pneumatic tires

Abstract

We provide pneumatic tires that achieve both fuel efficiency and ride comfort. [Solution] The present invention relates to a pneumatic tire having a profile that includes a contact surface and a first side outer surface. The tread portion has a first shoulder circumferential groove and a first shoulder land portion separated by the first shoulder circumferential groove and the first contact end Te1. The contact surface has a first imaginary line L1 that has a first angle θ1 of 74 to 80° with respect to the tire radial direction. The first side outer surface has a second imaginary line L2 that has a second angle θ2 of 36 to 40° with respect to the tire radial direction. The rubber hardness Gc (degrees) of the tread rubber 3G constituting the contact surface, the rubber hardness Gs (degrees) of the sidewall rubber 6G constituting the first side outer surface, the distance t (mm) in the tire radial direction between the first contact end Te1 and the tire equator C, and the contact width TW (mm) satisfy Equation 1. TIFF2026114787000006.tif24167

Description

Technical Field

[0001] The present invention relates to pneumatic tires.

Background Art

[0002] Conventionally, various pneumatic tires having specific profiles have been proposed. For example, Patent Document 1 below proposes a pneumatic tire that can achieve both noise performance and low fuel consumption performance by including a profile in which the distance from the maximum width position of the tire to the outer end position has a single radius of curvature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the resistance related to low fuel consumption performance includes, in addition to the rolling resistance improved by the pneumatic tire of Patent Document 1, the air resistance during running. Further improvement has been expected for the air resistance during running even in the pneumatic tire of Patent Document 1. In addition, there has also been a demand for improvement in ride comfort performance, although the profile for improving rolling resistance tends to deteriorate ride comfort performance.

[0005] The present invention has been devised in view of the above actual situation, and the main object thereof is to provide a pneumatic tire that can achieve both low fuel consumption performance and ride comfort performance.

Means for Solving the Problems

[0006] The present invention relates to a pneumatic tire having a profile defined on the outer surface of the tire meridian cross section in a normal state, which is an unloaded state in which the tire is mounted on a normal rim and adjusted to a normal internal pressure, wherein the profile includes a contact surface of a tread portion extending from a first contact end to a second contact end, and a first side outer surface of a sidewall portion extending inward in the tire radial direction from the first contact end, wherein a first position is defined on the first side outer surface at a distance of 15% of the tire cross section height inward in the tire radial direction from the tire equator of the contact surface, the tread portion has a first shoulder circumferential groove extending furthest towards the first contact end in the tire circumferential direction between the tire equator and the first contact end, and a first shoulder land portion separated by the first shoulder circumferential groove and the first contact end, wherein the contact surface has a first imaginary line which is a tangent at an intermediate position in the tire axial direction of the first shoulder land portion, which is the tire axis The first imaginary line is inclined inward in the tire radial direction toward the outward direction, and has a first angle of 74-80° with respect to the tire radial direction. The first outer side surface has a second imaginary line, which is tangent at the first position, inclined in the same direction as the first imaginary line with respect to the tire radial direction, and has a second angle of 36-40° with respect to the tire radial direction. The contact surface has a contact width TW (mm), which is the distance in the tire axial direction between the first contact end and the second contact end. The tread portion includes tread rubber constituting the contact surface, and the sidewall portion includes sidewall rubber constituting the first outer side surface. The rubber hardness Gc (degrees) of the tread rubber, the rubber hardness Gs (degrees) of the sidewall rubber, the distance t (mm) in the tire radial direction between the first contact end and the tire equator, and the contact width TW (mm) satisfy the following formula 1.

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[0007] The pneumatic tire of the present invention, by having the above-described configuration, can achieve both low fuel consumption and comfortable ride performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing one embodiment of the pneumatic tire of the present invention. [Figure 2] This is an enlarged view of section A of the profile in Figure 1. [Figure 3] This is a schematic diagram of the belt layer's development. [Figure 4] This is a schematic diagram of a mold for forming pneumatic tires. [Modes for carrying out the invention]

[0009] One embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1 is a meridian cross-sectional view of the pneumatic tire 1 in its normal state according to this embodiment. Here, "normal state" refers to the unloaded state in which the pneumatic tire 1 is mounted on a normal rim R and adjusted to the normal internal pressure. Unless otherwise specified, the dimensions of each part of the pneumatic tire 1 are values ​​measured in this normal state.

[0010] "Regular Rim R" refers to the rim specified for each tire by a standard system that includes the standard on which the pneumatic tire 1 is based. For example, it is a "Standard Rim" for JATMA, a "Design Rim" for TRA, and a "Measuring Rim" for ETRTO. If there is no standard system that includes the standard on which the pneumatic tire 1 is based, "Regular Rim R" refers to the rim with the smallest rim diameter and the smallest rim width among rims that can be mounted on and do not cause air leaks.

[0011] "Regular internal pressure" refers to the air pressure specified for each tire by each standard, if there is a standard system on which the pneumatic tire 1 is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "INFLATION PRESSURE" for ETRTO. If there is no standard system on which the pneumatic tire 1 is based, "regular internal pressure" refers to the air pressure specified for each tire by the manufacturer, etc.

[0012] As shown in Figure 1, the pneumatic tire 1 is suitably used, for example, as a passenger car tire. The pneumatic tire 1 of this embodiment has a profile 2 defined by the outer surface in the tire meridian cross-section in a normal state. The profile 2 of this embodiment includes the contact surface 3a of the tread portion 3 extending from the first contact end Te1 to the second contact end Te2.

[0013] The contact surface 3a has, for example, a tire equator C which is the midpoint in the tire axial direction between the first contact end Te1 and the second contact end Te2, and a contact width TW which is the distance in the tire axial direction between the first contact end Te1 and the second contact end Te2. Preferably, the first contact end Te1 is located at a distance t inward in the tire radial direction from the tire equator C.

[0014] Here, "first contact point Te1" and "second contact point Te2" are the outermost contact points in the tire axial direction when a pneumatic tire 1 in a normal state is loaded with 70% of its normal load and makes contact with a plane at a camber angle of 0°.

[0015] When there is a standard system including the standards on which the pneumatic tire 1 is based, the "normal load" is the load determined for each tire by each standard. In the case of JATMA, it is the "maximum load capacity"; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and in the case of ETRTO, it is the "LOAD CAPACITY". When there is no standard system including the standards on which the pneumatic tire 1 is based, the "normal load" is the load determined by the manufacturer or the like for each tire as the maximum applicable load when using the pneumatic tire 1.

[0016] The tread portion 3 of the present embodiment has a plurality of circumferential grooves 4 extending in the tire circumferential direction and a plurality of land portions 5 divided by the plurality of circumferential grooves 4. The plurality of circumferential grooves 4 may, for example, extend linearly in the tire circumferential direction, may extend in a zigzag shape, or may be mixed with those extending linearly and those extending in a zigzag shape. Such a tread portion 3 helps to achieve both the rigidity and the drainage performance of the land portion 5. <0000​​​​​​​​​​​​

[0020] FIG. 2 is an enlarged view of part A of profile 2 in FIG. 1. As shown in FIG. 2, the first imaginary line L1 of the present embodiment is inclined at a first angle θ1 with respect to the tire radial direction. The first angle θ1 is preferably 74° or more. By the first angle θ1 being 74° or more, excessive deformation during grounding can be suppressed, and the rolling resistance can be reduced. From such a viewpoint, the first angle θ1 is more preferably 76° or more, and even more preferably, 77° or more.

[0021] The first angle θ1 is preferably 80° or less. By the first angle θ1 being 80° or less, the flow of air during running from the tread portion 3 to the sidewall portion 6 described later becomes smooth, the separation of air is suppressed, and the air resistance during running can be reduced. From such a viewpoint, the first angle θ1 is more preferably 78° or less, and even more preferably, 77° or less.

[0022] From these facts, the first angle θ1 is preferably 74 to 80°, more preferably 76 to 78°, and even more preferably 77°. Note that the combination of the upper limit value and the lower limit value of these numerical ranges can be arbitrarily selected.

[0023] As shown in FIG. 1, the profile 2 of the present embodiment includes a first side outer surface 6a of the sidewall portion 6 extending from the first grounding end Te1 toward the inside in the tire radial direction, and a first bead outer surface 7a of the bead portion 7 located inside the first side outer surface 6a in the tire radial direction.

[0024] On the first side outer surface 6a of the present embodiment, a first position P1 is defined at a distance D1 of 15% of the tire section height SH from the tire equator C of the ground contact surface 3a toward the inside in the tire radial direction. It is desirable that a second imaginary line L2, which is a tangent line at the first position P1, is inclined in the same direction as the first imaginary line L1 with respect to the tire radial direction. Such a first side outer surface 6a helps to smooth the flow of air during running from the tread portion 3 to the sidewall portion 6 and suppress the separation of air.

[0025] As shown in Figure 2, the second dashed line L2 in this embodiment is inclined at a second angle θ2 with respect to the tire radial direction. The second angle θ2 is preferably 36° or more. When the second angle θ2 is 36° or more, the airflow from the tread portion 3 to the sidewall portion 6 during driving becomes smoother, suppressing air separation and reducing air resistance during driving. From this viewpoint, the second angle θ2 is more preferably 37° or more, and even more preferably 38° or more.

[0026] The second angle θ2 is preferably 40° or less. By having the second angle θ2 be 40° or less, air separation on the outer side of the sidewall portion 6 in the tire radial direction can be suppressed, thereby reducing air resistance during driving. From this viewpoint, the second angle θ2 is more preferably 39° or less, and even more preferably 38° or less.

[0027] Based on these considerations, the second angle θ2 is preferably 36 to 40°, more preferably 37 to 39°, and even more preferably 38°. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.

[0028] As shown in Figure 1, the tread portion 3 of this embodiment includes tread rubber 3G that constitutes the contact surface 3a. The sidewall portion 6 includes sidewall rubber 6G that constitutes the first side outer surface 6a.

[0029] The rubber hardness Gc (degrees) of the tread rubber 3G, the rubber hardness Gs (degrees) of the sidewall rubber 6G, the radial distance t (mm) between the first contact end Te1 and the tire equator C, and the contact width TW (mm) should preferably satisfy the following formula 1. Here, "rubber hardness" is the durometer A hardness measured at 23°C using a durometer type A, based on JIS-K6253.

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[0030] Such a pneumatic tire 1 can soften the input when driving over road surface protrusions, thereby improving the ride comfort performance of the pneumatic tire 1. Therefore, the pneumatic tire 1 of this embodiment can achieve both low fuel consumption and ride comfort.

[0031] In a more preferred embodiment, the rubber hardness Gc of the tread rubber 3G is 48 degrees or higher. Having a rubber hardness Gc of 48 degrees or higher in the tread rubber 3G helps maintain good shear stress in the tread rubber 3G, which helps improve the handling stability and braking performance of the pneumatic tire 1. From this viewpoint, the rubber hardness Gc of the tread rubber 3G is more preferably 55 degrees or higher.

[0032] The rubber hardness Gc of the tread rubber 3G is preferably 74 degrees or less. A rubber hardness Gc of 74 degrees or less allows the tread rubber 3G to absorb input from the road surface during driving, improving the ride comfort performance of the pneumatic tire 1. From this viewpoint, the rubber hardness Gc of the tread rubber 3G is more preferably 65 degrees or less.

[0033] Based on these considerations, the rubber hardness Gc of the tread rubber 3G is preferably 48 to 74 degrees, and more preferably 55 to 65 degrees. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.

[0034] The rubber hardness Gs of the sidewall rubber 6G is preferably 46 degrees or higher. Having a rubber hardness Gs of 46 degrees or higher in the sidewall rubber 6G helps maintain a good lateral spring constant, which contributes to improving the handling stability of the pneumatic tire 1. From this viewpoint, the rubber hardness Gs of the sidewall rubber 6G is more preferably 50 degrees or higher.

[0035] The rubber hardness Gs of the sidewall rubber 6G is preferably 60 degrees or less. Having a rubber hardness Gs of 60 degrees or less allows the sidewall rubber 6G to absorb input from the road surface during driving, improving the ride comfort performance of the pneumatic tire 1. From this viewpoint, the rubber hardness Gs of the sidewall rubber 6G is more preferably 55 degrees or less.

[0036] Based on these considerations, the rubber hardness Gs of the sidewall rubber 6G is preferably 48 to 74 degrees, and more preferably 50 to 55 degrees. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.

[0037] The rubber hardness Gs of the sidewall rubber 6G should preferably be less than the rubber hardness Gc of the tread rubber 3G. Such a pneumatic tire 1 can efficiently absorb input from the road surface during driving, thereby improving ride comfort.

[0038] The pneumatic tire 1 of this embodiment has a carcass 8 that extends from the tread portion 3 through the sidewall portion 6 to the bead portion 7, and a reinforcing layer 9 that is positioned on the radially outer side of the carcass 8 in the tread portion 3. With such a pneumatic tire 1, the rigidity of the tread portion 3 can be improved by the reinforcing layer 9, thereby improving ride comfort performance.

[0039] The carcass 8 has at least one carcass ply 8A, for example, one carcass ply 8A, which includes carcass cords (not shown) arranged at an angle of 60 to 90° with respect to the circumferential direction of the tire. Preferably, the carcass ply 8A includes a main body portion 8m that spans between a pair of bead portions 7 and a pair of folded portions 8t that are connected to the main body portion 8m and folded back from the inside to the outside in the tire axial direction around the bead core 10. Such a carcass 8 helps to suppress deformation under high load and improve the ride comfort performance of the pneumatic tire 1.

[0040] The reinforcing layer 9 includes, for example, a belt layer 11 positioned adjacent to the carcass 8 and a band layer 12 positioned outside the belt layer 11 in the tire radial direction. That is, the tread portion 3 of this embodiment is provided with the belt layer 11 and the band layer 12. Such a pneumatic tire 1 can improve the rigidity of the tread portion 3 through the belt layer 11 and the band layer 12.

[0041] The belt layer 11 includes, for example, a first belt ply 11A and a second belt ply 11B positioned outside the first belt ply 11A in the tire radial direction. Such a belt layer 11 can increase the rigidity of the tread portion 3 in the tire axial direction, suppressing excessive deformation and improving the ride comfort performance of the pneumatic tire 1.

[0042] Figure 3 is a schematic diagram of the unfolded belt layer 11. As shown in Figure 3, in the first belt ply 11A of the belt layer 11, for example, the belt cords 11c are arranged in a direction inclined at an angle λ with respect to the tire circumferential direction. In the second belt ply 11B of the belt layer 11 in this embodiment, the belt cords 11c are arranged in a direction inclined at an angle λ with respect to the tire circumferential direction in the opposite direction to that of the first belt ply 11A. Such a belt layer 11 can reduce the rigidity of the tread portion 3 in the tire circumferential direction and soften the input when driving over protrusions on the road surface.

[0043] The angle λ of the belt cord 11c with respect to the tire circumferential direction is preferably 22° or more. An angle λ of 22° or more of the belt cord 11c increases the rigidity of the tread portion 3 in the tire axial direction and reduces the rigidity in the tire circumferential direction. From this viewpoint, the angle λ of the belt cord 11c is more preferably 26° or more.

[0044] The angle λ of the belt cord 11c with respect to the tire circumferential direction is preferably 34° or less. By having an angle λ of 34° or less of the belt cord 11c, it is possible to suppress the excessive reduction of the rigidity of the tread portion 3 in the tire circumferential direction. From this viewpoint, the angle λ of the belt cord 11c is more preferably 30° or less.

[0045] Based on these considerations, the angle λ of the belt cord 11c with respect to the tire circumferential direction is preferably 22 to 34°, and more preferably 26 to 30°. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.

[0046] As shown in Figure 1, the band layer 12 has at least one band ply 12A, for example, one band cord (not shown) arranged at an angle of 5° or less with respect to the circumferential direction of the tire. Such a band layer 12 can improve the circumferential rigidity of the tread portion 3 of the tire by a hoop effect.

[0047] The distance t between the first contact end Te1 and the tire equator C is preferably 2% or more of the contact width TW. When the distance t is 2% or more of the contact width TW, the airflow from the tread portion 3 to the sidewall portion 6 during driving becomes smoother, suppressing air separation and reducing air resistance during driving. From this viewpoint, the distance t between the first contact end Te1 and the tire equator C is more preferably 3% or more of the contact width TW.

[0048] The distance t between the first contact point Te1 and the tire equator C is preferably 6% or less of the contact width TW. Having a distance D2 of 6% or less of the contact width TW suppresses excessive deformation during contact and reduces rolling resistance. From this viewpoint, the distance t between the first contact point Te1 and the tire equator C is more preferably 5% or less of the contact width TW.

[0049] Based on these considerations, the distance t between the first contact end Te1 and the tire equator C is preferably 2% to 6% of the contact width TW, and more preferably 3% to 5%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.

[0050] The maximum width W1 of the first shoulder land portion 5A in the axial direction of the tire is preferably 20% or more of the contact width TW. By having a maximum width W1 of the first shoulder land portion 5A of 20% or more of the contact width TW, air that has been swept around by the vehicle's influence during driving can be smoothly directed into the first shoulder circumferential groove 4A, thereby reducing air resistance during driving. Furthermore, by positioning the first shoulder circumferential groove 4A at a location with high ground pressure, it also helps to increase the driving speed at which hydroplaning occurs. From this viewpoint, the maximum width W1 of the first shoulder land portion 5A is more preferably 22% or more of the contact width TW.

[0051] The maximum width W1 of the first shoulder land portion 5A in the tire axial direction is preferably 30% or less of the contact width TW. By having the maximum width W1 of the first shoulder land portion 5A be 30% or less of the contact width TW, it is possible to suppress the rigidity of the first shoulder land portion 5A from becoming excessively high, thereby improving the handling stability performance of the pneumatic tire 1 and also helping to improve the drainage performance on the outer side in the tire axial direction. From this viewpoint, the maximum width W1 of the first shoulder land portion 5A is more preferably 28% or less of the contact width TW.

[0052] Based on these considerations, the maximum width W1 in the tire axial direction of the first shoulder land portion 5A is preferably 20% to 30% of the contact width TW, and more preferably 22% to 28%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.

[0053] The pneumatic tire 1 of this embodiment does not have a rim guard on the sidewall portion 6. Since such a pneumatic tire 1 does not have a rim guard, which has a significant impact on air resistance, it can reduce air resistance during driving.

[0054] A normal rim R has, for example, a first rim end R1 which is the end on the first grounding end Te1 side, a second rim end R2 which is the end on the second grounding end Te2 side, and a maximum width RW which is the distance in the rim width direction between the first rim end R1 and the second rim end R2.

[0055] The pneumatic tire 1 should preferably have a tire section width SW that is 6 mm or more larger than the maximum width RW in the rim width direction of the regular rim R. Such a pneumatic tire 1 can prevent the regular rim R from contacting curbs, etc., even without a rim guard, and can achieve both durability and fuel efficiency. Here, the tire section width SW is the maximum width in profile 2 and does not include localized protrusions or rim guards.

[0056] The radial distance d between the first rim edge R1 and the first bead outer surface 7a is preferably 3 mm or less. Such a first bead outer surface 7a suppresses the generation of turbulence between the first rim edge R1 and the first bead outer surface 7a, and by maintaining the kinetic energy of the air, it is possible to reduce air resistance during driving.

[0057] It is desirable that the first side outer surface 6a has a second position P2 located at a distance D2 of 25% of the tire cross-sectional height SH, inward from the tire equator C in the tire radial direction, and a third position P3 located at a distance D3 of 19 mm inward from the tire equator C in the tire radial direction. In this embodiment, the first side outer surface 6a has a fourth position P4 located inward in the tire radial direction from the virtual intersection Pv of the first virtual line L1 and the second virtual line L2.

[0058] As shown in Figure 2, it is desirable that the tire radial distance D4 between the first position P1 and the second position P2 is equal to the tire radial distance D4 between the first position P1 and the fourth position P4. In this case, the first position P1 is an intermediate position in the tire radial direction between the second position P2 and the fourth position P4. Such a first position P1 is suitable as a representative point of the outer region of the first side outer surface 6a in the tire radial direction.

[0059] Figure 4 is a schematic diagram of a mold M for forming a pneumatic tire 1. As shown in Figures 1 to 4, the mold M of this embodiment includes a tread mold M1 for forming the tread portion 3 and a side mold M2 for forming the sidewall portion 6. The pneumatic tire 1 has, for example, a mold divider line ML between the tread mold M1 and the side mold M2.

[0060] As shown in Figure 2, the mold splitting line ML preferably includes a stepped portion 13 having a height h of 0.4 mm or less. Such a stepped portion 13 can suppress the occurrence of cracks originating from the mold splitting line ML and improve the durability of the pneumatic tire 1.

[0061] Furthermore, by keeping the height h of the stepped portion 13 to 0.4 mm or less, the increase in air resistance during driving can be suppressed, improving the fuel efficiency of the pneumatic tire 1. Here, the height h of the stepped portion 13 is the maximum height of the step portion 13 protruding from the first side outer surfaces 6a on both sides in the tire radial direction in a direction perpendicular to the first side outer surfaces 6a.

[0062] The stepped portion 13 of the mold division line ML is preferably located between the second position P2 and the third position P3. By positioning the stepped portion 13 further outward in the tire radial direction than the second position P2, the decrease in airflow velocity near the maximum width position of the first side outer surface 6a can be suppressed, thereby reducing air resistance during driving.

[0063] Since the stepped portion 13 is located inward in the tire radial direction from the third position P3, the decrease in airflow velocity near the buttress on the outer side of the first side outer surface 6a in the tire radial direction can be suppressed, thereby reducing air resistance during driving.

[0064] As shown in Figure 1, the pneumatic tire 1 of this embodiment has a specified orientation for mounting on the vehicle in the tire axial direction. The first contact end Te1 of this embodiment is located on the outside of the vehicle when mounted on the vehicle. The second contact end Te2 is preferably located on the inside of the vehicle when mounted on the vehicle. Such a pneumatic tire 1 can define the profile 2 on the outside of the vehicle, which has a large impact on air resistance, as a shape that reduces air resistance, thereby improving fuel efficiency.

[0065] The circumferential grooves 4 of this embodiment include a second shoulder circumferential groove 4B that extends furthest towards the second contact end Te2 between the tire equator C and the second contact end Te2 in the tire circumferential direction. The circumferential grooves 4 include, for example, a first crown circumferential groove 4C that extends in the tire circumferential direction between the tire equator C and the first shoulder circumferential groove 4A, and a second crown circumferential groove 4D that extends in the tire circumferential direction between the tire equator C and the second shoulder circumferential groove 4B. Such circumferential grooves 4 have excellent drainage properties and help improve the wet performance of the pneumatic tire 1. Note that the circumferential grooves 4 are not limited to four, but may be three or fewer, or five or more.

[0066] The ground portion 5 of this embodiment has a second shoulder ground portion 5B, which is divided by a second shoulder circumferential groove 4B and a second contact end Te2. Preferably, the ground portion 5 includes a first middle ground portion 5C, which is divided by a first shoulder circumferential groove 4A and a first crown circumferential groove 4C, and a second middle ground portion 5D, which is divided by a second shoulder circumferential groove 4B and a second crown circumferential groove 4D. For example, the ground portion 5 includes a crown ground portion 5E, which is divided by a first crown circumferential groove 4C and a second crown circumferential groove 4D. Such a ground portion 5 has excellent rigidity and helps to improve the handling stability performance of the pneumatic tire 1.

[0067] Profile 2 of this embodiment includes a second side outer surface 6b of the sidewall portion 6 extending inward in the tire radial direction from the second contact end Te2, and a second bead outer surface 7b of the bead portion 7 located inward in the tire radial direction of the second side outer surface 6b.

[0068] Profile 2 may be formed symmetrically in the tire axial direction, for example, with respect to the tire equator C. In this case, the contact surface 3a of the second shoulder land portion 5B, the second side outer surface 6b, and the second bead outer surface 7b are symmetrical to the contact surface 3a of the first shoulder land portion 5A, the first side outer surface 6a, and the first bead outer surface 7a, respectively. Such a pneumatic tire 1 can reduce air resistance when driving inside the vehicle, thereby further improving fuel efficiency.

[0069] The sidewall portion 6 of this embodiment includes sidewall rubber 6G that constitutes the second side outer surface 6b. It is desirable that the sidewall rubber 6G of the second side outer surface 6b has the same rubber hardness Gs as the sidewall rubber 6G of the first side outer surface 6a. Such a pneumatic tire 1 has excellent balance in the tire axial direction and can further improve ride comfort performance. However, the rubber hardness Gs of the sidewall rubber 6G of the first side outer surface 6a and the rubber hardness Gs of the sidewall rubber 6G of the second side outer surface 6b may be different from each other.

[0070] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and can be implemented in various modified forms.

[0071] [Note] The present invention is as follows:

[0072] [Invention 1] It is a pneumatic tire, The tire has a profile defined by the outer surface in the meridional cross-section of a tire in a normal state, which is a tire mounted on a normal rim and adjusted to the normal internal pressure in an unloaded state. The profile includes a contact surface of the tread portion extending from a first contact end to a second contact end, and a first side outer surface of the sidewall portion extending inward in the tire radial direction from the first contact end. On the outer surface of the first side, a first position is defined at a distance of 15% of the tire cross-sectional height, located radially inward from the tire equator of the contact surface. The tread portion has a first shoulder circumferential groove that extends furthest towards the first contact end in the tire circumferential direction between the tire equator and the first contact end, and a first shoulder land portion that is separated by the first shoulder circumferential groove and the first contact end. The aforementioned contact surface has a first imaginary line, which is a tangent at the midpoint of the tire axial direction of the first shoulder land portion, that is inclined outward in the tire axial direction and inward in the tire radial direction. The first dashed line has a first angle of 74-80° with respect to the tire radial direction, The first outer side surface is such that the second imaginary line, which is tangent at the first position, is inclined in the same direction as the first imaginary line with respect to the tire radial direction. The second dashed line has a second angle of 36-40° with respect to the tire radial direction. The aforementioned contact surface has a contact width TW (mm), which is the distance in the tire axial direction between the first contact end and the second contact end. The tread portion includes the tread rubber that constitutes the contact surface. The sidewall portion includes the sidewall rubber that constitutes the first side outer surface. The rubber hardness Gc (degrees) of the tread rubber, the rubber hardness Gs (degrees) of the sidewall rubber, the radial distance t (mm) between the first contact end and the tire equator, and the contact width TW (mm) satisfy the following formula 1: Pneumatic tires.

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[0073] [Invention 2] The pneumatic tire according to the present invention 1, wherein the rubber hardness Gc of the tread rubber is 48 to 74 degrees.

[0074] [Invention 3] The pneumatic tire according to invention 1 or 2, wherein the rubber hardness Gs of the sidewall rubber is 46 to 60 degrees.

[0075] [4th Invention] The pneumatic tire according to any one of inventions 1 to 3, wherein the distance t (mm) between the first contact end and the tire equator is 2% to 6% of the contact width TW (mm).

[0076] [5th ​​Invention] A pneumatic tire according to any one of invention 1 to 4, having a tire cross-sectional width that is 6 mm or more greater than the maximum width in the rim width direction of the standard rim.

[0077] [Invention 6] The profile includes the first bead outer surface of the bead portion located radially inward of the first side outer surface of the tire, The pneumatic tire according to any one of inventions 1 to 5, wherein the distance in the tire radial direction between the first rim end, which is the end of the regular rim on the first contact end side, and the outer surface of the first bead is 3 mm or less.

[0078] [7th Invention] The mold has a split line between the tread mold for forming the tread portion and the side mold for forming the sidewall portion. The mold cut line includes a stepped portion having a height of 0.4 mm or less, as described in any one of invention 1 to 6.

[0079] [8th Invention] On the outer surface of the first side, a second position is defined at a distance of 25% of the tire cross-sectional height, located radially inward from the tire equator, and a third position is defined at a distance of 19 mm radially inward from the tire equator. The stepped portion is located between the second position and the third position, in the pneumatic tire according to the present invention, as described in 7.

[0080] [Invention 9] On the outer surface of the first side, a fourth position is defined which is located inside the tire radial direction of the virtual intersection of the first virtual line and the second virtual line. The pneumatic tire according to the present invention, wherein the first position is an intermediate position in the tire radial direction between the second position and the fourth position.

[0081] [Invention 10] The orientation in which it is installed on the vehicle is specified. The first contact end is located on the outside of the vehicle when mounted on the vehicle, as described in any one of invention 1 to 9. [Explanation of Symbols]

[0082] 1. Pneumatic tire 2 Profiles 3. Tread section 3a Ground plane 3G Tread Rubber 4A First shoulder circumferential groove 5A 1st Shoulder Track and Field Club 6a First side outer surface 6G Sidewall Rubber

Claims

1. It is a pneumatic tire, The tire has a profile defined by the outer surface in the meridional cross-section of a tire in a normal state, which is a tire mounted on a normal rim and adjusted to the normal internal pressure in an unloaded state. The profile includes a contact surface of the tread portion extending from a first contact end to a second contact end, and a first side outer surface of the sidewall portion extending inward in the tire radial direction from the first contact end. On the outer surface of the first side, a first position is defined at a distance of 15% of the tire cross-sectional height, located radially inward from the tire equator of the contact surface. The tread portion has a first shoulder circumferential groove that extends furthest towards the first contact end in the tire circumferential direction between the tire equator and the first contact end, and a first shoulder land portion that is separated by the first shoulder circumferential groove and the first contact end. The aforementioned contact surface has a first imaginary line, which is a tangent at the midpoint of the tire axial direction of the first shoulder land portion, that is inclined outward in the tire axial direction and inward in the tire radial direction. The first dashed line has a first angle of 74 to 80° with respect to the tire radial direction, The first side outer surface is such that the second imaginary line, which is tangent at the first position, is inclined in the same direction as the first imaginary line with respect to the tire radial direction. The second dashed line has a second angle of 36 to 40° with respect to the tire radius direction. The aforementioned contact surface has a contact width TW (mm), which is the distance in the tire axial direction between the first contact end and the second contact end. The tread portion includes the tread rubber that constitutes the contact surface. The sidewall portion includes the sidewall rubber that constitutes the first side outer surface. The rubber hardness Gc (degrees) of the tread rubber, the rubber hardness Gs (degrees) of the sidewall rubber, the radial distance t (mm) between the first contact end and the tire equator, and the contact width TW (mm) satisfy the following formula 1: Pneumatic tires. [Math 1]

2. The pneumatic tire according to claim 1, wherein the rubber hardness Gc of the tread rubber is 48 to 74 degrees.

3. The pneumatic tire according to claim 2, wherein the rubber hardness Gs of the sidewall rubber is 46 to 60 degrees.

4. The pneumatic tire according to any one of claims 1 to 3, wherein the distance t (mm) between the first contact end and the tire equator is 2% to 6% of the contact width TW (mm).

5. A pneumatic tire according to any one of claims 1 to 3, having a tire cross-sectional width that is 6 mm or more greater than the maximum width in the rim width direction of the standard rim.

6. The profile includes the first bead outer surface of the bead portion located on the inner side of the first side outer surface in the radial direction of the tire, The pneumatic tire according to any one of claims 1 to 3, wherein the distance in the tire radial direction between the first rim end, which is the end of the regular rim on the first contact end side, and the outer surface of the first bead is 3 mm or less.

7. The mold has a split line between the tread mold for forming the tread portion and the side mold for forming the sidewall portion. The pneumatic tire according to any one of claims 1 to 3, wherein the mold cut line includes a stepped portion having a height of 0.4 mm or less.

8. On the outer surface of the first side, a second position is defined at a distance of 25% of the tire cross-sectional height, located radially inward from the tire equator, and a third position is defined at a distance of 19 mm radially inward from the tire equator. The pneumatic tire according to claim 7, wherein the stepped portion is located between the second position and the third position.

9. On the outer surface of the first side, a fourth position is defined which is located inside the tire radial direction of the virtual intersection of the first virtual line and the second virtual line. The pneumatic tire according to claim 8, wherein the first position is an intermediate position in the tire radial direction between the second position and the fourth position.

10. The orientation in which it is installed on the vehicle is specified. The first contact end is located on the outside of the vehicle when mounted on the vehicle, as described in any one of claims 1 to 3.

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