mm or five steel single wires having a wire diameter of 0.4 mm can be used without being twisted.

Further, in the present invention, when the spiral belt layer 3 having a winding width of approximately 0.5 to 0.8 times the entire width of the tread is provided outside the carcass layer in the tire radial direction. The effect of relieving the step between the tread portion 11 and the sidewall portion 13 due to the hard rubber member 4 is remarkably obtained. When the spiral belt layer 3 is made narrower than the entire width of the tread, the spiral belt layer 3 is suddenly absent when the vehicle body is tilted (in-belt in-plane shear), as compared with the case where the spiral belt layer 3 has the entire tread width. Since the portion where the rigidity is lowered) is grounded, the rigidity step is further promoted. Therefore, by disposing the hard rubber member 4 in the buttress portion 12 as in this configuration, this rigidity step is alleviated and the change in grip can be made smooth. Moreover, since the shearing strain applied to the end portion of the spiral belt layer 3 can be relieved by relaxing the rigidity step, it is possible to prevent a crack failure that tends to occur at the end portion.

2 and 3 show a pneumatic tire for a motorcycle according to another preferred embodiment of the present invention. In the present invention, as shown in the drawing, the organic fiber cord is adjacent to the spiral belt layer 3 and wider than the spiral belt layer 3 and has an angle with respect to the tire equator direction of 30 degrees or more and less than 85 degrees. The belt crossing layer 5 is preferably disposed. This is because if the belt crossing layer is not present at the left and right shoulder portions of the tread portion 11 around which the spiral belt is not wound, the shear rigidity of the belt is lowered, and the belt is too weak. This is because the grip force is reduced.

When the angle of the belt crossing layer 5 arranged on the shoulder portion of the tread portion 11 with respect to the tire equator direction is less than 30 degrees, this is a direction approaching the angle of the spiral belt layer 3, and the belt extends in the tire equator direction. Brings difficult characteristics. This would be contrary to the spirit of the present invention in which the shoulder belt extends in the tire equator direction in the installation region. Therefore, when the belt is less than 30 degrees, the skeleton member is difficult to extend in the tire equator direction at the shoulder, the belt speed of the shoulder does not increase, and the tread of the shoulder remains in the braking deformation, and the traction grip Can't get. On the other hand, when the belt of the shoulder portion is 85 degrees or more, it is not possible to obtain a sufficient crossing effect as the belt crossing layer 5 (an effect of increasing the in-plane shear rigidity of the belt by superimposing belts in opposite directions), The in-plane rigidity of the shoulder belt is insufficient and a sufficient turning grip cannot be obtained. The angle is particularly preferably 45 degrees or more because the skeleton member is easy to extend in the tire equator direction. Moreover, 80 degree | times or less are good also when exhibiting in-plane shear rigidity. Therefore, it is preferably 45 degrees or more and 80 degrees or less.

The material of the belt crossing layer 5 is an organic fiber cord. If a cord having rigidity in the compression direction of the cord, such as a steel cord, is arranged as the belt crossing layer 5, the skeleton member has a characteristic that it is difficult to bend out of the plane, the ground contact area is reduced, and the grip force is reduced. . If it is an organic fiber cord, it does not have a great rigidity for compression in the cord direction, it can reduce the out-of-plane rigidity of the skeleton member and increase the ground contact area, and it is very strong in the tension direction of the cord This is because the in-plane rigidity can be effectively increased due to the rigidity. In the present invention, the belt crossing layer 5 may be disposed on the outer side in the tire radial direction of the spiral belt layer 3 as shown in FIG. 2, or the tire radius of the spiral belt layer 3 as shown in FIG. If it arrange | positions adjacent to the spiral belt layer 3, you may arrange | position in the direction inner side, and there will be no restriction | limiting in particular in the arrangement order.

Further, in the present invention, as shown in FIGS. 1 and 3, the angle with respect to the tire equator direction is between 85 degrees and 90 degrees between the tread layer of the tread portion 11 and the spiral belt layer 3 and adjacent to the tread layer. It is also preferable to dispose a belt reinforcing layer 6 made of an organic fiber cord. In the tread portion, the rigidity step at the boundary between the portion where the spiral belt layer 3 exists and the portion where the spiral belt layer 3 does not exist is large. In order to alleviate the level difference, the belt reinforcement layer is arranged continuously from the tire center to the tire shoulder as a belt adjacent to the tread layer, that is, as the outermost layer. it can.

The reason why the angle of the belt reinforcing layer 6 is set to 90 degrees with respect to the tire equator direction is that the step is most effectively prevented from being felt by arranging the cords along the width direction. Here, the reason why the angle is given a width of 85 degrees to 90 degrees includes a manufacturing error. Further, the arrangement width of the belt reinforcing layer 6 is 90% to 110% of the entire width of the tread. The purpose of the belt reinforcing layer 6 is to prevent the step from being felt, that is, the end of the spiral belt is covered with a member so that the outermost belt is not divided. Therefore, it is preferable to widen the arrangement width and cover the entire area of the tread. If the arrangement width is 90% or more of the total tread width, the step of the spiral belt can be sufficiently covered. In addition, about an upper limit, you may reach a sidewall part exceeding a tread width. However, if it exceeds 110%, there will also be a 90 degree belt in the sidewall portion of the tire, the sidewall will be difficult to bend, and the tire will be hard, that is, the tire will be difficult to bend. There is a risk that performance will deteriorate. Therefore, the upper limit was made 110%.

The belt reinforcing layer 6 is made of an organic fiber cord because a motorcycle tire has a very round cross section. If a steel cord having rigidity on the compression side of the cord is used in the tire width direction, the tire will bend. This is because the contact area is reduced. The organic fiber cord has low rigidity on the compression side of the cord, and there is no risk of reducing the ground contact area.

In addition, since the reason for providing the belt reinforcing layer 6 is to eliminate the step at the end of the spiral belt, the effect cannot be obtained if the diameter of the cord is too thin. On the other hand, if the diameter of the cord is too large, the cord has rigidity on the compression side of the cord although it is an organic fiber cord. Therefore, the diameter of the cord of the belt reinforcing layer 6 is preferably 0.5 mm or greater and 1.2 mm or less.

Here, as described above, the belt crossing layer 5 may be provided on the inner side or the outer side of the spiral belt layer 3 in the tire radial direction. When 5 is present in the tire radial direction inner side than the spiral belt layer 3, the belt reinforcing layer 6 is disposed immediately outside the spiral belt layer 3 in the tire radial direction (see FIG. 3). On the other hand, when the belt crossing layer 5 exists outside the spiral belt layer 3 in the tire radial direction, the belt reinforcing layer 6 is disposed immediately outside the outer belt in the tire radial direction of the two belt crossing layers 5 ( Not shown). In any case, it is necessary to dispose the belt reinforcing layer 6 immediately inside the tread portion 11 in the tire radial direction and adjacent to the tread portion 11.

FIG. 4 shows a cross-sectional view of a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. In the present invention, when the belt reinforcing layer 6 is disposed, as shown in the drawing, a buffer having a thickness of 0.3 to 1.5 mm is provided on the inner side in the tire radial direction of the belt reinforcing layer 6 and adjacent to the belt reinforcing layer 6. It is also preferable to dispose the rubber layer 7. The buffer rubber layer 7 has an effect of suppressing wear of the tread of the shoulder portion.

FIG. 8 shows the behavior in the tread width direction when the tire turns at a CA of 50 degrees. On the other hand, the deformation of the tread in the tire equator direction also shows the tread end in FIG. 8 in the region where the tread is in contact with the road surface. And the tread center area are different. This is because the belt speed is different between the area near the center of the ground contact shape and the area near the tread end of the ground contact shape. The tire of a motorcycle has a large roundness in the cross section in the width direction. Therefore, the belt radius, which is the distance from the rotating shaft to the belt, is larger in the region near the tread center. Therefore, the speed of the belt, that is, the belt speed until the tread moves away from the road surface after the tread comes into contact with the road surface, and the region near the tread center becomes faster. This is because the belt speed is obtained by multiplying the belt radius by the rotational angular velocity of the tire. Due to the speed difference in the equator direction of the belt, the tread is in the driving state near the center of the tire, and the braking state is in the region near the tread end of the tire (described above).

In the present invention, by reducing the width of the spiral belt layer, the belt in the portion where the spiral belt layer is not disposed extends along the ground in the tire equator direction, and the belt speed is improved. As described above, the simple deformation is alleviated. However, reducing the width of the spiral belt to alleviate it does not completely eliminate the extra deformation.

When the buffer rubber layer 7 is provided on the inner side of the belt reinforcing layer 6 in the tire radial direction, the buffer rubber layer 7 shears and deforms in the tire equator direction, so that the buffer rubber layer 7 takes over the driving deformation and braking deformation of the tread. The tread tire equator deformation is further alleviated. On the other hand, since the shock absorbing rubber layer 7 has the belt reinforcing layer 6 along the tire width direction on the upper surface thereof, it is not easily sheared and deformed in the tire width direction. Therefore, the buffer rubber layer 7 does not take over the deformation of the tread in the tire width direction, and the lateral shear deformation of the tread remains large even when the buffer rubber layer 7 is disposed. That is, the shock absorbing rubber layer 7 takes over the deformation of the tread only in the tire equator direction, reduces the deformation of the tread in the tire equator direction, and further improves the grip force, while, on the other hand, the deformation of the tread in the tire width direction. Without changing the shoulder, the lateral deformation of the tread is kept large and the lateral force is kept high. As in the present invention, when the spiral belt layer width is narrowed and the buffer rubber layer 7 is provided, the tread is further prevented from being deformed in the tire equator direction. preferable. The belt reinforcing layer 6 and the shock absorbing rubber layer 7 are preferably arranged widely, particularly in the range of 90% or more of the tread width, particularly 110% or less.

FIG. 5 shows a cross-sectional view of a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. In the present invention, as shown in the drawing, the rubber gauge on the outer side in the tire radial direction of the carcass layer in the bead portion side region C of the sidewall portion 13 is the outer side in the tire radial direction of the carcass layer in the tread portion side region D of the sidewall portion 13. It is preferable that the average value of the rubber gauge on the outer side in the tire radial direction of the carcass layer in the bead portion side region C is 0.2 to 2.0 mm. When the hard rubber member 4 is disposed in the buttress portion 12, the effect of increasing the bending rigidity of the buttress portion 12 is increased, and there is a risk of inducing a decrease in riding comfort due to an increase in springiness. As a countermeasure against this, it is effective to reduce this increase in springiness at the sidewall portion 13 near the bead portion 14 that has little influence on the rigidity step. Therefore, by reducing the thickness of the rubber gauge on the outer side in the tire radial direction of the carcass layer in the bead portion side region C of the sidewall portion 13, the spring property is reduced. The lower limit of the rubber gauge is set to 0.2 mm because the thinner the rubber gauge, the better. However, if it is less than 0.2 mm, it is difficult to manufacture. Furthermore, if the upper limit value is exceeded 2.0 mm, there is no difference from a normal side gauge, so the effect of reducing rigidity cannot be obtained. Here, from the half of the height from the tread end to the bead heel portion, the upper side in the tire radial direction is the tread portion side region D and the lower side in the tire radial direction is the bead portion side region C.

FIG. 6 shows a sectional view of a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. In the present invention, as shown in the drawing, the spiral belt layer 3 is divided into three in the width direction, and the tensile elastic modulus (hereinafter simply referred to as “ Is preferably lower than the tensile elastic modulus of the cord constituting the central region A. When the spiral belt layer 3 is made narrower than the entire width of the tread, the spiral belt layer 3 is suddenly absent when the vehicle body is tilted (in-belt in-plane shear), as compared with the case where the spiral belt layer 3 has the entire tread width. This will cause a sudden change of grip when the car body is finished, causing a problem that the rider feels a step in the tire and can not push down the car body. . In order to further alleviate this steep rigidity step, a cord having a tensile elastic modulus lower than that of the central region A is used for both end regions B of the spiral belt layer 3. By using such a configuration, the change in grip becomes smoother, so that the rider can tilt the vehicle body without feeling uncomfortable. Moreover, since the shearing strain applied to the end portion of the spiral belt layer 3 can be relieved by further relaxing the rigidity step, it is possible to prevent a crack failure that tends to occur at the end portion. Here, as a method of changing the elastic modulus in the both end region B and the central region A of the spiral belt layer 3, use of a different cord type for each region can be mentioned. In the present invention, the tensile elastic modulus of the cord is compared with the value measured under the same conditions such as temperature, and the tensile elastic modulus is measured in accordance with JISL1017-2002. The load-elongation curve obtained at ± 2 ° C. and 55% humidity was calculated from the slope of the tangent and the filament fineness. Here, the ratio when the spiral belt layer 3 is divided into three in the width direction can be set to, for example, both end regions B: 42.5 to 30% with respect to the center region A: 15 to 40%. .

In the tire of the present invention, it is important only that the buttress portion 12 satisfies the above conditions such as the placement of a rubber member harder than the rubber member of the tread portion 11 and the rubber member of the sidewall portion 13. Thus, the desired effect of the present invention can be obtained, and other conditions such as the tire structure and material are not particularly limited.

For example, the carcass 2 that forms the skeleton of the tire of the present invention is composed of at least one carcass ply formed by arranging relatively highly elastic textile cords in parallel with each other. The number of carcass plies may be one or two, or three or more. Further, both ends of the carcass 2 may be sandwiched and locked by the bead wire 1 from both sides as shown in FIG. 1 or the like, or may be folded around the bead core from the inside of the tire to the outside (not shown). Any fixing method may be used. Further, an inner liner is disposed on the innermost layer of the tire (not shown), and a tread pattern is appropriately formed on the surface of the tread portion 11 (not shown). The present invention is applicable not only to radial tires but also to bias tires.

Hereinafter, the present invention will be specifically described with reference to examples.
Example 1
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 1 was manufactured with a tire size of 190 / 50ZR17 in accordance with the following conditions. The test tire includes a carcass composed of two carcass plies (body plies) extending across a toroid between a pair of bead cores. Here, nylon fiber was used for the carcass ply. The angle of the two carcass was 90 degrees with respect to the radial direction (tire equator direction). Further, as shown in the figure, the end portion of the carcass ply was sandwiched by bead wires from both sides in the bead portion and locked by the bead core.

A spiral belt layer was arranged on the outer side of the carcass in the radial direction of the tire. The spiral belt layer was formed in a so-called spiral shape in which a steel cord twisted by a 1 × 5 type steel single wire having a diameter of 0.18 mm was spirally wound in the tire equator direction. The spiral belt layer is a method in which a belt-like body in which a single parallel cord is embedded in a coated rubber is wound in a spiral direction along the tire equator direction in the tire rotation axis direction. Formed with. The total width of the spiral belt layer is 170 mm, which corresponds to 0.71 times the total tread width (L) of 240 mm.

Also, a rubber member that is harder than the rubber member of the tread portion and the rubber member of the sidewall portion is disposed in the buttress portion. The hard rubber member was arranged with a width of 0.04 L from the end of the tread portion, and the hardness was four times that of the rubber member of the sidewall portion.

A belt reinforcing layer made of an aromatic polyamide fiber having an angle of 90 degrees with respect to the tire equator direction was disposed outside the spiral belt layer in the tire radial direction. Aromatic polyamide fibers were twisted to form a cord having a diameter of 0.7 mm, and the cord was driven into 50 cords / 50 mm and arranged at 90 degrees with respect to the tire equator direction. The width is the same as the tread width. A tread layer having a thickness of 7 mm was disposed outside the belt reinforcing layer in the tire radial direction.

(Example 2)
A tire of Example 2 was produced in the same manner as Example 1 except that the spiral belt width was 120 mm (0.5 times the total tread width).

(Example 3)
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 2 was produced according to the following conditions. One carcass ply was arranged in the radial direction (angle with respect to the tire equator direction was 90 degrees). In addition, a spiral belt layer exists outside the carcass ply in the tire radial direction. The material and driving of the spiral belt layer are the same as in the first embodiment. Two belt crossing layers (abbreviated as “crossing layers” in Tables 1 and 2) are arranged outside the spiral belt layer in the tire radial direction. The belt crossing layer was formed by twisting aromatic polyamide into a cord having a diameter of 0.5 mm and placing it at 50 pieces / 50 mm. The angle of the belt crossing layer is 60 degrees with respect to the tire equator direction, and crosses each other. The width of the belt crossing layer was 250 mm on the first sheet (inner side) and 230 mm on the second sheet (outer side). A belt reinforcing layer of 90 degrees with respect to the tire equator direction is not provided outside the belt crossing layer in the tire radial direction. The tire of Example 3 was manufactured in the same manner as Example 1 except for the above.

Example 4
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 3 was produced according to the following conditions. One carcass ply was placed in the radial direction. In addition, two belt crossing layers similar to those in Example 3 were disposed on the inner side in the tire radial direction of the spiral belt layer. Therefore, in this case, the belt crossing layer exists immediately outside the carcass in the tire radial direction, and the spiral belt layer exists outside the belt crossing layer in the tire radial direction. The configuration of the spiral belt layer is the same as that of Example 3. A belt reinforcing layer having an angle of 90 degrees with respect to the tire equator direction exists outside the spiral belt layer in the tire radial direction. The outermost belt reinforcing layer has the same configuration as in the first embodiment. A tread exists on the outer side in the tire radial direction of the outermost belt reinforcing layer.

(Example 5)
A tire of Example 5 was produced in the same manner as Example 4 except that the belt reinforcing layer on the outer side in the tire radial direction of the spiral belt layer of Example 4 was removed.

(Example 6)
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 4 was produced according to the following conditions. A rubber layer having a thickness of 0.6 mm is disposed on the inner side in the tire radial direction of the outermost belt reinforcing layer. The material of the rubber layer is the same as the coating rubber used for the belt reinforcing layer. The width of the rubber layer is also the same as the width 240 mm of the belt reinforcing layer. Otherwise, the tire of Example 6 was made in the same manner as Example 4.

(Example 7)
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 5 was produced according to the following conditions. The rubber gauge outside the tire radial direction of the carcass layer in the bead portion side region of the sidewall portion is made thinner than the rubber gauge outside the tire radial direction of the carcass layer in the tread portion side region of the sidewall portion, and in the bead portion side region The average value of the rubber gauge on the outer side in the tire radial direction of the carcass layer was set to 1.0 mm. Otherwise, the tire of Example 7 was made in the same manner as Example 6.

(Example 8)
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 6 was produced according to the following conditions. As a member in the end region of the spiral belt layer, an aromatic polyamide fiber is twisted and driven with a cord having a diameter of 0.7 mm to make 50 pieces / 50 mm, and a steel cord is used as a member in the center region of the spiral belt layer. , The tensile elastic modulus of the cord of the member in both end regions was made lower than the tensile elastic modulus of the cord of the member in the central region. Here, the ratio of each region was set to 40% for both end regions B with respect to 20% for the central region A: 20%. Otherwise, the tire of Example 8 was made in the same manner as Example 6.

(Examples 9 to 12)
Examples 9 to 12 have the same configuration as that of Example 4, and only the types of rubber members arranged in the buttress portion are changed as shown in Tables 1 and 2 below.

(Conventional example 1)
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 7 was produced according to the following conditions. One carcass ply was placed in the radial direction. A belt crossing layer was disposed outside the carcass in the radial direction of the tire. The material of the belt crossing layer is the same as in Example 3. One spiral belt layer is disposed outside the belt crossing layer in the tire radial direction. The spiral belt is a steel belt, and driving is 50 pieces / 50 mm.

(Conventional example 2)
The crossing belt is removed from Conventional Example 1. Two carcass plies were arranged in the radial direction.

(Comparative Example 1)
A tire of Comparative Example 1 was produced in the same manner as in Example 4 except that there was no rubber member arranged in the buttress portion.

(Comparative Example 2)
A tire of Comparative Example 2 was produced in the same manner as Comparative Example 1 except that the spiral belt layer width was 100 mm.

(Example 13)
A tire of Example 13 was made in the same manner as Example 4 except that the rubber member was 0.15 L wide from the end of the tread part and arranged in the buttress part.

(Example 14)
A tire of Example 14 was produced in the same manner as in Example 4 except that the rubber member disposed in the buttress portion was very hard, 25 times as hard as the rubber member in the sidewall portion.

The following prescribed tests were carried out for each of the obtained tires. Tables 1 and 2 summarize the tire structures of Examples 1 to 14, Comparative Examples 1 and 2, and Conventional Examples 1 and 2.

<Drum test>
First, it was measured using a drum whether the traction when the vehicle body was tilted, which is the main object of the present invention, was improved. The method for measuring traction using a drum is as follows.

As a testing machine, sandpaper was pasted on a drum with a diameter of 3 m, and the surface of the sandpaper was likened to the road surface. The drum was rolled at a speed of 80 km / h, and a tire was pressed onto the drum at a CA of 35 degrees and a CA of 50 degrees. Each test tire was filled with an internal pressure of 240 kPa and pressed with a load of 1471 N (150 kgf). The tire has a chain that transmits power to the rotating shaft, and a driving force can be applied. The driving force was applied using a motor. The tire was rotated at 80 km / h, and driving force was applied to accelerate the tire linearly to 120 km / h in a time of 3 seconds. At this time, since the drum rolls at 80 km / h, the driving force is applied to the tire, and the traction can be measured with the vehicle body tilted.

The force acting in the direction parallel to the tire rotation axis (that is, the tire width direction) and the force acting in the direction perpendicular to the tire rotation axis are measured by a force sensor installed at the center of the tire wheel, and these forces are measured by the camber. The force in the drum width direction and the drum rotation direction are decomposed according to the angle, the force in the drum width direction is Fy, and the force in the drum rotation direction is Fx (Fx and Fy are coordinates with respect to the ground). That is, Fy indicates a lateral force for turning the motorcycle, and Fx indicates a driving force for accelerating the motorcycle. By drawing these as Fx on the horizontal axis and Fy on the vertical axis, a waveform as shown in FIG. 9 is obtained. Although this is called a friction ellipse, the intercept of Fy at Fx0 indicates a pure lateral force at a driving force of 0, and this is a force called camber thrust. In this test, the grip performance of a tire in a traction state can be evaluated by applying a driving force to the tire to accelerate the rotation of the tire. With time, the waveform of the graph moves in the positive direction of Fx. The maximum value of Fx can be said to be an index of traction grip.

The maximum value of Fx at CA 35 degrees in Example 1 was 102, and the maximum value of Fx at CA 50 degrees was 103, and the performance of other examples was evaluated by an index. The obtained results are shown in Table 3 below.

<Driving test>
Next, in order to confirm the performance improvement effect of the two-wheeled vehicle tire of the present invention, a result of a steering performance comparison test using an actual vehicle will be described. Since each of the test tires was a rear tire, an actual vehicle test was performed by exchanging only the rear tire. The front tire was always fixed with a conventional one. The evaluation method is described below.

Each test tire was mounted on a 1000cc sports-type motorcycle, and the vehicle was run on a test course. The steering stability (cornering performance) was comprehensively evaluated by a 10-point method based on the feeling of the test rider. On the course, the motorcycle ran intensely in consideration of motorcycle racing, and the maximum speed reached 180 km / h. The test items are low-speed corner traction performance (acceleration performance from a state where the vehicle body is largely defeated at a speed of 50 km / h), high-speed corner traction performance (acceleration performance from a state where the vehicle body is slightly defeated at a speed of 120 km / h), The grip stability (discontinuity) when the car body is tilted down. The test results obtained are summarized in Table 3.

* 1 Indicates the width and hardness from the end of the tread part of the rubber member.
* 2 The value in parentheses is the ratio of the width of the spiral belt layer to the tread width.
* 3 The average value of the rubber gauge on the outer side in the tire radial direction of the carcass layer in the bead side region.

* 4 Indicates the material and width of the spiral belt layer.

It is clear that the stability of the present example is significantly improved when compared with Comparative Example 1 in which the spiral width is narrowed without placing a hard rubber member in the buttress portion. Thus, it was confirmed that the effect of reducing the rigidity step by the hard rubber member was very large.

In Example 1, there is no crossing belt. Therefore, manufacturing costs can be saved. Compared to the conventional example 2, in the comparison of the ones without the crossing belt, the Fx index of the CA 35 degree and the CA 50 degree is improved in the example 1, and the traction performance is improved in the actual vehicle test in both the low speed corner and the high speed corner. I understand that.

Examples 3 and 5 have two crossing belts. Compared with the prior art examples 1 and 2, the traction performance is significantly improved.

Comparison of Example 4 and Example 6 shows that the traction performance is improved by the buffer rubber layer.

In addition, the comparison between Example 5 and Examples 4 and 6 shows the effect of the outermost belt reinforcing layer and the buffer rubber layer on the stability when folded. By adding the outermost belt reinforcement layer and the shock absorbing rubber layer, the rigidity step is eliminated and the stability is increased.

From the relationship between Examples 4, 5, and 6, the effects of the outermost belt reinforcement layer and the hard rubber member of the buttress portion on the stability when collapsed are found. By combining the hard rubber member of the buttress portion with the outermost belt reinforcing layer, the collapse property is greatly improved, and further, the rigidity step is eliminated and the stability is greatly increased.

From the relationship between Examples 6, 7, and 8, the effect of thinning the rubber gauge on the outer side in the tire radial direction of the carcass layer in the bead portion side region of the sidewall portion and the change of the spiral belt end member on the stability when collapsed I understand. By combining the hard rubber member of the buttress portion, the thinning of the rubber gauge, and the change of the spiral belt end member, the folding property is further improved, and the effect of increasing the stability by another step is obtained.

From Examples 1 and 2, the influence of the width of the spiral belt layer can be seen. If the width of the spiral belt layer is widened, the Fx index at the time of large CA is improved, that is, a large effect can be obtained at a low-speed corner at the time of large CA that greatly depresses the vehicle body. However, when the full width of the tread is used as in Conventional Examples 1 and 2, there is no effect of improving the traction performance. When the sparele belt layer width is narrowed, a large effect can be obtained at a small CA, that is, at a high-speed corner of about 35 degrees CA. However, if it is made too narrow as in Comparative Example 2, the effect is lost.

From the comparison between Example 4 and Examples 9 to 14 and Comparative Example 1, it can be seen that the arrangement width of the hard rubber member in the buttress portion and the effect on the stability when collapsed are brought down. For stability when collapsed, the rubber member is effective if there is an arrangement width of about 0.01 L and a hardness of about twice, but Comparative Example 1 below (when there is no rubber member) ) Is clearly ineffective. Further, the rubber member is effective even when the arrangement width is about 0.1 L and the hardness is about 20 times, but it is harder than that (Example 13: 0.15 L) and hard (Example 14: 25 times). In some cases, in the stability at the time of collapse, the effect is diminished and the improvement effect cost is small. From this result, it can be seen that the arrangement width of the rubber member should be about 0.01 L to 0.1 L and the hardness should be 2 to 20 times.

Examples 7 and 8 are obtained by adding conditions for buffer rubber layer, rubber gauge thinning and spiral belt end member change to Example 4. In this evaluation, both the traction performance and the stability performance when collapsed are the best results, and it can be seen that the performance improvement at a much higher level can be achieved compared to the conventional example. In addition, with regard to the fall stability performance of the vehicle body, the result exceeds the conventional example in which the spiral belt layer is arranged to the end, and the effect of the above combination can be seen.

From the above results, it has been found that according to the present invention, it is possible to achieve a high level of both the steering stability performance (traction performance) when turning the vehicle body and the stability when the vehicle body is lowered.

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass 3 Belt layer 4 Rubber member 5 Belt crossing layer 6 Belt reinforcement layer 7 Buffer rubber layer 11 Tread part 12 Buttress part 13 Side wall part 14 Bead part A Central part area B Both end area C Bead part of side wall part Side region D Tread part side region of sidewall part

Claims

A bead core embedded in each of the pair of left and right bead portions, a carcass layer composed of at least one carcass extending across the toroidal shape between the pair of bead portions, and an outer side in the tire radial direction of the carcass layer A belt layer composed of at least one belt, and a tread portion disposed on the outer side in the tire radial direction of the belt layer. In pneumatic tires for motorcycles that are sequentially equipped,
A pneumatic tire for a motorcycle, wherein a rubber member harder than the rubber member of the tread portion and the rubber member of the sidewall portion is disposed in the buttress portion.
The spiral belt layer having an arrangement width of approximately 0.5 to 0.8 times the entire width of the tread as the belt layer is provided on the outer side in the tire radial direction of the carcass layer. Pneumatic tires for motorcycles.
The spiral belt layer is divided into three in the width direction, and the tensile elastic modulus of the cord constituting the end region of the three-split spiral belt layer is lower than the tensile elastic modulus of the cord constituting the central region. The pneumatic tire for a motorcycle according to claim 2.
The rubber gauge outside the tire radial direction of the carcass layer in the bead portion side region of the sidewall portion is thinner than the rubber gauge outside the tire radial direction of the carcass layer in the tread portion side region of the sidewall portion, and The pneumatic tire for a motorcycle according to claim 1, wherein an average value of a rubber gauge on the outer side in the tire radial direction of the carcass layer in a bead portion side region in the sidewall portion is 0.2 to 2.0 mm.
The rubber gauge outside the tire radial direction of the carcass layer in the bead portion side region of the sidewall portion is thinner than the rubber gauge outside the tire radial direction of the carcass layer in the tread portion side region of the sidewall portion, and The pneumatic tire for a motorcycle according to claim 2, wherein an average value of a rubber gauge on an outer side in a tire radial direction of the carcass layer in a bead portion side region in the sidewall portion is 0.2 to 2.0 mm.
Adjacent to the spiral belt layer, a belt intersection layer made of an organic fiber cord that is wider than the spiral belt layer and has an angle with respect to the tire equator direction of 30 degrees or more and less than 85 degrees is disposed. The pneumatic tire for a motorcycle according to claim 2.
Between the tread layer of the tread portion and the spiral belt layer, a belt reinforcing layer made of organic fiber cords in contact with the tread layer and having an angle with respect to the tire equator direction of 85 degrees to 90 degrees is 90% of the total width of the tread. The pneumatic tire for a motorcycle according to claim 2, wherein the tire is disposed with a width of not less than 100% and not more than 110%.
The pneumatic tire for a motorcycle according to claim 7, wherein a cushioning rubber having a thickness of 0.3 to 1.5 mm is disposed on the inner side in the tire radial direction of the belt reinforcing layer and adjacent to the belt reinforcing layer.