pneumatic tires

Abstract

We offer pneumatic tires that achieve both fuel efficiency and wet performance. [Solution] The present invention relates to a pneumatic tire 1 including a contact surface 3a extending from a first contact end Te1 to a second contact end Te2, and a first side outer surface 6a extending inward in the tire radial direction from the first contact end Te1. The tread portion 3 has a first shoulder circumferential groove 4A and a first shoulder land portion 5A separated by the first shoulder circumferential groove 4A and the first contact end Te1. The contact surface 3a has a first virtual line L1, which is tangent to the first shoulder land portion 5A at an intermediate position Pm in the tire axial direction, having a first angle θ1 of 74 to 80° with respect to the tire radial direction. The first side outer surface 6a has a second virtual line L2, which is tangent to the first position P1, having a second angle θ2 of 36 to 40° with respect to the tire radial direction. The maximum width W1 of the first shoulder land portion 5A in the tire axial direction is 20% to 30% of the contact width TW.

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 capable of achieving 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 driving. Further improvement has been expected for the air resistance during driving even in the pneumatic tire of Patent Document 1. In addition, there has also been a demand for improvement in wet performance, although the profile for improving rolling resistance tends to deteriorate wet 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 capable of achieving both low fuel consumption performance and wet 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 radially inward from the first contact end, wherein the first side outer surface has a defined first position at a distance of 15% of the tire cross section height radially inward from the tire equator of the contact surface, and the tread portion is divided by 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 the first shoulder circumferential groove and the first contact end. The tire is a pneumatic tire having a first shoulder land portion, the contact surface having a first imaginary line which is the tangent at the midpoint of the first shoulder land portion in the tire axial direction, which is inclined outward in the tire axial direction and inward in the tire radial direction, and the first imaginary line has a first angle of 74 to 80° with respect to the tire radial direction, the first side outer surface having a second imaginary line which is the tangent at the first position, which is inclined in the same direction as the first imaginary line with respect to the tire radial direction, which is a second angle of 36 to 40° with respect to the tire radial direction, the contact surface having a contact width which is the distance in the tire axial direction between the first contact end and the second contact end, and the maximum width in the tire axial direction of the first shoulder land portion is 20% to 30% of the contact width. [Effects of the Invention]

[0007] The pneumatic tire of the present invention, by having the above-described configuration, can reduce air resistance during driving while maintaining good hydroplaning performance, thereby achieving both low fuel consumption and wet performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing one embodiment of the profile of the pneumatic tire of the present invention. [Figure 2] This is an enlarged view of section A in Figure 1. [Figure 3]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 of this embodiment, showing the profile 2 in its normal state. 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] "Regular load" refers to the load 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 load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "LOAD CAPACITY" for ETRTO. If there is no standard system on which the pneumatic tire 1 is based, "Regular load" refers to the maximum load applicable when using the pneumatic tire 1, as specified by the manufacturer for each tire.

[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 a mixture of those extending linearly and those extending in a zigzag shape. Such a tread portion 3 helps to achieve both the rigidity and drainage performance of the land portion 5.

[0017] The plurality of circumferential grooves 4 of the present embodiment includes a first shoulder circumferential groove 4A that extends in the tire circumferential direction on the side closest to the first grounding end Te1 between the tire equator C and the first grounding end Te1. The plurality of land portions 5 of the present embodiment includes a first shoulder land portion 5A divided by the first shoulder circumferential groove 4A and the first grounding end Te1.

[0018] It is desirable that a first virtual line L1, which is a tangent line at the intermediate position Pm in the tire axial direction of the first shoulder land portion 5A, inclines inward in the tire radial direction toward the outer side in the tire axial direction for the ground contact surface 3a. Such a ground contact surface 3a helps to smooth the flow of air during running from the tread portion 3 to the sidewall portion 6 described later and suppress the separation of air.

[0019] Here, the intermediate position Pm of the first shoulder land portion 5A is a position that is separated by a distance W1 / 2, which is half of the maximum width W1 in the tire axial direction of the first shoulder land portion 5A, inward in the tire axial direction from the first grounding end Te1.

[0020] FIG. 2 is an enlarged view of part A in FIG. 1. As shown in FIG. 2, the first virtual line L1 of the present embodiment inclines 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 still more preferably 77° or more.

[0021] The first angle θ1 is preferably 80° or less. When the first angle θ1 is 80° or less, the air flow during running from the tread portion 3 to the sidewall portion 6 described later becomes smooth, air separation 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 still more preferably 77° or less.

[0022] From these, the first angle θ1 is preferably 74 to 80°, more preferably 76 to 78°, and still more preferably 77°. The combinations of the upper limit and the lower limit 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 inward in the tire radius direction from the first ground contact end Te1, and a first bead outer surface 7a of the bead portion 7 located inward in the tire radius direction of the first side outer surface 6a.

[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 inward in the tire radius direction from the tire equator C of the ground contact surface 3a. It is desirable that the second virtual line L2, which is a tangent line at the first position P1, of the first side outer surface 6a inclines in the same direction as the first virtual line L1 with respect to the tire radius direction. Such a first side outer surface 6a helps to smooth the air flow during running from the tread portion 3 to the sidewall portion 6 and suppress air separation.

[0025] As shown in FIG. 2, the second virtual line L2 of the present embodiment inclines at a second angle θ2 with respect to the tire radius direction. The second angle θ2 is preferably 36° or more. When the second angle θ2 is 36° or more, the air flow during running from the tread portion 3 to the sidewall portion 6 becomes smooth, air separation is suppressed, and the air resistance during running can be reduced. From such a viewpoint, the second angle θ2 is more preferably 37° or more, and still 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 maximum width W1 of the first shoulder land portion 5A in the tire axial direction 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.

[0029] 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.

[0030] 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.

[0031] Due to the synergistic effect of the above-mentioned components, the pneumatic tire 1 having profile 2 of this embodiment can reduce air resistance during driving while maintaining good hydroplaning performance, thereby achieving both low fuel consumption and wet performance.

[0032] In a more preferred embodiment, the regular rim R has 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.

[0033] 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.

[0034] 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.

[0035] Profile 2 of this embodiment includes a first bead outer surface 7a of the bead portion 7 located on the inside of the first side outer surface 6a in the tire radial direction, and a second bead outer surface 7b of the bead portion 7 located on the inside of the second side outer surface 6b in the tire radial direction.

[0036] 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.

[0037] The radial distance t between the first contact point Te1 and the tire equator C is preferably 2% or more of the contact width TW. A distance t of 2% or more of the contact width TW allows for smoother airflow from the tread portion 3 to the sidewall portion 6 during driving, suppressing air separation and reducing air resistance during driving. From this perspective, the distance t between the first contact point Te1 and the tire equator C is more preferably 3% or more of the contact width TW.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Figure 3 is a schematic diagram of a mold M for forming a pneumatic tire 1. As shown in Figures 1 to 3, 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.

[0043] As shown in Figure 2, the mold splitting line ML preferably includes a stepped portion 8 having a height h of 0.4 mm or less. Such a stepped portion 8 can suppress the occurrence of cracks originating from the mold splitting line ML and improve the durability of the pneumatic tire 1.

[0044] Furthermore, by keeping the height h of the stepped portion 8 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 8 is the maximum height of the step portion 8 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.

[0045] The stepped portion 8 of the mold division line ML is preferably located between the second position P2 and the third position P3. By positioning the stepped portion 8 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.

[0046] Since the stepped portion 8 is located inward in the tire radial direction from the third position P3, the reduction 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.

[0047] 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.

[0048] The tread portion 3 of this embodiment has three or more circumferential grooves 4 extending in the circumferential direction of the tire. Here, the first shoulder circumferential groove 4A is one of the three or more circumferential grooves 4. Such a tread portion 3 can increase the driving speed at which hydroplaning occurs and can improve the wet performance of the pneumatic tire 1.

[0049] 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, five or more, for example.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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. [Examples]

[0054] A pneumatic tire with the profile shown in Figure 1 and tire size 215 / 45R20 was prototyped based on the specifications in Table 1. The rolling resistance and wet performance of the prototype pneumatic tire were tested. Furthermore, air resistance was determined using a pneumatic tire model of the same tire size as the prototype. The test methods and calculation methods are as follows.

[0055] <Rolling resistance> The prototype pneumatic tires, in their standard configuration, were mounted on a drum testing machine, and their rolling resistance was measured according to the force method of ISO 28580. The results are shown as an index with Comparative Example 1 set to 100, where a higher number indicates lower rolling resistance.

[0056] <Wet performance> A prototype pneumatic tire in its standard configuration was mounted on a drum testing machine on an asphalt surface with a tire slip angle of 0° and rolled at a rotation speed of 50 km / h in 5 mm of water. The rotation speed of the drum testing machine was increased from 60 km / h to 140 km / h, and the rotation speed at which the maximum braking force was halved was measured. The results are shown as an index with Comparative Example 1 set to 100, and a higher value indicates a higher speed at which hydroplaning occurs and superior wet performance.

[0057] <Air resistance> Using a pneumatic tire model of the same tire size as the prototype pneumatic tire, aerodynamic simulations of the front wheels when mounted on a passenger car vehicle model were performed, and their drag coefficients were determined. The results are shown as an index with Comparative Example 1 set to 100, where a higher value indicates lower air resistance during driving.

[0058] The test results are shown in Table 1. [Table 1]

[0059] The test results confirmed that the pneumatic tire in the example reduced air resistance during driving while maintaining equivalent rolling resistance to the comparative example, and exhibited equivalent or better wet performance. Furthermore, the pneumatic tire in the example also showed improved overall performance, which is evaluated by summing the results of each test, compared to the comparative example. This confirmed that it was possible to reduce air resistance during driving while maintaining good hydroplaning performance, thus achieving both low fuel consumption and good wet performance.

[0060] [Note] The present invention is as follows:

[0061] [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 contact surface has a contact width which is the distance in the tire axial direction between the first contact end and the second contact end. The maximum width of the tire axial direction of the first shoulder portion is 20% to 30% of the contact width. Pneumatic tires.

[0062] [Invention 2] The tread portion has three or more circumferential grooves extending in the circumferential direction of the tire. The pneumatic tire according to the present invention 1, wherein the first shoulder circumferential groove is one of the three or more circumferential grooves.

[0063] [Invention 3] 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 invention 1 or 2 of the present invention.

[0064] [4th Invention] The pneumatic tire according to any one of inventions 1 to 3, wherein the distance in the radial direction of the tire between the first contact end and the tire equator is 2% to 6% of the contact width.

[0065] [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.

[0066] [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.

[0067] [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.

[0068] [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.

[0069] [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. [Explanation of symbols]

[0070] 1. Pneumatic tire 3. Tread section 3a Ground plane 4A First shoulder circumferential groove 5A 1st Shoulder Track and Field Club 6a First side outer surface

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 which is the distance in the tire axial direction between the first contact end and the second contact end. The maximum width of the first shoulder portion in the axial direction of the tire is 20% to 30% of the contact width. Pneumatic tires.

2. The tread portion has three or more circumferential grooves extending in the circumferential direction of the tire. The pneumatic tire according to claim 1, wherein the first shoulder circumferential groove is one of the three or more circumferential grooves.

3. The orientation in which it is installed on the vehicle is specified. The pneumatic tire according to claim 1 or 2, wherein the first contact end is located on the outside of the vehicle when mounted on the vehicle.

4. The pneumatic tire according to claim 1 or 2, wherein the distance in the radial direction of the tire between the first contact end and the tire equator is 2% to 6% of the contact width.

5. The pneumatic tire according to claim 1 or 2, 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 claim 1 or 2, 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 claim 1 or 2, 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.

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