JP2012140039A - Pneumatic tire for two-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for a two-wheeled vehicle, achieving both grip force and stability.SOLUTION: This tire 2 includes a tread 4 having an outer surface functioning as a tread surface 20, and a pair of reinforcing layers 14 extending in a peripheral direction. The reinforcing layers 14 are respectively buried in the tread 4. The complex modulus of elasticity Er* of each of the reinforcing layers 14 at 100°C is higher than the complex modulus of elasticity Et* of the tread 4 at 100°C. Preferably, in the tire 2, the ratio of the complex modulus of elasticity Er* to the complex modulus of elasticity Et* is 1.2-1.5. Preferably, in the tire 2, each of the reinforcing layers 14 is provided with a reference surface 34 extending substantially inward in an axial direction from one end 32 of the reinforcing layer 14 on the side of the tread surface 20. The reference surface 34 is inclined to the normal of the tread surface 20, passing through the inner end P of the reference surface 34.

Description

  The present invention relates to a pneumatic tire mounted on a two-wheeled vehicle.

  The tread of the tire is made of a crosslinked rubber. The tread has a shape protruding outward in the radial direction. The tread has a tread surface. This tread surface is in contact with the road surface.

  A two-wheeled vehicle turns with its body tilted. The tread of a motorcycle tire has a small radius of curvature from the viewpoint of easy turning. In this tire, the equatorial plane portion (crown region) of the tread is grounded when traveling straight ahead. During cornering, a region outside the crown region in the axial direction, in other words, a tread portion (shoulder region) close to the sidewall is grounded.

  Various studies have been made on treads from the viewpoint of improving tire performance. An example of this study is disclosed in Japanese Patent Application Laid-Open No. 2010-111163.

JP 2010-111163 A

  From the viewpoint of improving the grip force, the tread may be composed of a crosslinked rubber having a small complex elastic modulus. When this tire is used in a motorcycle race, there is a problem that this tire lacks stability.

  From the viewpoint of ensuring stability, the thickness of the tread may be reduced. However, a thin tread reduces the grip.

  From the viewpoint of ensuring stability, the entire tread may be reinforced with a reinforcing layer. However, this reinforcing layer also reduces the grip force. It is difficult to achieve both grip strength and stability.

  An object of the present invention is to provide a pneumatic tire for a two-wheeled vehicle that can achieve both gripping force and stability.

  A pneumatic tire for a motorcycle according to the present invention includes a tread whose outer surface forms a tread surface, a band positioned radially inward of the tread, and at least a pair of reinforcing layers extending in the circumferential direction. Yes. Each reinforcing layer is located outside the band in the radial direction. This reinforcing layer is embedded in the tread. The complex elastic modulus Er * at 100 ° C. of the reinforcing layer is larger than the complex elastic modulus Et * at 100 ° C. of the tread.

  Preferably, in the pneumatic tire for a motorcycle, the ratio of the complex elastic modulus Er * to the complex elastic modulus Et * is 1.2 or more and 1.5 or less.

  Preferably, in the pneumatic tire for a motorcycle, the reinforcing layer includes a reference surface that extends substantially inward in the axial direction from one end of the reinforcing layer on the tread surface side. The reference plane is inclined with respect to the normal line of the tread surface passing through the inner end of the reference plane.

  Preferably, in the pneumatic tire for a two-wheeled vehicle, the inclination angle of the reference plane is 10 ° or more and 70 ° or less.

  Preferably, in the pneumatic tire for a two-wheeled vehicle, a ratio of a circumferential length from the end of the tread surface to a position on the tread surface corresponding to one end of the reinforcing layer on the tread surface side with respect to a half circumferential length of the tread surface is 1/10 or more and 2/3 or less.

  Preferably, in the pneumatic tire for a motorcycle, a distance from the one end of the reinforcing layer on the tread surface side to the tread surface is 0 mm or more and 2.0 mm or less.

  Preferably, in the pneumatic tire for a motorcycle, a distance from the other end of the reinforcing layer on the band side to the band is 2.0 mm or less.

  Preferably, in this pneumatic tire for a motorcycle, the ratio of the length from the one end on the tread surface side of the reinforcing layer to the other end on the band side in the thickness direction of the tread with respect to the thickness of the tread is 0. .6 or more.

  Preferably, in the pneumatic tire for a motorcycle, the cross section of the reinforcing layer has a substantially rectangular shape. The thickness of this reinforcing layer is 1 mm or more and 5 mm or less.

  Preferably, in the pneumatic tire for a motorcycle, the reinforcing layer is composed of a main portion having a substantially rectangular cross section and a sub-portion capable of supporting the main portion on the radially inner side of the main portion. Yes. The main portion includes a reference surface extending substantially inward in the axial direction from one end of the main portion on the tread surface side. The reference plane is inclined with respect to the normal line of the tread surface passing through the inner end of the reference plane. The sub-portion has a shape that tapers inward in the radial direction from the main portion. The sub-portion includes a bottom surface that extends while being inclined with respect to the reference surface, and a side surface that extends from the bottom surface toward the tread surface. This side surface is orthogonal to the bottom surface.

  In the pneumatic tire for a motorcycle according to the present invention, the reinforcing layer buried in the tread can effectively contribute to the rigidity of the tread. According to this tire, both grip force and stability can be achieved.

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 partially enlarged sectional view showing a part of the tire of FIG. FIG. 3 is a cross-sectional view showing a part of a pneumatic tire according to another embodiment of the present invention. FIG. 4 is a partial enlarged cross-sectional view showing a part of the tire of FIG.

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

  The tire 2 shown in FIG. 1 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 two-wheeled vehicle. 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 tread 4 is made of a crosslinked rubber having excellent wear resistance. The tread 4 has a shape protruding outward in the radial direction. The tread 4 includes a tread surface 20. The tread surface 20 is in contact with the road surface.

  The sidewall 6 extends substantially inward in the radial direction from the end 22 of the tread 4. 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 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape. The core 24 is formed by winding a non-stretchable wire. Typically, a steel wire is used for the core 24. The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a first carcass ply 28a and a second carcass ply 28b. The first carcass ply 28 a and the second carcass ply 28 b are bridged between the beads 8 on both sides, and are along the inside of the tread 4 and the sidewall 6. The first carcass ply 28a and the second carcass ply 28b are folded around the core 24 from the inner side to the outer side in the axial direction.

  Although not shown, the first carcass ply 28a and the second carcass ply 28b are composed of 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 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 laminated on the outside of the carcass 10. Although not shown, the band 12 is composed of a cord and a topping rubber. The cord extends substantially in the circumferential direction and is wound spirally. The band 12 has a so-called jointless structure. The band 12 can contribute to the rigidity of the tire 2 in the radial direction. In the tire 2, the influence of the centrifugal force that acts during traveling is suppressed. The cord is usually made of organic fibers. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The reinforcing layer 14 is located on the radially outer side of the band 12. In the tire 2, the reinforcing layer 14 is located in the shoulder region of the tire 2. The reinforcing layer 14 extends in the circumferential direction. The reinforcing layer 14 has a ring shape.

  As shown in the figure, the tire 2 is provided with one reinforcing layer 14 in the shoulder region. In the tire 2, a plurality of reinforcing layers 14 may be provided in the shoulder region.

  The reinforcing layer 14 is made of a crosslinked rubber. In the tire 2, the complex elastic modulus Er * of the reinforcing layer 14 at 100 ° C. is larger than the complex elastic modulus Et * of the tread 4 described above at 100 ° C. More specifically, the complex elastic modulus Er * of the reinforcing layer 14 is larger than the complex elastic modulus Et * of the tread 4 in which the reinforcing layer 14 is embedded. The reinforcing layer 14 has a high modulus. The reinforcing layer 14 can contribute to the rigidity of the tread 4 portion of the tire 2. Since the reinforcing layer 14 maintains a high modulus at a high temperature, the reinforcing layer 14 can effectively contribute to the rigidity of the tire 2 when the tire 2 has a high temperature and travels at a high speed. As described above, the reinforcing layer 14 is located in the shoulder region 30. In particular, the reinforcing layer 14 can contribute to stability during high-speed turning.

In the present invention, the complex elastic modulus Er * of the reinforcing layer 14 and the complex elastic modulus Et * of the tread 4 are determined using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) in accordance with the provisions of “JIS K 6394”. It is measured under the conditions shown below.
Initial strain: 10%
Amplitude: ± 2.5%
Frequency: 10Hz
Deformation mode: Tensile
Measurement temperature: 100 ° C

  In the tire 2, the ratio of the complex elastic modulus Er * of the reinforcing layer 14 to the complex elastic modulus Et * of the tread 4 is preferably 1.2 or more and 1.5 or less. By setting this ratio to 1.2 or more, the reinforcing layer 14 can effectively contribute to the improvement of stability. By setting this ratio to 1.5 or less, the rigidity of the reinforcing layer 14 can be appropriately maintained. In the tire 2, the characteristics of the tread 4 portion do not change abruptly at the time of transition from straight traveling to turning traveling or at the time of transition from turning traveling to straight traveling. According to the tire 2, the rider can drive the two-wheeled vehicle without feeling uncomfortable.

  In the tire 2, the complex elastic modulus Et * of the tread 4 is preferably 1.0 MPa or more and preferably 3.0 MPa or less from the viewpoint that the tread 4 portion has an appropriate grip force. From the viewpoint that the reinforcing layer 14 can effectively contribute to the stability of the tire 2, the complex elastic modulus Er * of the reinforcing layer 14 is preferably 1.2 MPa or more, and preferably 4.5 MPa or less.

  In FIG. 1, what is indicated by a double arrow Ls is the length of the tread surface 20 from the end 22 of the tread surface 20 to the equator (hereinafter referred to as a circumferential length). This circumferential length Ls is a half circumferential length of the tread surface 20. What is indicated by a symbol PA represents a position on the tread surface 20 corresponding to one end 32 of the reinforcing layer 14 on the tread surface 20 side. What is indicated by a double-pointed arrow La is the circumference from the end 22 of the tread surface 20 to this position PA.

  In the tire 2, the ratio of the circumferential length La to the circumferential length Ls is preferably 1/10 or more, and more preferably 1/5 or more, from the viewpoint that the reinforcing layer 14 can effectively contribute to stability during turning. This ratio is preferably 2/3 or less, and more preferably 2/5 or less.

  In the tire 2, the cross section of the reinforcing layer 14 has a substantially rectangular shape. As shown, this cross section extends substantially in the axial direction. In this specification, the surface 34 located on the tread surface 20 side of the reinforcing layer 14 is referred to as a reference surface. The reference surface 34 extends substantially inward in the axial direction from one end 32 of the reinforcing layer 14 on the tread surface 20 side.

  In FIG. 2, what is indicated by a symbol P is an end (hereinafter referred to as an inner end) located on the inner side in the axial direction of the reference surface 34. A solid line L is a normal line of the tread surface 20 passing through the inner end P. In the tire 2, the reference surface 34 is inclined with respect to the normal L. In the drawing, an angle α indicates an angle formed by the reference plane 34 with respect to the normal L. This angle α is an inclination angle of the reference surface 34.

  In the tire 2, the reinforcing layer 14 is disposed such that the reference surface 34 is inclined with respect to the normal line L. The reinforcing layer 14 can effectively contribute to stability during turning. From this viewpoint, the inclination angle α of the reference surface 34 is preferably 10 ° or more, and preferably 70 ° or less.

  As illustrated, the reinforcing layer 14 is embedded in the tread 4. In the tire 2, the reinforcing layer 14 is not exposed. In the tire 2, the reinforcing layer 14 does not come into contact with the road surface. Since the tread 4 is always in contact with the road surface, the grip force is properly maintained. Moreover, since the reinforcing layer 14 supports the tire 2 from the inside, the stability is effectively improved. In the tire 2, the stability is improved without impairing the grip force. In the tire 2, both grip force and stability are achieved.

  In FIG. 2, the double arrow TA represents the thickness of the tread 4. This thickness TA is measured along the normal line L described above. A double-headed arrow t1 represents the shortest distance from one end 32 of the reinforcing layer 14 on the tread surface 20 side to the tread surface 20. A double-headed arrow t2 represents the shortest distance from the other end 36 of the reinforcing layer 14 on the band 12 side to the band 12. A double-headed arrow t3 represents a length from one end 32 on the tread surface 20 side of the reinforcing layer 14 to the other end 36 on the band 12 side in the thickness direction of the tread 4. This length t3 is obtained by subtracting the distance t1 and the distance t2 from the thickness TA. A double arrow tx represents the thickness of the reinforcing layer 14.

  In the tire 2, the distance t1 is preferably 0 mm or greater and 2.0 mm or less. By setting the distance t1 to be 0 mm or more, the tread 4 can appropriately contribute to the display of the gripping force. By setting the distance t1 to be 2.0 mm or less, the reinforcing layer 14 can effectively contribute to exhibiting stability.

  In the tire 2, the distance t2 is preferably 2.0 mm or less. When the distance t2 is set to 2.0 mm or less, the reinforcing layer 14 can effectively contribute to the display of stability. In the tire 2, the reinforcing layer 14 may be in contact with the band 12 from the viewpoint of improving the rigidity. Therefore, the lower limit value of the distance t2 is 0 mm.

  In the tire 2, the ratio of the length t3 to the thickness TA is preferably 0.6 or more. By setting this ratio to be 0.6 or more, the reinforcing layer 14 can effectively contribute to exhibiting stability. The tread 4 can appropriately contribute to exerting the grip force.

  In the tire 2, the thickness tx is preferably 1 mm or more and 5 mm or less. By setting the thickness tx to be 1 mm or more, the reinforcing layer 14 can effectively contribute to exhibiting stability. By setting the thickness tx to 5 mm or less, the rigidity of the reinforcing layer 14 can be appropriately maintained. In the tire 2, the characteristics of the tread 4 portion do not change abruptly at the time of transition from straight traveling to turning traveling or at the time of transition from turning traveling to straight traveling. According to the tire 2, the rider can drive the two-wheeled vehicle without feeling uncomfortable.

  The tire 2 is manufactured as follows. A raw cover (unvulcanized tire 2) is obtained by preforming. Although not shown, the tread 4 of the raw cover is formed by spirally winding a strip made of uncrosslinked rubber in the circumferential direction. In this manufacturing method, the reinforcing layer 14 embedded in the tread 4 is formed by combining the ring-shaped reinforcing layer 14 during the formation of the tread 4. This manufacturing method is called a strip wind method. The raw cover is put into the mold with the mold open and the bladder contracted. The mold is tightened and the bladder expands. The raw cover is pressed against the cavity surface of the mold by a bladder and pressurized. At the same time, the raw cover is heated. The rubber composition flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and the tire 2 is obtained.

  In the present invention, the size and angle of the tire 2 and each member of the tire to be described later are such that the tire 2 and the tire to be described later are incorporated in the regular rim, and the tire 2 and the tire to be described later are filled with air so as to have a regular internal pressure. Measured in state. During the measurement, no load is applied to the tire 2 and a tire described later. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 and a tire described later depend. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In this specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 2 and a tire described later depend. “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.

  FIG. 3 is a cross-sectional view showing a part of a pneumatic tire 38 according to another embodiment of the present invention. The tire 38 is a tubeless type. The tire 38 is attached to a two-wheeled vehicle. The tire 38 includes a tread 40, a sidewall 42, a bead 44, a carcass 46, a band 48, a reinforcing layer 50, an inner liner 52, and a chafer 54. The tire 38 has the same configuration as that of the tire 2 shown in FIG. 1 except for the reinforcing layer 50. In FIG. 3, 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 38 has a substantially bilaterally symmetric shape with the one-dot chain line CL in FIG. 4 as the center. This alternate long and short dash line CL represents the equator plane of the tire 38.

  The reinforcing layer 50 of the tire 38 is located on the outer side in the radial direction of the band 48 like the reinforcing layer 14 of the tire 2 shown in FIG. 1. The reinforcing layer 50 is located in the shoulder region 30 of the tire 38. The reinforcing layer 50 extends in the circumferential direction. The reinforcing layer 50 has a ring shape. As shown in the figure, in the tire 38, one reinforcing layer 50 is provided in the shoulder region 56. A plurality of reinforcing layers 50 may be provided in the shoulder region 56.

  FIG. 4 shows a portion of the reinforcing layer 50 of the tire 38 shown in FIG. In the tire 38, the reinforcing layer 50 includes a main part 58 and a sub part 60.

  The cross section of the main portion 58 has a substantially rectangular shape. This cross section extends substantially in the axial direction. In the tire 38, a surface 64 located on the tread surface 62 side of the main portion 58 is referred to as a reference surface. The reference surface 64 extends substantially inward in the axial direction from one end 66 of the main portion 58 on the tread surface 62 side.

  In FIG. 4, what is indicated by a symbol P is an end (hereinafter referred to as an inner end) located on the inner side in the axial direction of the reference surface 64. A solid line L is a normal line of the tread surface 62 passing through the inner end P. In the tire 38, the reference surface 64 is inclined with respect to the normal L. In the figure, the angle α indicates the angle formed by the reference plane 64 with respect to the normal L. This angle α is an inclination angle of the reference surface 64.

  The sub portion 60 is located on the radially inner side of the main portion 58. The sub part 60 supports the main part 58. The sub part 60 has a shape that tapers from the main part 58 substantially inward in the radial direction. In the tire 38, the sub-section 60 has a substantially triangular cross section.

  The sub part 60 includes a bottom surface 68 and side surfaces 70. The bottom surface 68 extends from the reference surface 64 along the band 48 substantially outward in the axial direction. The bottom surface 68 extends with an inclination with respect to the reference surface 64. The side surface 70 extends from the bottom surface 68 toward the tread surface 62. In the tire 38, the side surface 70 is orthogonal to the bottom surface 68.

  In the tire 38, the reinforcing layer 50 is made of a crosslinked rubber. In the tire 38, the complex elastic modulus Er * of the reinforcing layer 50 at 100 ° C. is larger than the complex elastic modulus Et * of the tread 40 described above at 100 ° C. The reinforcing layer 50 has a high modulus. The reinforcing layer 50 can contribute to the rigidity of the tread 40 portion of the tire 38. Since the reinforcing layer 50 maintains a high modulus at a high temperature, the reinforcing layer 50 can effectively contribute to the rigidity of the tire 38 when the tire 38 has a high temperature and travels at a high speed. Since the reinforcing layer 50 is located in the shoulder region 56, it can contribute to the stability particularly during high-speed turning. As described above, the reinforcing layer 50 includes the main portion 58 and the sub portion 60 that can support the main portion 58 on the radially inner side of the main portion 58. The reinforcing layer 50 can effectively increase the rigidity of the tread 40. The tire 38 is excellent in stability during high-speed turning.

  In the tire 38, the ratio of the complex elastic modulus Er * of the reinforcing layer 50 to the complex elastic modulus Et * of the tread 40 is preferably 1.2 or more and 1.5 or less. By setting this ratio to 1.2 or more, the reinforcing layer 50 can effectively contribute to the improvement of stability. By setting this ratio to 1.5 or less, the rigidity of the reinforcing layer 50 can be appropriately maintained. In the tire 38, the characteristic of the portion of the tread 40 does not change abruptly at the time of transition from straight traveling to turning traveling or from the turning traveling to straight traveling. According to the tire 38, the rider can drive the two-wheeled vehicle without feeling uncomfortable.

  In the tire 38, the complex elastic modulus Et * of the tread 40 is preferably 1.0 MPa or more and preferably 3.0 MPa or less from the viewpoint that the tread 40 portion has an appropriate grip force. From the viewpoint that the reinforcing layer 50 can effectively contribute to the stability of the tire 38, the complex elastic modulus Er * of the reinforcing layer 50 is preferably 1.2 MPa or more, and more preferably 4.5 MPa or less.

  In FIG. 3, what is indicated by a double arrow Ls is the circumference from the end 72 of the tread surface 62 to the equator. This circumferential length Ls is a half circumferential length of the tread surface 62. What is indicated by a symbol PA represents a position on the tread surface 62 corresponding to one end 66 on the tread surface 62 side of the main portion 58 forming a part of the reinforcing layer 50. What is indicated by a double-pointed arrow La is the circumference from the end 72 of the tread surface 62 to this position PA.

  In the tire 38, the ratio of the circumferential length La to the circumferential length Ls is preferably 1/10 or more, and more preferably 1/5 or more, from the viewpoint that the reinforcing layer 50 can effectively contribute to stability during turning. This ratio is preferably 2/3 or less, and more preferably 2/5 or less.

  As described above, in the tire 38, the reinforcing layer 50 is disposed such that the reference surface 64 of the main portion 58 forming a part thereof is inclined with respect to the normal line L. The reinforcing layer 50 can effectively contribute to stability during turning. From this viewpoint, the inclination angle α of the reference surface 64 is preferably 10 ° or more, and preferably 60 ° or less.

  As illustrated, the reinforcing layer 50 is embedded in the tread 40. In the tire 38, the reinforcing layer 50 is not exposed. In the tire 38, the reinforcing layer 50 does not come into contact with the road surface. Since the tread 40 is always in contact with the road surface, the grip force is properly maintained. Moreover, since the reinforcing layer 50 supports the tire 38 from the inside, the stability is effectively improved. In particular, in the tire 38, the reinforcing layer 50 includes a main portion 58 and a sub-portion 60 that can support the main portion 58 on the radially inner side of the main portion 58. The reinforcing layer 50 can effectively increase the rigidity of the tread 40. In the tire 38, the stability is improved without impairing the grip force. In the tire 38, both grip force and stability are achieved.

  In FIG. 2, the double arrow TA represents the thickness of the tread 40. This thickness TA is measured along the normal line L described above. A double-headed arrow t1 represents the shortest distance from one end 66 of the main portion 58 on the tread surface 62 side to the tread surface 62. A double-headed arrow t2 represents the shortest distance from the bottom surface 68 of the sub part 60 to the band 48. A double-headed arrow t3 represents the length from one end 66 of the main portion 58 on the tread surface 62 side to the bottom surface 68 of the sub portion 60 in the thickness direction of the tread 40. This length t3 is obtained by subtracting the distance t1 and the distance t2 from the thickness TA. A double arrow tx represents the thickness of the main portion 58.

  In the tire 38, the distance t1 is preferably 0 mm or greater and 2.0 mm or less. By setting the distance t1 to be 0 mm or more, the tread 40 can appropriately contribute to the display of the gripping force. By setting this distance t1 to be equal to or less than 2.0 mm, the reinforcing layer 50 can effectively contribute to exhibiting stability.

  In the tire 38, the distance t2 is preferably 2.0 mm or less. By setting the distance t2 to be equal to or less than 2.0 mm, the reinforcing layer 50 can effectively contribute to exhibiting stability. In the tire 38, the reinforcing layer 50 may be in contact with the band 48 from the viewpoint of improving rigidity. Therefore, the lower limit value of the distance t2 is 0 mm.

  In the tire 38, the ratio of the length t3 to the thickness TA is preferably 0.6 or more. By setting this ratio to be 0.6 or more, the reinforcing layer 50 can effectively contribute to exhibiting stability. The tread 40 can appropriately contribute to the display of the grip force.

  In the tire 38, the thickness tx is preferably 1 mm or greater and 5 mm or less. By setting the thickness tx to be 1 mm or more, the reinforcing layer 50 can effectively contribute to exhibiting stability. By setting the thickness tx to 5 mm or less, the rigidity of the reinforcing layer 50 can be appropriately maintained. In the tire 38, the characteristic of the portion of the tread 40 does not change abruptly at the time of transition from straight traveling to turning traveling or from the turning traveling to straight traveling. According to the tire 38, the rider can drive the two-wheeled vehicle without feeling uncomfortable.

  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 FIGS. 1 and 2 and having the specifications shown in Table 1 below was obtained. The size of this tire is 210 / 60R420. The complex elastic modulus Er * at 100 ° C. of the reinforcing layer is 2.6 MPa. The complex elastic modulus Et * of the tread is 2.0 MPa. Therefore, the ratio (Er * / Et *) is 1.3. The thickness tx of this reinforcing layer is 4.0 mm. The ratio (La / Ls) of the circumferential length La from the end of the tread surface to the position PA on the tread surface corresponding to one end on the tread surface side of the reinforcing layer to the half circumferential length Ls of this tread surface is 1/3. . A distance t1 from one end of the reinforcing layer to the tread surface is 2.0 mm. This reinforcing layer is in contact with the band. The distance t2 from the other end of the reinforcing layer on the band side to the band is 0 mm. The ratio (t3 / TA) of the length t3 from one end of the reinforcing layer to the other end in the thickness direction of the tread with respect to the thickness TA of the tread is 0.7. The inclination angle α of the reference surface of the reinforcing layer is 20 °.

[Example 2-5]
A tire was obtained in the same manner as in Example 1 except that the complex elastic modulus Er * of the reinforcing layer, the complex elastic modulus Et * of the tread, and the ratio (Er * / Et *) were as shown in Table 1 below.

[Example 6-9]
A tire was obtained in the same manner as in Example 1 except that the inclination angle α was as shown in Table 2 below.

[Example 10-13]
Tires were obtained in the same manner as in Example 1 except that the ratio (t3 / TA) was as shown in Tables 2 and 3 below.

[Examples 14-15]
A tire was obtained in the same manner as in Example 1 except that the distance t2 was as shown in Table 3 below.

[Examples 16-18]
Tires were obtained in the same manner as in Example 1 except that the distance t1 was as shown in Tables 3 and 4 below.

[Examples 19-20 and 23-24]
Tires were obtained in the same manner as in Example 1 except that the ratio (La / Ls) was as shown in Tables 4 and 5 below.

[Examples 25-28]
Tires were obtained in the same manner as in Example 1 except that the thickness tx was as shown in Tables 5 and 6 below.

[Examples 21-22]
Tires were obtained in the same manner as in Example 1 except that the thickness tx, the ratio (La / Ls), the distance t2, the ratio (t3 / TA), and the inclination angle α were as shown in Tables 4 and 5 below.

[Example 29]
A pneumatic tire of Example 32 having the basic configuration shown in FIGS. 3 and 4 and having the specifications shown in Table 6 below was obtained. The size of this tire is 210 / 60R420. The reinforcing elastic layer has a complex elastic modulus Er * at 100 ° C. of 2.6 MPa. The complex elastic modulus Et * of the tread is 2.0 MPa. Therefore, the ratio (Er * / Et *) is 1.3. This reinforcing layer is composed of a main part and a sub part. The thickness tx of this main part is 4.0 mm. The ratio (La / Ls) of the circumferential length La from the end of the tread surface to the position PA on the tread surface corresponding to one end on the tread surface side of the main portion to the half circumferential length Ls of this tread surface is 1/3. . A distance t1 from one end of the main part to the tread surface is 2.0 mm. This reinforcing layer is in contact with the band. A distance t2 from the bottom surface of the sub part of the reinforcing layer to the band is 0 mm. The ratio (t3 / TA) of the length t3 from one end of the main part to the bottom surface of the sub part in the thickness direction of the tread with respect to the thickness TA of the tread is 0.7. The inclination angle α of the reference surface of the main part is 20 °.

[Comparative Example 1]
Comparative Example 1 is a conventional tire. This tire is not provided with a reinforcing layer. The complex elastic modulus Et * of the tread of this tire is 2.0 MPa.

[Grip strength and stability]
The prototype tire was mounted on the rear wheel of a sports-type two-wheeled vehicle (4-cycle) with a displacement of 1000 cc and filled with air so that the internal pressure was 200 kPa. A commercially available tire (size: 125 / 80R420) was attached to the front wheel and filled with air so that the internal pressure was 200 kPa. This motorcycle was run on a circuit course with asphalt on the road surface, and sensory evaluation was performed by the rider. Evaluation items are grip strength and stability. The results are shown in the following Table 1, Table 2, Table 3, Table 4, Table 5, and Table 6 as indices. Larger numbers are preferable.

  As shown in Table 1, Table 2, Table 3, Table 4, Table 5, and Table 6, the tires of the examples have higher evaluation than the tires of the comparative examples. From this evaluation result, the superiority of the present invention is clear.

  The pneumatic tire described above can be applied to various vehicles.

2, 38 ... Tire 4, 40 ... Tread 14, 50 ... Reinforcement layer 20, 62 ... Tread surface 22, 32, 36, 66, 72 ... End 30, 56 ... Shoulder Area 34, 64 ... Reference plane 58 ... Main part 60 ... Sub part 68 ... Bottom 70 ... Side

Claims (10)

A tread whose outer surface forms a tread surface, a band located radially inward of the tread, and at least a pair of reinforcing layers extending in the circumferential direction,
Each reinforcement layer is located radially outside this band,
This reinforcement layer is embedded in this tread,
A pneumatic tire for a two-wheeled vehicle, wherein the reinforcing elastic layer has a complex elastic modulus Er * at 100 ° C larger than the complex elastic modulus Et * of the tread at 100 ° C.   The pneumatic tire for a motorcycle according to claim 1, wherein a ratio of the complex elastic modulus Er * to the complex elastic modulus Et * is 1.2 or more and 1.5 or less. The reinforcing layer includes a reference surface extending substantially inward in the axial direction from one end on the tread surface side of the reinforcing layer;
The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the reference plane is inclined with respect to a normal line of the tread surface passing through an inner end of the reference plane.   The pneumatic retirement for a motorcycle according to claim 3, wherein the inclination angle of the reference surface is 10 ° or more and 70 ° or less.   The ratio of the peripheral length from the end of the tread surface to the position on the tread surface corresponding to one end of the reinforcing layer on the tread surface side to the half peripheral length of the tread surface is 1/10 or more and 2/3 or less. Item 5. A pneumatic tire for a motorcycle according to any one of Items 1 to 4.   The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein a distance from one end of the reinforcing layer on the tread surface side to the tread surface is 0 mm or more and 2.0 mm or less.   The pneumatic tire for a motorcycle according to any one of claims 1 to 6, wherein a distance from the other end on the band side of the reinforcing layer to the band is 2.0 mm or less.   The ratio of the length from the one end on the tread surface side of the reinforcing layer to the other end on the band side in the thickness direction of the tread to the thickness of the tread is 0.6 or more. A pneumatic retire for a motorcycle according to any one of the above. The cross section of the reinforcing layer has a substantially rectangular shape,
The pneumatic retirement for a motorcycle according to any one of claims 1 to 8, wherein the thickness of the reinforcing layer is 1 mm or more and 5 mm or less. The reinforcing layer is composed of a main portion having a substantially rectangular cross section and a sub-portion capable of supporting the main portion on the radially inner side of the main portion,
The main portion includes a reference surface extending substantially inward in the axial direction from one end of the main portion on the tread surface side.
The reference plane is inclined with respect to the normal line of the tread surface passing through the inner end of the reference plane,
This sub-portion has a shape that tapers radially inward from the main portion,
The sub-portion includes a bottom surface extending obliquely with respect to the reference surface, and a side surface extending from the bottom surface toward the tread surface.
The pneumatic retirement for a motorcycle according to claim 1 or 2, wherein the side surface is orthogonal to the bottom surface.

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