Tire, vehicle and tire design method

Abstract

The present application provides a tire, a vehicle, and a tire design method, which can exhibit excellent drainage performance in a state where a camber angle other than zero is imparted. A plurality of circumferential grooves continuously extending in a tire circumferential direction are formed in a tread portion (2). When a tire is mounted on a regular rim, filled with a regular internal pressure, and grounded on a plane with a regular load applied at a predetermined camber angle θ other than zero, and a tire circumferential line at which a ground length in the tire circumferential direction becomes the largest is set as an inclined ground center line (GL), the circumferential grooves include a first circumferential groove (3) disposed on a first side (S1) in a tire axial direction with respect to the inclined ground center line (GL) and a second circumferential groove (4) disposed on a second side (S2) in the tire axial direction with respect to the inclined ground center line (GL).

Description

TECHNICAL FIELD

[0001] The present application relates to a tire having a tread pattern. BACKGROUND

[0002] In the past, a tire in which improvement of drainage performance is achieved by determining the groove shape of a tread portion has been studied (for example, refer to Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2005-145307

[0004] In a vehicle running on a loop, a slightly large negative camber angle that is not zero is often given in advance. However, when the tire described in the above Patent Document 1 is given a camber angle, the ground contact shape changes, and sometimes the desired drainage performance cannot be exhibited. SUMMARY

[0005] The present application has been made in view of the above-described actual circumstances, and a main object thereof is to provide a tire that can exhibit excellent drainage performance in a state in which a camber angle that is not zero is given.

[0006] The present application is a tire having a tread portion in which a plurality of circumferential grooves that extend continuously in the tire circumferential direction are formed in the tread portion, and in which, when a tire circumferential line in which the ground contact length in the tire circumferential direction becomes the largest is set as a tilted ground contact center line in a state in which the tire is mounted on a normal rim, filled with a normal internal pressure, and brought into ground contact with a plane with a predetermined camber angle that is not zero applied, the circumferential grooves include: a first circumferential groove that is disposed on a first side in the tire axial direction with respect to the tilted ground contact center line; and a second circumferential groove that is disposed on a second side in the tire axial direction with respect to the tilted ground contact center line.

[0007] In the tire of the present application, it is preferable that the absolute value of the camber angle be 2° to 4°.

[0008] In the tire of the present application, it is preferable that a tread pattern that is asymmetric with respect to the tire equator be formed in the tread portion.

[0009] In the tire of the present application, it is preferable that the first circumferential groove and the second circumferential groove be disposed symmetrically with respect to the tilted ground contact center line.

[0010] In the tire of the present application, it is preferable that the first circumferential groove and the second circumferential groove be disposed on the first side with respect to the tire equator.

[0011] In the tire of the present application, it is preferable that the width of the circumferential groove be 3% to 10% of the tread width.

[0012] In the tire of the present application, it is preferable that the circumferential grooves be only two.

[0013] In the tire of the present application, preferably, a profile of a tread surface of a land portion divided by the first circumferential groove and the second circumferential groove in a tire meridian section is circular arc shape.

[0014] In the tire of the present application, preferably, a tire axial length of the land portion is 15 mm to 60 mm.

[0015] In the tire of the present application, preferably, the tread portion includes an inner side tread portion located on an inner side of a vehicle when mounted to the vehicle by a specified direction of installation to the vehicle and an outer side tread portion located on an outer side of the vehicle when mounted to the vehicle, and a radius of curvature of a profile of a tread surface of the inner side tread portion is smaller than a radius of curvature of a profile of a tread surface of the outer side tread portion in a tire meridian section.

[0016] The present application is a vehicle mounted with the tire of the present application, the tire being mounted at a camber angle of -4° to -2° to the ground.

[0017] The present application is a method of designing the tire, including a calculation step of calculating a position of a tire axial direction of the inclined ground contact center line, and a step of arranging the first circumferential groove and the second circumferential groove with respect to the inclined ground contact center line, the calculation step including a step of finding a contact point at which an imaginary line inclined by an angle corresponding to the camber angle with respect to a tire axial direction contacts a profile of a tread surface in a tire meridian section, and a step of finding the inclined ground contact center line by a line parallel to a tire circumferential direction passing through the contact point.

[0018] In the tire of the present application, the first circumferential groove is arranged on a first side and the second circumferential groove is arranged on a second side with respect to the inclined ground contact center line at the predetermined camber angle which is not zero. Since the circumferential grooves are arranged on both sides of the inclined ground contact center line, an excellent drainage performance can be obtained in a state where the camber angle is imparted. Thus, the tire of the present application can exert an excellent drainage performance in a state where it is mounted to an actual vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a front view of a vehicle mounted with the tire of the present application.

[0020] Figure 2 is a meridian sectional view of a tread portion of the tire of Figure 1

[0021] Figure 3 is a view showing a ground shape in an inclined load state of the tire of Figure 1

[0022] Figure 4 ​​is a flowchart showing a procedure of a tire design method of the present embodiment.

[0023] Figure 5 is a diagram showing Figure 4 a contact point calculation procedure.

[0024] Explanation of Reference Signs

[0025] 1: tire; 2: tread portion; 3: circumferential groove; 3: 1st circumferential groove; 4: circumferential groove; 4: 2nd circumferential groove; 5: land portion; 20: tread surface; 21: inner side tread portion; 22: outer side tread portion; 100: vehicle; CL: tire equator; CP: contact point; GL: inclined ground center line; R1: radius of curvature; R2: radius of curvature; S1: 1st side; S2: 2nd side; TP: tread pattern; TW: tread width; VL: imaginary line; Θ: camber angle. DETAILED DESCRIPTION

[0026] Hereinafter, one embodiment of the present application will be described based on the drawings.

[0027] Figure 1 A vehicle 100 on which the tire 1 of the present embodiment is mounted is shown. The tire 1 of the present embodiment is suitable for the vehicle 100 that runs on a race track.

[0028] The present tire 1 is preferably mounted to the vehicle 100 in such a manner as to become a predetermined camber angle Θ to the ground. The camber angle Θ to the ground set in a race track run is, for example, -4° to -2°.

[0029] Figure 2 is a meridian sectional view of the tread portion 2 of the tire 1. As Figure 2 shown, the tire 1 of the present embodiment has a tread portion 2.

[0030] A plurality of circumferential grooves, in the present embodiment, circumferential grooves 3, 4, are formed in the tread portion 2 so as to extend continuously along the tire circumferential direction. The tread pattern TP is formed on the tread surface 20 of the tread portion 2 by the circumferential grooves 3, 4, and the like.

[0031] The width of the circumferential grooves 3, 4 of the present embodiment is preferably 3% to 10% of the tread width TW.

[0032] The above "tread width TW" refers to the distance in the tire axial direction between the tread ends Te, Te. The "tread end Te" refers to the ground contact position most outward in the tire axial direction when a regular load is applied to the tire 1 in a regular state and the tire is grounded on a flat surface with a camber angle of 0 degrees.

[0033] The "regular state" refers to a state in which the tire is mounted to a regular rim (omitted from the drawing) and filled with a regular internal pressure without a load. Hereinafter, unless otherwise mentioned, the dimensions and the like of each portion of the tire are values measured in this regular state.

[0034] "Normal rim" is a rim determined in accordance with each standard in a standard system including the standard to which the tire is subjected, for example, "Standard rim" if JATMA, "Design Rim" if TRA, and "Measuring Rim" if ETRTO.

[0035] "Normal internal pressure" means the air pressure determined in accordance with each standard in a standard system including the standard to which the tire is subjected, for example, "Maximum air pressure" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, and "INFLATION PRESSURE" if ETRTO.

[0036] "Normal load" means the load determined in accordance with each standard in a standard system including the standard to which the tire is subjected, for example, "Maximum load capacity" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, and "LOAD CAPACITY" if ETRTO.

[0037] In the case where no standard is applied as in a tire for a racing car, the normal rim, the normal internal pressure, and the normal load are applied to the rim, the air pressure, and the load recommended by the manufacturer.

[0038] By making the width of the circumferential grooves 3, 4 3% or more of the tread width TW, the drainage performance is improved, and the single lap time on a wet road surface is easily shortened. On the other hand, by making the width of the circumferential grooves 3, 4 10% or less of the tread width TW, the rigidity of the tread portion 2 in the tire axial direction is improved, and thus the handling stability performance on a dry road surface is improved and the single lap time is easily shortened.

[0039] Figure 3 The ground contact shape when the normal load is applied to the tire 1 at the camber angle θ and the tire contacts a plane (set as a camber load state) is shown. In Figure 3 , the ground contact region of the tire 1 is depicted by a point-based hatching.

[0040] The camber angle θ is not a predetermined angle of zero. As Figure 1 shown in , the camber angle θ set in a circuit race is mostly -4° to -2°, and thus the absolute value of the camber angle θ is preferably 2° to 4°.

[0041] In Figure 3In the inclined load state, the tire circumferential line in which the tire circumferential length becomes the largest is indicated as an inclined ground contact center line GL.

[0042] In the tire 1 of the present embodiment, the first circumferential groove 3 is disposed on the first side S1 in the tire axial direction with respect to the inclined ground contact center line GL. Also, the second circumferential groove 4 is disposed on the second side S2 in the tire axial direction with respect to the inclined ground contact center line GL. The first side S1 and the second side S2 are in a positional relationship opposite to each other with respect to the inclined ground contact center line GL.

[0043] In the tire 1 of the present embodiment, the first circumferential groove 3 is disposed on the first side S1 and the second circumferential groove 4 is disposed on the second side S2 with respect to the inclined ground contact center line GL. That is, since the circumferential grooves are disposed on both sides of the inclined ground contact center line GL, excellent drainage performance can be obtained in the state in which the camber angle θ is imparted, particularly at the time of braking on a wet road surface. Thus, the tire 1 of the present application can exhibit excellent drainage performance in the state in which it is mounted on an actual vehicle.

[0044] It is preferable that the tread pattern TP be formed in the tread portion 2 so as to be asymmetric with respect to the tire equator CL. For example, in the tire 1 mounted on a vehicle in which a relatively large camber angle θ is set, by disposing the first circumferential groove 3 and the second circumferential groove 4 on the first side S1 with respect to the tire equator CL, the drainage performance of the first side S1 is improved, and it is easy to shorten the single lap time on a wet road surface. Also, the rigidity in the tire axial direction of the second side S2 is improved, and thus the handling stability performance on a dry road surface is improved and it is easy to shorten the single lap time.

[0045] It is preferable that the first circumferential groove 3 and the second circumferential groove 4 be disposed symmetrically with respect to the inclined ground contact center line GL. With such a first circumferential groove 3 and a second circumferential groove 4, the first circumferential groove 3 and the second circumferential groove 4 are disposed evenly with respect to the inclined ground contact center line GL in the inclined load state in which it is assumed that the tire 1 is mounted on a vehicle. Thus, the drainage performance is improved, and it is easy to shorten the single lap time on a wet road surface.

[0046] In the tire 1 of the present embodiment, since the circumferential grooves are disposed on both sides of the inclined ground contact center line GL, even if there are two circumferential grooves 3, 4, excellent drainage performance can be obtained, and it is expected that the single lap time on a wet road surface can be shortened. Thus, the number of circumferential grooves is preferably only two. Such a tire 1 has high rigidity in the tire axial direction, and it is possible to improve the handling stability performance on a dry road surface and it is expected that the single lap time can be shortened.

[0047] As Figure 2As shown, the present tire 1 has a land portion 5 in the tread portion 2 divided by the first circumferential groove 3 and the second circumferential groove 4. The vicinity of the oblique ground center line GL is a region where the ground pressure is high in the oblique load state. By providing the land portion 5 on the oblique ground center line GL, a greater cornering force is easily generated, thereby improving the cornering stability performance on a dry road surface and easily shortening the lap time.

[0048] The profile of the tread surface 20 in the land portion 5 is preferably circular arc-shaped. According to the land portion 5 in which the profile of the tread surface 20 is circular arc-shaped, as Figure 3 As shown, the ground-contacting end in the tire circumferential direction in the land portion 5 is convex. Therefore, on a wet road surface, when the land portion 5 grounds in the oblique load state, water is divided to both sides of the oblique ground center line GL by the tread surface 20 of the land portion 5 as shown by the arrows in the drawing, and flows into the circumferential grooves 3, 4. Thus, the water drainage efficiency to the circumferential grooves 3, 4 is improved, and the lap time on a wet road surface is easily shortened.

[0049] The tire axial length W of the land portion 5 is preferably 15 mm to 60 mm. By making the length W 15 mm or more, the rigidity of the tread portion 2 in the tire axial direction in the vicinity of the oblique ground center line GL is improved, thereby improving the cornering stability performance on a dry road surface and easily shortening the lap time. By making the length W 60 mm or less, the water drainage performance in the vicinity of the oblique ground center line GL is improved, and the lap time on a wet road surface is easily shortened.

[0050] The tire 1 of the present embodiment preferably designates the orientation in which the tire 1 is mounted to the vehicle 100. For example, as Figure 1 As shown, it is preferable to designate that the first side S1 is located on the inner side of the vehicle, and the second side S2 is located on the outer side of the vehicle. Thus, by the circumferential grooves 3, 4 located on the inner side of the vehicle on which a greater ground pressure acts when straight running, good water drainage performance is obtained at the time of braking, and the lap time on a wet road surface is easily shortened. Also, since the circumferential grooves 3, 4 are not provided on the outer side of the vehicle on which a greater ground pressure acts when cornering, the rigidity in the tire axial direction is improved, thereby improving the cornering stability performance on a dry road surface and easily shortening the lap time.

[0051] The present tire 1 mounted to the vehicle 100 based on the above designation has an inner side tread portion 21 and an outer side tread portion 22. The inner side tread portion 21 is the tread portion 2 located on the first side S1, that is, the inner side of the vehicle. The outer side tread portion 22 is the tread portion 2 located on the second side S2, that is, the outer side of the vehicle.

[0052] As shown, the land portion 5 has a first land portion 5a and a second land portion 5b. The first land portion 5a is located on the inner side of the vehicle, that is, the first side S1. The second land portion 5b is located on the outer side of the vehicle, that is, the second side S2. Figure 2As shown, in the tire 1, the curvature radius Rl of the profile of the tread 20 of the inner side tread portion 21 is preferably smaller than the curvature radius R2 of the profile of the tread 20 of the outer side tread portion 22. With such a curvature radius Rl of the inner side tread portion 21, the inner side tread portion 21 on which a greater ground pressure acts at the time of straight running is given a good drainage performance, and it is easy to shorten the single lap time on a wet road. With such a curvature radius R2 of the outer side tread portion 22, the ground contact area of the outer side tread portion 22 on which a greater ground pressure acts at the time of cornering is made large, and the handling stability performance on a dry road is improved and it is easy to shorten the single lap time.

[0053] Figure 4 A process of designing the tire 1 of the present embodiment is shown. The tire design method includes a calculation process #1 and a groove arrangement process #2.

[0054] In the calculation process #1, the position of the tire axis direction of the inclined ground center line GL is calculated. In the calculation of the position of the inclined ground center line GL, for example, a computer device having a CPU (Central Processing Unit) and a memory storing a program for executing the action of the CPU and various information is used.

[0055] The calculation process #1 includes a contact point calculation process #11 and an inclined ground center line calculation process #12.

[0056] Figure 5 The contact point calculation process #11 is shown. In the contact point calculation process #11, the contact point CP of the virtual line VL with the profile of the tread 20 is calculated. The "virtual line VL" is a line for calculating the contact point CP, and is a line inclined by an angle θ corresponding to the camber angle with respect to the tire axis direction in the tire meridian cross section. The angle θ is set in accordance with the wheel alignment of the vehicle on which the tire 1 is mounted.

[0057] In the contact point calculation process #11, the virtual line VL is moved in the tire radial direction, and the contact point CP of the virtual line VL with the profile of the tread 20 is calculated. The contact point CP is regarded as the center when the tire 1 to which the camber angle θ is imparted is grounded on a plane.

[0058] In the inclined ground center line calculation process #12, a line parallel to the tire circumferential direction passing through the contact point CP is calculated. The line parallel to the tire circumferential direction passing through the contact point CP is regarded as the inclined ground center line GL. Therefore, by calculating the distance from the tire equator CL to the contact point CP, a parallel line or the like shifted from the tire equator CL in the tire axis direction by the above distance is drawn, and thus the inclined ground center line GL is obtained. In the present tire design method, by regarding the above parallel line as the inclined ground center line GL, the inclined ground center line GL can be obtained by a simple calculation.

[0059] In the groove arrangement step #2, the 1st circumferential groove 3 and the 2nd circumferential groove 4 are arranged with respect to the inclined ground contact center line GL. The 1st circumferential groove 3 and the 2nd circumferential groove 4 are arranged, for example, in accordance with the tire axial length W of the land 5 set in advance. Thereafter, other grooves (for example, a cross groove extending in the tire axial direction, etc.) are arranged as necessary.

[0060] According to the present tire design method, the inclined ground contact center line GL is obtained by simple calculation, whereby the 1st circumferential groove 3 and the 2nd circumferential groove 4 are arranged, and the tread pattern TP is designed.

[0061] The above describes the tire 1 of the present application in detail, but the present application is not limited to the above-described specific embodiments, and can be implemented in various ways. For example, the present application is particularly suitable as a tire mounted on a loop running vehicle provided with a large camber angle θ, but is not limited to such a vehicle, and can be widely used for a vehicle imparted with a camber angle other than zero.

[0062] Also, grooves other than the 1st circumferential groove 3 and the 2nd circumferential groove 4, for example, a cross groove extending in the tire axial direction, etc., can be provided in the tread portion 2. Also, a circumferential groove having a width smaller than 3% of the tread width TW can be provided.

[0063]

EXAMPLE

[0064] A tire having a basic pattern of Figure 2 , 3 of size: 205 / 55R16 was trial-produced based on the specifications of Table 1, assembled on a rim of size: 16 x 7.0J, and inflated to an internal pressure of 220 kPA. The above-described rim was mounted on four wheels of an FR vehicle of displacement: 2000 cc, and the wet road performance and the dry road performance were evaluated. The specifications of each of the test tires other than those described in Table 1 were the same. The test methods were as follows.

[0065] <Wet road performance>

[0066] The above-described vehicle was brought into a test course of an asphalt road surface having a water depth of 2 mm, and the braking G at the time of full braking with one occupant was measured. The result was an index with Example 1 as 100, and the larger the value, the more excellent the wet road performance.

[0067] <Dry road performance>

[0068] The above-described vehicle was brought into the above-described test course in a dry state, and the steering stability performance with one occupant was evaluated by the sense of a test driver. The result was an index with Example 1 as 100, and the larger the value, the more excellent the dry road performance.

[0069] In addition, by taking the sum of the index of the wet road performance and the score of the dry road performance, the comprehensive performance can also be evaluated.

[0070] [Table 1]

[0071] Comparative Example 1 Comparative Example 2 Example 1 Depth of circumferential groove (mm) 6 6 6 Width of circumferential groove (mm) 10 10 10 Number of circumferential grooves 2 2 2 Position of 1st circumferential groove 1st side 2nd side 1st side Position of 2nd circumferential groove 1st side 2nd side 2nd side Wet performance (index) 85 90 100 Dry performance (score) 100 90 100

[0072] From Table 1, it is confirmed that the tire of the example can significantly improve the wet performance and the dry performance in balance compared with the comparative example.

[0073] A tire of the above size having a basic pattern of Figure 2 , 3 was trial-produced based on the specifications of Table 2, and the wet performance and the dry performance were evaluated in the same manner as the above tire.

[0074] <Wet performance>

[0075] The result is an index with Example 2 as 100, and the larger the value, the more excellent the wet performance.

[0076] <Dry performance>

[0077] The result is an index with Example 2 as 100, and the larger the value, the more excellent the dry performance.

[0078] [Table 2]

[0079]

[0080] A tire of the above size having a basic pattern of Figure 2 , 3 was trial-produced based on the specifications of Table 3, and the wet performance and the dry performance were evaluated in the same manner as the above tire.

[0081] <Wet performance>

[0082] The result is an index with Example 5 as 100, and the larger the value, the more excellent the wet performance.

[0083] <Dry performance>

[0084] The result is an index with Example 5 as 100, and the larger the value, the more excellent the dry performance.

[0085] [Table 3]

[0086] Example 5 Example 6 Depth of circumferential groove (mm) 6 6 Width of circumferential groove (mm) 10 10 Number of circumferential grooves 2 3 Position of 1st circumferential groove 1st side 1st side Position of 2nd circumferential groove 2nd side 2nd side Position of 3rd circumferential groove --- 2nd side Wet performance (index) 100 105 Dry performance (score) 100 90

[0087] A tire of the above size having a basic pattern of Figure 2 , 3 was trial-produced based on the specifications of Table 4, and the wet performance and the dry performance were evaluated in the same manner as the above tire.

[0088] <Wet performance>

[0089] The result is an index with Example 7 as 100, and the larger the value, the more excellent the wet performance.

[0090] <dry road performance>

[0091] The result is an index with Example 7 as 100, and the larger the value, the more excellent the dry road performance.

[0092] [Table 4]

[0093] Example 7 Example 8 Depth of circumferential groove (mm) 6 6 Width of circumferential groove (mm) 10 10 Number of circumferential grooves 2 2 Position of 1st circumferential groove 1st side 1st side Position of 2nd circumferential groove 2nd side 2nd side Land tread contour Straight line shape Circular arc shape Wet performance (index) 100 110 Dry performance (score) 100 100

[0094] A tire of the above size having a basic pattern of Figure 2 , 3 was trial-produced based on the specifications of Table 5, and the wet performance and dry performance were evaluated in the same manner as the above tires.

[0095] <dry road performance>

[0096] The result is an index with Example 11 as 100, and the larger the value, the more excellent the wet performance.

[0097] <dry road performance>

[0098] The result is an index with Example 11 as 100, and the larger the value, the more excellent the dry road performance.

[0099] [Table 5]

[0100] Example 9 Example 10 Example 11 Example 12 Example 13 Depth of circumferential groove (mm) 6 6 6 6 6 Width of circumferential groove (mm) 10 10 10 10 10 Number of circumferential grooves 2 2 2 2 2 Position of 1st circumferential groove 1st side 1st side 1st side 1st side 1st side Position of 2nd circumferential groove 2nd side 2nd side 2nd side 2nd side 2nd side Length W (mm) 10 15 40 60 70 Wet performance (index) 110 105 100 95 90 Dry performance (score) 90 95 100 105 110

[0101] A tire of the above size having a basic pattern of Figure 2 , 3 was trial-produced based on the specifications of Table 6, and the wet performance and dry performance were evaluated in the same manner as the above tires.

[0102] <dry road performance>

[0103] The result is an index with Example 14 as 100, and the larger the value, the more excellent the wet performance.

[0104] <dry road performance>

[0105] The result is an index with Example 14 as 100, and the larger the value, the more excellent the dry road performance.

[0106] [Table 6]

[0107] Example 14 Example 15 Example 16 Depth of circumferential groove (mm) 6 6 6 Width of circumferential groove (mm) 10 10 10 Number of circumferential grooves 2 2 2 Position of 1st circumferential groove 1st side 1st side 1st side Position of 2nd circumferential groove 2nd side 2nd side 2nd side Radius of curvature of tread portion R1 > R2 R1 = R2 R1 < R2 Wet performance (index) 100 110 120 Dry performance (score) 100 110 120

Claims

1. A tire having a tread portion, wherein a plurality of circumferential grooves are formed in the tread portion so as to extend continuously in a tire circumferential direction, when a tire circumferential line in which a ground contact length in the tire circumferential direction becomes the largest is set as an inclined ground center line when the tire is mounted on a regular rim, filled with a regular internal pressure, and grounded on a plane with a regular load applied at a predetermined camber angle which is not zero, the circumferential grooves include: a first circumferential groove which is disposed on a first side in a tire axial direction with respect to the inclined ground center line; and a second circumferential groove which is disposed on a second side in the tire axial direction with respect to the inclined ground center line, the tire is mounted at a negative camber angle, the tread portion includes an inner side tread portion which is located on an inner side of a vehicle when mounted on the vehicle by specifying an orientation toward the vehicle installation, and an outer side tread portion which is located on an outer side of the vehicle when mounted on the vehicle, in a tire meridian cross section, a radius of curvature of a profile of a tread surface of the inner side tread portion is smaller than a radius of curvature of a profile of a tread surface of the outer side tread portion, the first circumferential groove and the second circumferential groove are symmetrically disposed with respect to the inclined ground center line, the inclined ground center line being a line passing through a contact point which is a point at which an imaginary line inclined by an angle corresponding to the camber angle with respect to the tire axial direction in the tire meridian cross section contacts the profile of the tread surface of the tread portion.

2. The tire according to claim 1, wherein an absolute value of the camber angle is 2° to 4°.

3. The tire according to claim 1 or 2, wherein a tread pattern is formed in the tread portion so as to be asymmetric with respect to a tire equator.

4. The tire according to claim 1 or 2, wherein the first circumferential groove and the second circumferential groove are disposed on the first side with respect to the tire equator.

5. The tire according to claim 1 or 2, wherein a width of the circumferential groove is 3% to 10% of a tread width.

6. The tire according to claim 1 or 2, wherein the circumferential groove is only two.

7. The tire according to claim 1 or 2, wherein in a tire meridian cross section, a profile of a tread surface of a land portion divided by the first circumferential groove and the second circumferential groove is a circular arc shape.

8. The tire according to claim 7, wherein a tire axial length of the land portion is 15 mm to 60 mm.

9. A vehicle on which the tire according to any one of claims 1 to 8 is mounted, wherein the tire is mounted at a camber angle of -4° to -2° with respect to the ground.

10. A tire design method of designing the tire according to any one of claims 1 to 8, wherein the tire design method includes the following steps: a calculation step of calculating a position in the tire axial direction of the inclined ground center line; and a step of disposing the first circumferential groove and the second circumferential groove with respect to the inclined ground center line, the calculation step includes the following steps: a step of finding a contact point at which an imaginary line inclined by an angle corresponding to the camber angle with respect to the tire axial direction in a tire meridian cross section contacts a profile of a tread surface of the tread portion; and a step of calculating a position in the tire axial direction of the inclined ground center line. a step of obtaining the tilted center line of contact by a line parallel to the tire circumferential direction passing through the contact point. a step of obtaining the tilted center line of contact by a line parallel to the tire circumferential direction passing through the contact point.

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