JP6121202B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire. More particularly, 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. The tire is grounded on the tread surface.

  A two-wheeled vehicle turns with its body tilted. From the viewpoint of easy turning, the tread of a motorcycle tire has a small radius of curvature.

  In this tire, the equatorial plane portion (center portion) of the tread is grounded when traveling straight ahead. In the cornering, a portion outside the center portion in the axial direction is grounded. In races, riders often turn their motorcycles to the limit. This state is called “full bank”. In this full bank, the end portion (shoulder portion) of the tread is grounded.

  In racing tires, grip performance is important. Various studies have been made on treads from the viewpoint of improving grip performance. Examples of this study are disclosed in Japanese Patent Application Laid-Open Nos. 07-195906, 2002-059709, and 2009-173247.

JP 07-195906 A JP 2002-059709 A JP 2009-173247 A

  The tire tread temperature rises for a while after starting running. In the tread, contact with the road surface is repeated. For this reason, the tread is worn by running. As wear progresses, the thickness of the tread decreases. Conversely, as the tread becomes thinner, the temperature of the tread decreases. In races that continue to run, the tread temperature varies.

  A tire tread may be composed of a base layer and a cap layer laminated on the base layer. In this tire, the cap layer is grounded. In order to improve the grip performance, it is effective to employ a cap layer having a large compliance.

  Loss compliance varies with temperature. For this reason, even if it has sufficient loss compliance at 120 ° C., for example, loss compliance may be insufficient at 100 ° C. Moreover, the cap layer having a large loss compliance is easily worn. With this tire, it is difficult to keep the grip performance stable.

  An object of the present invention is to provide a pneumatic tire excellent in grip performance.

The pneumatic tire according to the present invention has a tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, and each of which is radially inward of the sidewalls. A pair of positioned beads are provided, and a carcass spanned between one bead and the other bead along the inside of the tread and the sidewall. The tread includes a base layer and a cap layer located on the radially outer side of the base layer. The cap layer is composed of a plurality of layers stacked in the radial direction. The loss compliance LC1a measured at a temperature of 120 ° C. of the outermost first layer among the plurality of layers is 0.13 MPa ⁻¹ or more. The loss compliance LC1b measured at a temperature of 70 ° C. of this first layer is 0.13 MPa ⁻¹ or more. The loss compliance LC2 measured at a temperature of 100 ° C. of the second layer located inside the first layer is 0.19 MPa ⁻¹ or more.

Preferably, in this pneumatic tire, the loss compliance LC1a of the first layer is 0.17 MPa ⁻¹ or more and 0.24 MPa ⁻¹ or less. Loss compliance LC1b of the first layer is 0.13 MPa ^-1 or 0.20 MPa ^-1 or less. The loss compliance LC2 of the second layer is 0.19 MPa ⁻¹ or more and 0.29 MPa ⁻¹ or less.

Preferably, in the pneumatic tire, the cap layer includes a third layer on the radially inner side of the second layer. The third layer, loss compliance LC3, measured at a temperature of 80 ° C. is 0.17 MPa ^-1 or 0.25 MPa ^-1 or less.

Preferably, in the pneumatic tire, loss compliance LC1a of the first layer is not more than 0.13 MPa ^-1 or 0.20 MPa ^-1. The loss compliance LC1b of the first layer is 0.17 MPa ⁻¹ or more and 0.23 MPa ⁻¹ or less. The loss compliance LC2 of the second layer is 0.20 MPa ⁻¹ or more and 0.30 MPa ⁻¹ or less.

In the pneumatic tire according to the present invention, the tread cap layer includes a plurality of layers laminated in the radial direction. In this tire, the loss compliance LC1a measured at a temperature of 120 ° C. of the first layer located on the outermost side in the radial direction is 0.13 MPa ⁻¹ or more, and the loss compliance measured at a temperature of 70 ° C. LC1b is 0.13 MPa ⁻¹ or more. This first layer can contribute to the grip performance of the tire in the process of temperature rise that continues for a while after starting running.

  In this tire, the first layer is worn by running. As this wear progresses, the tread becomes thinner and the temperature of the tread decreases.

In this tire, the loss compliance LC2 measured at a temperature of 100 ° C. of the second layer located inside the first layer is 0.19 MPa ⁻¹ or more. In this tire, even if the first layer is worn and the second layer is exposed by running, the second layer can contribute to the grip performance.

  Thus, in this tire, the loss compliance of each layer is appropriately adjusted according to the state of the tread. Even if the tread becomes thin due to wear and the temperature of the tread decreases, the tire continues to exhibit good grip performance stably. According to the present invention, a pneumatic tire excellent in grip performance can be obtained.

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 cross-sectional view showing a part of a pneumatic tire according to another embodiment of the present invention. 3A is an enlarged cross-sectional view showing a part of the center portion of the tread in the tire of FIG. 2, and FIG. 3B is an enlarged cross-sectional view showing a part of the middle portion of the tread. FIG. 3C is an enlarged sectional view showing a part of the shoulder portion of the tread. FIG. 4 is a cross-sectional view showing a part of a pneumatic tire according to still another embodiment of the present invention.

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

  FIG. 1 shows a pneumatic tire 2 as a first embodiment. In FIG. 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire 2. The shape of the tire 2 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 2 includes a tread 4, a sidewall 6, a wing 8, a bead 10, a carcass 12, a band 14, and an inner liner 16. The tire 2 is a tubeless type. The tire 2 is attached to a two-wheeled vehicle. Specifically, the tire 2 is attached to the rear wheel of a two-wheeled vehicle.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 18 that comes into contact with the road surface. In the tire 2, no groove is formed on the tread surface 18. A groove may be cut in the tread surface 18 to form a tread pattern.

  The tread 4 has a base layer 20 and a cap layer 22. The cap layer 22 is located on the radially outer side of the base layer 20. The cap layer 22 is laminated on the base layer 20. The base layer 20 is made of a crosslinked rubber having excellent adhesiveness. A typical base rubber of the base layer 20 is natural rubber. The cap layer 22 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The sidewall 6 is made of a crosslinked rubber having excellent cut resistance and weather resistance. The side wall 6 prevents the carcass 12 from being damaged.

  The wing 8 is located between the tread 4 and the sidewall 6. The wing 8 is joined to each of the tread 4 and the sidewall 6. The wing 8 is made of a crosslinked rubber having excellent adhesiveness.

  The bead 10 is located radially inward of the sidewall 6. The bead 10 includes a core 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  The carcass 12 includes a carcass ply 28. The carcass ply 28 is bridged between the beads 10 on both sides. The carcass ply 28 extends along the tread 4 and the sidewall 6. The carcass ply 28 is folded around the core 24 from the inner side to the outer side in the axial direction. By this folding, the main portion 30 and the folding portion 32 are formed in the carcass ply 28.

  The carcass ply 28 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 75 ° to 90 °. In other words, the carcass 12 has a radial structure. The cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The carcass 12 may be formed from two or more carcass plies 28.

  The band 14 is located radially outside the carcass 12. The band 14 is laminated with the carcass 12 on the inner side in the radial direction of the tread 4. Although not shown, the band 14 is composed of a cord and a topping rubber. The cord is wound in a spiral. The band 14 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. The band 14 can contribute to the rigidity of the tire 2 in the radial direction. The band 14 can suppress the influence of centrifugal force that acts during traveling. The tire 2 is excellent in high speed stability. The cord is made of organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 16 is located inside the carcass 12. The inner liner 16 is joined to the inner surface of the carcass 12. The inner liner 16 is made of a crosslinked rubber. For the inner liner 16, rubber having excellent air shielding properties is used. A typical base rubber of the inner liner 16 is butyl rubber or halogenated butyl rubber. The inner liner 16 holds the internal pressure of the tire 2.

  As shown in FIG. 1, the cap layer 22 of the tread 4 includes a plurality of layers stacked in the radial direction. In the tire 2, the cap layer 22 is composed of three layers. Of these layers, the outermost layer in the radial direction is referred to as a first layer 34. The layer located inside the first layer 34 is referred to as a second layer 36. The layer located further inside the second layer 36 is referred to as a third layer 38. The cap layer 22 includes a first layer 34, a second layer 36 and a third layer 38.

  In the tire 2, the loss compliance LC of each layer constituting the tread 4 is appropriately adjusted. As a result, the grip performance is improved.

The loss compliance LC is represented by the ratio [E ″ / (E *) ² ] of the loss elastic modulus E ″ to the square of the complex elastic modulus E *. In calculating the loss compliance LC, the complex elastic modulus E * and the loss elastic modulus E ″ are used. The complex elastic modulus E * and the loss elastic modulus E ″ are as follows according to the provisions of “JIS K 6394”. According to the measurement conditions, a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) is used. In this measurement, a plate-shaped test piece (length = 45 mm, width = 4 mm, thickness = 2 mm) is formed from the rubber composition for each layer constituting the tread 4. This test piece is used for measurement.

Initial strain: 10%
Amplitude: ± 2.5%
Frequency: 10Hz
Deformation mode: Tensile
Measurement temperature: 70 ° C, 80 ° C, 100 ° C, 120 ° C

  When the two-wheeled vehicle starts running, the temperature of the tire 2 increases. This temperature rising process continues for a while after the start of traveling. On a circuit course where the air temperature is 25 ° C. or higher, or the road surface temperature is 40 ° C. or higher, the temperature of the tire 2 tends to rise.

In the tire 2, the loss compliance LC1a of the first layer 34 measured at a temperature of 120 ° C. is 0.13 MPa ⁻¹ or more. Thereby, the first layer 34 can contribute to the grip performance in the temperature rising process. From this viewpoint, the loss compliance LC1a is preferably 0.17 MPa ⁻¹ or more. Excessive loss compliance LC1a affects the wear resistance. From this viewpoint, the loss compliance LC1a is preferably 0.24 MPa ⁻¹ or less.

In the tire 2, the loss compliance LC1b of the first layer 34 measured at a temperature of 70 ° C. is 0.13 MPa ⁻¹ or more. Thereby, even in a state where the tire 2 is cold immediately after the start of traveling, the first layer 34 can contribute to the grip performance. Excessive loss compliance LC1b affects the wear resistance. From this viewpoint, the loss compliance LC1b is preferably 0.20 MPa ⁻¹ or less.

The first layer 34 is worn by running. As wear progresses, the thickness of the tread 4 decreases. As the tread 4 becomes thinner, the temperature of the tread 4 decreases. In the tire 2, the second layer 36 is located inside the first layer 34. The loss compliance LC2 measured at a temperature of 100 ° C. of the second layer 36 is 0.19 MPa ⁻¹ or more. In the tire 2, when the first layer 34 is worn and the second layer 36 is exposed, the second layer 36 can contribute to the grip performance. Excessive loss compliance LC2 affects the wear resistance. From this viewpoint, the loss compliance LC2 is preferably 0.29 MPa ⁻¹ or less.

The second layer 36 is also worn by running. As wear progresses, the thickness of the tread 4 further decreases. Thereby, the temperature of the tread 4 further decreases. From the viewpoint of maintaining grip performance, the loss compliance LC3 measured at a temperature of 80 ° C. of the third layer 38 located inside the second layer 36 is preferably 0.17 MPa ⁻¹ or more. Thereby, when the second layer 36 is worn and the third layer 38 is exposed, the third layer 38 can contribute to the grip performance. An excessive loss compliance LC3 affects the wear resistance. In this respect, the loss compliance LC3 is preferably 0.25 MPa ⁻¹ or less.

In the tire 2, the base layer 20, loss compliance LCb, measured at a temperature of 100 ° C. is preferably 0.07 MPa ^-1 or 0.12 MPa ^-1 or less. By setting the loss compliance LCb to 0.07 MPa ⁻¹ or more, the base layer 20 can contribute to the rigidity of the tread 4. By setting the loss compliance LCb to 0.12 MPa ⁻¹ or less, heat generation due to deformation of the base layer 20 is suppressed. This base layer 20 can contribute to reduction of rolling resistance.

In the tire 2, from the viewpoint that the first layer 34 effectively contributes to grip performance in a circuit course where the air temperature is 25 ° C. or higher or the road surface temperature is 40 ° C. or higher, loss compliance LC1a is a 0.17 MPa ^-1 or 0.24 MPa ^-1 or less, loss compliance LC1b the first layer 34 preferably is a 0.13 MPa ^-1 or 0.20 MPa ^-1 or less. Furthermore, from the viewpoint that the second layer 36 effectively contributes to grip performance in this circuit course, the loss compliance LC2 of the second layer 36 is preferably set to 0.19 MPa ⁻¹ or more and 0.29 MPa ⁻¹ or less. . And in terms of the third layer 38 is effectively contributes to the grip performance in this circuit course, loss compliance LC3 of the third layer 38 preferably is a 0.17 MPa ^-1 or 0.25 MPa ^-1 or less .

  Thus, in the tire 2, the loss compliance of each layer is appropriately adjusted according to the state of the tread 4. Even if the tread 4 becomes thin due to wear and the temperature of the tread 4 decreases, the tire 2 continues to exhibit good grip performance stably. In particular, the tread 4 of the tire 2 can effectively contribute to grip performance on a circuit course in which the air temperature is 25 ° C. or higher or the road surface temperature is 40 ° C. or higher. According to the present invention, a pneumatic tire 2 having excellent grip performance can be obtained.

  In the tire 2, the hardness H1a of the first layer 34 measured at a temperature of 120 ° C. is preferably 30 or greater and 40 or less. By setting the hardness H1a to 30 or more, the first layer 34 can contribute to the rigidity of the tire 2 particularly in the temperature rising process that continues for a while after the two-wheeled vehicle starts to travel. The tire 2 is excellent in handling stability and traction performance. By setting the hardness H1a to 40 or less, the influence of the first layer 34 on the rigidity can be suppressed. The tire 2 is excellent in grip performance and ride comfort.

  In the tire 2, the hardness H1b of the first layer 34 measured at a temperature of 70 ° C. is preferably 38 or more and 47 or less. By setting the hardness H1b to be equal to or greater than 38, the first layer 34 can effectively contribute to the rigidity of the tire 2 particularly in a state where the tire 2 is cold immediately after the start of traveling of the two-wheeled vehicle. The tire 2 is excellent in handling stability and traction performance. By setting the hardness H1b to 47 or less, the influence on the rigidity by the first layer 34 is suppressed. The tire 2 is excellent in grip performance and ride comfort.

  In the present invention, the hardness is JIS-A hardness. This hardness is measured by a type A durometer in accordance with the provisions of “JIS-K6253”. More specifically, the hardness is measured by pressing a type A durometer against the cross section shown in FIG. The hardness H2 of the second layer 36, the hardness H3 of the third layer 38, and the hardness Hb of the base layer 20, which will be described later, are also measured in the same manner as the hardness H1a and the hardness H1b described above. The tire 2 is put into an oven set at a predetermined temperature, and after the tire 2 is allowed to stand in the oven for 3 hours, the above-described hardness is measured.

  In the tire 2, the hardness H2 measured at a temperature of 100 ° C. of the second layer 36 is preferably 30 or greater and 40 or less. The second layer 36 can contribute to the rigidity of the tire 2 by setting the hardness H2 to 30 or more. The tire 2 is excellent in handling stability and traction performance. By setting the hardness H2 to 40 or less, the influence of the second layer 36 on the rigidity is suppressed. The tire 2 is excellent in grip performance and ride comfort.

  In the tire 2, the hardness H3 measured at a temperature of 80 ° C. of the third layer 38 is preferably 30 or more and 40 or less. The third layer 38 can contribute to the rigidity of the tire 2 by setting the hardness H2 to 30 or more. The tire 2 is excellent in handling stability and traction performance. By setting the hardness H3 to 40 or less, the influence of the third layer 38 on the rigidity is suppressed. The tire 2 is excellent in grip performance and ride comfort.

  In the tire 2, the hardness Hb of the base layer 20 measured at a temperature of 100 ° C. is preferably 35 or more and 50 or less. By setting the hardness Hb to 35 or more, the base layer 20 can contribute to the rigidity of the tread 4. The tire 2 is excellent in handling stability. By setting the hardness Hb to 50 or less, the influence of the base layer 20 on the rigidity can be suppressed. The tire 2 is excellent in ride comfort.

  In the tire 2, the modulus M1 of the first layer 34 is preferably 4.5 MPa or more and 7.0 MPa or less. By setting the modulus M1 to 4.5 MPa or more, the first layer 34 can contribute to the rigidity of the tire 2. The tire 2 is excellent in handling stability and traction performance. By setting the modulus M1 to 7.0 MPa or less, the influence of the first layer 34 on the rigidity can be suppressed. The tire 2 is excellent in grip performance and ride comfort.

In the present invention, the modulus M1 is a tensile stress at 300% elongation. The modulus M1 is measured in accordance with the provisions of “JIS-K6251”. The conditions are as follows.
Specimen shape = No. 4 dumbbell Environmental temperature = 100 ° C
Test machine = Toyo Seiki Seisakusho Co., Ltd. trade name "Strograph"
Tensile speed = 500mm / min
The modulus M2 of the second layer 36, the modulus M3 of the third layer 38, and the modulus Mb of the base layer 20 described later are also measured in the same manner as the modulus M1 of the first layer 34.

  In the tire 2, the modulus M2 of the second layer 36 is preferably 3.0 MPa or more and 5.0 MPa or less. By setting the modulus M2 to 3.0 MPa or more, the second layer 36 can contribute to the rigidity of the tire 2. The tire 2 is excellent in handling stability and traction performance. By setting the modulus M2 to be equal to or lower than 5.0 MPa, the influence of the second layer 36 on the rigidity is suppressed. The tire 2 is excellent in grip performance and ride comfort.

  In the tire 2, the modulus M3 of the third layer 38 is preferably 2.5 MPa or more and 4.5 MPa or less. By setting the modulus M3 to 2.5 MPa or more, the third layer 38 can contribute to the rigidity of the tire 2. The tire 2 is excellent in handling stability and traction performance. By setting the modulus M3 to 4.5 MPa or less, the influence of the third layer 38 on the rigidity can be suppressed. The tire 2 is excellent in grip performance and ride comfort.

  In the tire 2, the modulus Mb of the base layer 20 is preferably 4.5 MPa or more and 7.5 MPa or less. By setting the modulus Mb to 4.5 MPa or more, the base layer 20 can contribute to the rigidity of the tire 2. The tire 2 is excellent in handling stability. By setting the modulus Mb to 7.5 MPa or less, the influence of the base layer 20 on the rigidity can be suppressed. The tire 2 is excellent in ride comfort.

  In the tire 2, it is preferable that each layer constituting the cap layer 22 has a modulus higher than that of a layer located inside in the radial direction. In other words, the first layer 34 preferably has a modulus M1 that is higher than the modulus M2 of the second layer 36, and the second layer 36 preferably has a modulus M2 that is higher than the modulus M3 of the third layer 38. Thereby, in the tire 2 in the running state, the rigidity of the tread 4 is appropriately maintained. The tire 2 is excellent in handling stability and traction performance. From this viewpoint, the difference (M1−M2) between the modulus M1 and the modulus M2 is preferably 0.1 MPa or more. From the same viewpoint, the difference (M2−M3) between the modulus M2 and the modulus M3 is preferably 0.1 MPa or more. From the viewpoint of suppressing a change in rigidity when the tread 4 becomes thin due to wear, the difference (M1−M2) between the modulus M1 and the modulus M2 is preferably 1.0 MPa or less. From the same viewpoint, the difference (M2−M3) between the modulus M2 and the modulus M3 is preferably 1.0 MPa or less.

  In FIG. 1, the double arrow T <b> 1 represents the thickness of the first layer 34. A double-headed arrow T2 represents the thickness of the second layer 36. A double-headed arrow T3 represents the thickness of the third layer 38. A double-headed arrow Tb represents the thickness of the base layer 20. In the present application, each of the thickness T1, the thickness T2, the thickness T3, and the thickness Tb is measured along the equator plane in the cross section shown in FIG. The sum of the thickness T1, the thickness T2, and the thickness T3 is the thickness of the cap layer 22 measured along the equator plane.

  In the tire 2, the thickness T <b> 1 is preferably equal to or greater than 1.0 mm, and is preferably equal to or less than 4.5 mm, from the viewpoint that the first layer 34 can effectively contribute to grip performance in the temperature rising process.

  In the tire 2, when the second layer 36 is exposed due to wear of the first layer 34, the thickness T2 is preferably 1.0 mm or more from the viewpoint that the second layer 36 can effectively contribute to the grip performance. The thickness T2 is preferably 4.5 mm or less, and more preferably 3.0 mm or less.

  In the tire 2, the thickness T <b> 3 is preferably 1.0 mm or more from the viewpoint that when the third layer 38 is exposed due to wear of the second layer 36, the third layer 38 can effectively contribute to the grip performance. The thickness T3 is preferably 4.5 mm or less, and more preferably 3.0 mm or less.

  In the tire 2, the ratio of the thickness T1 to the thickness of the cap layer 22 is preferably 0.15 or more and 0.70 or less from the viewpoint that the first layer 34 can effectively contribute to the grip performance in the temperature rising process. Is preferred.

  In the tire 2, the ratio of the thickness T <b> 2 to the thickness of the cap layer 22 from the viewpoint that when the second layer 36 is exposed due to wear of the first layer 34, the second layer 36 can effectively contribute to grip performance. Is preferably 0.15 or more, and preferably 0.70 or less.

  In the tire 2, the ratio of the thickness T <b> 3 to the thickness of the cap layer 22 from the viewpoint that when the third layer 38 is exposed due to wear of the second layer 36, the third layer 38 can effectively contribute to the grip performance. Is preferably 0.15 or more, and preferably 0.70 or less.

  In the tire 2, the thickness Tb of the base layer 20 is preferably 0.5 mm or greater and 2.0 mm or less. The base layer 20 can contribute to the rigidity of the tire 2 by setting the thickness Tb to 0.5 mm or more. The tire 2 is excellent in handling stability. By setting the thickness Tb to 2.0 mm or less, the influence of the base layer 20 on the rigidity of the tire 2 can be suppressed. The tire 2 is excellent in ride comfort.

  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. The same applies to tires described later.

  FIG. 2 shows a pneumatic tire 40 as a second embodiment. In FIG. 2, the vertical direction is the radial direction of the tire 40, the horizontal direction is the axial direction of the tire 40, and the direction perpendicular to the paper surface is the circumferential direction of the tire 40. In FIG. 2, an alternate long and short dash line CL represents the equator plane of the tire 40. The shape of the tire 40 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 40 includes a tread 42, a sidewall 44, a wing 46, a bead 48, a carcass 50, a band 52, and an inner liner 54. The tire 40 is a tubeless type. The tire 40 is attached to a two-wheeled vehicle.

  The tread 42 has a base layer 56 and a cap layer 58. The tire 40 has the same configuration as that of the tire 2 shown in FIG. 1 except for the cap layer 58 of the tread 42.

  In the tire 40, the cap layer 58 includes a plurality of layers stacked in the radial direction. The cap layer 58 includes a pair of first layers 60, a second layer 62 in which the first layers 60 are stacked, and a third layer 64 in which the second layers 62 are stacked.

  The third layer 64 is located on the radially outer side of the base layer 56. The third layer 64 is laminated with the base layer 56. In the cross section shown in FIG. 2, the third layer 64 extends from one end of the tread 42 to the other end of the tread 42 via the equator plane. The end of the third layer 64 coincides with the end 68 of the tread surface 66.

  The second layer 62 is located outside the third layer 64 in the radial direction. In the cross section shown in FIG. 2, the second layer 62 extends from one end side of the tread 42 to the other end side of the tread 42 via the equator plane. The portion of the end 70 of the second layer 62 has a shape that tapers substantially outward in the axial direction. The end 70 of the second layer 62 is located on the inner side in the axial direction from the end 68 of the tread surface 66, in other words, the end of the third layer 64. The position of the end 70 of the second layer 62 is the boundary between the second layer 62 and the third layer 64 on the tread surface 66.

  As described above, the cap layer 58 has a pair of first layers 60. In the tire 40, the left and right first layers 60 are spaced apart in the axial direction. Each first layer 60 is located radially outside the second layer 62. The portion of the inner end 72 in the axial direction of the first layer 60 has a shape that tapers inward in the axial direction. The inner end 72 of the first layer 60 is located on the outer side in the axial direction from the equator plane. The position of the inner end 72 of the first layer 60 is the boundary of the tread surface 66 between the first layer 60 and the second layer 62 on the equator plane side. A portion of the axially outer end 74 of the first layer 60 has a shape that tapers substantially outward in the axial direction. The outer end 74 of the first layer 60 is located on the inner side in the axial direction than the end 70 of the second layer 62. The position of the outer end 74 of the first layer 60 is a boundary on the end side of the tread 42 between the first layer 60 and the second layer 62 on the tread surface 66.

  In the tire 40, a region from the inner end 72 of one first layer 60 to the inner end 72 (not shown) of the other first layer 60 in the cap layer 58 is referred to as a center portion C. The center portion C includes a second layer 62 and a third layer 64. A region of the cap layer 58 from the inner end 72 of the first layer 60 to the outer end 74 is referred to as a middle portion M. The middle portion M includes a first layer 60, a second layer 62, and a third layer 64. A region of the cap layer 58 from the outer end 74 of the first layer 60 to the end 70 of the second layer 62 is referred to as a first shoulder portion S. The first shoulder portion S includes a second layer 62 and a third layer 64. The region from the end 70 of the second layer 62 to the end of the third layer 64, in other words, the end 68 of the tread surface 66 in the cap layer 58 is referred to as a second shoulder portion T. The second shoulder portion T includes a third layer 64. In the tire 40, the cap layer 58 of the tread 42 includes a center portion C located on the equator plane, a pair of middle portions M that are located outside the center portion C in the axial direction, and each middle portion M. A pair of first shoulder portions S positioned on the outer side in the axial direction, and a pair of second shoulder portions T positioned on the outer side in the axial direction of the first shoulder portion S, respectively. The cap layer 58 is composed of seven regions in the axial direction.

  In a race in which the running state is continued, the temperature of the tread 42 becomes maximum in the middle portion M. In the tire 40, the middle portion M includes a first layer 60, a second layer 62, and a third layer 64 that are stacked in the radial direction.

In this tire 40, the first layer 60 is equivalent to the first layer 34 described above with respect to the cap layer 22 of the tire 2 shown in FIG. In the tire 40, the loss compliance LC1a measured at a temperature of 120 ° C. of the first layer 60 is 0.13 MPa ⁻¹ or more. The first layer 60 can contribute to grip performance in the temperature rising process. Preferably, the loss compliance LC1a of the first layer 60 is 0.24 MPa ⁻¹ or less. The first layer 60 can contribute to wear resistance.

In the tire 40, the loss compliance LC1b of the first layer 60 measured at a temperature of 70 ° C. is 0.13 MPa ⁻¹ or more. The first layer 60 can contribute to grip performance even when the tire 40 is cold immediately after the start of traveling. Preferably, the loss compliance LC1b of the first layer 60 is 0.20 MPa ⁻¹ or less. The first layer 60 can contribute to wear resistance.

In the middle portion M, the second layer 62 is located on the radially inner side of the first layer 60. This second layer 62 is equivalent to the second layer 34 described above with respect to the cap layer 22 of the tire 2 shown in FIG. In the tire 40, the loss compliance LC2 measured at a temperature of 100 ° C. of the second layer 62 is 0.19 MPa ⁻¹ or more. In the tire 40, even if the first layer 60 is worn and the second layer 62 is exposed, the second layer 62 can contribute to the grip performance. Preferably, the loss compliance LC2 of the second layer 62 is 0.29 MPa ⁻¹ or less. The second layer 62 can contribute to wear resistance.

In the middle portion M, the third layer 64 is located inside the second layer 62 in the radial direction. This third layer 64 is equivalent to the third layer 38 described above with respect to the cap layer 22 of the tire 2 shown in FIG. In the tire 40, the loss compliance LC3 measured at a temperature of 80 ° C. of the third layer 64 is preferably 0.17 MPa ⁻¹ or more. Thereby, even if the second layer 62 is worn and the third layer 64 is exposed, the third layer 64 can contribute to the grip performance. Preferably, the loss compliance LC3 of the third layer 64 is 0.25 MPa ⁻¹ or less. The third layer 64 can contribute to wear resistance.

In the tire 40, the center portion C includes a second layer 62 and a third layer 64 stacked in the radial direction. In the tire 40, the center portion C has the second highest temperature after the middle portion M in a race in which the running state is continued. The outermost layer of the center portion C is the second layer 62. As described above, the loss compliance LC2 measured at a temperature of 100 ° C. of the second layer 62 is 0.19 MPa ⁻¹ or more. The second layer 62 can contribute to grip performance. As described above, the loss compliance LC2 of the second layer 62 is preferably 0.29 MPa ⁻¹ or less. The second layer 62 can contribute to wear resistance.

In the center portion C, the third layer 64 is located on the radially inner side of the second layer 62. As described above, the loss compliance LC3 measured at a temperature of 80 ° C. of the third layer 64 is preferably 0.17 MPa ⁻¹ or more. In the tire 40, even if the second layer 62 is worn and the third layer 64 is exposed, the third layer 64 can contribute to the grip performance. As described above, the loss compliance LC3 of the third layer 64 is preferably 0.25 MPa ⁻¹ or less. The third layer 64 can contribute to wear resistance.

In the tire 40, the first shoulder portion S includes a second layer 62 and a third layer 64 that are stacked in the radial direction, like the center portion C described above. The outermost layer of the first shoulder portion S is the second layer 62. In the tire 40, the first shoulder portion S has a temperature equal to or lower than that of the center portion C in a race in which the running state is continued. As described above, the loss compliance LC2 measured at a temperature of 100 ° C. of the second layer 62 is 0.19 MPa ⁻¹ or more. In the first shoulder portion S, the second layer 62 can contribute to grip performance. As described above, the loss compliance LC2 of the second layer 62 is preferably 0.29 MPa ⁻¹ or less. The second layer 62 can contribute to wear resistance.

In the first shoulder portion S, the third layer 64 is located inside the second layer 62 in the radial direction. As described above, the loss compliance LC3 measured at a temperature of 80 ° C. of the third layer 64 is preferably 0.17 MPa ⁻¹ or more. In the tire 40, even if the second layer 62 is worn and the third layer 64 is exposed, the third layer 64 can contribute to the grip performance. As described above, the loss compliance LC3 of the third layer 64 is preferably 0.25 MPa ⁻¹ or less. The third layer 64 can contribute to wear resistance.

In the tire 40, the second shoulder portion T includes a third layer 64. In the tire 40, in the race in which the running state is continued, the temperature of the tread 42 is minimized at the second shoulder portion T. As described above, the loss compliance LC3 measured at a temperature of 80 ° C. of the third layer 64 is preferably 0.17 MPa ⁻¹ or more. In the second shoulder portion T of the tire 40, the third layer 64 can contribute to grip performance. As described above, the loss compliance LC3 of the third layer 64 is preferably 0.25 MPa ⁻¹ or less. The third layer 64 can contribute to wear resistance.

  Thus, in the tire 40, the loss compliance of each layer is appropriately adjusted according to the state of the tread 42. Even if the tread 42 becomes thin due to wear and the temperature of the tread 42 decreases, the tire 40 continues to exhibit good grip performance stably. In particular, the tread 42 of the tire 40 can effectively contribute to grip performance on a circuit course where the air temperature is 25 ° C. or higher or the road surface temperature is 40 ° C. or higher. According to the present invention, a pneumatic tire 40 having excellent grip performance can be obtained.

  In FIG. 2, a double arrow WA represents the length from the equator plane to the end 68 of the tread surface 66. This length WA is half of the length of the tread surface 66. A double arrow WC represents the length from the equator plane to the inner end 72 of the first layer 60. This length WC is half of the length of the outer surface of the center portion C. A double arrow WM represents a length from the inner end 72 of the first layer 60 to the outer end 74 thereof. This length WM is the length of the outer surface of the middle part M. A double arrow WS represents the length from the outer end 74 of the first layer 60 to the end 70 of the second layer 62. This length WS is the length of the outer surface of the first shoulder portion S. A double-headed arrow WT represents the length from the end 70 of the second layer 62 to the end 68 of the tread surface 66. This length WT is the length of the outer surface of the second shoulder portion T. In the present application, the length WA, the length WC, the length WM, the length WS, and the length WT are measured along the tread surface 66 in the cross section shown in FIG.

  As described above, in the race where the running state is continued, the temperature of the tread 42 becomes maximum in the middle portion M. The center part C has the second highest temperature after the middle part M. The first shoulder portion S has a temperature equal to or lower than that of the center portion C. In the second shoulder portion T, the temperature of the tread 42 is minimum. The ratio of the length WC to the length WA is preferably 0.2 or more, and preferably 0.3 or less, from the viewpoint that good grip performance can be obtained as the entire tread 42. The ratio of the length WM to the length WA is preferably 0.3 or more, and more preferably 0.6 or less. The ratio of the length WS to the length WA is preferably 0.1 or more, and preferably 0.2 or less. The ratio of the length WT to the length WA is preferably 0.1 or more, and more preferably 0.2 or less.

  FIG. 3A shows a part of the center portion C of the cap layer 58. In FIG. 3A, a double-headed arrow T2c represents the thickness of the second layer 62 in the center portion C. A double-headed arrow T3c represents the thickness of the third layer 64 in the center portion C. The thickness T2c and the thickness T3c are measured along the equator plane.

  In the race where the running state is continued, the thickness T2c is preferably 1.0 mm or more, and preferably 4.5 mm or less from the viewpoint that the center portion C continues to exhibit good grip performance. The thickness T3c is preferably 1.0 mm or more, and preferably 3.0 mm or less.

  FIG. 3B shows a part of the middle portion M of the cap layer 58. In FIG. 3B, the symbol PM represents a point where the length WM described above is halved. A solid line LM represents a normal line of the tread surface 66 at the point PM. A double-headed arrow T1m represents the thickness of the first layer 60 in the middle portion M. A double-headed arrow T2m represents the thickness of the second layer 62 in the middle portion M. A double-headed arrow T3m represents the thickness of the third layer 64 in the center portion C. The thickness T1m, the thickness T2m, and the thickness T3m are measured along the normal line LM. The sum of the thickness T1m, the thickness T2m, and the thickness T3m is the thickness of the cap layer 58 in the tire 40.

  In the race where the running state is continued, the thickness T1m is preferably 1.0 mm or more, and more preferably 4.5 mm or less from the viewpoint that the middle portion M continues to exhibit good grip performance. The thickness T2m is preferably 1.0 mm or more, and more preferably 4.5 mm or less. The thickness T3m is preferably 1.0 mm or more, and more preferably 4.5 mm or less.

  FIG. 3C shows a part of the shoulder portion of the cap layer 58. In FIG. 3B, the solid line LS represents the normal line of the tread surface 66 at the boundary between the middle portion M and the first shoulder portion S. The solid line LT represents the normal line of the tread surface 66 at the boundary between the first shoulder portion S and the second shoulder portion T. A double-headed arrow T2s represents the thickness of the second layer 62 in the first shoulder portion S. A double-headed arrow T3s represents the thickness of the third layer 64 in the first shoulder portion S. A double-headed arrow T3t represents the thickness of the third layer 64 in the second shoulder portion T. The thickness T2s and the thickness T3s are measured along the normal line LS. The thickness T3t is measured along the normal line LT.

  In the race where the running state is continued, the thickness T2s is preferably 1.0 mm or more, and more preferably 4.5 mm or less, from the viewpoint that the first shoulder portion S continues to exhibit good grip performance. The thickness T3s is preferably 1.0 mm or more, and more preferably 4.5 mm or less. From the viewpoint that the second shoulder portion T continues to exhibit good grip performance, the thickness T3t is preferably 2.0 mm or more, and more preferably 5.0 mm or less.

  FIG. 4 shows a pneumatic tire 76 as a third embodiment. In FIG. 4, the vertical direction is the radial direction of the tire 76, the horizontal direction is the axial direction of the tire 76, and the direction perpendicular to the paper surface is the circumferential direction of the tire 76. In FIG. 4, an alternate long and short dash line CL represents the equator plane of the tire 76. The shape of the tire 76 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 76 includes a tread 78, a sidewall 80, a wing 82, a bead 84, a carcass 86, a band 88, and an inner liner 90. The tire 76 is a tubeless type. The tire 76 is attached to a two-wheeled vehicle.

  The tread 78 has a base layer 92 and a cap layer 94. The tire 76 has the same configuration as that of the tire 2 shown in FIG. 1 except for the cap layer 94 of the tread 78.

  As shown in FIG. 4, the cap layer 94 of the tread 78 includes a plurality of layers stacked in the radial direction. In the tire 76, the cap layer 94 is composed of two layers. Of these layers, the outermost layer in the radial direction is referred to as a first layer 96. The layer located inside the first layer 96 is referred to as a second layer 98. The cap layer 94 includes a first layer 96 and a second layer 98.

  Also in the tire 76, as in the tread 78 of the tire 76 shown in FIG. 1, the loss compliance LC of each layer constituting the tread 78 is appropriately adjusted. As a result, the grip performance is improved.

  When the two-wheeled vehicle starts traveling, the temperature of the tire 76 increases. This temperature rising process continues for a while after the start of traveling. In a circuit course in which the air temperature is 20 ° C. or lower or the road surface temperature is 35 ° C. or lower, the tire 76 is cooled by the outside air, so that the air temperature is 25 ° C. or higher or the road temperature is 40 ° C. or higher. The temperature of the tire 76 does not increase as in the case of running on the course.

In the tire 76, the loss compliance LC1b of the first layer 96 measured at a temperature of 70 ° C. is 0.13 MPa ⁻¹ or more. Thereby, the first layer 96 can contribute to the grip performance in the temperature rising process. From this viewpoint, the loss compliance LC1b is more preferably 0.17 MPa ⁻¹ or more. Excessive loss compliance LC1b affects the wear resistance. In this respect, the loss compliance LC1b is preferably 0.23 MPa ⁻¹ or less.

In the tire 76, the loss compliance LC1a of the first layer 96 measured at a temperature of 120 ° C. is 0.13 MPa ⁻¹ or more. As a result, even when the tire 76 spins and the temperature suddenly increases, the first layer 96 can contribute to the grip performance. Excessive loss compliance LC1a affects the wear resistance. In this respect, the loss compliance LC1a is preferably 0.20 MPa ⁻¹ or less.

The first layer 96 is worn by running. As wear progresses, the thickness of the tread 78 decreases. As the tread 78 becomes thinner, the temperature of the tread 78 decreases. In the tire 76, the second layer 98 is located inside the first layer 96. The loss compliance LC2 measured at a temperature of 100 ° C. of the second layer 98 is 0.19 MPa ⁻¹ or more. In the tire 76, when the first layer 96 is worn and the second layer 98 is exposed, the second layer 98 can contribute to grip performance. From this viewpoint, the loss compliance LC2 is preferably 0.20 MPa ⁻¹ or more. Excessive loss compliance LC2 affects the wear resistance. From this viewpoint, the loss compliance LC2 is preferably 0.30 MPa ⁻¹ or less.

In the tire 76, in the circuit course where the air temperature is equal to or lower than 20 ° C. or the road surface temperature is equal to or lower than 35 ° C., from the viewpoint that the first layer 96 effectively contributes to grip performance, loss compliance LC1a is a 0.13 MPa ^-1 or 0.20 MPa ^-1 or less, loss compliance LC1b the first layer 96 preferably is a 0.17 MPa ^-1 or 0.23 MPa ^-1 or less. Furthermore, from the viewpoint that the second layer 98 effectively contributes to grip performance in this circuit course, the loss compliance LC2 of the second layer 98 is preferably set to 0.20 MPa ⁻¹ or more and 0.30 MPa ⁻¹ or less. .

  Thus, in the tire 76, the loss compliance of each layer is appropriately adjusted according to the state of the tread 78. Even if the tread 78 becomes thin due to wear and the temperature of the tread 78 decreases, the tire 76 continues to exhibit good grip performance stably. In particular, the tread 78 of the tire 76 can effectively contribute to grip performance on a circuit course where the air temperature is 20 ° C. or lower or the road surface temperature is 35 ° C. or lower. According to the present invention, a pneumatic tire 76 having excellent grip performance can be obtained.

  In the tire 76, the hardness H1b of the first layer 96 measured at a temperature of 70 ° C. is preferably 36 or more and 45 or less. By setting the hardness H1b to be equal to or greater than 36, the first layer 96 can contribute to the rigidity of the tire 76 particularly in the temperature rising process that continues for a while after the two-wheeled vehicle starts to travel. The tire 76 is excellent in handling stability and traction performance. By setting the hardness H1b to 47 or less, the influence of the first layer 96 on the rigidity can be suppressed. The tire 76 is excellent in grip performance and ride comfort.

  In the tire 76, the hardness H1a of the first layer 96 measured at a temperature of 120 ° C. is preferably 33 or greater and 40 or less. By setting the hardness H1a to 33 or more, the first layer 96 can contribute to the rigidity of the tire 76 even when the tire 76 spins and the temperature suddenly rises. The tire 76 is excellent in handling stability and traction performance. By setting the hardness H1a to 40 or less, the influence of the first layer 96 on the rigidity can be suppressed. The tire 76 is excellent in grip performance and ride comfort.

  In the tire 76, the hardness H2 measured at a temperature of 100 ° C. of the second layer 98 is preferably 25 or more and 35 or less. The second layer 98 can contribute to the rigidity of the tire 76 by setting the hardness H2 to 25 or more. The tire 76 is excellent in handling stability and traction performance. By setting the hardness H2 to 35 or less, the influence of the second layer 98 on the rigidity is suppressed. The tire 76 is excellent in grip performance and ride comfort.

  In the tire 76, the modulus M1 of the first layer 96 is preferably 5.0 MPa or more and 7.0 MPa or less. By setting the modulus M1 to 5.0 MPa or more, the first layer 96 can contribute to the rigidity of the tire 76. The tire 76 is excellent in handling stability and traction performance. By setting the modulus M1 to 7.0 MPa or less, the influence of the first layer 96 on the rigidity can be suppressed. The tire 76 is excellent in grip performance and ride comfort.

  In the tire 76, the modulus M2 of the second layer 98 is preferably 2.5 MPa or more and 3.5 MPa or less. By setting the modulus M2 to 2.5 MPa or more, the second layer 98 can contribute to the rigidity of the tire 76. The tire 76 is excellent in handling stability and traction performance. By setting the modulus M2 to 3.5 MPa or less, the influence of the second layer 98 on the rigidity is suppressed. The tire 76 is excellent in grip performance and ride comfort.

  In the tire 76, the first layer 96 preferably has a modulus M1 higher than the modulus M2 of the second layer 98. Thereby, the rigidity of the tread 78 is appropriately maintained in the tire 76 in the traveling state. The tire 76 is excellent in handling stability and traction performance. From this viewpoint, the difference (M1−M2) between the modulus M1 and the modulus M2 is preferably 1.5 MPa or more. From the viewpoint of suppressing the change in rigidity when the tread 78 becomes thin due to wear, the difference (M1−M2) between the modulus M1 and the modulus M2 is preferably 3.0 MPa or less.

  In FIG. 4, the double arrow T <b> 1 represents the thickness of the first layer 96. A double-headed arrow T2 represents the thickness of the second layer 98. In the present application, each of the thickness T1, the thickness T2, and the thickness Tb is measured along the equator plane in the cross section shown in FIG. The sum of the thickness T1 and the thickness T2 is the thickness of the cap layer 94 measured along the equator plane.

  In the tire 76, the thickness T1 is preferably equal to or greater than 1.5 mm, and preferably equal to or less than 5.0 mm, from the viewpoint that the first layer 96 can effectively contribute to the grip performance in the temperature rising process.

  In the tire 76, when the second layer 98 is exposed due to wear of the first layer 96, the thickness T2 is preferably 1.5 mm or more from the viewpoint that the second layer 98 can effectively contribute to grip performance. 5.0 mm or less is more preferable.

  In the tire 76, the ratio of the thickness T1 to the thickness of the cap layer 94 is preferably 0.20 or more and 0.80 or less from the viewpoint that the first layer 96 can effectively contribute to the grip performance in the temperature rising process. Is preferred.

  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.

[Experiment 1]
[Example 1]
A pneumatic tire (tire size = 200 / 60R420) of Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 2 below was obtained. In Example 1, the tread cap layer is composed of three layers, a first layer, a second layer, and a third layer.

The loss compliance LC1a measured at a temperature of 120 ° C. in the first layer was set to 0.19 MPa ⁻¹ . The loss compliance LC1b measured at a temperature of 70 ° C. of this first layer was 0.15 MPa ⁻¹ . The hardness H1a of this first layer measured at a temperature of 120 ° C. was 36. The hardness H1b of this first layer measured at a temperature of 70 ° C. was 40. The 300% modulus M1 measured at a temperature of 100 ° C. of this first layer was set to 4.7 MPa. The thickness T1 of the first layer was 1.5 mm.

The loss compliance LC2 of the second layer measured at a temperature of 100 ° C. was set to 0.21 MPa ⁻¹ . The hardness H2 of this second layer measured at a temperature of 100 ° C. was 35. The 300% modulus M2 measured at a temperature of 100 ° C. of this first layer was 4.5 MPa. The thickness T1 of this first layer was 2.5 mm.

The third layer, loss compliance LC3, measured at a temperature of 80 ° C. was set to 0.17 MPa ^-1. The hardness H3 of this third layer measured at a temperature of 80 ° C. was 38. The 300% modulus M3 measured at a temperature of 100 ° C. of this third layer was set to 4.3 MPa. The thickness T3 of this first layer was 2.5 mm.

The loss compliance LCb measured at a temperature of 100 ° C. of the base layer was 0.10 MPa ⁻¹ . The hardness Hb of the base layer measured at a temperature of 100 ° C. was 48. The 300% modulus Mb measured at a temperature of 100 ° C. of this third layer was set to 5.9 MPa. The thickness Tb of this first layer was 1.5 mm.

[Example 2-6 and Comparative Example 1]
Tires of Examples 2-6 and Comparative Example 1 in the same manner as in Example 1 except that the first layer loss compliances LC1a and LC1b, hardness H1a and H1b, and modulus M1 are as shown in Table 1 below. Got.

[Examples 7-10 and Comparative Example 2]
Tires of Examples 7-10 and Comparative Example 2 were obtained in the same manner as in Example 1 except that the loss compliance LC2, hardness H2, and modulus M2 of the second layer were as shown in Table 2 below.

[Examples 11-14]
Tires of Examples 11-14 were obtained in the same manner as in Example 1 except that the third layer had loss compliance LC3, hardness H3, and modulus M3 as shown in Table 3 below.

[Example 16-30]
Tires of Examples 16-30 were obtained in the same manner as in Example 1 except that the thicknesses T1, T2, and T3 were as shown in Tables 4, 5, and 6 below.

[Comparative Example 3-5]
A tire of Comparative Example 3-5 was obtained in the same manner as in Example 1 except that the cap layer was composed of a single layer.

[Example 15]
A tire of Example 15 was obtained in the same manner as Example 1 except that the tread configuration was as shown in FIG. Note that the ratio of the half length WC of the outer surface of the center portion to the half length WA of the tread surface was 0.25. The ratio of the length WM of the outer surface of the middle part to the length WA was 0.50. The ratio of the length WS of the outer surface of the first shoulder portion to the length WA was 0.10. The ratio of the length WT of the outer surface of the second shoulder portion to the length WA was 0.15. The thickness T2c of the second layer in the center portion was 1.0 mm. The thickness T3c of the third layer in this center portion was 1.0 mm. The thickness T1m of the first layer in the middle part was 1.5 mm. The thickness T2m of the second layer in the middle part was 2.5 mm. The thickness T3m of the third layer in this middle part was 2.5 mm. The thickness T2s of the second layer in the first shoulder portion was 4.0 mm. The thickness T3s of the third layer in the first shoulder portion was 2.5 mm. The thickness T3t of the third layer in the second shoulder portion was 6.5 mm.

[Evaluation of grip performance (1)]
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 air was filled so that the internal pressure was 290 kPa. The size of the rim of the rear wheel was 6.25 × 420. A commercially available tire (size = 125 / 80R420) was mounted on the front wheel and filled with air so that the internal pressure was 250 kPa. The size of the rim of the front wheel was 3.50 × 420. The two-wheeled vehicle was run on a circuit course with asphalt on the road surface (the number of laps was 40 laps), and a sensory evaluation by a rider was performed. The circuit course temperature was 32 ° C. The road surface temperature was 47 ° C. The evaluation item is grip performance. The results in 1 to 5 laps, 6 to 10 laps, 11 to 20 laps, and 21 to 40 laps are shown in Tables 1 to 6 below as indices. Larger numbers are preferable.

  As shown in Tables 1 to 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.

[Experiment 2]
[Example 31]
A pneumatic tire of Example 31 (tire size = 200 / 60R420) having the basic configuration shown in FIG. 4 and the specifications shown in Table 8 below was obtained. In Example 31, the tread cap layer is composed of two layers, a first layer and a second layer.

The loss compliance LC1a measured at a temperature of 120 ° C. of the first layer was set to 0.14 MPa ⁻¹ . The loss compliance LC1b measured at a temperature of 70 ° C. of this first layer was 0.18 MPa ⁻¹ . The hardness H1a of the first layer measured at a temperature of 120 ° C. was set to 35. The hardness H1b measured at a temperature of 70 ° C. of this first layer was 43. The 300% modulus M1 measured at a temperature of 100 ° C. of this first layer was set to 6.1 MPa. The thickness T1 of the first layer was 1.5 mm.

The loss compliance LC2 measured at a temperature of 100 ° C. of the second layer was set to 0.25 MPa ⁻¹ . The hardness H2 of this second layer measured at a temperature of 100 ° C. was 29. The 300% modulus M2 measured at a temperature of 100 ° C. of this first layer was 3.2 MPa. The thickness T1 of this first layer was 5.0 mm.

The loss compliance LCb measured at a temperature of 100 ° C. of the base layer was 0.10 MPa ⁻¹ . The hardness Hb of the base layer measured at a temperature of 100 ° C. was 48. The 300% modulus Mb measured at a temperature of 100 ° C. of this third layer was set to 5.9 MPa. The thickness Tb of this first layer was 1.5 mm.

[Examples 32-36 and Comparative Example 6]
Tires of Examples 32-36 and Comparative Example 6 in the same manner as in Example 31, except that the loss compliance LC1a and LC1b, the hardness H1a and H1b, and the modulus M1 are as shown in Table 7 below. Got.

[Examples 37-39 and Comparative Example 7]
Tires of Examples 37 to 39 and Comparative Example 7 were obtained in the same manner as Example 31 except that the loss compliance LC2, hardness H2, and modulus M2 of the second layer were as shown in Table 8 below.

[Examples 40-45]
Tires of Examples 40-45 were obtained in the same manner as Example 31 except that the thickness T1 and the thickness T2 were as shown in Table 9 below.

[Comparative Example 8-9]
A tire of Comparative Example 8-9 was obtained in the same manner as in Example 31 except that the cap layer was composed of a single layer.

[Evaluation of grip performance (2)]
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 air was filled so that the internal pressure was 290 kPa. The size of the rim of the rear wheel was 6.25 × 420. A commercially available tire (size = 125 / 80R420) was mounted on the front wheel and filled with air so that the internal pressure was 250 kPa. The size of the rim of the front wheel was 3.50 × 420. The two-wheeled vehicle was run on a circuit course with asphalt on the road surface (the number of laps was 40 laps), and a sensory evaluation by a rider was performed. The circuit course temperature was 16 ° C. The road surface temperature was 26 ° C. The evaluation item is grip performance. The results in 1 to 5 laps, 6 to 10 laps, 11 to 20 laps, and 21 to 40 laps are shown in Tables 7 to 10 as indices. Larger numbers are preferable.

  As shown in Tables 7 to 10, 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, 40, 76 ... tire 4, 42, 78 ... tread 6, 44, 80 ... sidewall 10, 48, 84 ... bead 12, 50, 86 ... carcass 20, 56, 92 ... Base layer 22, 58, 94 ... Cap layer 34, 60, 96 ... First layer 36, 62, 98 ... Second layer 38, 64 ... Third layer

Claims (4)

A tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from an end of the tread, a pair of beads each positioned radially inward of the sidewall, and the tread And a carcass stretched between one bead and the other bead along the inside of the sidewall,
The tread includes a base layer and a cap layer located on the radially outer side of the base layer,
The cap layer is composed of a plurality of layers laminated in the radial direction,
The loss compliance LC1a measured at a temperature of 120 ° C. of the first layer located on the outermost side among the plurality of layers is 0.13 MPa ⁻¹ or more,
Loss compliance LC1b measured at a temperature of 70 ° C. of the first layer is 0.13 MPa ⁻¹ or more,
The pneumatic tire whose loss compliance LC2 measured under the temperature of 100 degreeC of the 2nd layer located inside the said 1st layer is 0.19 Mpa- ¹ or more. The loss compliance LC1a of the first layer is 0.17 MPa ⁻¹ or more and 0.24 MPa ⁻¹ or less,
Loss compliance LC1b of the first layer is at 0.13 MPa ^-1 or 0.20 MPa ^-1 or less,
The pneumatic tire according to claim ¹ whose loss compliance LC2 of said 2nd layer is 0.19MPa- ¹ or more and 0.29MPa- ¹ or less. The cap layer includes a third layer radially inward of the second layer;
The third layer is loss compliance LC3, measured at a temperature of 80 ° C. is 0.17 MPa ^-1 or 0.25 MPa ^-1 or less, pneumatic tire according to claim 1 or 2. Loss compliance LC1a of the first layer is at 0.13 MPa ^-1 or 0.20 MPa ^-1 or less,
The loss compliance LC1b of the first layer is 0.17 MPa ⁻¹ or more and 0.23 MPa ⁻¹ or less,
The pneumatic tire according to claim 1, wherein the loss compliance LC2 of the second layer is 0.20 MPa ^-1 or more and 0.30 MPa ^-1 or less.

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