JP6756163B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In recent years, there has been a particularly strong demand for fuel efficiency of vehicles due to consideration for the environment. Since tires affect the fuel efficiency of vehicles, the development of "fuel-efficient tires" that contribute to the reduction of fuel efficiency is underway. In order to achieve low fuel consumption by tires, it is important to reduce the rolling resistance of the tires.

The mass of the tire affects the rolling resistance. From the viewpoint of reducing rolling resistance, weight reduction of tires may be considered. There is a way to reduce the volume of rubber on the tread and sidewalls for weight reduction. However, reducing the volume of rubber can be a factor in reducing the trauma resistance of the tire.

Some tires have a reinforcing layer on their side to improve trauma resistance. For example, a tire provided with a rubber reinforcing layer on the inner surfaces of a buttress region and a bead region is reported in Japanese Patent Application Laid-Open No. 2008-290540.

JP-A-2008-290540

Further, a tire having improved traumatic resistance and reduced rolling resistance is desired. The weight reduction of the sidewalls can be a factor in reducing the trauma resistance in particular. However, in order to prevent the deterioration of the traumatic resistance of the conventional reinforcing layer, it is necessary to increase the thickness of the reinforcing layer. This increases the mass of the tire. This reduces the effect of sidewall weight reduction. With conventional tires, it has sometimes been difficult to achieve both good traumatic resistance and low rolling resistance.

An object of the present invention is to provide a tire in which good traumatic resistance and low rolling resistance are realized.

The pneumatic tire according to the present invention includes a pair of sidewalls, a pair of beads each located radially inside the sidewalls, a carcass bridged between the two beads, and the inside of the carcass. It has an inner liner located in and a pair of first reinforcing layers. Each first reinforcing layer is located on the inner side in the axial direction of the sidewall in the vicinity of the buttress portion of the tire. The puncture energy of the first reinforcing layer is 70 J or more.

Preferably, the material of the first reinforcing layer is urethane.

Preferably, the first reinforcing layer is sandwiched between the carcass and the inner liner.

Preferably, the ratio (S1 / SH) of the height S1 from the bead baseline to the midpoint of the first reinforcing layer to the height SH from the bead baseline to the radial outer edge of the carcass is 0.8. It is 0.9 or more and 0.9 or less.

Preferably, the ratio (L1 / SH) of the length L1 of the first reinforcing layer measured along the inner surface of the first reinforcing layer to the height SH from the bead baseline to the radial outer end of the carcass. Is 0.23 or more and 0.50 or less.

Preferably, the thickness T1 of the first reinforcing layer is 0.5 mm or more and 1.5 mm or less.

Preferably, the tire further comprises a pair of second reinforcing layers. Each second reinforcing layer is located inside the bead in the axial direction. The puncture energy of the second reinforcing layer is 70 J or more.

Preferably, the material of the second reinforcing layer is urethane.

Preferably, the second reinforcing layer is sandwiched between the carcass and the inner liner.

Preferably, it is located on the axial inner surface of the bead portion, and when the point at which the thickness of the bead portion is maximized is PT, the inside of the second reinforcing layer from the bead baseline. The ratio (H2 / TH) of the height H2 to the point to the height TH from the bead baseline to the point PT is 0.9 or more and 1.1 or less.

Preferably, the ratio (L2 / SH) of the length L2 of the second reinforcing layer measured along the inner surface of the second reinforcing layer to the height SH from the bead baseline to the radial outer end of the carcass. Is 0.23 or more and 0.50 or less.

Preferably, the thickness T2 of the second reinforcing layer is 0.5 mm or more and 1.5 mm or less.

In the pneumatic tire according to the present invention, the first reinforcing layer is located on the inner side in the axial direction of the sidewall in the vicinity of the buttress portion of the tire. The puncture energy of the first reinforcing layer is 70 J or more. This first reinforcing layer has excellent absorption of impact energy. When the tire rides on the curb, the side portion of the tire is greatly deformed so that the vicinity of the maximum width position protrudes outward in the axial direction. The buttress part of the tire is sandwiched between the curb and the rim. At this time, a large impact is applied to the buttress portion. This first reinforcing layer effectively absorbs the impact at this time. This first reinforcing layer reduces the deformation of the side portion with respect to the applied load when the buttress portion is sandwiched between the curb and the rim. This tire is less prone to trauma. This tire has excellent trauma resistance. Further, the first reinforcing layer having excellent absorption of impact energy can suppress trauma even if its thickness is reduced. The influence of this first reinforcing layer on the mass of the tire can be reduced. With this tire, the effect of reducing the weight of the sidewall can be maintained. This tire achieves low rolling resistance.

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 an enlarged cross-sectional view showing a part of the tire of FIG.

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

FIG. 1 shows the pneumatic tire 2. In FIG. 1, the vertical direction is the radial direction of the tire 2, the left-right 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, the alternate long and short dash line CL represents the equatorial plane of the tire 2. The shape of the tire 2 is symmetrical with respect to the equatorial plane except for the tread pattern.

In the present invention, the dimensions and angles of each member of the tire 2 are measured in a state where the tire 2 is incorporated in the 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. As used herein, the term "regular rim" means a rim defined in the standard on which Tire 2 relies. The "standard rim" in the JATTA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are regular rims. As used herein, the normal internal pressure means the internal pressure defined in the standard on which the tire 2 relies. The "maximum air pressure" in the JATTA standard, the "maximum value" in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are regular internal pressures. In the present specification, the normal load means the load defined in the standard on which the tire 2 relies. The "maximum load capacity" in the JATTA standard, the "maximum value" in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads.

The tire 2 has a tread 4, a pair of sidewalls 6, a pair of clinches 8, a pair of beads 10, a carcass 12, a belt 14, a band 16, an inner liner 18, a pair of first reinforcing layers 20, and a pair of second reinforcements. It includes layer 22. This tire 2 is a tubeless type. The tire 2 is mounted on a passenger car.

The tread 4 has a shape that is convex outward in the radial direction. The tread 4 forms a tread surface 24 that comes into contact with the road surface. A groove 26 is carved on the tread surface 24. A tread pattern is formed by the groove 26. Although not shown, the tread 4 has a base layer and a cap layer. The cap layer is located radially outside the base layer. The cap layer is laminated on the base layer. The base layer is made of crosslinked rubber having excellent adhesiveness. A typical base rubber for the base layer is natural rubber. The cap layer is made of crosslinked rubber having excellent wear resistance, heat resistance and grip.

Each sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The radial outer edge of the sidewall 6 is joined to the tread 4. The radial inner edge of the sidewall 6 is joined to the clinch 8. The sidewall 6 is made of crosslinked rubber having excellent cut resistance and weather resistance. The sidewall 6 is located outside the carcass 12 in the axial direction. The sidewall 6 prevents damage to the carcass 12.

Each clinch 8 is located radially inside the sidewall 6. The clinch 8 is located outside the bead 10 and the carcass 12 in the axial direction. The clinch 8 is made of a crosslinked rubber having excellent wear resistance. The clinch 8 comes into contact with the flange of the rim.

Each bead 10 is located axially inside the clinch 8. The bead 10 includes a core 28 and an apex 30 extending radially outward from the core 28. The core 28 is ring-shaped and includes a wound non-stretchable wire. A typical material for wire is steel. The apex 30 is tapered outward in the radial direction. Apex 30 is made of high hardness crosslinked rubber.

The carcass 12 is made of a carcass ply 32. The carcass ply 32 is bridged between the beads 10 on both sides. The carcass ply 32 runs along the inside of the tread 4 and sidewall 6. The carcass ply 32 is folded around the core 28 from the inside to the outside in the axial direction. Due to this folding, the carcass ply 32 is formed with a main portion 32a and a folded portion 32b.

The carcass ply 32 is composed of a large number of parallel cords and a topping rubber. The absolute value of the angle each code makes with respect to the equatorial plane is 75 ° to 90 °. In other words, the carcass 12 has a radial structure. The cord consists of organic fibers. Preferred organic fibers include polyethylene terephthalate fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers and aramid fibers. The carcass 12 may be formed from two or more carcass plies 32.

The belt 14 is located inside the tread 4 in the radial direction. The belt 14 is laminated with the carcass 12. The belt 14 reinforces the carcass 12. The axial width of the belt 14 is preferably 0.7 times or more the maximum width of the tire 2.

The belt 14 of the tire 2 is composed of an inner layer 14a and an outer layer 14b. As is clear from FIG. 1, the outer layer 14b is located radially outside the inner layer 14a. In the axial direction, the width of the outer layer 14b is slightly smaller than the width of the inner layer 14a. The axial width of the outer layer 14b is usually 0.85 times or more and 0.95 times or less the axial width of the inner layer 14a.

Although not shown, each of the inner layer 14a and the outer layer 14b consists of a number of parallel cords and topping rubbers. In other words, the belt 14 contains a large number of cords in parallel. Each cord is inclined with respect to the equatorial plane. The absolute value of the tilt angle is usually 10 ° or more and 35 ° or less. The direction of inclination of the cord of the inner layer 14a with respect to the equatorial plane is opposite to the direction of inclination of the cord of the outer layer 14b with respect to the equatorial plane. The preferred material for the cord is steel. Organic fibers may be used for the cord. The belt 14 may include three or more layers.

The band 16 is located on the outer side in the radial direction of the belt 14. In the axial direction, the width of the band 16 is larger than the width of the belt 14. Although not shown, the band 16 comprises a cord and a topping rubber. The cord is spirally wound. The band 16 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. Since the belt 14 is restrained by this cord, the lifting of the belt 14 is suppressed. The axial width of the band 16 is preferably 1.05 times or more, preferably 1.10 times or less, the axial width of the belt 14. The cord consists of organic fibers. Preferred organic fibers include nylon fibers, polyethylene terephthalate fibers, rayon fibers, polyethylene naphthalate fibers and aramid fibers.

The inner liner 18 is located inside the carcass 12. The inner liner 18 is joined to the inner surface of the carcass 12. The inner liner 18 is made of crosslinked rubber. Rubber having excellent air shielding properties is used for the inner liner 18. A typical base rubber of the inner liner 18 is butyl rubber or halogenated butyl rubber. The inner liner 18 holds the internal pressure of the tire 2.

Each first reinforcing layer 20 is located in the vicinity of the buttress portion. The first reinforcing layer 20 is located inside the sidewall 6 in the axial direction. In this embodiment, the first reinforcing layer 20 is sandwiched between the carcass 12 and the inner liner 18.

The puncture energy of the first reinforcing layer 20 is 70 J or more. In other words, the first reinforcing layer 20 is excellent in shock absorption. The preferred material for the first reinforcing layer 20 is urethane.

In the present invention, the puncture energy of the first reinforcing layer 20 and the second reinforcing layer 22, which will be described later, is a puncture impact tester (Shimadzu Corporation) under the following measurement conditions in accordance with the provisions of "JIS K 7211". It is measured using the product name "Hydroshot"). In this measurement, a plate-shaped test piece (length = 60 mm, width = 60 mm, thickness = 2 mm) is formed from the materials of the first reinforcing layer 20 and the second reinforcing layer 22. This test piece is used for measurement.
Inner diameter of support: 40 mm
Striker diameter: 20 mm
Specimen fixed / non-fixed: fixed
Impact speed: 4.4 m / s

In the puncture impact test, the maximum test force and puncture displacement are measured together with the puncture energy. To give an example of the measurement results, the urethane used in this embodiment had a puncture energy of 93.8 J, a maximum test force of 3.28 kN, and a puncture displacement of 48.2 mm.

Each second reinforcing layer 22 is located at a portion of the bead 10 of the tire 2. The second reinforcing layer 22 is located inside the bead 10 in the axial direction. In this embodiment, the second reinforcing layer 22 is sandwiched between the carcass 12 and the inner liner 18. Specifically, the second reinforcing layer 22 is sandwiched between the main portion 32a and the inner liner 18.

The puncture energy of the second reinforcing layer 22 is 70 J or more. In other words, the second reinforcing layer 22 has excellent shock absorption. The preferred material for the second reinforcing layer 22 is urethane. In this embodiment, the first reinforcing layer 20 and the second reinforcing layer 22 are made of the same urethane. The first reinforcing layer 20 and the second reinforcing layer 22 may be made of different materials. The tire 2 does not have to include the second reinforcing layer 22.

The action and effect of the present invention will be described below.

When the tire rides on the curb, the side portion of the tire is greatly deformed so that the vicinity of the maximum width position protrudes outward in the axial direction. The buttress part of the tire is sandwiched between the curb and the rim. A big impact is applied to the buttress part. This can cause trauma to the tire. This trauma is particularly likely to occur on tires that have sidewalls that are thinned to reduce weight. In order to improve the trauma resistance of the tire, there is a method of inserting a reinforcing layer on the side portion of the tire. However, in order to prevent the deterioration of the traumatic resistance of the conventional reinforcing layer, it is necessary to increase the thickness of the reinforcing layer. This increases the mass of the tire. This reduces the effect of reducing the weight of the sidewall 6. With conventional tires, it has sometimes been difficult to achieve both good traumatic resistance and low rolling resistance.

In the pneumatic tire 2 according to the present invention, the first reinforcing layer 20 is located inside the sidewall 6 in the axial direction in the vicinity of the buttress portion of the tire 2. The puncture energy of the first reinforcing layer 20 is 70 J or more. The first reinforcing layer 20 is excellent in absorption of impact energy. When the buttress portion is sandwiched between the curb and the rim, the first reinforcing layer 20 effectively absorbs the impact applied to the buttress portion. Further, the first reinforcing layer 20 reduces the deformation of the side portion with respect to the applied load when the buttress portion is sandwiched between the curb and the rim. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance.

From the viewpoint of further improving the traumatic resistance of the tire 2, the puncture energy of the first reinforcing layer 20 is preferably 80 J or more, and more preferably 90 J or more.

The first reinforcing layer 20 having excellent absorption of impact energy can suppress trauma even if its thickness is reduced. The influence of the first reinforcing layer 20 on the mass of the tire 2 can be reduced. With this tire 2, the effect of reducing the weight of the sidewall 6 can be maintained. In this tire 2, low rolling resistance is realized.

The thickness T1 of the first reinforcing layer 20 is preferably 0.5 mm or more. By setting the thickness T1 to 0.5 mm or more, the first reinforcing layer 20 effectively contributes to the improvement of the traumatic resistance of the tire 2. This tire 2 has excellent trauma resistance. From this viewpoint, the thickness T1 is more preferably 0.8 mm or more. The thickness T1 is preferably 1.5 mm or less. By setting the thickness T1 to 1.5 mm or less, the influence of the first reinforcing layer 20 on the tire 2 mass can be effectively suppressed. In this tire 2, low rolling resistance is realized. From this viewpoint, the thickness T1 is more preferably 1.3 mm or less.

When the tire rides on the curb, the bead part of the tire is also sandwiched between the curb and the rim. A big impact is also applied to the bead part. This can cause trauma to the tire. As described above, the tire 2 preferably further includes a second reinforcing layer 22 located inside the bead 10 in the axial direction. The puncture energy of the second reinforcing layer 22 is 70 J or more. The second reinforcing layer 22 is excellent in absorbing impact energy. When the portion of the bead 10 is sandwiched between the curb and the rim, the second reinforcing layer 22 effectively absorbs the impact applied to the portion of the bead 10. When the portion of the bead 10 is sandwiched between the curb and the rim, the second reinforcing layer 22 reduces the deformation of the side portion with respect to the applied load. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance.

From the viewpoint of further improving the traumatic resistance of the tire 2, the puncture energy of the second reinforcing layer 22 is preferably 80 J or more, and more preferably 90 J or more.

The second reinforcing layer 22, which is excellent in absorbing impact energy, can suppress trauma even if its thickness is reduced. The influence of the second reinforcing layer 22 on the mass of the tire 2 can be reduced. With this tire 2, the effect of reducing the weight of the sidewall 6 can be maintained. In this tire 2, low rolling resistance is realized.

The thickness T2 of the second reinforcing layer 22 is preferably 0.5 mm or more. By setting the thickness T2 to 0.5 mm or more, the second reinforcing layer 22 effectively contributes to the improvement of the traumatic resistance of the tire 2. This tire 2 has excellent trauma resistance. From this viewpoint, the thickness T2 is more preferably 0.8 mm or more. The thickness T2 is preferably 1.5 mm or less. By setting the thickness T2 to 1.5 mm or less, the influence of the second reinforcing layer 22 on the tire 2 mass can be effectively suppressed. In this tire 2, low rolling resistance is realized. From this viewpoint, the thickness T2 is more preferably 1.3 mm or less.

In FIG. 1, the solid line BBL is a bead baseline. The bead baseline BBL is a line that defines the rim diameter of the rim R (see JATTA). This bead baseline BBL extends axially. The double-headed arrow L1 is the length of the first reinforcing layer 20 measured along the inner surface of the first reinforcing layer 20. The point C1 is the midpoint of the first reinforcing layer 20. That is, the length from the point C1 to the end of the first reinforcing layer 20 measured along the inner surface of the first reinforcing layer 20 is L1 / 2. The double-headed arrow H1 is the radial height from the bead baseline BBL to the point C1. The double-headed arrow SH is the radial height from the bead baseline BBL to the radial outer edge of the carcass 12.

The ratio of the height H1 to the height SH (H1 / SH) is preferably 0.8 or more and 0.9 or less. By setting the ratio (H1 / SH) to 0.8 or more and 0.9 or less, the first reinforcing layer 20 effectively alleviates the impact applied to the buttress portion. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance.

The ratio (L1 / SH) of the length L1 to the height SH is preferably 0.23 or more. By setting the ratio (L1 / SH) to 0.23 or more, the first reinforcing layer 20 effectively contributes to the improvement of the traumatic resistance of the tire 2. This tire 2 has excellent trauma resistance. From this point of view, the ratio (L1 / SH) is more preferably 0.32 or more. The ratio (L1 / SH) is preferably 0.50 or less. By setting the ratio (L1 / SH) to 0.50 or less, the influence of the first reinforcing layer 20 on the tire 2 mass is effectively suppressed. In this tire 2, low rolling resistance is realized. From this viewpoint, the ratio (L1 / SH) is more preferably 0.40 or less.

In FIG. 1, the double-headed arrow L2 is the length of the second reinforcing layer 22 measured along the inner surface of the second reinforcing layer 22. The point C2 is the midpoint of the second reinforcing layer 22. That is, the length from the point C2 to the end of the second reinforcing layer 22 measured along the inner surface of the second reinforcing layer 22 is L2 / 2. The double-headed arrow H2 is the radial height from the bead baseline BBL to the point C2. The point PT is a point on the inner side surface in the axial direction of the portion of the bead 10. At the position of the point PT, the thickness of the portion of the bead 10 is maximized. Here, the thickness of the portion of the bead 10 is the distance between the inner surface and the outer surface of the portion of the bead 10 measured along a normal line drawn from a point on the inner surface. In the embodiment of FIG. 1, the position of the point C2 and the position of the point PT are the same. The double-headed arrow TH is the radial height from the bead baseline BBL to the point PT. In the embodiment of FIG. 1, the height H2 and the height TH are the same.

The ratio of the height H2 to the height TH (H2 / TH) is preferably 0.9 or more and 1.1 or less. By setting the ratio (H2 / TH) to 0.9 or more and 1.1 or less, the second reinforcing layer 22 effectively alleviates the impact applied to the portion of the bead 10. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. In the embodiment of FIG. 1, since the position of the point C2 and the position of the point PT are the same, the ratio (H2 / TH) is 1.0.

The ratio (L2 / SH) of the length L2 to the height SH is preferably 0.23 or more. By setting the ratio (L2 / SH) to 0.23 or more, the second reinforcing layer 22 effectively contributes to the improvement of the traumatic resistance of the tire 2. This tire 2 has excellent trauma resistance. From this point of view, the ratio (L2 / SH) is more preferably 0.32 or more. The ratio (L2 / SH) is preferably 0.50 or less. By setting the ratio (L2 / SH) to 0.50 or less, the influence of the second reinforcing layer 22 on the tire 2 mass is effectively suppressed. In this tire 2, low rolling resistance is realized. From this viewpoint, the ratio (L2 / SH) is more preferably 0.40 or less.

As shown in the above-described embodiment, the first reinforcing layer 20 is preferably sandwiched between the carcass 12 and the inner liner 18. By sandwiching the first reinforcing layer 20 between the carcass 12 and the inner liner 18, it is possible to prevent the position of the first reinforcing layer 20 from shifting when the tire 2 rolls or when the tire 2 rides on the curb. There is. The first reinforcing layer 20 effectively cushions the impact applied to the buttress portion. This tire 2 has excellent trauma resistance.

As shown in the above-described embodiment, the second reinforcing layer 22 is preferably sandwiched between the carcass 12 and the inner liner 18. By sandwiching the second reinforcing layer 22 between the carcass 12 and the inner liner 18, the position of the second reinforcing layer 22 is suppressed from being displaced when the tire 2 rolls or when the tire 2 rides on the curb. There is. The second reinforcing layer 22 effectively cushions the impact applied to the portion of the bead 10. This tire 2 has excellent trauma resistance.

The loss tangent of the first reinforcing layer 20 is preferably 0.08 or less. When the tire 2 rolls, the first reinforcing layer 20 repeatedly deforms and restores. In the first reinforcing layer 20 having a loss tangent of 0.08 or less, heat generation due to this deformation and restoration is small. The influence of the heat generated by the first reinforcing layer 20 on the rolling resistance is suppressed. In this tire 2, low rolling resistance is realized. The lower limit of the loss tangent of the first reinforcing layer 20 is not specified.

The loss tangent of the second reinforcing layer 22 is preferably 0.08 or less. When the tire 2 rolls, the second reinforcing layer 22 repeatedly deforms and restores. In the second reinforcing layer 22 having a loss tangent of 0.08 or less, heat generation due to this deformation and restoration is small. The influence of the heat generated by the second reinforcing layer 22 on the rolling resistance is suppressed. In this tire 2, low rolling resistance is realized. The lower limit of the loss tangent of the second reinforcing layer 22 is not specified.

The complex elastic modulus of the first reinforcing layer 20 is preferably 10 MPa or more. The first reinforcing layer 20 having a complex elastic modulus of 10 MPa or more effectively reduces the deformation of the side portion when the tire 2 rides on the curb. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. From this viewpoint, the complex elastic modulus of the first reinforcing layer 20 is more preferably 20 MPa or more. The complex elastic modulus of the first reinforcing layer 20 is preferably 60 MPa or less. In the first reinforcing layer 20 having a complex elastic modulus of 60 MPa or less, the influence on the rigidity of the side portion is suppressed. The rigidity of this side portion is properly maintained. This tire 2 maintains a good ride comfort. From this viewpoint, the complex elastic modulus of the first reinforcing layer 20 is more preferably 50 MPa or less.

The complex elastic modulus of the second reinforcing layer 22 is preferably 10 MPa or more. The second reinforcing layer 22 having a complex elastic modulus of 10 MPa or more effectively reduces the deformation of the side portion when the tire 2 rides on the curb. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. From this viewpoint, the complex elastic modulus of the second reinforcing layer 22 is more preferably 20 MPa or more. The complex elastic modulus of the second reinforcing layer 22 is preferably 60 MPa or less. In the second reinforcing layer 22 having a complex elastic modulus of 60 MPa or less, the influence on the rigidity of the side portion is suppressed. The rigidity of this side portion is properly maintained. This tire 2 maintains a good ride comfort. From this viewpoint, the complex elastic modulus of the second reinforcing layer 22 is more preferably 50 MPa or less.

In the present invention, the loss tangent and the complex elastic modulus of the first reinforcing layer 20 and the second reinforcing layer 22 are determined by a viscoelastic spectrometer (Iwamoto Seisakusho Co., Ltd.) under the following measurement conditions in accordance with the provisions of "JIS K 6394". It is measured using the trade name "VESF-3") manufactured by Japan. In this measurement, a plate-shaped test piece (length = 45 mm, width = 4 mm, thickness = 2 mm) is formed from the materials of the first reinforcing layer 20 and the second reinforcing layer 22. This test piece is used for measurement.
Initial distortion: 10%
Amplitude: ± 2.0%
Frequency: 10Hz
Deformation mode: Tensile
Measurement temperature: 70 ° C

The hardness of the first reinforcing layer 20 is preferably 70 or more. The first reinforcing layer 20 having a hardness of 70 or more effectively reduces the deformation of the side portion when the tire 2 rides on the curb. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. From this viewpoint, the hardness of the first reinforcing layer 20 is more preferably 80 or more. The hardness of the first reinforcing layer 20 is preferably 110 or less. In the first reinforcing layer 20 having a hardness of 110 or less, the influence on the rigidity of the side portion is suppressed. The rigidity of this side portion is properly maintained. This tire 2 maintains a good ride comfort. From this viewpoint, the hardness of the first reinforcing layer 20 is more preferably 100 or less.

The hardness of the second reinforcing layer 22 is preferably 70 or more. The second reinforcing layer 22 having a hardness of 70 or more effectively reduces the deformation of the side portion when the tire 2 rides on the curb. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. From this viewpoint, the hardness of the second reinforcing layer 22 is more preferably 80 or more. The hardness of the second reinforcing layer 22 is preferably 110 or less. In the second reinforcing layer 22 having a hardness of 110 or less, the influence on the rigidity of the side portion is suppressed. The rigidity of this side portion is properly maintained. This tire 2 maintains a good ride comfort. From this viewpoint, the hardness of the second reinforcing layer 22 is more preferably 100 or less.

In the present invention, the hardness of the first reinforcing layer 20 and the second reinforcing layer 22 is measured by a type A durometer according to the provisions of "JIS K6253". This durometer is pressed against a test piece made of the materials of the first reinforcing layer 20 and the second reinforcing layer 22, and the hardness is measured. The measurement is made at a temperature of 23 ° C.

The breaking strength (tensile stress at break) of the first reinforcing layer 20 is preferably 30 MPa or more. The first reinforcing layer 20 having a breaking strength of 30 MPa or more effectively reduces the deformation of the side portion when the tire 2 rides on the curb. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. From this viewpoint, the breaking strength of the first reinforcing layer 20 is more preferably 40 MPa or more. The upper limit of the breaking strength of the first reinforcing layer 20 is not specified. The elongation rate of the first reinforcing layer 20 at the time of breaking is preferably 300% or more and 550% or less.

The breaking strength (tensile stress at breaking) of the second reinforcing layer 22 is preferably 30 MPa or more. The second reinforcing layer 22 having a breaking strength of 30 MPa or more effectively reduces the deformation of the side portion when the tire 2 rides on the curb. This tire 2 is less likely to cause trauma. This tire 2 has excellent trauma resistance. From this viewpoint, the breaking strength of the second reinforcing layer 22 is more preferably 40 MPa or more. The upper limit of the breaking strength of the second reinforcing layer 22 is not specified. Further, the elongation rate of the second reinforcing layer 22 at the time of breaking is preferably 300% or more and 550% or less.

In the present invention, the breaking strength of the first reinforcing layer 20 and the second reinforcing layer 22 is measured based on JIS K 6251.

As described in the above-described embodiment, urethane is preferable as the material of the first reinforcing layer 20. By using urethane as the material of the first reinforcing layer 20, the first reinforcing layer 20 satisfying the preferable ranges of puncture energy, loss tangent, complex elastic modulus, hardness, breaking strength and elongation at break can be formed. From this point of view, urethane rubber is more preferable as the material of the first reinforcing layer 20. Urethane rubber can be classified into a casting type that uses a liquid raw material, a miraculous type that uses the same processing method as general rubber, and a thermoplastic type that uses the same processing method as a thermoplastic resin, depending on the molding method. As the material of the first reinforcing layer 20, a miraculous type urethane rubber is more preferable. Casting type or thermoplastic type urethane rubber may be used.

As described in the above-described embodiment, urethane is preferable as the material of the second reinforcing layer 22. By using urethane as the material of the second reinforcing layer 22, the second reinforcing layer 22 can be formed which satisfies the preferable ranges of puncture energy, loss tangent, complex elastic modulus, hardness, breaking strength and elongation at break. From this point of view, urethane rubber is more preferable as the material of the first reinforcing layer 20. Urethane rubber can be classified into a casting type that uses a liquid raw material, a miraculous type that uses the same processing method as general rubber, and a thermoplastic type that uses the same processing method as a thermoplastic resin, depending on the molding method. As the material of the first reinforcing layer 20, a miraculous type urethane rubber is more preferable. Casting type or thermoplastic type urethane rubber may be used.

As described above, the first reinforcing layer 20 and the second reinforcing layer 22 provide the tire 2 with both good traumatic resistance and low rolling resistance. In addition to this, by appropriately adjusting the contour near the buttress portion and the structure of the belt 14, further reduction in rolling resistance can be realized. By combining the first reinforcing layer 20 and the second reinforcing layer 22 with the contour near the buttress portion and the optimization of the structure of the belt 14, even better traumatic resistance and low rolling resistance can be realized. In the following, the contour around the buttress portion and the optimization of the structure of the belt 14 will be described.

In the present invention, the contour of the outer surface is referred to as a profile. This profile is determined based on the dimensions measured with the tire 2 incorporated into the regular rim and the tire 2 filled with air to give it a regular internal pressure. If the tread surface 24 forming a part of the outer surface has a groove 26, the profile is expressed using the virtual tread surface 24 obtained on the assumption that the groove 26 does not exist. If the sidewall 6 is provided with grooves or protrusions, this profile is represented using the virtual outer surface of the sidewall 6 obtained assuming that there are no grooves or protrusions. In FIG. 1, the profile of the tire 2 is represented by a solid line OL.

FIG. 2 shows a part of the tire 2 shown in FIG. In FIG. 2, the profile of the tire 2 is represented by a solid line OL. This profile OL includes a ground plane 34 and a side surface 36 extending substantially inward in the radial direction from the ground plane 34. In FIG. 2, the point PB represents the boundary between the ground plane 34 and the side surface 36. This point PB is represented by the outermost end in the axial direction of the portion where the tire 2 is in contact with the road surface when a normal load is applied to the tire 2 under the normal internal pressure. In the present invention, the zone from the left point PB (not shown) to the right point PB in the profile OL is the ground plane 34.

The tire 2 has a maximum width between the left and right side surfaces 36 in the axial direction. In other words, the maximum value of the distance between the side surfaces 36 in the axial direction is the maximum width of the tire 2. In FIG. 2, a point on the side surface 36 showing the maximum width is represented by a point PW. The solid line LB is a virtual straight line extending in the axial direction through this point PW. In the present invention, this solid line LB is referred to as a reference line.

In the figure, what is indicated by the symbol PE is the intersection of the ground plane 34 and the equatorial plane. In the present invention, this intersection PE is referred to as the equator. The solid line LE represents a virtual straight line extending in the axial direction through the equator PE. The outer diameter of the tire 2 is defined by the solid line LE.

In FIG. 2, the double-headed arrow HA represents the radial length from the reference line LB to the solid line LE. This length HA is the radial length from the reference line LB to the equatorial PE. In the present invention, this length HA is referred to as a reference length.

In FIG. 2, the point P1 is a point on the side surface 36 located radially outside the point PW. The double-headed arrow S1 represents the radial length from the reference line LB to this point P1. In this tire 2, the length S1 is 1/3 of the reference length HA. The point P1 is located on the side surface 36 which is located radially outside the point PW and whose radial length from the reference line LB corresponds to 1/3 of the reference length HA.

The point P2 is a point on the side surface 36 located radially outside the point P1. The double-headed arrow S2 represents the radial length from the point P1 to this point P2. In this tire 2, the length S2 is 1/3 of the reference length HA. The point P2 is located on the side surface 36 which is located radially outside the point P1 and whose radial length from the point P1 corresponds to 1/3 of the reference length HA.

The point P3 is a point on the side surface 36 located at an intermediate position between the points P2 and P1 in the radial direction. The point P4 is a point on the side surface 36 located at an intermediate position between the point P2 and the point PB in the radial direction.

In this embodiment, among the side surfaces 36 forming the profile OL of the outer surface, the zone from the point PB to the point PW is formed by three main arcs. These main arcs consist of a first main arc, a second main arc, and a third main arc.

The first main arc extends substantially outward in the radial direction from the point PW. The first main arc passes through the points PW and P1. In FIG. 2, what is indicated by the arrow RM1 is the radius of curvature of the first main arc.

The second main arc extends substantially outward in the radial direction from the first main arc. The second main arc passes through the points P1, P3 and P2. In FIG. 2, what is indicated by the arrow RM2 is the radius of curvature of the second main arc. Although not shown, in this tire 2, the center of the second main arc exists on a straight line passing through the point P1 and the center of the first main arc. In other words, the second main arc is in contact with the first main arc at point P1. The point P1 is a contact point between the first main arc and the second main arc. The point P1 is also the boundary between the first main arc and the second main arc.

The third main arc extends substantially outward in the radial direction from the second main arc. The third main arc passes through points P2, P4 and PB. In FIG. 2, what is indicated by the arrow RM3 is the radius of curvature of the third main arc. Although not shown, in this tire 2, the center of the third main arc exists on a straight line passing through the point P2 and the center of the second main arc. In other words, the third main arc is in contact with the second main arc at point P2. The point P2 is a contact point between the second main arc and the third main arc. The point P2 is also the boundary between the second main arc and the third main arc.

In conventional tires, the ground plane and the first arc are connected by a straight line in order to improve design efficiency. Therefore, in the conventional tire, when a load is applied, the strain tends to be concentrated on the boundary between the first arc and the straight line. Due to the peculiar deflection of conventional tires, the deflection of the sidewalls cannot sufficiently absorb the energy generated by the deformation. Therefore, in order to reduce the rolling resistance, for example, even if the mass is reduced, the expected effect cannot be obtained. Moreover, repeated bending in this straight portion may accelerate the increase in rolling resistance.

On the other hand, in this embodiment, a third arc and a second arc exist between the ground plane 34 and the first arc. In the tire 2, the ground contact surface 34 is connected to the first arc via a third arc and a second arc.

The second arc in contact with the first arc contributes to properly maintaining the distance from the carcass 12 to the profile OL. That is, in this tire 2, the carcass 12 gradually approaches the profile OL without suddenly approaching the profile OL, unlike the conventional tire in which the contact patch 34 and the first arc are connected by a straight line. In the tire 2, there is no portion having peculiar rigidity in the zone from the point PB to the point P1, in other words, the buttress region of the tire 2. This second arc can effectively contribute to the separation of the movement of the tread 4 portion of the tire 2 and the movement of the sidewall 6 portion thereof. The tire 2 flexes properly when a load is applied. In the tire 2, the influence of repeated bending in this region on rolling resistance is effectively suppressed. In this tire 2, the energy generated by the deformation is sufficiently absorbed by the deflection of the sidewall 6. With this tire 2, rolling resistance is reduced. The rolling resistance of the tire 2 is smaller than the rolling resistance of the conventional tire. Moreover, proper deflection also contributes to steering stability.

In this embodiment, the third arc in contact with the ground contact surface 34 contributes to equalizing the ground contact pressure on the shoulder of the tire 2. The uniform contact pressure suppresses shoulder drop wear on the shoulder. The tire 2 has excellent wear resistance.

In this embodiment, reduction of rolling resistance is achieved by optimizing the profile OL. Therefore, from the viewpoint of reducing rolling resistance, it is not necessary to reduce the volume of the tread 4, sidewall 6, belt 14, and the like. Since it is possible to have a belt 14 having appropriate specifications, steering stability and wear resistance are appropriately maintained. With this tire 2, a reduction in rolling resistance is achieved without impairing steering stability and wear resistance.

In this embodiment, the ratio of the radius of curvature R2 of the second arc to the radius of curvature R1 of the first arc is 1.45 or more and 3.26 or less. By setting this ratio to 1.45 or more, the deflection of the sidewall 6 is appropriately controlled. In the tire 2, the movement of the tread 4 portion and the movement of the sidewall 6 portion are effectively separated. This profile OL can effectively function in reducing rolling resistance. By setting this ratio to 3.26 or less, the tire 2 in which the distance from the carcass 12 to the profile OL in the zone from the point PB to the point P1 is appropriate can be obtained. In this tire 2, the influence on the rolling resistance due to the increase in mass based on the profile OL is suppressed. Even in this case, this profile OL can effectively function in reducing rolling resistance. Moreover, since the bending of the tire 2 in which this ratio is set to 1.45 or more and 3.26 or less is appropriate, good steering stability is also achieved.

In this embodiment, the ratio of the radius of curvature R3 of the third arc to the radius of curvature R1 of the first arc is 0.45 or more and 0.58 or less. In this tire 2, the shoulders come into contact with the road surface with a uniform contact pressure. Moreover, as described above, it is possible to have the belt 14 having appropriate specifications. This profile OL can contribute to the prevention of uneven wear such as shoulder drop wear. From this viewpoint, this ratio is preferably 0.46 or more, and preferably 0.56 or less.

From the viewpoint that the reduction of rolling resistance is achieved without considering the influence on the mass, the radius of curvature RM2 of the second arc is particularly high when the size of the tire 2 is represented by 195 / 65R15. It is preferably 80 mm or more and 180 mm or less. The radius of curvature RM3 of the third arc is preferably 25 mm or more and 31 mm or less.

In FIG. 2, the double-headed arrow BW / 2 represents half the axial width of the outer layer 14b. Therefore, the axial width of the outer layer 14b is represented by BW.

In this embodiment, when the nominal width is expressed by RW, the ratio of the axial width BW to the nominal width RW is preferably 0.66 or more and 0.77 or less. By setting this ratio to 0.66 or more, the axial width of the belt 14 is sufficiently secured. The belt 14 can contribute to steering stability and wear resistance. By setting this ratio to 0.77 or less, the axial width of the belt 14 is appropriately maintained. In the tire 2, the generation of cracks caused by the end of the belt 14 is effectively prevented. This tire 2 has excellent durability. Moreover, in this tire 2, the influence of the belt 14 on the mass is effectively suppressed.

In the present invention, the nominal width represented by the size of the tire 2 is referred to as the nominal width RW. For example, when the size of the tire 2 is represented by 195 / 65R15, "195" is the nominal width RW of the tire 2.

The ratio of the radius of curvature R3 of the third arc to the axial width BW is preferably 0.18 or more and 0.23 or less. By setting this ratio to 0.18 or more, the generation of cracks caused by the end of the belt 14 is effectively prevented. This tire 2 has excellent durability. From this point of view, this ratio is preferably 0.19 or more. By setting this ratio to 0.23 or less, the distance from the profile OL having the third arc having the radius of curvature R3 to the end of the belt 14 is appropriately maintained. In this tire 2, the influence of the profile OL on the mass of the tire 2 is effectively suppressed. Moreover, since the belt 14 is arranged at an appropriate position, the belt 14 can effectively contribute to steering stability and wear resistance. From this point of view, this ratio is preferably 0.22 or less.

As mentioned above, the belt 14 contains a large number of cords arranged in parallel. In this embodiment, the cord comprises a structure in which two strands of steel are twisted together. In this embodiment, the wire diameter of the wire is made smaller than that of a conventional tire. This strand is thinned. As a result, the weight of the tire 2 is further reduced.

The wire diameter of the wire of the belt 14 is preferably 0.27 mm or less. By setting the wire diameter of the strands to 0.27 mm or less, the influence of the belt 14 on the mass of the tire 2 is effectively suppressed. Further, by setting the wire diameter of the strands to 0.27 mm or less, the out-of-plane rigidity of the belt 14 can be appropriately suppressed. This reduces the distortion of the rubber on the tread 4. This contributes to further reduction of rolling resistance. This suppresses the occurrence of looseness at the end of the belt 14. This tire 2 has excellent durability. The wire diameter of the strand is preferably 0.23 mm or more. By setting the wire diameter of the wire to 0.23 mm or more, the tire 2 has sufficient strength. This tire 2 has excellent durability. From these viewpoints, the wire diameter of the strand is more preferably 0.25 mm.

The density of the cords of the belt 14 is obtained by measuring the number of cords (ends) existing per 50 mm width of the inner layer 14a or the outer layer 14b in the cross section perpendicular to the extending direction of the cords. In this embodiment, the cord densities of the inner layer 14a or the outer layer 14b are the same. In this embodiment, the cord density of the belt 14 is properly adjusted. As a result, the strength of the tire 2 is maintained while the weight of the tire 2 is reduced by thinning the wire.

The density of the cord of the belt 14 is preferably 53 ends / 50 mm or less. By setting the density of the cord to 53 ends / 50 mm or less, the influence of the belt 14 on the mass of the tire 2 is effectively suppressed. Further, by setting the cord density to 53 ends / 50 mm or less, the out-of-plane rigidity of the belt 14 can be appropriately suppressed. This reduces the distortion of the rubber on the tread 4. This contributes to further reduction of rolling resistance. This suppresses the occurrence of looseness at the end of the belt 14. The density of the cord of the belt 14 is preferably 47 ends / 50 mm or more. By setting the cord density to 47 ends / 50 mm or more, the tire 2 has sufficient strength. This tire 2 has excellent durability. From these viewpoints, the density of the cord is more preferably 50 ends / 50 mm.

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

[Example 1]
A pneumatic tire of Example 1 having the configuration shown in FIG. 1 was obtained. The size of the tire was 195 / 65R15. The material of the first reinforcing layer and the second reinforcing layer of this tire is urethane. The characteristics of this urethane are shown in Table 1. For comparison, the characteristics of the base layer, apex and sidewalls of this tire are also shown in the table. Furthermore, examples of the characteristics of the rubber reinforcing layer of the conventional tire are also shown. The properties of these rubbers are measured in the same manner as the properties of the first reinforcing layer and the second reinforcing layer described above.

Table 2 shows the thickness and length of the first reinforcing layer and the second reinforcing layer of Example 1. In this tire, the height SH is 125 mm. For this tire, the ratio (H1 / SH) is 0.85. The ratio (H2 / TH) is 1.0.

In the first embodiment, the radius of curvature R1 of the first arc is 55 mm. The radius of curvature R2 of the second arc was set to 130 mm. The radius of curvature R3 of the third arc was set to 28 mm. The axial width BW of the outer layer 14b forming a part of the belt 14 was set to 140 mm. The cord of the belt 14 of this tire has a structure in which two strands made of teal are twisted together. The wire diameter of this strand was 0.25 mm. The cord density was 50 ends / 50 mm.

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

[Comparative Example 2]
The tires of Comparative Example 2 were obtained in the same manner as in Example 1 except that the materials of the first reinforcing layer and the second reinforcing layer were the conventional rubber shown in Table 1.

[Example 2-7]
The tires of Example 2-7 were obtained in the same manner as in Example 1 except that the thickness T1 and the thickness T2 were as shown in Table 3.

[Example 8-12]
The tires of Example 8-12 were obtained in the same manner as in Example 1 except that the lengths L1 and L2 were changed so that the ratio (L1 / SH) and the ratio (L2 / SH) were as shown in Table 4.

[Tire mass]
The mass of the tire was measured. This result is shown in Table 2-4 below as an index value with Comparative Example 1 as 100. The smaller the number, the smaller the mass. The smaller the number, the more preferable.

[Rolling resistance]
The rolling resistance was measured under the following measurement conditions using a rolling resistance tester.
Rim used: 6.0JJ
Internal pressure: 230 kPa
Load: 4.24kN
Speed: 80km / h
This result is shown in Table 2-4 below as an index value with Comparative Example 1 as 100. The smaller the value, the more preferable.

[Injury resistance]
The tire was assembled into a 6.0 JJ rim and the tire was filled with air so that the internal pressure was 230 kPa. This tire was mounted on the testing machine. A load was applied to this tire, the buttress region of this tire and the region of the bead portion were sandwiched, and the load-strain curve at that time was measured. This measurement ended when the cord contained in the carcass broke. Based on the obtained curve, the integrated value of the load per unit strain (tire breaking energy) was calculated. This result is shown in Tables 2 to 4 below as an index with Comparative Example 1 as 100. The larger the value, the better the trauma resistance. That is, the larger the value, the more preferable.

As shown in Tables 2 to 4, the tires of the examples have higher evaluations than the tires of the comparative examples. From this evaluation result, the superiority of the present invention is clear.

The tires described above can also be applied to various vehicles.

2 ... Tire 4 ... Tread 6 ... Sidewall 8 ... Clinch 10 ... Bead 12 ... Carcass 14 ... Belt 14a ... Inner layer 14b ... Outer layer 16 ...・ ・ Band 18 ・ ・ ・ Inner liner 20 ・ ・ ・ First reinforcement layer 22 ・ ・ ・ Second reinforcement layer 24 ・ ・ ・ Tread surface 26 ・ ・ ・ Groove 28 ・ ・ ・ Core 30 ・ ・ ・ Apex 32 ・ ・・ Carcass ply 32a ・ ・ ・ Main part 32b ・ ・ ・ Folded part 34 ・ ・ ・ Ground plane 36 ・ ・ ・ Side

Claims (18)

A pair of sidewalls, a pair of beads each located radially inside the sidewall, a carcass bridged between the two beads, and a pair of inner liners located inside the carcass. Equipped with a first reinforcing layer,
Each first reinforcing layer is located on the inner side of the sidewall in the axial direction near the buttress portion of the tire.
Puncture energy of the first reinforcing layer state, and are more 70 J,
The material of the first reinforcement layer is a pneumatic tire Ru urethane der. The pneumatic tire according to claim 1, wherein the first reinforcing layer is sandwiched between the carcass and the inner liner. The ratio ( H 1 / SH) of the height H 1 from the bead baseline to the midpoint of the first reinforcing layer to the height SH from the bead baseline to the radial outer edge of the carcass is 0.8 or more. The pneumatic tire according to claim 1 or 2 , which is 0.9 or less. The ratio (L1 / SH) of the length L1 of the first reinforcing layer measured along the inner surface 36 of the first reinforcing layer to the height SH from the bead baseline to the radial outer end of the carcass is determined. The pneumatic tire according to any one of claims 1 to 3 , which is 0.23 or more and 0.50 or less. The pneumatic tire according to any one of claims 1 to 4 , wherein the thickness T1 of the first reinforcing layer is 0.5 mm or more and 1.5 mm or less. It also has a pair of second reinforcement layers,
Each second reinforcing layer is located inside the bead in the axial direction.
Puncture energy of the second reinforcing layer state, and are more 70 J,
A pneumatic tire in any of 5 the material of the SL second reinforcing layer from claim 1 Ru urethane der. The pneumatic tire according to claim 6 , wherein the second reinforcing layer is sandwiched between the carcass and the inner liner. When it is located on the axial inner surface 36 of the bead portion and the point where the thickness of the bead portion is maximized at this position is PT.
The ratio (H2 / TH) of the height H2 from the bead baseline to the midpoint of the second reinforcing layer to the height TH from the bead baseline to the point PT is 0.9 or more and 1.1 or less. The pneumatic tire according to claim 6 or 7 . The ratio (L2 / SH) of the length L2 of the second reinforcing layer measured along the inner surface 36 of the second reinforcing layer to the height SH from the bead baseline to the radial outer end of the carcass is determined. The pneumatic tire according to any one of claims 6 to 8 , which is 0.23 or more and 0.50 or less. The pneumatic tire according to any one of claims 6 to 9 , wherein the thickness T2 of the second reinforcing layer is 0.5 mm or more and 1.5 mm or less. The pneumatic tire according to any one of claims 6 to 10, wherein the loss tangent of the second reinforcing layer is 0.08 or less. The pneumatic tire according to any one of claims 6 to 11, wherein the complex elastic modulus of the second reinforcing layer is 10 MPa or more and 60 MPa or less. The pneumatic tire according to any one of claims 6 to 12, wherein the hardness of the second reinforcing layer is 70 or more and 110 or less. The pneumatic tire according to any one of claims 6 to 13, wherein the breaking strength of the second reinforcing layer is 30 MPa or more. The pneumatic tire according to any one of claims 1 to 14, wherein the loss tangent of the first reinforcing layer is 0.08 or less. The pneumatic tire according to any one of claims 1 to 15, wherein the complex elastic modulus of the first reinforcing layer is 10 MPa or more and 60 MPa or less. The pneumatic tire according to any one of claims 1 to 16, wherein the hardness of the first reinforcing layer is 70 or more and 110 or less. The pneumatic tire according to any one of claims 1 to 17, wherein the breaking strength of the first reinforcing layer is 30 MPa or more.

Images