JP2009096424A - Pneumatic tire for two-wheel vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a two-wheel vehicle capable of enhancing lateral grip force in turning of the two-wheel vehicle and reducing tread abrasion of a shoulder part. <P>SOLUTION: A rubber on a surface layer 15a arranged on a tread surface of the tire 10 for the two-wheel vehicle is a high loss rubber having relatively large magnitude of tan δ. A first different kind of rubber layer 15c comprising a different kind of rubber having an index of tan δ of 70, in which one end is positioned at tread end part 15z, the other end is in a range of 5-30% of tread deployment width when it is measured from the tread end part 15z and thickness is 20-70% of thickness of the whole of the tread is arranged on an inner layer of the surface layer 15a of the shoulder part 16. Thereby, heat generation by deformation of a tread rubber is reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle, and more particularly to improvement of a lateral grip during turning and prevention of tread wear of a shoulder portion.

A tire for a motorcycle has a feature of turning the vehicle body while turning. Therefore, the portion of the tire that contacts the road surface moves due to the inclination of the vehicle body. In other words, the tire center portion is used when going straight, and the shoulder portion of the tire is used when turning.
Also, when standing upright, the speed is high and a force in the front-rear direction (the equator direction of the tire) such as braking force and driving force is applied, but a large lateral force is applied when turning the vehicle body, so the tire shoulder has the above lateral High lateral grip corresponding to force is required. In other words, in order to turn a two-wheeled vehicle quickly, it is necessary to greatly depress the vehicle body in order to balance with the centrifugal force that increases with the turning speed, and the tire is placed on the road surface so that it can be opposed to the centrifugal force. Must be able to grip.
In other words, when the vehicle body is greatly tilted, if the grip of the tire is insufficient, the vehicle cannot turn quickly, so the influence of the grip on the shoulder portion on the turning performance is very large. Therefore, rubber with a high grip is used for the shoulder portion of the tire.
In addition, with respect to the center portion of the tire, a commercially available tire has a high frequency of straight running, and therefore rubber with high wear resistance is often used. On the other hand, in tires for races and competitions, the speed when going straight is very high, so rubber that does not generate heat is placed in the tread center part, or the tread center part has a double structure and rubber that does not generate heat is inside. Some ideas have been devised such as placing rubber with high grip outside.

Tread heat generation also becomes a problem in the tire shoulder. This heat generation increases as the strain repeatedly applied to the rubber increases, and increases as the tire rotation speed increases. In particular, not only motorcycle racing, but also general consumers, when riding hard, not only a large input is applied to the shoulder part of the tire, but also the car body turns at a relatively fast speed, so the heat of the tread rubber on the shoulder part Is big.
Since rubber has a property of softening when it generates heat, the rubber softens and the tread rigidity is lowered, so that the turning performance is lowered, the wear of the shoulder portion is advanced, and the rubber of the shoulder portion is deteriorated.

On the other hand, as a characteristic of rubber, loss tangent (tan δ) has a very large meaning in the magnitude of the force (or the coefficient of friction between the rubber and the road surface) when the rubber grips the road surface. Rubber with a large tan δ has a large energy loss due to deformation of the rubber and a high grip. However, since the energy loss is large, the rubber itself tends to generate heat when repeatedly deformed. Further, the heat-generated rubber has a characteristic of softening, and if the heat generation of the tread rubber of the tire becomes too large, the rigidity of the tread may be lowered and the steering stability performance may be deteriorated. That is, a rubber with a large tan δ has a good grip, but tends to generate heat and becomes soft when repeatedly used.
In particular, when motorcycle races and general consumers ride hard, not only does the tread rubber on the shoulder generate heat during running, but the turning performance deteriorates, but also the heat softens the rubber and reduces the tread rigidity. , Tires become slippery. As a result, the wear of the shoulder portion proceeds or the rubber of the shoulder portion deteriorates.

In conventional motorcycle tires, the rubber of the tire shoulder is mainly rubber with a high loss tangent (tan δ), which is a rubber with a high grip, that is, with a high friction coefficient, mainly for improving the grip. It was used. For example, in Patent Document 1, rubber having a tan δ of 0.4 to 0.8 is used for the tire shoulder portion in order to ensure grip, and a low fuel consumption product is ensured for the center portion of the tire. Therefore, a motorcycle tire using rubber having a tan δ of 0.05 to 0.3 is shown. Further, in Patent Document 2, a single-roll body in which a wide flat rubber is wound once around a tire shoulder portion, and a narrow and long rubber strip is wound around the tire shoulder portion in a circumferential direction and spirally. A rubber having a tan δ in the range of 0.2 to 0.4 is disposed for the tire shoulder portion, and a rubber having a tan δ of 80% or less of the tan δ of the tire shoulder portion rubber. Two-wheeled vehicle tires are shown.
JP-A-60-94804 JP 2006-256385 A

  However, when a rubber with a large tan δ is arranged in the tire shoulder portion as in the conventional motorcycle tire, a sufficient grip can be secured in the initial state, but the rubber tends to generate heat. There is a problem in wear resistance performance of the part. Furthermore, there has been a problem that the grip is lowered if the wear of the shoulder portion progresses due to repeated use or the rubber of the shoulder portion deteriorates.

Below, the problem when rubber with a large tan δ is arranged in the tire shoulder will be described in detail.
In a tire for a motorcycle, the turning performance when the vehicle body is largely tilted depends on a grip generated when one end of the tire tread is grounded. FIG. 10 is a view showing a cross section when the tire 50 is rotating while being grounded at a camber angle (hereinafter referred to as CA as a camber angle) of 50 degrees. CA is a wheel center line CL in the longitudinal cross section of the tire 50. And the Z axis which is the direction perpendicular to the road surface 60.
When the two-wheeled vehicle makes a turn with the vehicle body greatly depressed, that is, when the CA of the tire 50 is 45 degrees to 50 degrees, approximately ¼ of the entire width (tread width) of the tread 51 of the tire 50 is grounded. This grounded 1/4 region is divided into three equal parts, from the side closer to the tread end, to regions A, B, and C. Think. This is because a lateral force is generated in the tire 50 by the tread deformation, and a camber thrust (lateral force) is generated by the lateral deformation of the tread 51.
Note that when the ground is rotating at a CA of 50 degrees, the ground contact shape of the tread may be a shape lacking a part of an ellipse or a half-moon shape.

Here, the deformation in the tread width direction of the region B which is the center region of the ground plane will be described.
When the point in contact with the tread surface of the region B, that is, the road surface is Q point, and the point located at the deepest part of the tread inside this Q point is P point, Q is in contact with the road surface 60 when the tire 50 rolls on the ground. The point is fixed to the road surface 60 when the surface of the tread 51 comes into contact with the road surface 60, and moves linearly along the extending direction of the road surface 60, which is a direction perpendicular to the paper surface of FIG. On the other hand, the point P, which is the deepest part of the tread, draws a bow-like curve because the tire 50 rolls with a CA attached (the straight line indicated by P → P ′ → P in the figure is the above curve) The right side of the figure is the vehicle body side, and the left side is the vehicle body outside). Due to the difference between the movements of point P and point Q, the tread 51 receives a lateral shearing force in the vehicle body outer direction. The transverse shear force is maximized when the point Q is located directly under the load, that is, at the center of the ground contact surface in the tire circumferential direction. When the tread 51 is laterally deformed by such a lateral shearing force, a force in a direction opposite to the lateral shearing force is generated in the tire 50, that is, a camber thrust (lateral force) is generated on the vehicle body side. It becomes the side grip of time.
Because of the mechanism of camber thrust generation, the longer the contact length (the circumferential direction of the contact shape = the length in the equator direction), the greater the difference in the trajectory between the point P and the point Q. Sheared. On the other hand, when the contact length is short, the shear amount of the tread 51 (lateral direction = shear in the tire width direction) is small.
When the contact shape is a shape in which a part of an ellipse is missing, the contact length is the longest in region B, then the region A is long, and the C region is shortest in the above three regions. Thus, region B is subjected to the greatest shear, then region A has the greatest shear, and region C has less shear. On the other hand, when the contact shape is a half-moon shape, the region A and the region B are long with substantially the same contact length, and the contact length is short in the region C. There is little shear.
That is, in the shear at the time of large CA where the CA is 45 degrees to 50 degrees, the region A and the region B are sites that greatly increase the lateral force.

When observing the inclination angle (bank angle or CA) of a motorcycle, the motorcycle does not fall when the CA is 45 degrees to 50 degrees or more. That is, the region A is a region that contacts the ground only when the motorcycle is inclined at the maximum angle. The region B is also used mainly when the motorcycle is largely inclined. On the other hand, the region C is a region mainly used when the motorcycle is slightly tilted after being largely tilted, that is, when CA is around 40 degrees. In other words, the region C is used in the process of tilting the motorcycle, and is used not only when the motorcycle is further tilted, but also in the process of accelerating the motorcycle and standing upright. In particular, considering a rear tire with high wear, this region C is a region used when a motorcycle is greatly defeated and accelerated from there.
Since a motorcycle often transmits a large driving force when the CA is around 40 degrees, the region C can be said to be a region that frequently receives both a longitudinal driving input and a lateral lateral input during acceleration. As a result, this region C is a portion where tread wear is most advanced.

  On the other hand, as described above, when the tan δ of the tread rubber is large, the energy loss is large and the grip is large, but the heat generation is also large. If the heat is generated, the rubber becomes soft, and therefore, in a tire for a motorcycle having a thick tread rubber, the transverse shear rigidity of the tread rubber is lowered. As a result, not only the steering stability performance is impaired, but also slippage increases, which causes a problem of accelerated wear.

  Since tires for motorcycles require grip when turning, rubber with a large tan δ is usually placed on the shoulder portion of the tire. However, if the frequency of high-speed rotation with a CA of 45 to 50 degrees is high, The shoulder portion generates heat and the above-mentioned problems occur. In particular, in severe use conditions such as a motorcycle race that turns at high speed, repeated deformation of the strain is given at a high frequency, so heat generation is extremely large, and the temperature of the tread surface may exceed 120 ° C. Under such conditions, the larger the tan δ, the greater the heat generated, and the tread rubber is abnormally heated and softened by repeated use. As a result, the shear rigidity of the tread is reduced to deteriorate the steering stability performance, and the wear is promoted. Furthermore, when the tread becomes high temperature, the rubber in the tread portion tends to deteriorate. In a motorcycle race involving high-speed driving with severe input, if the temperature of the tread becomes too high, bubbles may be formed in the rubber, and cracks may develop from the bubbles and a part of the tread rubber may fall off.

The softening of the tread rubber is fatal for motorcycle tires. For motorcycle tires, the camber thrust generates lateral force. The camber thrust has a predetermined transverse shear displacement as shown by the locus between point P and point Q in FIG. That is, when the tire dimensions and the tire CA are determined, the trajectory of the belt is geometrically determined, and the distance at which the trajectories of the point P and the point Q are separated to the maximum is an amount capable of shearing the tread laterally. From the above characteristic belt behavior, when the elastic modulus of the tread rubber is lowered, the reaction force when the same displacement is applied is lowered. That is, when the tread rubber is heated and softened, the reaction force of the rubber when the same displacement is applied is reduced, so that the lateral force generated by the tire is reduced.
For this reason, the tread rubber must be able to produce the maximum grip while suppressing heat generation. That is, a rubber with a large tan δ is suitable for generating a high grip, but a rubber with a small tan δ is better for suppressing heat generation and preventing softening of the tread rubber.

Further, the deformation in the circumferential direction of the tread is different between the region A which is a region on the vehicle body side and the region C which is a region outside the vehicle body. This is because the region C is closer to the center of the tread and the region A is closer to the tread end, so the belt speed is different between the region C and the region A.
The characteristic of a tire for a motorcycle is that it has a larger roundness in the cross section in the width direction than the tire for a passenger car. Therefore, the belt radius, which is the distance from the rotating shaft to the belt, is small in the region A and large in the region C. . That is, the belt radius RC in the region C shown in FIG. 10 is larger than the belt radius RA in the region A. Therefore, the belt speed, that is, the speed of the belt until the tread leaves the ground after the tread contacts the road surface until the tread leaves the ground is higher in the region C. This is because the belt radius is obtained by multiplying the belt radius by the rotation speed of the tire, and the rotation speed of the tire is the same in both the region A and the region C. Due to the speed difference in the circumferential direction of the belt, the tread is in the driving state in the region C near the center of the tire, and the braking state is in the region A near the tread end of the tire. Driving means that when the tire is cut into a circle along the equator direction, the tread deformation is caused by the tread inner surface (the surface in contact with the skeleton member inside the tire) being sheared backward in the tire traveling direction and contacting the road surface. This is a shear deformation in which the tread surface 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, braking is the reverse of driving, and tread deformation is shear deformation in which the inside of the tire is sheared forward in the direction of travel and the tread surface that is in contact with the road surface is deformed rearward in the direction of travel of the tire. Tire movement.

Such deformation in the circumferential direction occurs only when the tire rolls in an idle state without receiving a driving force or a braking force. Due to the circumferential shear deformation, the tires easily slip from the road surface in the region A and the region C, and wear progresses. Further, the deformation in the circumferential direction of the tread gradually increases as the tire rotates after the tread surface contacts the road surface. Then, the deformation in the circumferential direction of the tread is maximized immediately before kicking out (leaving the tread away from the road surface). If the ground pressure becomes weak when kicking out, the tread slides from the road surface, causing wear. Such excessive deformation during turning tends to cause uneven wear on the tire shoulder portion, so it is better not to have such deformation. Such extra circumferential movement is repeated each time the tire rotates once. For this reason, cyclic deformation is applied to the rubber, and the rubber is likely to generate heat. This circumferential movement is a useless movement that does not contribute to the lateral grip at all, and this deformation promotes heat generation of the rubber and also promotes wear of the rubber.
In particular, when rubber with a large tan δ is used for the shoulder portion of the tire in order to enhance the lateral grip, heat generation is promoted not only by the lateral deformation but also by the above-mentioned circumferential deformation. There is.

  The present invention has been made in view of conventional problems, and it is an object of the present invention to provide a pneumatic tire for a motorcycle that can improve a lateral grip when turning a motorcycle and reduce tread wear of a shoulder portion. And

Means for Solving the Problems and Effects of the Invention

Invention of Claim 1 of this application is a pneumatic tire for two-wheeled vehicles provided with the belt layer and the tread rubber arrange | positioned on the tire radial direction outer side of this belt layer, Comprising: The tread rubber of a shoulder part is a tire radial direction A different rubber layer is provided on the inner side, one end of which is located at the end of the tread, the width is in the range of 5% to 30% of the tread developed width, and the loss tangent of rubber (hereinafter referred to as tan δ). ) Is smaller than tan δ of the rubber on the outer side in the tire radial direction than the different rubber layer. As a result, a lateral grip can be secured and heat generation at the shoulder portion can be suppressed, so that it is possible to obtain a tire for a motorcycle that has excellent turning performance and excellent steering stability and wear resistance. .
The width of the dissimilar rubber layer is set in the range of 5% to 30% of the tread deployment width, while suppressing heat generation at least at the area A (see FIG. 10) that contacts the ground at the maximum CA, and the temperature is too low to grip. This is because it is possible to prevent a decrease in the temperature.
The “width” of the tread rubber, belt layer, rubber layer, etc. refers to the length along the curved surface of the tread surface in the longitudinal section of the tire (cross section in the tread width direction), and “thickness” refers to the tire radial direction. Refers to the length along The “tread unfolding width” is the length from one end to the other end when the tread having a roundness in the width direction is unfolded to be a plane, and is along the curve of the tread surface. It is equal to the length from one end of the tread measured to the other end.
The tan δ is a value indicating how much energy is absorbed (changed to heat) when the rubber material is deformed, and is generally measured using a dynamic viscoelasticity measuring apparatus. For example, a displacement of a sine wave having a frequency of 15 kHz and a distortion of 5% is added to the rubber sample, and the reaction force at that time is measured and obtained. In the present invention, tan δ was measured using a dynamic viscoelasticity measuring device at a temperature of 50 ° C., a frequency of 15 kHz, and a strain of 5%. Further, in the case of a motorcycle tire or a racing tire, the tread temperature of the shoulder portion may exceed 100 ° C. Therefore, tan δ at 100 ° C. is measured according to the purpose, and this is used as tan δ of the present invention. Yes. It is preferable to use tan δ at 50 ° C. for general consumer tires, and it is preferable to use tan δ at 100 ° C. for racing tires.

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 different rubber layer is gradually narrowed from the tread surface side toward the inner side in the tire radial direction. Thereby, when the wear of the tread progresses, the ratio of the rubber having a small tan δ is also reduced, so that a decrease in the tread temperature due to the wear can be prevented. Accordingly, it is possible to prevent a decrease in grip due to wear of the tread.
According to a third aspect of the present invention, in the pneumatic tire for a motorcycle according to the first aspect, the width of the different rubber layer is gradually increased from the tread surface side toward the inner side in the tire radial direction. As a result, the closer to the shoulder end side, the greater the proportion of rubber with a small tan δ, so that heat generation in the regions A and B, which are regions that gain lateral force, can be effectively suppressed, and at the maximum CA A lateral grip can be secured.

According to a fourth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to third aspects, the maximum thickness of the dissimilar rubber layer is 20% to the thickness of the tread rubber. In this range, a sufficient heat generation suppression effect can be obtained, and a decrease in grip due to excessive heat generation suppression can be prevented.
According to a fifth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to fourth aspects, the tread rubber is measured from the tread end and the tread end of the tread rubber to a position of 10% of the tread deployed width. The average thickness of the tread rubber between the treads is smaller than the average thickness of the tread rubber between 10% to 25% of the tread deployment width as measured from the tread edge. Thereby, in addition to the effect of rubber having a small tan δ, the effect of maintaining the rigidity on the tread end side can be further enhanced, so that the turning performance and the steering stability performance can be further improved.

The invention according to claim 6 is the pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein a plurality of rubber layers are laminated in the tire radial direction in the tread center portion, The tan δ of at least one rubber layer of the rubber layer is smaller than the tan δ of rubber disposed on the tread surface. Thereby, since heat generation of rubber can be suppressed also in the tread center portion, it is possible to improve the driving and braking characteristics when traveling straight. The tread center portion is located in the center portion of the tread and is an area having a width of about 25% of the total tread width (tread developed width), and is in contact with the road surface when the tread motorcycle stands upright. Corresponds to the part.
According to a seventh aspect of the present invention, in the pneumatic tire for a motorcycle according to the sixth aspect, the rubber disposed on the tread surface of the tread center portion and the rubber adjacent to the tire surface side of the different rubber layer are continuous. It is characterized by being connected. Thereby, since the rubber seed | species which forms a tread can be decreased, manufacture of a tire can be performed efficiently.
The invention according to claim 8 is the pneumatic tire for a motorcycle according to claim 6 or claim 7, wherein the rubber of the innermost rubber layer of the tread center portion is the same as the rubber of the different rubber layer, and The innermost rubber layer and the dissimilar rubber layer are continuously connected to each other. As a result, since the number of rubber types can be reduced even for the rubber layer having a small tan δ, not only can the tire be molded more efficiently, but also the temperature rise on the center side of the different rubber layer can be suppressed.

The invention according to claim 9 is the pneumatic tire for a motorcycle according to any one of claims 1 to 8, wherein the width (length along the tire width direction) is at least part of the wall surface of the tread edge. Is a hard rubber having a thickness of 6 mm or less, which can suppress softening of the tread due to heat generation, and can prevent the tread from falling when the tread is laterally deformed. The hard rubber is harder than the rubber forming the tread, and more specifically, refers to rubber having a Shore A hardness of 60 or more and 90 or less at room temperature. The Shore A hardness is a hardness (rebound hardness) determined by the height of jumping of the sphere when a steel ball or diamond sphere is dropped on the surface of the material, and the higher the value, the harder the material.
According to a tenth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to ninth aspects, at least a part of the tread rubber includes a narrow and long rubber strip along the tire circumferential direction. It is characterized in that it is formed by being spirally stacked and wound. Thereby, even in a tire for a motorcycle having a large roundness, the molding accuracy can be ensured, so that a tire with high shape accuracy can be obtained.

The invention according to claim 11 is the pneumatic tire for a motorcycle according to any one of claims 1 to 10, wherein the reinforcing member is less likely to extend in the circumferential direction, and the arrangement angle (cord angle) of the reinforcing member with respect to the tire equator direction. Is further provided with a spiral belt layer having an angle of 0 to 5 degrees. As a result, tire expansion due to centrifugal force can be prevented, and a high-performance two-wheeled vehicle tire excellent in steering stability performance during high-speed traveling can be obtained.
The invention according to claim 12 is the pneumatic tire for a motorcycle according to claim 11, wherein a belt layer having a cord angle of 80 degrees to 90 degrees is arranged outside the spiral belt layer in the tire radial direction. Thereby, since the spiral belt layer can be protected, durability of the tire can be improved. Moreover, since the foundation of the tread becomes stronger in the lateral direction (tire width direction), a high lateral force can be maintained.
The invention according to claim 13 is the pneumatic tire for a motorcycle according to claim 12, wherein a buffer rubber layer having a thickness of 0.3 mm to 3.0 mm is disposed between the spiral belt layer and the belt layer. It is characterized by being. As a result, only the circumferential deformation of the tread driving deformation and braking deformation due to the difference in belt speed of the shoulder portion can be absorbed by the shear deformation of the buffer rubber layer, so that a high lateral force is maintained. Heat generation due to the deformation in the circumferential direction of the tread can be prevented.

The invention according to claim 14 is the pneumatic tire for a motorcycle according to any one of claims 11 to 13, wherein the width of the spiral belt layer is 60% to 90% of the tread developed width. Thus, since the belt layer can extend in the tire circumferential direction on the tread end side, braking deformation of the tread can be suppressed. Therefore, heat generation due to repeated deformation is reduced and slipping can be reduced, so that heat generation due to slipping can also be reduced. Therefore, softening of rubber can be prevented. Further, since the slip is reduced, the wear resistance is also improved.
A fifteenth aspect of the present invention is the pneumatic tire for a motorcycle according to any one of the first to fourteenth aspects, wherein the dynamic elastic modulus of the dissimilar rubber is outside the rubber layer in the tire radial direction. It is characterized by being smaller than the dynamic elastic modulus, and this makes it possible to improve the grip when heat generation is not yet sufficient, such as immediately after the start of traveling.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
Best Mode
FIG. 1 is a cross-sectional view showing a configuration of a motorcycle tire 10 according to the best mode 1, in which CL indicated by a one-dot chain line is a wheel center line. The two-wheeled vehicle tire 10 includes a body ply 12 straddling a pair of bead cores 11C disposed in the bead portion 11 in a toroidal shape, and a spiral belt layer disposed outside the body ply 12 in the tire radial direction. 13 and two crossing belt layers 14A and 14B arranged on the outer side in the tire radial direction of the spiral belt layer 13, and a rubber member (tread) on the outer side in the tire radial direction of the crossing belt layers 14A and 14B. A tread layer 15 made of rubber is disposed.
The body ply 12 is made by twisting a plurality of reinforcing members made of fibers such as steel cord or nylon (hereinafter referred to as cord) in parallel at a predetermined driving interval, and is formed into a sheet shape with unvulcanized rubber. The cord angle, which is the inclination angle of the cord with respect to the equator direction when arranged on a tire, is 90 degrees (radial).
The spiral belt layer 13 is a belt layer having a cord angle of 0 to 5 degrees with respect to the equator direction, and is formed by covering one or more cords with rubber and winding the cord around the tread portion in a spiral manner. It is.
The crossing belt layers 14A and 14B are formed by arranging cords made by twisting fibers of steel cords or aromatic polyamides at predetermined driving intervals, and the cord angle with respect to the equator direction is 50 degrees. The two crossing belt layers 14A and 14B are arranged so as to cross each other.
The tread layer 15 has a width of 240 mm (hereinafter referred to as a tread development width), and a tread pattern is formed on the surface thereof. FIG. 2 is a diagram showing an example thereof. In this example, a tread pattern in which oblique grooves 15P having a width of a = 8 mm and a depth of 5 mm are alternately arranged in a left and right shape is adopted. The proportion of the oblique groove 15P in the entire tread is 10%.
On the other hand, the width of the spiral belt layer 13 is 220 mm, the width of the first crossing belt layer (inner crossing belt layer) 14A is 250 mm, and the width of the second crossing belt layer (outer crossing belt layer) 14B is 230 mm. It is. In addition, the said tread expansion | deployment width | variety and the width | variety of the spiral belt layer 13 and the crossing belt layers 14A and 14B point out the length measured along the curved surface of the tread surface in the longitudinal cross-section of a tire.

The tread layer 15 includes a surface layer 15 a disposed on the tire surface side, a first dissimilar rubber layer 15 c disposed on the inner side in the tire radial direction of the surface layer 15 a of the shoulder portion 16, and a surface layer 15 a of the center portion 17. An internal intermediate disposed between the second dissimilar rubber layer 15d disposed on the inner side in the tire radial direction and the first and second dissimilar rubber layers 15c, 15d on the inner side in the tire radial direction of the surface layer 15a. The surface layer 15a and the inner intermediate layer 15b are made of high-loss rubber having a relatively large loss tangent (tan δ) (for example, tan δ = 0.3).
The value of the above tan δ is a value measured using a dynamic viscoelasticity measuring device such as a viscoelasticity measuring device manufactured by Rheometrics, Inc., and measured under measurement conditions of a temperature of 50 ° C., a frequency of 15 Hz, and a strain of 5%. Is. Hereinafter, the magnitude of tan δ is represented by an index with the value of tan δ of the high-loss rubber as 100.
The tread rubber of the shoulder portion 16 has two layers as described above. The surface is the surface layer 15a, and the surface layer 15a is the inner side in the tire radial direction, that is, the inner layer of the tread has a tanδ index of 70. A first different rubber layer 15c made of rubber is provided. One end of the first different rubber layer 15c is located at the tread end portion 15z, and the other end is located within a range of 5% to 30% of the tread developed width from the tread end portion. That is, the width W of the first different rubber layer 15c is in the range of 5% to 30% of the tread developed width. Further, the thickness is in the range of 20% to 70% of the total thickness of the tread layer 15.
The tread rubber of the center portion 17 is also composed of two layers, the surface is a surface layer 15a, and the inner layer is provided with a second different rubber layer 15d made of a different rubber having a small tan δ. In this example, as the rubber of the second different rubber layer 15d, the same rubber as the rubber of the first different rubber layer 15c and having an index of tan δ of 70 is used.
The center portion 17 is a portion where the tread is in contact with the road surface when the motorcycle is upright, and is located in the center portion of the tread, and the width thereof is an area of about 25% of the tread deployed width. In this example, the width of the second different rubber layer 15d is 15% to 25% of the tread developed width.

In the motorcycle tire 10 of the present invention, a high-loss rubber having a relatively large tan δ is arranged on the surface layer 15a which is also the surface side of the tread of the shoulder portion 16, and the index of tan δ is 70 in the inner layer. The first different rubber layer 15c is disposed. Thereby, since the heat generation by deformation becomes small compared with the case where the whole shoulder part 16 is comprised with high-loss rubber, the heat generation of the shoulder part 16 can be suppressed. Accordingly, it is possible to suppress a decrease in the shear rigidity of the shoulder portion 16 due to the softening of rubber, so that it is possible to ensure steering stability performance and to suppress the promotion of wear. Moreover, since the high-loss rubber is arranged on the surface layer of the shoulder portion 16, a lateral grip equivalent to the conventional one can be ensured.
Here, it is important that the range in which the first different rubber layer 15c is disposed is a range from 5% to 30% of the tread developed width from the end portion of the tread. That is, if the range in which the dissimilar rubber having a small tan δ is disposed is less than 5%, the volume of the dissimilar rubber is too small to obtain a sufficient effect. In addition, the upper limit of the range in which the dissimilar rubber having a small tan δ is set to 30% is that if the range in which the dissimilar rubber is disposed is widened to a region where the heat generation is not large, the tread temperature is lowered too much to obtain a sufficient grip. This is because it may not be possible. This is because the area that contacts the ground during large CA is 1/4 of the tread deployment width, that is, the area between the tread end 15z and the position 25% of the tread deployment width measured from the tread end 15z. Since a large driving force is applied even in a CA 40 degree region where the vehicle body is slightly raised from CA, the amount of heat generated by the tread is large. Therefore, when the region where the heat generation is large at CA 40 degrees is included, the region where the heat generation is large is a region between the tread end portion 15z and a position of about 30% of the tread developed width as measured from the tread end portion 15z. Therefore, in order to reliably suppress the heat generation of the shoulder portion 16 without reducing the grip, the range in which the dissimilar rubber having a small tan δ is arranged is measured from the end portion of the tread from the end portion of the tread. It is necessary to make it into the range from 5% to 30%.

In this example, the thickness of the first different rubber layer 15c is set to 20% to 70% of the thickness of the tread rubber. However, when the thickness is less than 20%, this is a rubber having a small tan δ. This is because the layer is too thin to obtain a sufficient heat generation suppressing effect. Further, when the thickness exceeds 70%, in particular in a region where the frequency of use is low, such as the region A (see FIG. 10), it becomes impossible to generate heat up to a temperature at which the tread temperature should be raised, and a lateral force (camber) This is because the (thrust) decreases. In addition, assuming that the tire is worn, if the thickness of the different rubber exceeds 70%, the different rubber appears on the surface even when the wear does not progress so much, and the grip is lowered. This is because the dissimilar rubber having a small tan δ has less bite into the fine irregularities of the aggregate contained in asphalt or the like than the high-loss rubber, so that the friction coefficient is lowered and the grip is lowered. Accordingly, the thickness of the first different rubber layer 15c is preferably in the range of 20% to 70% of the total thickness of the tread, and more preferably in the range of 20% to 50%. In particular, unlike tires for competition, commercially available tires are often used even if wear progresses. Therefore, the first dissimilar rubber is used to prevent the dissimilar rubber from appearing on the surface due to wear. The thickness of the rubber layer 15c is preferably in the range of 20% to 40% of the thickness of the tread rubber.
When the thickness of the first different rubber layer 15c is different in the tire width direction, it is preferable that the thickness at the thickest portion is within the above thickness range.

Further, by providing the second different rubber layer 15d made of a different rubber having a small tan δ in the inner layer portion of the tread of the center portion 17, not only the rolling resistance during straight running is improved but also the lateral grip can be improved. it can. This is because the center portion 17 serves as a side portion when the CA is making a large turn, and the second dissimilar rubber layer 15d suppresses the temperature rise of the center portion 17 so that the surface layer 15a If the softening of the rubber is prevented, the rigidity of the center portion 17 is increased, so that a strong lateral force can be received. That is, when the lateral force is increased by providing the first dissimilar rubber layer 15c, the deformation of the tire also increases, but the center portion 17 is reinforced by providing the second dissimilar rubber layer 15d. Steering stability is improved.
The second dissimilar rubber layer 15d may be disposed on the entire center portion 17, but if it is 15% or more of the total width of the tread, the temperature rise of the center portion 17 can be sufficiently suppressed. The width of the different rubber layer 15d is preferably 15% to 25% of the total width of the tread.
In this example, the rubber on the tire surface side of the second different rubber layer 15d and the rubber adjacent to the tire surface side of the first different rubber layer 15c are both high loss rubbers having a relatively large tan δ. In addition, since the surface layer 15a is formed by continuous connection, the rubber forming the surface layer 15a is used as the first and second dissimilar rubber layers 15c and 15d and the inner middle when the tire is molded. The layer 15b may be wound on the layer 15b. That is, the rubber on the tire surface side of the second dissimilar rubber layer 15d and the rubber adjacent to the tire surface side of the first dissimilar rubber layer 15c are wound together. It can be done efficiently.
Further, when molding the rubber of each of the layers 15a to 15d of the tread layer 15, it is preferable that a narrow and long rubber strip is spirally overlapped and molded along the tire circumferential direction. Thereby, even if it is a tire for motorcycles with big roundness, since the precision of fabrication can be secured, a tire with high shape accuracy can be obtained.

Thus, according to the best mode 1, the rubber of the surface layer 15a disposed on the tread surface is a high-loss rubber having a relatively large tan δ and the inner layer of the surface layer 15a of the shoulder portion 16. Further, one end is located at the tread end portion 15z and the other end is measured from the tread end portion 15z and is in a range of 5% to 30% of the tread deployed width, Since the first dissimilar rubber layer 15c having a thickness of 20% to 70% is disposed to reduce heat generation due to deformation of the tread rubber, heat generation of the shoulder portion 16 can be suppressed. Therefore, since the fall of the shear rigidity of the shoulder part 16 can be suppressed while ensuring a sufficient lateral grip, the steering stability performance can be ensured and the acceleration of wear can be suppressed.
Further, the inner layer of the surface layer 15a of the center portion 17 is provided with a second different rubber layer 15d made of rubber having the same tan δ as the rubber of the first different rubber layer 15c, and the temperature of the center portion 17 is increased. Therefore, not only the driving / braking performance during straight traveling is improved, but also the rigidity of the center portion 17 is increased and a strong lateral force can be received, so that the steering stability performance can be further improved.
Further, the rubber on the tire surface side of the second dissimilar rubber layer 15d is a high-loss rubber having a relatively large tan δ and continuously connected to form the surface layer 15a. The rubber on the tire surface side of the rubber layer 15d and the rubber adjacent to the tire surface side of the first different rubber layer 15c can be wound together. Therefore, the tire can be manufactured efficiently. At this time, if the rubber of each of the layers 15a to 15d of the tread layer 15 is formed by winding a narrow and long rubber strip spirally along the tire circumferential direction, the molding accuracy is ensured. Therefore, a tire with high shape accuracy can be obtained.
Further, in this example, a spiral belt layer 13 is provided between the body ply 12 and the intersecting belt layers 14A and 14B, which is difficult to extend in the circumferential direction and has a cord angle of 0 degrees to 5 degrees with respect to the equator direction. Since the tire is prevented from expanding due to centrifugal force, it is possible to obtain a two-wheeled vehicle tire excellent in steering stability performance at high speeds.

In the best mode 1, the tan δ of the high-loss rubber constituting the surface layer 15a and the inner intermediate layer 15b is set to 0.3, and the tan δ of the different rubber constituting the first and second different rubber layers 15c and 15d. Is a rubber having an index of 70 (tan δ = 0.21). However, the value of tan δ of the high loss rubber is not limited to this, and a value with a large grip, that is, a coefficient of friction (for example, tan δ). = About 0.25 to 0.55). At this time, it is important to make the tan δ of the first and second dissimilar rubber layers 15c, 15d disposed in the inner layer of the tread smaller than the tan δ of the high-loss rubber. The index of tan δ is preferably in the range of 50-80.
If the index of tan δ of the first and second dissimilar rubber layers 15c, 15d is less than 50, the tread temperature is further reduced, but the rubber behaves harder, resulting in greater slippage on the tread surface and lower grip. To do. On the other hand, when the index of tan δ of the rubber exceeds 80, the difference between the surface layer 15a and the rubber is small, and the heat generation suppressing effect is not sufficient. Therefore, the range of the index of tan δ is appropriately 50-80.

In the above example, the thickness of the tread rubber is constant in the tire width direction, but the thickness of the tread rubber on the tread end portion 15z side where the rubber having a small tan δ is arranged is larger than the thickness of the tread rubber in other portions. If the thickness is reduced, the effect of disposing rubber with a small tan δ can be further enhanced. If the thickness of the tread rubber (tread gauge) is reduced, the tread rigidity of the portion is improved. The purpose of disposing a rubber having a small tan δ on the inner side in the tire radial direction of the tread rubber of the shoulder portion is to suppress heat generation and not reduce the elastic modulus of the rubber. In this way, by reducing the thickness of the tread layer 15 where the rubber having a small tan δ is thinned, the effect of maintaining the tread rigidity can be further obtained, so that the turning performance and the steering stability performance can be further improved. it can.
In addition, since the tread rigidity is proportional to the cube of the thickness of the tread layer 15, for example, when the thickness of the tread layer 15 is 8 mm, a sufficient effect can be obtained by reducing the thickness by about 0.5 mm to 1.5 mm. be able to. Further, the range in which the thickness of the tread layer 15 is reduced is preferably up to a position of 10% of the tread development width. That is, in the range up to 10% of the tread development width, the tread rubber thickness is measured from the tread edge 15z, and the average tread between the position of 10% to 25% of the tread development width is measured. What is necessary is just to make it thinner than the thickness of rubber. Note that when the entire shoulder portion 16 is thinned, the tread rigidity of the shoulder portion 16 is improved, but slippage of the tire surface is increased as a whole, and the wear life is reduced. Therefore, it is better not to reduce the thickness of the tread rubber in the region B or the region C (see FIG. 10) where the contact frequency is high even when the rubber having a small tan δ is arranged.

In the above example, the second dissimilar rubber layer 15d made of a dissimilar rubber having a small tan δ is also provided on the inner layer of the tread of the center part 17 to increase the rigidity of the center part 17. In addition to the layer 15d, if a hard rubber layer having a shore hardness of 60 to 90 at room temperature is disposed on the inner layer of the center portion 17, the rigidity of the center portion 17 can be further increased. The braking characteristics and steering stability performance can be further improved.
In the above example, the rubber on the tire surface side of the second different rubber layer 15d and the rubber adjacent to the tire surface side of the first different rubber layer 15c are integrated, but as shown in FIG. Further, the first dissimilar rubber layer 15c is provided with a connecting layer 15m extending from the end on the center portion 17 side toward the center portion 17 to connect to the second dissimilar rubber layer 15d. If the different rubber layer 15c is continuously connected to the second different rubber layer 15d, the number of rubber types can be reduced even in the rubber layer having a small tan δ, so that the tire can be manufactured more efficiently. Can do. At the same time, since the temperature rise on the center portion 17 side of the first different rubber layer 15c can be suppressed at the same time, the grip is improved. However, in this case, the thickness of the connecting portion 15m is preferably thinner than the thickness of the first dissimilar rubber layer 15c, and is not more than half the thickness of the first dissimilar rubber layer 15c. It is more preferable. Thereby, the fall of the grip by excessive heat_generation | fever suppression can be prevented.
[First embodiment]

The tire according to the present invention (Examples 1 to 11) provided with a different rubber layer having a small tan δ in the inner layer on the tread end side of the shoulder portion shown in FIG. 1 and a conventional tire having no different rubber layer (conventional example) 1, 2) and a tire (Comparative Examples 1 to 4) having a different rubber layer but not having an appropriate width or thickness, and measuring the lateral force at 50 degrees CA for each of the above tires. FIG. 4 shows the results of the temperature measurement of the shoulder portion of the drum, the rolling resistance test when traveling straight, the evaluation test of the steering stability performance by the driver, and the temperature measurement of the shoulder portion after running.
The tire is a motorcycle tire, and the tire size is 190 / 50ZR17.
Each of these tires has a single body ply straddling a pair of bead cores in a toroidal shape. In this embodiment, the body ply is made of a nylon cord twisted to a diameter of 0.6 mm, arranged in parallel at a driving interval of 65/50 mm, and formed into a sheet with unvulcanized rubber as a carcass member. ing. The body ply is radial (angle with respect to the equator direction is 90 degrees). Further, the body ply is fixed by being wound around the bead core at the bead portion.
In addition, the spiral belt layer uses a cord in which an aromatic polyamide (trade name: Kevlar) fiber is twisted to a diameter of 0.7 mm and arranged so that a driving interval is 50/50 mm. The cord may be made of steel. In this case, for example, a steel cord in which a steel single wire having a diameter of 0.21 mm is twisted in a 1 × 3 type may be wound in a spiral shape at a driving interval of 30/50 mm.
The two crossing belt layers are formed by arranging cords made by twisting aromatic polyamide fibers to a diameter of 0.7 mm at a driving interval of 30/50 mm, and the cord angle is 50 degrees.
Further, the thickness of the tread rubber is 7 mm, and the thickness from the center portion to the shoulder portion is the same except for Example 11.
In addition, the developed width of the tread is 240 mm, the width of the spiral belt layer is 220 mm, the first crossing belt layer (inner crossing belt layer) is 250 mm, the second crossing belt layer (outer crossing belt layer) The width is 230 mm.
The above basic structure is common to each tire.

Moreover, the difference in tread rubber is as follows.
The type of rubber constituting the tire tread of Conventional Example 1 is one, and the size of tan δ of this rubber is 0.3. The tan δ is measured under measurement conditions of a temperature of 50 ° C., a frequency of 15 Hz, and a strain of 5%. Hereinafter, the magnitude of tan δ is represented by an index with tan δ = 0.3 being 100.
The tire of Conventional Example 2 has two rubber layers in the center portion. The surface rubber is a rubber having a tan δ index of 100, and the inner layer rubber is a rubber having a tan δ index of 70. The inner layer has a rubber width of 120 mm.
In the tire tread end of the first embodiment, different types of rubber are arranged. The width of this different rubber is 60 mm (25% of the developed width of the tread), the thickness is 4 mm (57% of the thickness of the tread layer), and the index of tan δ is 70. The boundary in the depth direction between the dissimilar rubber and the rubber closer to the center is substantially perpendicular to the depth direction and is not inclined. Further, the center portion has two layers, the rubber of the surface layer is a rubber having an index of tan δ of 100, and the rubber of the inner layer is a rubber having an index of tan δ of 70. The inner layer has a rubber width of 120 mm.
The tires of Examples 2, 3, and 4 were obtained by changing the widths of the different types of rubbers of Example 1 to 15 mm (6%), 20 mm (8%), and 72 mm (30%), respectively. Same as tire.
The tires of Comparative Examples 1 and 2 are the same as the tires of Example 1 except that the width of the dissimilar rubber of Example 1 is changed to 10 mm (4%) and 84 mm (35%), respectively.
The tires of Examples 5 and 6 were the same as the tires of Example 1 except that the thicknesses of the different types of rubbers of Example 1 were changed to 2 mm (29%) and 5 mm (71%), respectively.
The tires of Comparative Examples 3 and 4 were the same as the tires of Example 1 except that the thicknesses of the different types of rubbers of Example 1 were changed to 1 mm (14%) and 7 mm (100%), respectively.
The tires of Examples 7, 8, and 9 are the same as the tires of Example 1 except that the tan δ index of the dissimilar rubber of Example 1 is changed to 90, 60, and 40, respectively.
Further, the tire of Example 10 is the same as the tire of Example 1 except that the center portion of Example 1 has a single layer. The index of tan δ of the rubber at the center is 100.
The tire of Example 11 is the same as the tire of Example 1 except that the average thickness of rubber in the range of 10% from the end of the tread of Example 1 is reduced by 0.7 mm.

About each said tire, the following measurements and evaluation were performed.
(1) Measurement of lateral force at 50 degrees CA and temperature measurement of the shoulder portion of the drum A # 40 paper file was affixed to the surface of a tire built in a wheel with a rim width of 6 inches and a rim diameter of 17 inches. It is pressed against a 3m diameter steel drum with a camber angle (CA) of 50 degrees, a load of 1500 N, and a slip angle (SA) of 0 degrees, and rotated at a speed of 40 km / h. Measure with a three-component force meter. This lateral force is the camber thrust. The internal pressure of the tire is 240 kPa.
The lateral force was measured 5 minutes after the tire started rotating. At this time, the tire is sufficiently warm. Therefore, the temperature of the shoulder portion immediately after stopping the drum after running for 5 minutes was measured, and this was taken as the temperature of the shoulder portion of the drum.
The lateral force of the tire of Conventional Example 1 was 1350N. The lateral force of other tires is represented by an index with the lateral force of Conventional Example 1 as 100.
(2) Rolling resistance test during straight running The rolling resistance test was performed using a rolling resistance tester. The measurement conditions are an internal pressure of 240 kPa, a load of 1500 N, a camber angle (CA) of 0 degree, a slip angle (SA) of 0 degree, and a speed of 80 km / h. The value of the rolling resistance is shown as an index with the rolling resistance of the tire of Conventional Example 1 being 100, and the smaller this index is, the smaller the resistance is and the fuel economy can be saved.
(3) Steering performance evaluation test by driver and measurement of shoulder temperature after running A comprehensive driving stability test by an experienced driver was conducted at the test course. The prepared tire was a rear tire, and only the rear tire was changed for a real vehicle test. The front tire was fixed with a conventional one.
The tires were mounted on a 1000cc sports-type motorcycle and the vehicle was run on a test course, and the evaluation was centered on the cornering performance when turning the vehicle. The evaluation points were comprehensively evaluated by a 10-point method based on the feeling of a test rider.
The layout of the test course was provided with six corners that could be defeated to 50 degrees CA at a speed of around 50 km / h, so that the side grip performance when the vehicle was largely defeated could be confirmed. The lap time for one lap was about 60 seconds, and the lap time was 15 laps.
Moreover, the temperature of the shoulder part immediately after 15 rounds of travel was measured, and this was made into the temperature of the shoulder part after driving | running | working a real vehicle.

The effects of the present invention can be seen from the above test results.
Comparing the results of Conventional Example 2 without internal rubber with the results of Examples 1 to 4 in which a different type of tan δ rubber having a width of 15 mm to 72 mm is arranged inside the tread end, Examples 1 to 4 It can be seen that in both cases, the temperature of the shoulder portion is lower than in Conventional Example 2 and the lateral force at the drum = camber thrust is increased. It can be seen that the decrease in the temperature of the shoulder portion and the increase in the lateral force increase as the width of the different rubber increases. In Examples 1 to 4, the evaluation of the steering stability performance is higher than that of Conventional Example 2, and the temperature of the shoulder portion after traveling is lower than that of Conventional Example 2. Accordingly, it was confirmed that if a different kind of rubber having a small tan δ is disposed inside the tread end, the temperature rise of the shoulder portion can be suppressed and the lateral grip performance can be improved.
Further, in Comparative Example 1 in which the width of the different rubber is 10 mm, the result is almost the same as that in Conventional Example 2. Therefore, when the width of the different rubber is less than 5% of the tread development width, the width is too small. It can be seen that the effect of disposing different types of rubber inside the tread edge cannot be obtained. On the contrary, in Comparative Example 2 in which the width of the different rubber is 84 mm, the lateral force and the temperature of the shoulder portion are almost the same as those in Example 4 in which the width is 72 mm. Lower than. Therefore, even if the width of the different rubber is made larger than 30%, not only does the lateral force increase and the temperature of the shoulder portion not decrease, but also the steering stability performance deteriorates. As a result, it was confirmed that it was 5% to 30% of the tread development width, and more preferably 8% to 25%.
As can be seen from a comparison between Example 1 and Example 4, the steering stability performance decreases when the width is increased to a certain extent. This is because when the width of the different rubber becomes wider, the rubber behaves harder, so that slippage during driving increases and adversely affects steering stability performance. In Examples 1 to 4, the rubber width is 60 mm (25%). Example 1 is the highest evaluation.

Comparing the results of Conventional Example 2 without internal rubber with the results of Examples 1, 5, and 6 in which different types of rubbers with small tan δ having thicknesses of 2 mm, 4 mm, and 5 mm are disposed inside the tread edge, In each of 1, 5, and 6, the temperature of the shoulder portion is lower than that of the conventional example 2 and the lateral force on the drum is increased, and the steering stability performance and the temperature drop of the shoulder portion after running are also improved. I understand that. As the thickness of the different types of rubber increases, the lateral force and the shoulder temperature are improved. However, as can be seen from the comparison between the first embodiment and the sixth embodiment, the steering stability performance decreases when the thickness is increased to a certain level. This is because, when the thickness of the different rubber becomes thicker, the rubber behaves harder, so that slippage during driving increases and adversely affects the steering stability performance.
On the other hand, in Comparative Example 3 where the thickness of the different rubber is less than 20% (1 mm) of the entire tread, although slightly improved compared to Conventional Example 2, the effect is small because it is too thin. On the contrary, in Comparative Example 4 in which the thickness of the different rubber is 7 mm, the lateral force is lower than that in Conventional Example 2. This is due to the fact that the dissimilar rubber with a small tanδ with a small lateral grip is exposed on the grounding surface. Although the temperature of the shoulder portion of the drum has decreased, the temperature of the shoulder portion of the actual vehicle has increased conversely. is doing. Therefore, it is necessary to dispose different types of rubbers having a small tan δ inside, and the thickness should be within a range of 20% to 70%, more preferably 30% to 70% of the entire tread. Was confirmed.

  As can be seen by comparing the results of Conventional Example 1 and Conventional Example 2 and Example 1 and Example 10, when the rubber at the center portion is made of two layers, different types of rubber are arranged inside the tread end. It was confirmed that the effect was further enhanced. That is, in the conventional example 2 in which the rubber at the center portion is two layers compared to the conventional example 1 in which the different types of rubber are not disposed inside the tread end, the rolling resistance during straight traveling is merely improved. In Example 10 in which different types of rubber are arranged inside the tread end and Example 1 in which two rubber layers in the center part are further provided, not only rolling resistance during straight running but also steering stability performance is enhanced. Therefore, it can be seen that the lateral grip is also improved. The reason why the lateral force in the drum test is not improved is that the CA is 50 degrees in the drum test, so the center part is not grounded, and therefore the effect of making the center part two layers cannot be obtained. Therefore, in the actual running test, the temperature of the tire center portion also rises, so that the effect of making the center portion into two layers is remarkable.

Comparing the results of Example 1 with the results of Examples 7, 8 and 9, even when the tan δ index of the different rubber is 90, the effect of disposing the different rubber is obtained, but the effect is small. The smaller the index of tanδ of rubber, the better. However, if the index of tan δ of the different rubber is lowered to 40 as in Example 9, the temperature of the shoulder portion is lowered, but the lateral force and the steering stability performance are lowered. Therefore, it is understood that the range of 50 to 80 is appropriate as the index of tan δ of the different rubber. When the index of tan δ is further reduced, the rubber behaves hard and slippage on the tread surface increases and grip decreases.
Moreover, when the result of Example 11 and the result of Example 1 are compared, it can be seen that Example 11 is improved over all of lateral force, shoulder temperature, and steering stability performance. As a result, when the thickness of the surface rubber at the end of the tread is reduced while maintaining the thickness of the different rubber, not only the rigidity of the portion is increased, but also the ratio of the different rubber is increased. It was confirmed that the lateral force and steering stability performance can be improved by suppressing the temperature rise.

Best Mode 2
FIG. 5 is a diagram showing a configuration of the motorcycle tire 20 according to the best mode 2. As shown in FIG. The two-wheeled vehicle tire 20 is assumed to be used for competition, and includes two body plies 22A and 22B, a spiral belt layer 23 disposed outside the body plies 22A and 22B in the tire radial direction, and the spiral belt layer 23. One radial belt layer 24 arranged on the outer side in the tire radial direction of the tire, a tread layer 25 made of a rubber member arranged on the outer side in the tire radial direction of the radial belt layer 24, the spiral belt layer 23 and the radial belt layer And a cushioning rubber layer 28 disposed between them.
The two body plies 22A and 22B are, for example, a plurality of cords made of fibers such as aromatic polyamide (trade name: Kevlar), which are twisted and arranged in parallel at a predetermined driving interval. When it is in the form of a sheet and arranged on a tire, the cord angle of the cord with respect to the equator direction is 40 degrees. These two body plies 22 cross each other, and two of the body plies 22 are gathered together at the bead portion 21 and fixed by being sandwiched by bead wires 22W from both sides.
The spiral belt layer 23 is a belt layer having a cord angle with respect to the equator direction of 0 to 5 degrees, and is formed by covering one or more cords with rubber and winding the cord around the tread portion in a spiral manner. It is.
The radial belt layer 24 is formed by twisting cords made of aromatic polyamide fibers at predetermined driving intervals, and the cord angle with respect to the equator direction is 80 to 90 degrees.
The developed width of the tread layer 25 is 240 mm, and the width of the spiral belt layer 23 and the width of the radial belt layer 24 are also 240 mm.
The tread layer 25 is composed of a shoulder portion 26 and a center portion 27. The shoulder portion 26 includes a shoulder surface layer 25a located on the tire surface side and a first different rubber layer 25b located on the inner layer. is there. On the other hand, the center portion 27 includes a center surface layer 25c located on the tire surface side and a second different rubber layer 25d located on the inner layer. An intermediate layer 25m made of high-loss rubber is disposed between the shoulder portion 26 and the center portion 27.
The high-loss rubber is a rubber having a tan δ of 0.4 at 100 ° C., and the rubber constituting the shoulder surface layer 25a is also a high-loss rubber. On the other hand, the tan δ at 100 ° C. of the rubber constituting the first and second different rubber layers 25b, 25d is 0.25, and the tan δ at 100 ° C. of the rubber of the center surface layer 25c is 0.35.

In the case of tires used in competitions, since the tires are often used at high speeds and at large CAs, the general-purpose motorcycle shown in FIG. The rigidity of the tire is made higher than that of the tire 10, and the tan δ of the rubber constituting the center surface layer 25c is made smaller than the tan δ of the rubber constituting the intermediate layer 15m that is the rubber on both sides thereof.
As described above, by arranging the center surface layer 25c made of rubber having a small tan δ on the surface portion of the center portion 27, the center portion 27 can be compared with the case where the second dissimilar rubber layer 25d is simply provided on the inner layer. Heat generation can be suppressed. Thereby, since the rigidity of the center part 27 can be improved, while being able to improve the rolling resistance at the time of going straight, the steering stability performance can be improved.

Moreover, in this example, since the radial belt layer 24 is used as the belt layer disposed on the outer side in the radial direction of the spiral belt layer 23, a high lateral force can be maintained. That is, the outermost layer of the belt layer has a belt layer extending almost in the tire width direction with a cord angle of 80 degrees to 90 degrees with respect to the equator direction, and since this is widely disposed on the shoulder portion 27, the foundation of the tread layer 25 is Strengthens in the lateral direction (tire width direction). Therefore, since the radial belt layer 24 has rigidity against the transverse shear of the tread, a high lateral force can be maintained. That is, even if the rubber generates heat and softens somewhat, the presence of the radial belt layer 24 in the inside can exert strength in the lateral direction.
Further, as described above, the spiral belt layer 23 is effective in preventing the tire from expanding due to centrifugal force and improving the steering stability performance during high-speed traveling. Further, since the belt rigidity can be kept relatively high only by the spiral belt layer 23, there is a tire in which the belt layer is configured only by the spiral belt layer 23. Further, when the spiral belt layer 23 is provided, the belt rigidity is increased, so that the belt to be matched with the cord angle with respect to the equator direction as in the cross belt layers 14A and 14B of the two-wheeled vehicle tire 10 shown in the best mode 1. Is almost 40 to 80 degrees, and the spiral belt layer 23 almost receives the internal pressure of the tire. Therefore, if the spiral belt layer 23 is damaged, it may lead to a tire burst. For example, when the tread is worn and thinned, when a protrusion is stepped on at high speed, or when the tire is used even though it is worn, and the spiral belt layer 23 is exposed, the spiral belt layer 23 may break. Therefore, if a belt layer along the width direction, such as the radial belt layer 24, is provided outside the spiral belt layer 23 in the radial direction, the spiral belt layer 23 can be reliably protected.

  Further, in this example, a buffer rubber layer 28 having a thickness of 0.3 mm to 3.0 mm is provided between the spiral belt layer 23 and the radial belt layer 24 to prevent uneven wear and heat generation. . This is because the shock absorbing rubber layer 28 is sheared and deformed in the circumferential direction to absorb the circumferential deformation of the driving deformation and braking deformation of the tread layer 25. Since the buffer rubber layer 28 does not absorb the deformation in the width direction, the lateral deformation of the tread is kept large. Therefore, it is possible to prevent heat generation due to the circumferential deformation of the tread while maintaining a high lateral force. In particular, when the first different rubber layer 25b is provided on the inner layer of the shoulder portion 26 and a different rubber having a small tan δ is arranged as in this example, the first different rubber is deformed by the deformation of the buffer rubber layer 28. Since the distortion of the shoulder surface layer 25a made of high-loss rubber disposed on the surface side of the layer 25b is reduced, heat generation can be further prevented. It is preferable that the buffer rubber layer 28 and the radial belt layer 24 are arranged widely so as to overlap with the end portion of the tread and the position where the first dissimilar rubber layer 25b is arranged.

In the best mode 2, the width Ws of the spiral belt layer 23 is substantially the same as the tread development width. However, if the width Ws of the spiral belt layer 23 is smaller than the tread development width, heat generation is further prevented. In addition, the wear resistance can be improved. If the spiral belt layer 23 is not disposed at least in the region A (see FIG. 10 for the regions A, B, and C of the shoulder portion 26), the radial belt layer is formed on the tread end portion 25z side. This is because the tread 24 can be extended in the tire circumferential direction, so that braking deformation of the tread can be suppressed. That is, the fact that the radial belt layer 24 extends in the circumferential direction in the region is that the belt speed is increased, and the belt speed difference between the region A and the region C is reduced. Thereby, since unnecessary deformation (braking deformation) in the tread circumferential direction is suppressed, heat generation of rubber due to repeated deformation is reduced. As a result, slippage can be reduced, heat generation due to slippage can be reduced, and rubber softening can be prevented. Further, since the slip is reduced, the wear resistance is also improved. Therefore, a rubber having a higher coefficient of friction (grip), that is, a rubber having a larger tanδ than the conventional one can be disposed on the surface of the tread end.
The width of the spiral belt layer 23 is preferably 60% to 90% of the developed tread width. If the width of the spiral belt layer 23 exceeds 90% of the developed tread width, the belt layer becomes less stretched in the tire circumferential direction, making it difficult to suppress braking deformation of the tread. On the contrary, if the width of the spiral belt layer 23 is less than 60% of the tread developed width, a region where the spiral belt layer 23 does not exist is formed in the region C. Therefore, in the region C, the belt layer extends in the tire circumferential direction. As a result, the belt speed difference between the area A and the area C is not reduced so much. Therefore, the effect of suppressing the braking deformation is reduced, and the heat generation of rubber due to repeated deformation cannot be reduced. In addition, since the spiral belt layer 23 does not exist in most of the ground contact area, the tagging effect is weakened and the steering stability performance at high speed is reduced. Therefore, the width of the spiral belt layer 23 is preferably 60% to 90%.

In addition, as shown in FIG. 6, if the hard rubber 29 is arranged on the wall surface of the tread end portion 25z so as to suppress the softening of the tread rubber due to heat generation, the tread is prevented from falling when the tread is laterally deformed. can do. The hard rubber 29 is harder than any rubber that forms the tread layer 25. Thereby, it is possible to prevent the tread end portion 25z from floating from the road surface.
The hard rubber 29 should not be exposed on the wall surface. This is because the hard rubber 29 is hard and has a low friction coefficient. When the hard rubber 29 reaches the tread surface, not only the frictional force cannot be improved due to contact with the road surface, but conversely, the contact area of the soft rubber (high loss rubber) is reduced. Therefore, in this example, the hard rubber 29 is arranged so that the position of the hard rubber 29 on the outer side in the tire radial direction is a depth of about d = 1 mm from the tread surface.
Further, when the thickness (length along the tire width direction) D of the hard rubber 29 is increased, the amount of rubber in the first different rubber layer 25b disposed in the inner layer of the region A is reduced. Is preferably 6 mm or less even at the maximum thickness. The thickness D of the hard rubber 29 depends on its hardness, but the effect can be exhibited if it is 1 mm or more. More preferably 2 mm to 5 mm.

In the above example, the dynamic elastic modulus E ′ of the rubber was not defined, but the dynamic elastic modulus E ′ (L) of the rubber having a small tan δ constituting the first different rubber layer 25b was determined as the shoulder surface. If it is made smaller than the dynamic elastic modulus E ′ (H) of the high-loss rubber constituting the layer 25a, it is possible to improve the grip when heat generation is not yet sufficient, just after the start of running.
In other words, the rubber behaves hard at low temperatures, so the tread surface slips and a sufficient grip cannot be obtained. Therefore, in order to obtain a grip in the initial stage of travel, the rubber of the shoulder surface layer 25a can be moved easily by reducing the dynamic elastic modulus E ′ (L) of the rubber having a small tan δ constituting the first different rubber layer. Then, if the warming of the shoulder portion 26 is improved, it is possible to balance the grip at the initial stage of travel and the subsequent grip.

In the best modes 1 and 2, the width of the first dissimilar rubber layer 15c (or the first dissimilar rubber layer 25b) is constant in the thickness direction, but may be changed depending on the purpose of use. . For example, when it is important that the tread temperature is not lowered to a certain extent even when worn, the width of the dissimilar rubber layer 15c is gradually increased from the tread surface side toward the inner side in the tire radial direction as shown in FIG. You can make it narrower. This is because when the tread is worn, the thickness of the tread is reduced and shear deformation is reduced, so the amount of heat generated is also reduced.However, when the width of the different rubber is constant in the thickness direction, the rubber having a smaller tanδ as the tread is worn. Therefore, the tread temperature is too low and the grip may be lowered. Therefore, if the width of the dissimilar rubber layer 15c (or the first dissimilar rubber layer 25b) is gradually narrowed from the tread surface side toward the inner side in the tire radial direction, the state in which wear has progressed, that is, the amount of generated heat is small. In this state, the ratio of the rubber having a small tan δ is also reduced, so that a decrease in the tread temperature due to wear of the tread can be prevented, and a decrease in grip due to wear can be prevented.
If it is not desired to lose the lateral grip at the maximum CA due to heat generation, the width of the first different rubber layer 15c (or the first different rubber layer 25b) is changed from the tread surface side to the inner side in the tire radial direction. You should gradually widen toward it. Specifically, as shown in FIG. 8A, the cross-sectional shape of the first dissimilar rubber layer 15c may be substantially trapezoidal, or may be substantially triangular as shown in FIG. 8B. . As a result, the closer to the end of the shoulder portion 16, the greater the proportion of rubber with a smaller tan δ. Therefore, heat generation in the regions A and B that greatly contribute to the occurrence of lateral grip at the maximum CA is effectively suppressed. be able to. Therefore, it is possible to sufficiently secure the lateral grip at the time of maximum CA.
[Second Example]

The two-wheeled vehicle tire assumed for competition shown in FIG. 5 is a tire according to the present invention (Examples 12 to 20) provided with a different rubber layer having a small tan δ in the inner layer on the tread end portion 25z side of the shoulder portion, and a different rubber. The width of the conventional tire having no layer (Conventional Example 3), the tire having no different rubber layer but having hard rubber (Comparative Example 5), the tire having the buffer rubber layer (Comparative Example 6), and the spiral belt layer A tire having a narrow width (Comparative Example 7) was prepared, and the results of a lateral force test at 50 degrees CA and an evaluation test of steering stability performance by a driver were shown in the table of FIG.
The tire is a motorcycle tire, and the tire size is 190 / 50ZR17.
Each of these tires has two body plies. In this body ply, an aromatic polyamide (trade name: Kevlar) fiber is twisted to have a diameter of 0.6 mm, and this is arranged so that driving at the tire center portion is 40/50 mm. These two body plies cross each other, and the angle at the tire center portion is 40 degrees with respect to the equator direction. The body ply reaches the bead part, and two sheets are gathered together at the bead part and fixed by being sandwiched by bead wires from both sides.
The spiral belt layer was formed by twisting seven steel single wires having a diameter of 0.12 mm to form one steel cord, and winding it in a spiral shape so that the driving distance was 50/50 mm.
In the radial belt layer, aromatic polyamide fibers twisted to a diameter of 0.6 mm were arranged at a driving interval of 50/50 mm.
The thickness of the tread layer is uniform from the center part to the shoulder part, 8 mm, and the developed width of the tread is 240 mm. The width of the spiral belt layer is 240 mm in Conventional Example 3, Example 12, and Comparative Examples 5 and 6, 180 mm in Examples 13 to 20 and Comparative Example 7, and the width of the 90-degree belt layer is 240 mm. It is.
The above basic structure is common to each tire.

Moreover, the difference in tread rubber is as follows.
In the center portion of the tire tread layer of Conventional Example 3, a rubber having a width of 120 mm and a tan δ of 0.25 at 100 ° C. is disposed with a thickness of 4 mm. In addition, a rubber having a width of 90 mm and a tan δ of 0.35 at 100 ° C. is disposed on the upper portion. And the rubber whose tan-delta is 0.4 at 100 degreeC is arrange | positioned in the tread center part both surface layer part.
Tire of Example 12 The tire of Example 12 is the same as that of the tire of Conventional Example 3 except that different types of rubber are arranged inside the tread ends.
The width of the dissimilar rubber is 60 mm (25% of the developed width of the tread), the thickness is 4 mm (57% of the thickness of the tread layer), and the tan δ at 100 ° C. is 0.25. The boundary in the depth direction between the dissimilar rubber and the rubber closer to the center is substantially perpendicular to the depth direction and is not inclined.
The tire of Example 13 is the same as the tire of Example 12 except that the width of the spiral belt layer of Example 12 is changed to 180 mm.
The tire of Example 14 is the same as the tire of Example 13 except that the shape of the dissimilar rubber of Example 13 is changed to a type having a narrow radial inner width as shown in FIG.
The tire of Example 15 is the same as the tire of Example 13 except that the shape of the dissimilar rubber of Example 13 is changed to a type having a wide radial inner width as shown in FIG. It is.
The tire of Example 16 is the same as the tire of Example 13 except that the shape of the dissimilar rubber of Example 13 is changed to a triangular type as shown in FIG.
In the tire of Example 17, the shape of the dissimilar rubber of Example 13 is changed to a type in which the radially inner rubber extends in the center direction and is connected to the dissimilar rubber in the center portion inner layer as shown in FIG. The rest is the same as the tire of Example 13.
The tire of Example 18 is the same as the tire of Example 12 except that the dynamic elastic modulus E ′ of the dissimilar rubber of Example 12 is 70% of the dynamic elastic modulus E ′ of Example 12. .
As shown in FIG. 6, the tire of Example 19 is the same as the tire of Example 12 except that hard rubber is disposed on the wall surface of the tread edge of Example 12.
The tire of Example 20 is the same as the tire of Example 12 except that a cushion rubber is disposed between the spiral belt layer and the crossing belt layer of Example 12.
The tire of Comparative Example 5 is the same as the tire of Conventional Example 3 except that hard rubber is disposed on the wall surface of the tread edge of the tire of Conventional Example 3.
The tire of Comparative Example 6 is the same as the tire of Conventional Example 3 except that a buffer rubber is disposed between the spiral belt layer and the crossing belt layer of the tire of Conventional Example 3.
The tire of Comparative Example 7 is the same as the tire of Conventional Example 3 except that the width of the spiral belt layer of the tire of Conventional Example 3 is changed to 180 mm.

Prepare three of each of the above tires, one for lateral force evaluation when it is new, the other for lateral force evaluation assuming the progress of wear by scraping the tread surface, and the other for actual vehicle testing. did.
(1) Lateral force evaluation at 50 degrees CA (when new)
A tire built into a wheel with a rim width of 6 inches and a rim diameter of 17 inches is mounted on a steel drum with a diameter of # 40 and a camber angle (CA) of 50 degrees and a load of 1500 N. , Slip angle (SA) is pressed at 0 degree and rotated at a speed of 1000 km / h, and the lateral force at this time is measured with a three-component force meter attached to the rotating shaft of the tire. This lateral force is the camber thrust. Note that the internal pressure of the tire is 200 kPa.
The lateral force was measured 5 minutes after the tire started rotating. At this time, the tire is sufficiently warm. Therefore, the temperature of the shoulder portion immediately after stopping the drum after running for 5 minutes was measured, and this was taken as the temperature of the shoulder portion of the drum.
The lateral force was 1900 N for the tire of Conventional Example 3. The lateral force of other tires is represented by an index with the lateral force of Conventional Example 3 set to 100.
(2) Lateral force evaluation assuming wear A tire similar to the 3m drum in (1) above was rotated on a tire whose surface was uniformly cut by 3mm from the center to the shoulder (hereinafter referred to as a 3mm cut product). Then, the lateral force and the temperature of the shoulder portion after 5 minutes were measured. The lateral force was expressed as an index with the lateral force of Conventional Example 3 taken as 100.
(3) Evaluation of driving stability performance by driver A comprehensive driving stability performance test by an experienced driver was conducted on the test course. The prepared tire was a rear tire, and only the rear tire was changed for a real vehicle test. The front tire was fixed with a conventional one.
The motorcycle was used for competition by modifying a sport type motorcycle with 1000cc tires, and running on the circuit was assumed assuming competition. The maximum speed at this time was 320 km / h. The evaluation points were comprehensively evaluated by a 10-point method based on the feeling of a test rider. The test was performed for 20 laps, and the average lap time for the first 10 laps and the average lap time for the last 10 laps were obtained. In addition, the feeling of steering stability performance was also evaluated for the first 10 laps and the second 10 laps. The layout of the test course had four corners where the car body was greatly lowered at a speed of 80 km / h to 120 km / h.
In addition, the temperature of the shoulder portion immediately after running for 20 laps was measured.
(4) Evaluating the amount of wear Before starting the actual vehicle test, weigh the tires, and after removing 20 laps on the test course, remove any dirt or debris that has adhered to the tires. Measure the weight. Since the special test course had many corners, wear was concentrated on the shoulder. Therefore, the weight difference of the tire after running with respect to the new tire was evaluated as the wear amount of the shoulder portion of the tire. The amount of wear of each tire was expressed as an index with the amount of wear in Conventional Example 3 as 100. In addition, the amount of wear of the shoulder portion of Conventional Example 3 was 4 mm.

The effects of the present invention can be seen from the above test results.
Comparing the result of Conventional Example 3 with the result of Example 13 in which a different kind of rubber with a small tan δ is arranged inside the tread end and the width of the spiral belt layer is narrow, in Example 13, a new article is also a 3 mm machined product. In both cases, the lateral force index is improved by 8 to 8.5. Also, the lap time when running on the circuit is 1.0 seconds or more faster, and the effect is clear. Furthermore, the amount of wear is 20% less than that of Conventional Example 3. That is, in Example 13, the tire grip is improved and the slip of the tire is suppressed, and as a result, the wear amount is significantly reduced.
This is because the width of the spiral belt layer is simply narrowed as in Comparative Example 7, or the single effect in which a dissimilar rubber having a small tan δ is disposed inside the tread end as in Example 12, It shows that the effect increases by combining both. For example, regarding the amount of wear, Comparative Example 7 is 7% less than Conventional Example 3, and Example 12 is 6% less than Conventional Example 3. Therefore, when both are simply combined, the calculation is improved by 13%. However, in actuality, the wear amount of Example 13 in which both are combined is 20% less than that of Conventional Example 3. This is thought to be due to the fact that by combining the two, a synergistic effect is exhibited, the grip level is further increased, the tire is less slippery, and the wear resistance is dramatically improved.
In addition, the temperature of the shoulder portion after running is also much lower than that of Conventional Example 3, Comparative Example 7, and Example 12 in Example 13, so there is also a synergistic effect on the temperature of the shoulder portion. You can see that it is being demonstrated.

When the result of Example 13 and the result of Example 14 are compared, in Example 14, the grip when the thickness of the tread is reduced due to wear is high. This is because when the shape of the different rubber does not change in the thickness direction of the tread as in Example 13, not only does the amount of heat generated by the wear progress and the thickness of the tread become thin, but also in the shoulder portion. The effect of increasing the proportion of rubber with a small tan δ is added to greatly reduce the tread temperature. For this reason, since rubber behaves hard, there is a tendency that slip increases and grip decreases. On the other hand, as in Example 14, when the proportion of the different rubber is thinner toward the inside in the tire radial direction, the proportion of the rubber having a small tan δ in the shoulder portion becomes smaller as the wear proceeds. A decrease in the tread temperature can be suppressed. When the tread temperature after wear is too low, it is possible to control the balance with the shape as in Example 14. In Example 14, there is an effect even when the wear amount is 3 mm to 4 mm. Therefore, it is considered that the effect can be further exhibited when the wear further proceeds.
Further, comparing the results of Example 13 with the results of Examples 15 and 16, in Examples 15 and 16, although the initial grip is slightly lowered, the grip is not only sufficiently higher than that of Conventional Example 3, but also wear. The grip when the tread thickness is reduced is high. In this way, as in Examples 15 and 16, if the shape of the rubber having a smaller tan δ is larger toward the end of the shoulder portion, the temperature of the shoulder portion can be maintained at a certain level, so that the maximum CA is obtained. It has been confirmed that the lateral grip of can be prevented from being lost due to heat generation.

Further, comparing the result of Example 13 with the result of Example 17, in Example 17, the temperature of the shoulder portion hardly changes, but the initial grip is improved and the score in the actual vehicle is also high. Thus, as in Example 17, it was confirmed that the rigidity of the center portion can be increased by extending the rubber having a small tan δ to the center side and decreasing the tan δ inside the center side.
Also, comparing the results of Example 13 with the results of Example 18, in Example 18, which is a rubber having a small tan δ and a small dynamic elastic modulus E ′, the score and lap time of the first 10 laps in an actual vehicle are improved. is doing. According to the comments of the evaluated riders, this is because the warmth of the shoulder at the beginning of running is good and the grip at the beginning of running is high. When rubber with a small tan δ is arranged in the shoulder portion as in Example 13, when the heat generation is not yet sufficient immediately after the start of running, the tread surface slips because the rubber behaves hard at low temperatures, and the grip May not be sufficient.
As described above, it was confirmed that if a rubber having a small tan δ and a small dynamic elastic modulus E ′ is used, a grip at the beginning of running can be secured.

Comparing the results of Example 13 with the results of Example 19, in Example 19 in which hard rubber was disposed at the tread end, not only the grip was greatly improved, but also the circuit score was improved. On the other hand, when the result of Conventional Example 3 without internal rubber is compared with the result of Comparative Example 5 in which hard rubber is arranged at the tread end of Conventional Example 3, the amount of wear is slightly improved in Comparative Example 5. The other characteristics were almost the same as those of Conventional Example 3. As described above, it was confirmed that when the rubber having a small tan δ is arranged in the shoulder portion, the effect of arranging the hard rubber at the tread end can be sufficiently exhibited.
Further, in Example 20 having a buffer rubber layer, the temperature of the shoulder portion is as low as 10 ° C. and the grip is greatly improved in both a new product and a 3 mm machined product. Recorded the highest score and the fastest lap time. Also, the amount of wear was very small. On the other hand, in Comparative Example 6 in which the buffer rubber layer was arranged in Conventional Example 3 without internal rubber, the grip was not improved so much even though the temperature of the shoulder portion was as low as 10 ° C.
Example 20 shows such excellent characteristics because the grip is improved by placing rubber with a small tan δ in the shoulder portion, and the slip is reduced by narrowing the width of the spiral belt layer. It is thought that this is because the wear resistance performance and the grip are drastically improved by overlapping the effect of further improving the grip by arranging the buffer rubber.
By the way, in terms of the amount of wear, only 7% (conventional example 3 and comparative example 7) is achieved by narrowing the width of the spiral belt layer, and 8% (conventional example 3 and comparative example 6) simply by disposing the buffer rubber layer. The effect of 6% (conventional example 3 and example 12) can be obtained only by placing rubber having a small tan δ, but when these are simply added, the effect is 21%. However, in Example 20, the amount of wear is smaller by 36% compared to Conventional Example 3, so that the cushioning rubber layer is not simply arranged, but synergistically combined with the present invention. The effect can be enhanced.

  Thus, according to the present invention, it is possible to improve the lateral grip during turning of the two-wheeled vehicle and reduce the wear of the tread of the shoulder portion, so that the steering stability performance is excellent and the wear resistance performance is also excellent. A pneumatic tire for a motorcycle can be provided.

1 is a diagram showing a configuration of a motorcycle tire according to a best mode 1 of the present invention. It is a figure which shows an example of the tread pattern of the tire for two-wheeled vehicles. It is a figure which shows the other structure of the tire for two-wheeled vehicles by this invention. It is a figure which shows the specification of a prototype tire (for general use) and its evaluation result. It is a figure which shows the structure of the tire for two-wheeled vehicles which concerns on the best form 2 of this invention. It is a figure which shows an example of the cross-sectional shape of the dissimilar rubber layer by this invention. It is a figure which shows the other example of the cross-sectional shape of the dissimilar rubber layer by this invention. It is a figure which shows the other example of the cross-sectional shape of the dissimilar rubber layer by this invention. It is a figure which shows the specification of a prototype tire (for competition) and its evaluation result. It is principal part sectional drawing when the tire for two-wheeled vehicles is earth | grounded at CA50 degree | times.

Explanation of symbols

10 motorcycle tires, 11 bead parts, 11C bead cores, 12 body plies, 13 spiral belt layers, 14A, 14B cross belt layers, 15 tread layers,
15a surface layer, 15b internal intermediate layer, 15c first dissimilar rubber layer,
15d second dissimilar rubber layer, 15z tread edge, 16 shoulder,
17 Center part,
20 motorcycle tires (for competition), 21 bead parts, 22W bead wire,
22A, 22B body ply, 23 spiral belt layer, 24 radial belt layer, 25 tread layer, 25a shoulder surface layer, 25b first different rubber layer,
25c center surface layer, 25d second dissimilar rubber layer, 25m intermediate layer,
25z tread edge, 26 shoulder, 27 center, 28 cushioning rubber layer,
29 Hard rubber.

Claims (15)

  A pneumatic tire for a motorcycle including a belt layer and a tread rubber disposed on the outer side in the tire radial direction of the belt layer, wherein the tread rubber on the shoulder portion includes a different rubber layer on the inner side in the tire radial direction. The dissimilar rubber layer has one end located at the end of the tread, the width is in the range of 5% to 30% of the tread deployment width, and the loss of rubber with the loss tangent of the rubber located outside the dissimilar rubber layer in the tire radial direction A pneumatic tire for a motorcycle, characterized by being smaller than a tangent.   2. The pneumatic tire for a motorcycle according to claim 1, wherein the width of the different rubber layer is gradually narrowed from the tread surface side toward the inner side in the tire radial direction.   2. The pneumatic tire for a motorcycle according to claim 1, wherein the width of the different rubber layer gradually increases from the tread surface side toward the inner side in the tire radial direction.   The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein a maximum value of the thickness of the different rubber layer is in a range of 20% to 70% of a thickness of the tread rubber. .   The average tread rubber thickness between the tread end of the tread rubber and the position of 10% of the tread deployed width measured from the tread end is the position of 10% of the tread deployed width measured from the tread end. The pneumatic tire for a motorcycle according to any one of claims 1 to 4, wherein the pneumatic tire is thinner than an average tread rubber thickness between 1 to 25%.   A plurality of rubber layers are laminated in the tire radial direction in the tread center portion, and the loss tangent of the rubber of at least one of the inner rubber layers is smaller than the loss tangent of the rubber of the rubber layer disposed on the tread surface. The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein the pneumatic tire is a motorcycle.   The pneumatic tire for a motorcycle according to claim 6, wherein the rubber disposed on the tread surface of the tread center portion and the rubber adjacent to the tire surface side of the different rubber layer are continuously connected.   The rubber of the innermost rubber layer of the tread center portion is the same as the rubber of the different rubber layer, and the innermost rubber layer and the different rubber layer are continuously connected. The pneumatic tire for a motorcycle according to claim 6 or claim 7.   The pneumatic tire for a motorcycle according to any one of claims 1 to 8, wherein a hard rubber having a width of 6 mm or less is disposed on at least a part of the wall surface of the tread edge.   10. The tread rubber according to claim 1, wherein at least a part of the tread rubber is formed by winding a narrow and long rubber strip spirally along a tire circumferential direction. The pneumatic tire for motorcycles according to the above.   The pneumatic tire for a motorcycle according to any one of claims 1 to 10, further comprising a spiral belt layer having an arrangement angle of the reinforcing member with respect to a tire equator direction of 0 to 5 degrees.   The pneumatic tire for a motorcycle according to claim 11, wherein a belt layer having an array angle of 80 to 90 degrees with respect to the tire equator direction of the reinforcing member is disposed outside the spiral belt layer in the tire radial direction. tire.   The pneumatic tire for a motorcycle according to claim 12, wherein a buffer rubber layer having a thickness of 0.3 mm to 3.0 mm is disposed between the spiral belt layer and the belt layer.   The pneumatic tire for a motorcycle according to any one of claims 11 to 13, wherein a width of the spiral belt layer is 60% to 90% of a tread developed width.   15. The motorcycle air according to claim 1, wherein a dynamic elastic modulus of the different kind of rubber is smaller than a dynamic elastic modulus of a rubber located on the outer side in the tire radial direction of the rubber layer. Enter tire.

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