JP5188136B2 - Motorcycle tires - Google Patents

Description

  The present invention relates to a motorcycle tire.

  In a tire mounted on a motorcycle, the radius of curvature of the tread is small from the viewpoint of easy turning. During straight running, the center portion (center region) of the tread is grounded. This center region can mainly affect the straight running performance. During cornering, the area outside the center area in the axial direction is grounded. In particular, when the motorcycle is turned while being tilted to the limit, a portion (side region) near the tread end is grounded. This side region can mainly affect the turning performance.

  Recent motorcycles have high performance and can run at high speed. A motorcycle can travel straight at a high speed and turn at a high speed. Further improvement in running performance is desired for the tire mounted on the motorcycle. With the aim of improving straight running performance and turning performance, studies have been made on the configuration of cords included in belts and bands.

  There is a radial tire with a jointless band. The band has a cord wound spirally and extending substantially circumferentially. This band can contribute to straight running stability at high speeds. However, since this tire is inferior in rigidity, handling is heavy. This tire is inferior in exercise performance. Since this band cannot contribute to the generation of cornering power, this tire also has poor turning performance.

  Japanese Patent Application Laid-Open No. 2005-254992 discloses a belt in which the angle of the cord with respect to the circumferential direction gradually changes from the equator toward the end. This belt can contribute to both straight running performance and turning performance.

Japanese Patent Application Laid-Open No. 2007-182098 discloses a belt including a first cord that extends substantially in the circumferential direction and a second cord whose planar shape is an arc. This belt contributes to both driving performance and turning performance.
JP 2005-254992 A JP 2007-182098 A

  From the viewpoint of improving tire performance, there is a tire in which a reinforcing layer is laminated on a band having a jointless structure. This reinforcement layer is provided with the reinforcement cord which inclines and extends with respect to the circumferential direction. Since this reinforcing layer can contribute to the rigidity of the tire, the handling of the tire is light. With this tire, the exercise performance is improved.

  In this tire, the tire stiffness can be controlled by adjusting the angle (inclination angle) formed by the reinforcing cord with respect to the circumferential direction. In the reinforcing layer having the reinforcing cord having a large inclination angle, the exercise performance can be improved while maintaining the ground contact area and securing the traction grip.

  In this tire, the inclination angle β of the reinforcing cord inside the side region is usually larger than the inclination angle α of the reinforcing cord inside the center region. For this reason, the inclination angle β of the reinforcing layer formed to have a large inclination angle α from the viewpoint of securing a traction grip during straight traveling is extremely large. A large inclination angle β affects the rigidity of the side region. With this tire, a sufficient side grip cannot be obtained, so it is impossible to turn at high speed. This tire is inferior in turning performance.

  The inclination angle α of the reinforcing layer formed so as to have a small inclination angle β from the viewpoint of securing a side grip during cornering is extremely small. A small inclination angle α affects the rigidity of the center region. In this tire, the ground contact area in the center region is insufficient. With this tire, it is not possible to secure a sufficient traction grip when traveling straight ahead. This tire is inferior in acceleration performance.

  An object of the present invention is to provide a tire for a motorcycle that is excellent in motion performance and grip performance.

  The motorcycle tire according to the present invention includes a tread whose width is the maximum width of the tire, a band located inside the tread in the radial direction, and a reinforcing layer laminated on the band. The tread has a shape protruding outward in the radial direction. This band includes a band cord wound spirally and extending substantially in the circumferential direction. The reinforcing layer includes a reinforcing cord. The reinforcing cord extends from one end to the other end while being inclined in the same direction with respect to the circumferential direction. The absolute value of the first inclination angle of the reinforcing cord near the center in the axial direction is larger than the absolute value of the second inclination angle of the reinforcing cord near the tread end.

  Preferably, in this tire, the ratio of the height in the radial direction to the position where the maximum width of the tread becomes the tire height is 0.2 or more and 0.6 or less.

  Preferably, in this tire, the difference between the absolute value of the first inclination angle and the absolute value of the second inclination angle is 5 ° or more.

  Preferably, in this tire, the absolute value of the first inclination angle is not less than 60 ° and not more than 88 °. The absolute value of the second inclination angle is not less than 45 ° and not more than 80 °.

  In this tire, the absolute value of the inclination angle α of the reinforcing cord near the center in the axial direction is larger than the absolute value of the inclination angle β of the reinforcing cord near the tread end. A tire having such a reinforcing cord is excellent in exercise performance and grip performance.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 is a cross-sectional view showing a part of a pneumatic tire 2 according to an embodiment of the present invention. In FIG. 1, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. The tire 2 has a substantially left-right symmetric shape centered on a one-dot chain line CL in FIG. This alternate long and short dash line CL represents the equator plane of the tire 2. The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a band 12, a reinforcing layer 14, an inner liner 16 and a chafer 18. The tire 2 is a tubeless type. The tire 2 is attached to a motorcycle.

  The tread 4 is made of a crosslinked rubber having excellent wear resistance. The tread 4 includes a tread surface 20. The tread surface 20 is in contact with the road surface. A groove 22 is carved in the tread surface 20. The groove 22 forms a tread pattern. The groove 22 may not be cut in the tread 4.

  In FIG. 1, point PT represents the tread end. The axial distance between the left and right tread ends PT is the width of the tread 4. As shown in the drawing, the tread end PT is located outside the tire 2 in the axial direction. In the tire 2, the width of the tread 4 is the tire maximum width. In the tire 2, the tread end PT is a position where the tread 4 has the maximum tire width.

  The tire 2 is attached to a motorcycle. From the viewpoint of easy turning, the radius of curvature of the tread 4 is small. The tread 4 has a shape protruding outward in the radial direction. During straight running, the center portion (center region 24) of the tread 4 is grounded. During cornering, the area outside the center area 24 in the axial direction is grounded. In particular, when the motorcycle is turned while being tilted to the limit, the portion (side region 26) near the tread end PT is grounded.

  The sidewall 6 extends substantially inward in the radial direction from the tread end PT. The sidewall 6 is made of a crosslinked rubber. The sidewall 6 absorbs an impact from the road surface by bending. Furthermore, the sidewall 6 prevents the carcass 10 from being damaged.

  The bead 8 is located substantially inward of the sidewall 6 in the radial direction. The bead 8 includes a core 28 and an apex 30 that extends radially outward from the core 28. The core 28 has a ring shape. The core 28 includes a plurality of non-stretchable wires (typically steel wires). The apex 30 is tapered outward in the radial direction. The apex 30 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a carcass ply 32. The carcass ply 32 is spanned between the beads 8 on both sides, and extends along the inside of the tread 4 and the sidewall 6. The carcass ply 32 is folded around the core 28 from the inner side to the outer side in the axial direction.

  Although not shown, the carcass ply 32 includes a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is usually 70 ° to 90 °. In other words, the carcass 10 has a radial structure. The cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. A carcass 10 having a bias structure may be employed.

  The band 12 is located on the inner side in the radial direction of the tread 4. The band 12 is located outside the carcass 10 in the radial direction. The band 12 includes a band ply 34. An end 36 of the band ply 34 is located in the vicinity of the tread end PT. The band ply 34 effectively reinforces the tread 4. Although not shown, the band ply 34 is composed of a band cord and a topping rubber. The band cord is spirally wound and extends substantially in the circumferential direction. The band ply 34 has a so-called jointless structure. The band ply 34 can contribute to the rigidity of the tire 2 in the radial direction. In the tire 2, the influence of the centrifugal force acting during traveling is suppressed. This band 12 can contribute to the durability and running stability of the tire 2. The band cord is usually made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. Steel may be used as the material of the band cord.

  The reinforcing layer 14 is laminated with the band 12. In the tire 2, the reinforcing layer 14 is located on the radially inner side of the band 12. The reinforcing layer 14 is located on the radially outer side of the carcass 10. The reinforcing layer 14 is laminated with the carcass 10. The reinforcing layer 14 reinforces the tire 2. This reinforcing layer 14 can contribute to the handling of the tire 2. The tire 2 is excellent in exercise performance. The reinforcing layer 14 may be laminated on the outside of the band 12 in the radial direction.

  The reinforcing layer 14 includes an inner reinforcing ply 38 and an outer reinforcing ply 40. The inner reinforcing ply 38 is located on the radially outer side of the carcass ply 32. The inner reinforcing ply 38 is laminated on the carcass ply 32. An end 42 of the inner reinforcing ply 38 is located in the vicinity of the tread end PT. The inner reinforcing ply 38 effectively reinforces the tread 4 portion of the tire 2. The outer reinforcing ply 40 is located on the radially outer side of the inner reinforcing ply 38. The outer reinforcing ply 40 is laminated on the inner reinforcing ply 38. The outer reinforcing ply 40 is located on the radially inner side of the band ply 34 described above. In the tire 2, the outer reinforcing ply 40 is laminated on the band ply 34. The end 44 of the outer reinforcing ply 40 is located in the vicinity of the tread end PT. The outer reinforcing ply 40 effectively reinforces the tread 4 portion of the tire 2. In the tire 2, the width of the outer reinforcing ply 40 is larger than the width of the inner reinforcing ply 38.

  Although not shown, in the tire 2, the inner reinforcing ply 38 is made of a reinforcing cord and a topping rubber. This reinforcing cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, polyethylene naphthalate fibers, and aramid fibers.

  Although not shown, in the tire 2, the outer reinforcing ply 40 is composed of a reinforcing cord and a topping rubber. This reinforcing cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, polyethylene naphthalate fibers, and aramid fibers.

  FIG. 2 is a development view showing a part of the reinforcing layer 14 of the tire 2 of FIG. 1. In FIG. 2, the inner reinforcing ply 38 and the outer reinforcing ply 40 are shown. In FIG. 2, the vertical direction is the circumferential direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the radial direction. FIG. 2 shows one reinforcing cord 46 included in the inner reinforcing ply 38 and one reinforcing cord 48 included in the outer reinforcing ply 40. In FIG. 2, an alternate long and short dash line CL represents the equator plane of the tire 2.

  In FIG. 2, the double arrow line WH represents the width of the reinforcing layer 14. As shown, the end 44 of the outer reinforcement ply 40 is located axially outside the end 42 of the inner reinforcement ply 38. In the tire 2, the end 44 of the outer reinforcing ply 40 is the end of the reinforcing layer 14. The width WH is obtained by measuring the distance from one end 44 of the outer reinforcing ply 40 to the other end 44. When the end 42 of the inner reinforcing ply 38 is positioned axially outside the end 44 of the outer reinforcing ply 40, the end 42 of the inner reinforcing ply 38 is the end of the reinforcing layer 14, and this width WH It can be obtained by measuring the distance from one end 42 of the reinforcing ply 38 to the other end 42.

  In FIG. 2, an alternate long and two short dashes line LA represents the position of the reinforcing layer 14 that is a predetermined distance away from the equator plane. In the tire 2, the region indicated between the left and right alternate long and two short dashes lines LA is near the center in the axial direction of the reinforcing layer 14. A double arrow line WA represents the width of this region. In the tire 2, the width WA is one third of the width WH. In the present specification, a region between one two-dot chain line LA and the other two-dot chain line LA is referred to as a center portion 50.

  In FIG. 2, a two-dot chain line LB represents a position away from the end 44 of the reinforcing layer 14 by a predetermined distance. In the tire 2, a region from the end 44 to the two-dot chain line LB is in the vicinity of the tread end PT of the reinforcing layer 14. A double arrow line WB represents the width of this region. In the tire 2, the width WB is 1/6 of the width WH. In the present specification, a region outside the two-dot chain line LB in the axial direction is referred to as a side portion 52. The two-dot chain line LB is a boundary line of the side portion 52.

  In the tire 2, the reinforcement cord 46 included in the inner reinforcement ply 38 extends while being inclined with respect to the circumferential direction. As shown in the figure, the reinforcing cord 46 is inclined upward from the right side to the left side on the paper surface. In other words, the reinforcing cord 46 extends from one end 42 to the other end 42 while being inclined in the same direction with respect to the circumferential direction. The inner reinforcing ply 38 including the reinforcing cord 46 can contribute to the rigidity of the tire 2.

  In the tire 2, the reinforcement cord 48 included in the outer reinforcement ply 40 extends while being inclined with respect to the circumferential direction. As shown in the drawing, the reinforcing cord 48 is inclined upward from the left side to the right side on the paper surface. In other words, the reinforcing cord 48 extends from one end 44 to the other end 44 while being inclined in the same direction with respect to the circumferential direction. In the tire 2, the inclination direction of the reinforcement cord 48 is opposite to the inclination direction of the reinforcement cord 46 included in the inner reinforcement ply 38 described above. The outer reinforcing ply 40 including the reinforcing cord 48 can contribute to the rigidity of the tire 2.

  FIG. 3 is a schematic view showing the reinforcing cord 46 included in the inner reinforcing ply 38 in the center portion 50 of the reinforcing layer 14 of FIG. In FIG. 3, one reinforcing cord 46 is shown. In FIG. 3, the angle α represents a first inclination angle formed by the reinforcing cord 46 in the center portion 50 with respect to the circumferential direction.

  In the tire 2, the reinforcing cord 46 in the center portion 50 has a large absolute value of the first inclination angle α. The inner reinforcing ply 38 in the center portion 50 is located inside the center region 24 of the tread 4. The inner reinforcing ply 38 in the center portion 50 can contribute to exercise performance while maintaining a ground contact area and securing a traction grip. In the tire 2, a sufficient traction grip can be obtained during straight traveling. The tire 2 is excellent in grip performance without impairing motion performance. The tire 2 is excellent in acceleration performance when traveling straight.

In the tire 2, the absolute value of the first inclination angle α is preferably 60 ° or more and 88 ° or less from the viewpoint that the inner reinforcing ply 38 in the center portion 50 can effectively contribute to the tire rigidity. By setting the first inclination angle α to 60 ° or more, the inner reinforcing ply 38 in the center portion 50 can contribute to the grip performance. Sufficient traction is generated in the tire 2. The tire 2 is excellent in acceleration performance. From this viewpoint, the first inclination angle α is more preferably 65 ° or more, and more preferably 70 ° or more. By setting the first inclination angle α to 88 ° or less, the rigidity can be appropriately maintained. The tire 2 is excellent in exercise performance. From this viewpoint, the first inclination angle α is more preferably 85 ° or less, and more preferably 80 ° or less. In the tire 2, the first angle obtained by measuring the angle formed by the reinforcing cord 46 with respect to the equator plane CL from the viewpoint that the inner reinforcing ply 38 in the center portion 50 can further effectively contribute to the tire rigidity. based on the tilt angle alpha _0, the tire rigidity is controlled.

  4A is a schematic view showing a reinforcing cord 46 included in the inner reinforcing ply 38 on one side portion 52 of the reinforcing layer 14 in FIG. 2, and FIG. FIG. 6 is a schematic diagram showing a reinforcing cord 46 included in an inner reinforcing ply 38 on the other side portion 52. In FIG. 4A and FIG. 4B, one reinforcing cord 46 is shown. 4A and 4B, the angle β represents the second inclination angle formed by the reinforcing cord 46 in the side portion 52 with respect to the circumferential direction.

  In the tire 2, the reinforcing cord 46 in the side portion 52 has an absolute value of a small second inclination angle β. The inner reinforcing ply 38 in the side portion 52 is located inside the side region 26 of the tread 4. The inner reinforcing ply 38 in the side portion 52 can contribute to the rigidity of the side region 26 of the tire 2. In the tire 2, a sufficient side grip can be obtained. The tire 2 is excellent in grip performance. The tire 2 can turn at a high speed. The tire 2 is excellent in turning performance.

In the tire 2, the absolute value of the second inclination angle β is preferably 45 ° or more and 80 ° or less from the viewpoint that the inner reinforcing ply 38 in the side portion 52 can effectively contribute to tire rigidity. By setting the second inclination angle β to 45 ° or more, excessive rigidity of the inner reinforcement ply 38 in the side portion 52 can be suppressed. In the tire 2, the side grip can be appropriately maintained. From this viewpoint, the second inclination angle β is more preferably 50 ° or more, and particularly preferably 55 ° or more. By setting the second inclination angle β to 80 ° or less, the inner reinforcing ply 38 in the side portion 52 can effectively contribute to the tire rigidity. Since the tire 2 has a large side grip, the tire 2 can turn at a high speed. The tire 2 is excellent in grip performance. The tire 2 can turn at a high speed. The tire 2 is excellent in turning performance. From this viewpoint, the second inclination angle β is more preferably 75 ° or less, and more preferably 70 ° or less. In the tire 2, the second angle obtained by measuring the angle formed by the reinforcing cord 46 with respect to the boundary line LB from the viewpoint that the inner reinforcing ply 38 in the side portion 52 can further effectively contribute to the tire rigidity. based on the angle of inclination beta _0, the tire rigidity is controlled.

In the tire 2, the difference between the maximum absolute value of the first inclination angle α and the minimum absolute value of the second inclination angle β is 5 ° or more. By setting this difference to be 5 ° or more, the inner reinforcing ply 38 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in exercise performance and grip performance. In addition, from the viewpoint of maintaining exercise performance and grip performance, this difference is preferably 20 ° or less, and more preferably 10 ° or less. From the viewpoint of appropriate control of tire rigidity, in the tire 2, it is particularly preferable that the difference between the absolute value of the first inclination angle α _{0 and} the absolute value of the second inclination angle β ₀ is 5 ° or more and 10 ° or less. .

  FIG. 5 is a schematic view showing a reinforcing cord 48 included in the outer reinforcing ply 40 in the center portion 50 of the reinforcing layer 14 of FIG. In FIG. 5, a single reinforcing cord 48 is shown. In FIG. 5, the angle γ represents a first inclination angle formed by the reinforcing cord 48 in the center portion 50 with respect to the circumferential direction.

  In the tire 2, the reinforcing cord 48 in the center portion 50 has a large absolute value of the first inclination angle γ. The outer reinforcing ply 40 in the center portion 50 is located inside the center region 24 of the tread 4. The outer reinforcing ply 40 in the center portion 50 can contribute to exercise performance while maintaining a ground contact area and securing a traction grip. In the tire 2, a sufficient traction grip can be obtained during straight traveling. The tire 2 is excellent in grip performance without impairing motion performance. The tire 2 is excellent in acceleration performance when traveling straight.

In the tire 2, the absolute value of the first inclination angle γ is preferably 60 ° or more and 88 ° or less from the viewpoint that the outer reinforcing ply 40 in the center portion 50 can effectively contribute to the tire rigidity. When the first inclination angle γ is set to 60 ° or more, the outer reinforcing ply 40 in the center portion 50 can contribute to the grip performance. Sufficient traction is generated in the tire 2. The tire 2 is excellent in acceleration performance. In this respect, the first inclination angle γ is more preferably 65 ° or more, and more preferably 70 ° or more. By setting the first inclination angle γ to 88 ° or less, the rigidity can be appropriately maintained. The tire 2 is excellent in exercise performance. In this respect, the first inclination angle γ is more preferably 85 ° or less, and more preferably 80 ° or less. In the tire 2, the first angle obtained by measuring the angle formed by the reinforcing cord 48 with respect to the equator plane CL from the viewpoint that the outer reinforcing ply 40 in the center portion 50 can further effectively contribute to the tire rigidity. Based on the inclination angle γ ₀ , the tire stiffness is controlled.

  FIG. 6A is a schematic view showing a reinforcing cord 48 included in the outer reinforcing ply 40 on one side portion 52 of the reinforcing layer 14 of FIG. 2, and FIG. 6B is a diagram of the reinforcing layer 14. FIG. 6 is a schematic diagram showing a reinforcing cord 48 included in an outer reinforcing ply 40 in the other side portion 52. In FIG. 6A and FIG. 6B, one reinforcing cord 48 is shown. In FIG. 6A and FIG. 6B, the angle η represents the second inclination angle formed by the reinforcing cord 48 in the side portion 52 with respect to the circumferential direction.

  In the tire 2, the reinforcing cord 48 in the side portion 52 has a small absolute value of the second inclination angle η. The outer reinforcing ply 40 in the side portion 52 is located inside the side region 26 of the tread 4. The outer reinforcing ply 40 in the side portion 52 can contribute to the rigidity of the side region 26 of the tire 2. In the tire 2, a sufficient side grip can be obtained. The tire 2 is excellent in grip performance. The tire 2 can turn at a high speed. The tire 2 is excellent in turning performance.

In the tire 2, the absolute value of the second inclination angle η is preferably 45 ° or more and 80 ° or less from the viewpoint that the outer reinforcing ply 40 in the side portion 52 can effectively contribute to the tire rigidity. By setting the second inclination angle η to 45 ° or more, excessive rigidity of the outer reinforcing ply 40 in the side portion 52 can be suppressed. In the tire 2, the side grip can be appropriately maintained. From this viewpoint, the second inclination angle η is more preferably 50 ° or more, and particularly preferably 55 ° or more. By setting the second inclination angle η to 80 ° or less, the outer reinforcing ply 40 in the side portion 52 can effectively contribute to the tire rigidity. Since the tire 2 has a large side grip, the tire 2 can turn at a high speed. The tire 2 is excellent in grip performance. The tire 2 can turn at a high speed. The tire 2 is excellent in turning performance. From this viewpoint, the second inclination angle η is more preferably 75 ° or less, and more preferably 70 ° or less. In the tire 2, the second angle obtained by measuring the angle formed by the reinforcing cord 48 with respect to the boundary line LB from the viewpoint that the outer reinforcing ply 40 in the side portion 52 can further effectively contribute to the tire rigidity. The tire stiffness is controlled based on the inclination angle η ₀ .

In the tire 2, the difference between the maximum absolute value of the first inclination angle γ and the minimum absolute value of the second inclination angle η is 5 ° or more. By setting this difference to be 5 ° or more, the inner reinforcing ply 38 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in exercise performance and grip performance. In addition, from the viewpoint of maintaining exercise performance and grip performance, this difference is preferably 20 ° or less, and more preferably 10 ° or less. From the viewpoint of appropriate control of tire rigidity, in the tire 2, it is particularly preferable that the difference between the absolute value of the first inclination angle γ _{0 and} the absolute value of the second inclination angle η ₀ is 5 ° or more and 10 ° or less. .

  In FIG. 1, a solid line BBL is a bead base line. This bead base line is a line that defines the rim diameter (see JATMA) of the rim on which the tire 2 is mounted. A double arrow line HA is the height in the radial direction of the tire 2. The double arrow line HT is the height in the radial direction from the bead base line to the tread end PT. The double arrow line HB is the height in the radial direction from the bead base line to the end 36 of the band 12. A double arrow line HR is a radial height from the bead base line to the end 44 of the reinforcing layer 14.

  In the tire 2, the ratio of the radial height HT to the radial height HA is preferably 0.2 or more and 0.6 or less. By setting this ratio to 0.2 or more, the tread surface 20 of the tire 2 has an appropriate curvature radius. The center region 24 of the tread 4 can be sufficiently grounded. The tire 2 can travel straight ahead stably. From this viewpoint, the ratio is more preferably 0.25 or more, and more preferably 0.30 or more. By setting this ratio to 0.6 or less, the side region 26 of the tread 4 can be sufficiently grounded during turning. The tire 2 can turn in a stable manner. In this respect, the ratio is more preferably equal to or less than 0.55, and particularly preferably equal to or less than 0.50.

  In the tire 2, the ratio of the radial height HB to the radial height HT is preferably 0.8 or more and 1.2 or less. By setting this ratio to 0.8 or more, the band 12 effectively reinforces the tire 2. The tire 2 is excellent in high speed running performance. In this respect, the ratio is more preferably equal to or greater than 0.85, and more preferably equal to or greater than 0.90. By setting this ratio to 1.2 or less, excessive rigidity due to the band 12 can be suppressed. In the tire 2, grip performance can be maintained. In this respect, the ratio is more preferably 1.15 or less and particularly preferably 1.10 or less.

  In the tire 2, the ratio of the radial height HR to the radial height HT is preferably 0.7 or more and 1.2 or less. By setting this ratio to 0.7 or more, the reinforcing layer 14 effectively reinforces the tire 2. Since the handling is light, the tire 2 is excellent in exercise performance. In this respect, the ratio is more preferably equal to or greater than 0.85, and more preferably equal to or greater than 0.90. By setting this ratio to 1.2 or less, excessive rigidity due to the band 12 can be suppressed. In the tire 2, grip performance can be maintained. From this viewpoint, the ratio is more preferably 1.10 or less, and particularly preferably 1.00 or less.

  In the tire 2, the density of the reinforcing cord 46 in the center portion 50 of the inner reinforcing ply 38 is preferably 15 ends / 5 cm or more, more preferably 20 ends / 5 cm or more, from the viewpoint of achieving both exercise performance and grip performance. Ends / 5 cm or more are particularly preferable. The density is preferably 60 ends / 5 cm or less, more preferably 50 ends / 5 cm or less, and particularly preferably 40 ends / 5 cm or less. This density is obtained by measuring the number (ends) of the reinforcing cords 46 existing around the 5 cm width of the center portion 50 of the inner reinforcing ply 38 in a cross section perpendicular to the longitudinal direction of the reinforcing cords 46. The density of the reinforcing cords 46 and 48 in the side portion 52 of the inner reinforcing ply 38 and the center portion 50 and the side portion 52 of the outer reinforcing ply 40, which will be described later, is also measured in the same manner.

  In the tire 2, the density of the reinforcing cord 46 in the side portion 52 of the inner reinforcing ply 38 is preferably 15 ends / 5 cm or more, more preferably 20 ends / 5 cm or more from the viewpoint of achieving both exercise performance and grip performance. Ends / 5 cm or more are particularly preferable. This density is preferably 60 ends / 5 cm or less, more preferably 50 ends / 5 cm or less, and particularly preferably 40 ends / 5 cm or less.

  In the tire 2, the density of the reinforcing cord 48 in the center portion 50 of the outer reinforcing ply 40 is preferably 15 ends / 5 cm or more, more preferably 20 ends / 5 cm or more, from the viewpoint of achieving both exercise performance and grip performance. Ends / 5 cm or more are particularly preferable. The density is preferably 60 ends / 5 cm or less, more preferably 50 ends / 5 cm or less, and particularly preferably 40 ends / 5 cm or less.

  In the tire 2, the density of the reinforcing cord 48 in the side portion 52 of the outer reinforcing ply 40 is preferably 15 ends / 5 cm or more, more preferably 20 ends / 5 cm or more, from the viewpoint of achieving both exercise performance and grip performance. Ends / 5 cm or more are particularly preferable. This density is preferably 60 ends / 5 cm or less, more preferably 50 ends / 5 cm or less, and particularly preferably 40 ends / 5 cm or less.

  The tire 2 is manufactured as follows. First, a strip-shaped sheet is formed which is composed of the reinforcing cords 46 and 48 and the topping rubber and in which the reinforcing cords 46 and 48 extend in the longitudinal direction. This sheet is then fed to the former. Other members are also supplied to the former. Other members include the inner liner 16, the carcass ply 32, the band ply 34, the sidewall 6, the tread 4, and the like. These rubber members are assembled in the former, and the green tire 2 is obtained. In this assembly, after the carcass ply 32 is formed, the inner reinforcing ply 38 is formed by sequentially connecting the ends of the seat so that the width direction thereof coincides with the circumferential direction of the tire 2. At this time, the rotation of the drum of the former is controlled, and this sheet is arranged so that the first inclination angle α of the reinforcing cord 46 is larger than the second inclination angle β. After the inner reinforcing ply 38 is formed, the outer reinforcing ply 40 is formed by sequentially connecting the ends of the sheet so that the width direction thereof coincides with the circumferential direction of the tire 2. At this time, the rotation of the drum of the former is controlled, and this sheet is arranged so that the first inclination angle γ of the reinforcing cord 48 is larger than the second inclination angle η. The process in which the green tire is obtained in this way is referred to as a molding process.

  Next, the green tire is subjected to a vulcanization process. In the vulcanization process, the green tire is first put into an opened mold. When thrown, the bladder is contracted. When thrown, the bladder is positioned inside the green tire. Next, the bladder expands due to gas filling. This expansion causes the green tire to deform. This deformation is called shaping. Next, the mold is tightened. Next, the internal pressure of the bladder is increased. The green tire is pressed between the cavity surface of the mold and the outer surface of the bladder. The green tire is heated by heat conduction from the bladder and the mold. The rubber composition of the green tire flows by pressurization and heating. The rubber composition causes a crosslinking reaction by heating, and the tire 2 is obtained.

  In the present invention, the size and angle of each member of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and the tire 2 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 2. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 2 relies. “Maximum air pressure” in JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A pneumatic tire of Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 1 below was obtained. The tire size is 210 / 60R420. The reinforcing layer of the tire includes an inner reinforcing ply and an outer reinforcing ply. The inner reinforcement ply has a reinforcement cord. This reinforcing cord is made of an aramid fiber. The fineness of the reinforcing cord is 800 dtex / 2. The first inclination angle α of the reinforcing cord included in the inner reinforcing ply at the center portion of the reinforcing layer is 80 ° (degree). The second inclination angle β of the reinforcing cord included in the inner reinforcing ply on the side portion of the reinforcing layer is 70 °. The outer reinforcing ply has a reinforcing cord. This reinforcing cord is made of an aramid fiber. The fineness of the reinforcing cord is 800 dtex / 2. The first inclination angle γ of the reinforcing cord included in the outer reinforcing ply at the center portion of the reinforcing layer is −80 °. The second inclination angle η of the reinforcing cord included in the outer reinforcing ply on the side portion of the reinforcing layer is −70 °.

[Comparative Examples 2 to 4 and Examples 2 to 5]
Other than the first inclination angle α and the second inclination angle β of the reinforcement cord included in the inner reinforcement ply and the first inclination angle γ and the second inclination angle η of the reinforcement cord included in the outer reinforcement ply as shown in Table 1 below A tire was obtained in the same manner as in Example 1.

[Comparative Example 1]
A tire was obtained in the same manner as in Example 1 except that the reinforcing layer was not provided.

[Real car evaluation]
A reference tire was mounted on the front wheel of a racing vehicle with a displacement of 1000 cc. The tire rim is MT 3.75 × 420. The internal pressure of the tire is 200 kPa. Prototype tires were mounted on the rear wheels. The tire size of this rear wheel is 210 / 60R420, and the rim is MT6.25 × 420. Sensory evaluation by riders was performed on a circuit course composed of asphalt roads. The results are shown in Table 1 below as index values with Comparative Example 3 taken as 100. Larger values indicate better results. Evaluation items are motility, rigidity, side grip, and traction grip.

  As shown in Table 1, the tires of the examples are excellent in mobility, rigidity, side grip and traction. From this evaluation result, the superiority of the present invention is clear.

  The motorcycle tire according to the present invention can be mounted on various vehicles.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a development view showing a part of the reinforcing layer of the tire of FIG. 1. FIG. 3 is a schematic view showing a reinforcing cord included in an inner reinforcing ply in the center portion of the reinforcing layer in FIG. 2. 4A is a schematic view showing a reinforcing cord included in an inner reinforcing ply on one side portion of the reinforcing layer in FIG. 2, and FIG. 4B shows the other side portion of the reinforcing layer. It is the schematic diagram by which the reinforcement cord contained in a certain inner side reinforcement ply was shown. FIG. 5 is a schematic view showing a reinforcing cord included in the outer reinforcing ply in the center portion of the reinforcing layer in FIG. 2. FIG. 6A is a schematic view showing a reinforcing cord included in an outer reinforcing ply on one side portion of the reinforcing layer of FIG. 2, and FIG. 6B shows the other side portion of the reinforcing layer. It is the schematic diagram by which the reinforcement cord contained in a certain outer side reinforcement ply was shown.

Explanation of symbols

2 ... tyre 4 ... tread 6 ... side wall 8 ... bead 10 ... carcass 12 ... band 14 ... reinforcing layer 16 ... inner liner 18 ... chafer 24 ... Center area 26 ... Side area 28 ... Core 30 ... Apex 32 ... Carcass ply 34 ... Band ply 38 ... Inner reinforcement ply 40 ... Outer reinforcement ply 46 .... Reinforcement cord 48 ... Reinforcement cord 50 ... Center part 52 ... Side part

Claims (3)

It has a tread whose width is the maximum width of the tire, a band located inside the tread in the radial direction, and a reinforcing layer laminated on this band,
This tread has a radially outwardly convex shape,
The band includes a band cord wound spirally and extending substantially circumferentially;
The reinforcing layer includes an inner reinforcing ply and an outer reinforcing ply, and the outer reinforcing ply is laminated on the inner reinforcing ply.
The inner reinforcing ply and the outer reinforcing ply each include a reinforcing cord,
The reinforcing cord extends from one end to the other end in an inclined direction in the same direction with respect to the circumferential direction,
The absolute value of the first inclination angle of the reinforcing cord in the vicinity of the axial center is larger than the absolute value of the second inclination angle of the reinforcing cord in the vicinity of the tread end,
The absolute value of the first inclination angle is not less than 60 ° and not more than 88 °,
The absolute value of the first inclination angle, the difference between the absolute value of the second inclination angle state, and are more than 5 ° 20 ° or less,
A motorcycle tire in which the inclination direction of the reinforcement cord of the outer reinforcement ply and the inclination direction of the reinforcement cord of the inner reinforcement ply are reversed .   2. The tire according to claim 1, wherein a ratio of a height in a radial direction up to a position where the tire has a maximum tire width to a tire height is 0.2 or more and 0.6 or less.   The tire according to claim 1 or 2, wherein an absolute value of the second inclination angle is not less than 45 ° and not more than 80 °.

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