Tire

Abstract

To make both low air resistance and satisfactory cornering power characteristics compatible.SOLUTION: A tire as one example according to an embodiment comprises a tread having grooves formed thereon and a shoulder arranged adjacent to outside in a width direction of the tread, whose direction of mounting on a vehicle is designated. A curvature radius (Rso) of an outer peripheral surface of a first shoulder positioned at an outside of a vehicle with the tire mounted on the vehicle is larger than a curvature radius (Rsi) of a second shoulder positioned at an inside of the vehicle. In the tread, when a region positioned between a tire equator and the first shoulder is defined as a first region and a region positioned between the tire equator and the second shoulder is defined as a second region, a ratio (Vo) of areas of the grooves to areas of the first region is smaller than a ratio (Vi) of areas of the grooves to the areas of the second region.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire, and more particularly to a tire in which the mounting direction with respect to a vehicle is specified.

Background Art

[0002] Conventionally, a tire in which the radius of curvature of the left and right shoulder portions is asymmetric with respect to the tire equator and the mounting direction with respect to a vehicle is specified is known (see, for example, Patent Document 1). In the tire of Patent Document 1, the radius of curvature of the shoulder located outside the vehicle in a state of being mounted on the vehicle is larger than the radius of curvature of the shoulder located inside the vehicle, and the groove area ratio and groove depth near the ground contact end of the tread satisfy predetermined conditions. Patent Document 1 describes an effect that wear of the shoulder located inside the vehicle can be effectively suppressed while maintaining handling stability and steering feel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since the air resistance of a vehicle greatly affects the fuel consumption performance, reduction of air resistance is also required for tires that form part of the vehicle. However, it is not easy to reduce air resistance without impairing the basic performance of the tire. As a result of the study by the present inventor, it has been found that when a structure considering reduction of air resistance is adopted, it particularly greatly affects the cornering power characteristics. Conventional tires including the tire of Patent Document 1 still have room for improvement in achieving both low air resistance and good cornering power characteristics.

[0005] An object of the present invention is to provide a tire capable of achieving both low air resistance and good cornering power characteristics.

Means for Solving the Problems

[0006] The tire according to the present invention includes a tread in which grooves are formed and a shoulder adjacent to the outer side in the width direction of the tread, and is a tire in which the mounting direction with respect to the vehicle is specified. In a state where the tire is mounted on the vehicle, the radius of curvature (Rso) of the outer peripheral surface of the first shoulder located on the outer side of the vehicle is larger than the radius of curvature (Rsi) of the outer peripheral surface of the second shoulder located on the inner side of the vehicle. In the tread, when the region located between the tire equator and the first shoulder is defined as the first region and the region located between the tire equator and the second shoulder is defined as the second region, the ratio (Vo) of the groove area to the area of the first region is smaller than the ratio (Vi) of the groove area to the area of the second region.

Advantages of the Invention

[0007] According to the tire of the present invention, it is possible to achieve both low air resistance and good cornering power characteristics.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, an example of an embodiment of a tire according to the present invention will be described in detail. The embodiment described below is merely an example, and the present invention is not limited to the following embodiments. In addition, a configuration formed by selectively combining each component of a plurality of embodiments and modification examples described below is included in the present invention.

[0010] FIG. 1(a) is a diagram schematically showing a part of a cross-section in the width direction of a tire 1 which is an example of an embodiment. FIG. 1(b) is a diagram showing the outline of the outer peripheral surface of the tire 1 extracted from the cross-sectional view of FIG. 1(a).

[0011] As shown in FIG. 1, the tire 1 includes a tread 10 which is a portion in contact with the road surface, and a pair of shoulders 11 adjacent to the outer side in the width direction of the tread 10. Further, the tire 1 includes a pair of sidewalls 12 extending radially inward in the tire diameter direction from each shoulder 11, and a pair of beads 13 fixed to the rim of the wheel. The tread 10, the shoulders 11, the sidewalls 12, and the beads 13 are formed in an annular shape along the tire circumferential direction. The shoulders 11, the sidewalls 12, and the beads 13 form the left and right side surfaces of the tire 1.

[0012] The tire 1 is a pneumatic tire filled with air at a predetermined pressure. The tire 1 generally includes a carcass 14, a belt 15, and an inner liner 16. The carcass 14 is a cord layer covered with rubber, and forms a skeleton of the tire 1 that withstands loads, impacts, air pressure, etc. The belt 15 is a reinforcing band disposed between the tread rubber constituting the tread 10 and the carcass 14, and tightly presses the carcass 14 to increase the rigidity of the tire 1. The inner liner 16 is a rubber layer provided on the inner peripheral surface of the carcass 14, and holds the air pressure of the tire 1. Further, the bead 13 has a bead core 17 and a bead filler 18.

[0013] The tire 1 is a tire with different radii of curvature on the surfaces of the left and right shoulders 11, and the mounting direction with respect to the vehicle is specified. As will be described in detail later, in the state where the tire 1 is mounted on the vehicle, the radius of curvature of the outer surface of the first shoulder 11A located on the outer side of the vehicle is larger than the radius of curvature of the outer surface of the second shoulder located on the inner side of the vehicle. In other words, the tire 1 is mounted on the vehicle such that the first shoulder 11A faces the outer side of the vehicle and the second shoulder 11B faces the inner side of the vehicle. In this case, the air resistance of the tire 1 can be effectively reduced.

[0014] Preferably, the tire 1 is provided with a display for indicating the mounting direction with respect to the vehicle. Generally, a symbol called a serial is provided on the side surface of the tire 1. The serial includes information such as a size code, a manufacturing date (manufacturing year and week), and a manufacturing location (manufacturing plant code). By providing the serial only on the side surface of the first shoulder 11A side of the tire 1, or by providing different serials on the side surface of the first shoulder 11A side and the side surface of the second shoulder 11B side, the mounting direction of the tire 1 with respect to the vehicle can be specified. As a specific example, the manufacturing plant code and the size code are provided on both side surfaces of the tire 1, and the manufacturing year and week are provided only on the side surface of the first shoulder 11A side.

[0015] The tread 10 has a grounding end E. In this specification, the grounding end E means both ends in the tire width direction of the region that contacts the flat road surface when a load of 70% of the normal load (maximum load capacity) at the normal internal pressure is applied in a state where the unused tire 1 is mounted on a normal rim and filled with air to reach the normal internal pressure. Also, in this specification, the grounding end E is defined as the boundary between the tread 10 and the shoulder 11. The shoulder 11 is a portion that does not contact the flat road surface during normal driving and is also called a buttless region.

[0016] Here, the "regular rim" is the rim defined by the tire standard, which is the "standard rim" in JATMA, the "Design Rim" in TRA, and the "Measuring Rim" in ETRTO. The "regular internal pressure" is the "maximum air pressure" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "INFLATION PRESSURE" in ETRTO. The "regular load" is the "maximum load capacity" in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and the "LOAD CAPACITY" in ETRTO.

[0017] The tread 10 has a plurality of main grooves 20 extending in the tire circumferential direction and a plurality of land portions partitioned by the main grooves 20. The main grooves 20 function as drainage channels for removing rainwater and the like existing between the tread 10 and the road surface. In the present embodiment, four main grooves 20 are formed in the tread 10. The four main grooves 20 have, for example, substantially the same depth and substantially the same width as each other. The land portion is a protruding portion protruding radially outward in the tire diameter direction from the reference surface of the tread 10. The reference surface is a virtual surface along the bottom surface of the main groove 20 and means the outer peripheral surface of the tread 10 when there is no land portion.

[0018] The tread 10 has, as the above land portions, a center land portion 21, a mediate land portion 22, and a shoulder land portion 23. The center land portion 21 is disposed at the center in the width direction of the tread 10, and the shoulder land portions 23 are disposed at both ends in the width direction of the tread 10. The mediate land portion 22 is disposed between the center land portion 21 and each shoulder land portion 23. In the present embodiment, cross grooves crossing each land portion in the width direction are formed, and each land portion is partitioned by the main grooves 20 and the cross grooves and formed in a block shape.

[0019] The center land portion 21 is formed on the tire equator CL along the tire circumferential direction. The tire equator CL means a line along the tire circumferential direction passing through the center in the tire width direction. In this specification, in the tread 10, the region located between the tire equator CL and the first shoulder 11A is defined as the first region R1, and the region located between the tire equator CL and the second shoulder 11B is defined as the second region R2. That is, the region from the tire equator CL to the ground contact end E on the outer side of the vehicle is the first region R1, and the region from the tire equator CL to the ground contact end E on the inner side of the vehicle is the second region R2.

[0020] In the first region R1 of the tread 10, a first intermediate land portion 22A and a first shoulder land portion 23A are formed, and in the second region R2, a second intermediate land portion 22B and a second shoulder land portion 23B are formed (see FIG. 2 described later). Although details will be described later, the block shapes of the first intermediate land portion 22A and the second intermediate land portion 22B are different from each other, and the block shapes of the first shoulder land portion 23A and the second shoulder land portion 23B are different from each other. And the ratio of the groove area to the area of the first region R1 is smaller than the ratio of the groove area to the area of the second region R2. In this case, good cornering power (CP) characteristics can be ensured.

[0021] Due to the configuration of the present invention, the boundary between the shoulder 11 and the sidewall 12 does not need to be clear, but in this embodiment, the outer end in the tire width direction of the shoulder land portion 23 extending from the tread 10 to the side surface of the tire 1 is the boundary between the shoulder 11 and the sidewall 12. Generally, the shoulder 11 and the sidewall 12 are made of different rubbers. The tread 10 and the shoulder 11 may be made of the same rubber or different rubbers.

[0022] Hereinafter, with reference to FIGS. 1 and 2, the configurations of the tread 10 and the shoulder 11 will be described in more detail. FIG. 2 is a plan view schematically showing a part of the tread 10. In FIG. 2, dot hatching is applied to the upper surface of each land portion. The upper surface of the land portion is the surface facing the outer side in the tire radial direction and is the ground contact surface of the tread 10 in contact with the road surface.

[0023] As shown in FIG. 1, the tire 1 includes a first shoulder 11A and a second shoulder 11B having different radii of curvature from each other. And, as described above, the radius of curvature (Rso) of the outer peripheral surface of the first shoulder 11A is larger than the radius of curvature (Rsi) of the outer peripheral surface of the second shoulder 11B (Rso>Rsi). FIG. 1(b) shows Rso and Rsi. As shown in FIG. 1(b), Rso is the radius of curvature of the outer peripheral surface of the first shoulder 11A in the widthwise cross-section of the tire 1, and Rsi is the radius of curvature of the outer peripheral surface of the second shoulder 11B in the widthwise cross-section of the tire 1.

[0024] The outer peripheral surface of each shoulder 11 is curved toward the outside of the tire 1, but the first shoulder 11A is less curved than the second shoulder 11B. In the example shown in FIG. 1, the outer peripheral surface of the second shoulder 11B is more angular than the outer peripheral surface of the first shoulder 11A. Note that the radius of curvature of the inner peripheral surface of each shoulder 11 is not particularly limited and, for example, may be the same for each other.

[0025] The outer peripheral surface of each shoulder 11 may have a constant radius of curvature throughout and may be formed by one arc, but in the example shown in FIG. 1, the radius of curvature of the outer peripheral surface varies in each shoulder 11. That is, the outer peripheral surface of the first shoulder 11A is formed by a plurality of arcs having different degrees of curvature. Similarly, the outer peripheral surface of the second shoulder 11B is formed by a plurality of arcs having different degrees of curvature.

[0026] When the outer peripheral surface of each shoulder 11 is formed by a plurality of arcs, the minimum value of the radius of curvature (Rso) of the outer peripheral surface of the first shoulder 11A is made larger than the minimum value of the radius of curvature (Rsi) of the outer peripheral surface of the second shoulder 11B (the minimum value of Rso > the minimum value of Rsi). That is, when comparing the radii of curvature at the portions where the degree of curvature is the largest (the portions where the curvature is the maximum) in each shoulder 11, the condition of Rso > Rsi is satisfied. The portion where the radius of curvature is the minimum is preferably closer to the ground end E than the boundary with the side wall 12. The radius of curvature of at least one of each shoulder 11 may be the minimum at the ground end E.

[0027] A preferred example of the radius of curvature (Rso) of the first shoulder 11A is 6 mm or more and 45 mm or less, more preferably 20 mm or more and 40 mm or less, or 30 mm or more and 40 mm or less. When the outer peripheral surface of the first shoulder 11A is formed by a plurality of arcs, it is preferable that at least the radius of curvature corresponding to the arc with the largest degree of curvature, that is, the minimum value of the radius of curvature, is within this range, and the radii of curvature corresponding to all the arcs may be within this range. If the radius of curvature (Rso) is within this range, it is possible to effectively reduce the air resistance while maintaining good CP characteristics.

[0028] A preferred example of the radius of curvature (Rsi) of the second shoulder 11B is 1 mm or more and 40 mm or less, more preferably 2 mm or more and less than 20 mm, or 2 mm or more and 10 mm or less. When the outer peripheral surface of the second shoulder 11B is formed by a plurality of arcs, it is preferable that at least the minimum value of the radius of curvature is within this range. Although it will be described in detail later, if the radius of curvature (Rsi) is within this range, the air flow received from the front of the tire 1 when the vehicle is running can be effectively changed into a propulsive force that pushes the tire 1 in the vehicle traveling direction.

[0029] Regarding the radius of curvature of each shoulder 11, it is preferable to satisfy the condition of 5 mm ≤ Rso - Rsi. In this case, the effect of reducing the air resistance of the tire 1 becomes more remarkable. The difference (Rso - Rsi) in the radius of curvature of each shoulder 11 is more preferably 10 mm or more, particularly preferably 20 mm or more, or 25 mm or more. Considering only the reduction of air resistance, the upper limit of the difference (Rso - Rsi) in the radius of curvature is not particularly limited. However, if the difference becomes too large, for example, it will affect the wear of the tire 1 and reduce the durability. Therefore, 50 mm or less is preferable. More preferably, it is 40 mm or less, and particularly preferably 35 mm or less. An example of the preferable range of the difference (Rso - Rsi) in the radius of curvature is 5 mm ≤ Rso - Rsi ≤ 50 mm.

[0030] As described above, since the radius of curvature of each shoulder 11 of the tire 1 is Rso > Rsi, the contact width of the first region R1 of the tread 10 located on the outer side of the vehicle is narrower than the contact width of the second region R2 of the tread 10 located on the inner side of the vehicle. That is, the length from the tire equator CL to the contact end E located on the outer side of the vehicle is slightly shorter than the length from the tire equator CL to the contact end E located on the inner side of the vehicle.

[0031] As shown in FIG. 2, the tread 10 has a tread pattern that is asymmetric with respect to the tire equator CL. As described above, the block shapes of the land portions in the first region R1 and the second region R2 of the tread 10 are different, and the ratio of the area of the grooves to the area of each region is different. The area of each region means the total area of each region including the grooves in the plan view of the tread 10. The area of the grooves means the area of the grooves in the plan view of the tread 10.

[0032] In the present embodiment, four main grooves 20 are formed in the first region R1 and the second region R2 in two each with the same width and the same depth. Further, the center land portion 21 has a shape that is symmetric with respect to the tire equator CL. A transverse groove 24 having a certain width is formed across the entire width of the land portion in the center land portion 21. On the other hand, the area of the transverse grooves formed in each intermediate land portion 22 and each shoulder land portion 23 is different between the first region R1 and the second region R2.

[0033] In the example shown in FIG. 2, the number of transverse grooves 25A formed in the first intermediate land portion 22A of the first region R1 is smaller than the number of transverse grooves 25B formed in the second intermediate land portion 22B of the second region R2. Also, the width of the transverse groove 26A formed in the first shoulder land portion 23A of the first region R1 is smaller than the width of the transverse groove 26B formed in the second shoulder land portion 23B of the second region R2. And the ratio (Vo) of the groove area to the area of the first region R1 is smaller than the ratio (Vi) of the groove area to the area of the second region R2 (Vo < Vi).

[0034] As described above, for the tire 1, the contact width of the first region R1 is narrower than the contact width of the second region R2. Generally, when the contact width becomes narrower, the CP characteristics deteriorate. However, according to the tire 1, by reducing the groove area ratio (Vo) of the first region R1, the contact area is expanded, and good CP characteristics are ensured. Also, since the transverse grooves also affect the air resistance, reducing the groove area ratio (Vo) of the first region R1 suppresses the turbulent flow generated due to the transverse grooves and also contributes to reducing the air resistance.

[0035] Regarding the groove area ratio of the tread 10, it is preferable to satisfy the condition of Vi - Vo ≤ 15%. If the difference (Vi - Vo) in the groove area ratio is too large, for example, the left - right rigidity balance of the tire may be disrupted, and the basic performance of the tire including the CP characteristics may deteriorate. For this reason, the difference (Vi - Vo) in the groove area ratio is preferably 15% or less, more preferably 14% or less, and particularly preferably 13% or less.

[0036] An example of the groove area ratio (Vo) of the first region R1 is 15% or more and 35% or less. If Vo is within this range, good CP characteristics can be ensured without impairing the performance such as drainage characteristics and braking characteristics. An example of the groove area ratio (Vi) of the second region R2 is 20% or more and 40% or less. An example of the preferable range of the difference (Vi - Vo) in the groove area ratio is 5% ≤ Vi - Vo ≤ 15%.

[0037] The number of the transverse grooves 25A formed in the first intermediate land portion 22A is, for example, not less than two times and not more than five times the number of the transverse grooves 25B formed in the second intermediate land portion 22B. The transverse grooves 25A and 25B are each arranged at equal intervals in the tire circumferential direction, for example. The widths of the transverse grooves 25A and 25B may be the same, or the width of the transverse groove 25A may be greater than the width of the transverse groove 25B. However, in a plan view of the tread 10, it is preferable that the total area of the transverse grooves 25A is smaller than the total area of the transverse grooves 25B.

[0038] The width of the transverse groove 26A formed in the first shoulder land portion 23A is, for example, not less than 0.5 times and less than 1.0 times, or not less than 0.5 times and not more than 0.8 times the width of the transverse groove 26B formed in the second shoulder land portion 23B. The transverse grooves 26A and 26B are each arranged at equal intervals in the tire circumferential direction, for example. The number of the transverse grooves 26A and 26B may be the same, or the number of the transverse grooves 26A may be greater than the number of the transverse grooves 26B. However, in a plan view of the tread 10, it is preferable that the total area of the transverse grooves 26A is smaller than the total area of the transverse grooves 26B.

[0039] According to the tire 1 having the above-described configuration, it is possible to achieve both low air resistance and good CP characteristics. Hereinafter, with reference to FIG. 3, the operation and effect of such a tire 1 will be described in detail. FIG. 3 is a diagram schematically showing a part of a vehicle 100 to which the tire 1 is mounted. For comparison, a conventional tire 2 is shown in FIG. 4.

[0040] As shown in FIGS. 3 and 4, when the vehicle 100 travels, air hits the tires 1 and 2, and air resistance is generated by the tires 1 and 2. On the other hand, when air hits the tires 1 and 2, the air flow is disturbed on the sides of the tires 1 and 2, and a swirling turbulent flow is generated. Since this turbulent flow flows in the traveling direction of the vehicle, a propulsive force that pushes the tires 1 and 2 in the traveling direction is generated. Since the side surfaces of the tires 1 and 2 located inside the vehicle 100 are widely covered by the vehicle body, a swirling turbulent flow that promotes the rotation of the tires 1 and 2 is likely to be generated inside the vehicle, and an effective propulsive force can be obtained. On the other hand, as a result of the study by the present inventor, it has been found that outside the vehicle 100, the generated swirl is small and an effective propulsive force cannot be obtained.

[0041] Therefore, in the tire 1, the radius of curvature (Rsi) of the second shoulder 11B located inside the vehicle 100 is reduced to make it susceptible to turbulent flow, and the radius of curvature (Rso) of the first shoulder 11A located outside the vehicle 100 is increased to smooth the air flow. By reducing the radius of curvature (Rsi) to make the second shoulder 11B angular, it becomes easier to generate a swirling turbulent flow and to receive the turbulent flow. On the other hand, since the effect of turbulent flow is small outside the vehicle 100, by increasing the radius of curvature (Rso) to gently curve the first shoulder 11A, the air is smoothly flowed from the front to the rear, reducing the air resistance.

[0042] That is, according to the tire 1, it is possible to greatly reduce the air resistance as a whole by actively using the swirling turbulent flow inside the vehicle and suppressing the generation of turbulent flow outside the vehicle to smooth the air flow. In the conventional tire 2, an effective propulsive force due to turbulent flow cannot be obtained outside the vehicle, and a large air resistance is generated. On the other hand, in the tire 1, since the radius of curvature of each shoulder 11 is Rso > Rsi, the contact width is narrower in the first region R1 of the tread 10 located outside the vehicle than in the second region R2 of the tread 10 located inside the vehicle with respect to the tire equator CL.

[0043] Therefore, in the tire 1, by setting the groove area ratio of each region to Vo < Vi, good CP characteristics are ensured. In particular, since the lateral grooves also affect the air resistance, reducing the area of the lateral grooves in the first region R1 also contributes to reducing the air resistance. In a speed range where centrifugal force is generated, the vehicle cannot turn unless a cornering force (CF) that balances the centrifugal force acts on the contact surface. The cornering power (CP) represents the gradient of the CF near a slip angle of zero. When turning the steering wheel, the traveling direction and the direction in which the tire is facing do not match, and this angle is called the slip angle. Generally, when the contact width becomes narrower, the CP characteristics deteriorate and slipping becomes easier, but according to the tire 1, a high CP value can be obtained.

[0044] Note that the above-described embodiments can be appropriately modified in design without impairing the object of the present invention. For example, if the groove area ratio in the tread satisfies the condition of Vo < Vi, the left and right intermediate land portions may have the same shape, or the left and right shoulder land portions may have the same shape. However, it is preferable that the total area of the lateral grooves of the shoulder land portion located outside the vehicle in the state where the tire is mounted on the vehicle is smaller than the total area of the lateral grooves of the shoulder land portion located inside the vehicle.

[0045] In addition, in the above-described embodiment, a tread pattern having block-shaped land portions partitioned by main grooves and lateral grooves is exemplified, but each land portion may be continuously formed in a rib shape in the tire circumferential direction. The tread pattern shown in FIG. 2 is an example of a suitable pattern, but the tread pattern is not limited thereto.

Explanation of Reference Numerals

[0046] 1 Tire, 10 Tread, 11 Shoulder, 11A First Shoulder, 11B Second Shoulder, 12 Sidewall, 13 Bead, 14 Carcass, 15 Belt, 16 Inner Liner, 17 Bead Core, 18 Bead Filler, 20 Main Groove, 21 Center Land Portion, 22 Intermediate Land Portion, 22A First Intermediate Land Portion, 22B Second Intermediate Land Portion, 23 Shoulder Land Portion, 23A First Shoulder Land Portion, 23B Second Shoulder Land Portion, 24, 25A, 25B, 26A, 26B Lateral Grooves, E Contact End, R1 First Region, R2 Second Region

Claims

1. A tire comprising a tread with grooves formed therein and a shoulder adjacent to the outer side in the width direction of the tread, wherein the mounting direction with respect to the vehicle is specified, and when the tire is mounted on the vehicle, the radius of curvature (Rso) of the outer peripheral surface of the first shoulder located on the outer side of the vehicle is larger than the radius of curvature (Rsi) of the outer peripheral surface of the second shoulder located on the inner side of the vehicle, the radius of curvature (Rso) is 30 mm or more and 40 mm or less, the radius of curvature (Rsi) is 2 mm or more and less than 20 mm, the difference (Rso - Rsi) between the radius of curvature (Rso) and the radius of curvature (Rsi) is 20 mm or more, in the tread, when the region located between the tire equator and the first shoulder is defined as the first region and the region located between the tire equator and the second shoulder is defined as the second region, the ratio (Vo) of the groove area to the area of the first region is smaller than the ratio (Vi) of the groove area to the area of the second region. A tire.

2. The radius of curvature (Rsi) is 2 mm or more and 10 mm or less, The difference (Rso - Rsi) between the radius of curvature (Rso) and the radius of curvature (Rsi) is 25 mm or more. The tire according to claim 1.

3. The tire according to claim 1 or 2, wherein the groove area ratio of the tread satisfies the condition of 5% ≤ Vi - Vo ≤ 15%.

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