Tire

Abstract

To provide a tire having a tread part constituted of five land parts, which is improved in noise performance and braking performance, while maintaining wet performance.SOLUTION: The tire comprises a tread part 2 in which a direction of mounting to a vehicle is designated. The tread part 2 includes five land parts 4 partitioned into four circumferential grooves 3. An inner shoulder land part 11 is smallest in width in a tire axial direction of a grounding surface among the five land parts 4. An inner shoulder lateral groove 16 extends from an inner end away by a certain distance in the tire axial direction from the inner shoulder circumferential groove 5 up to a position beyond an inner tread end Ti. Inner shoulder sipes 17 extend from the inner shoulder circumferential groove 5 up to the position beyond the inner tread end Ti.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Conventionally, various tires (hereinafter sometimes referred to as "five-rib tires") in which the tread portion is composed of five land portions in the tire axial direction have been proposed. Further, the pneumatic tire of Patent Document 1 below is a five-rib tire, and regulates the groove volume ratios of the crown rib, the middle rib, and the shoulder rib in relation to each other, aiming to enhance the cornering power and improve the handling stability performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent tires, it has been required to achieve both reduction of vehicle exterior noise and improvement of braking performance, and this tendency is particularly remarkable in Europe. It is considered effective to reduce the volume of the grooves in the tread portion in order to reduce vehicle exterior noise and improve braking performance. However, such a method is accompanied by deterioration of wet performance.

[0005] The present invention has been devised in view of the above actual situation, and with a tire having a tread portion composed of five land portions as a premise, the main problem is to improve the noise performance and the braking performance while maintaining the wet performance.

Means for Solving the Problems

[0006] The present invention relates to a tire having a tread portion with a specified mounting orientation on a vehicle. The tread portion includes an outer tread end that becomes the outside of the vehicle when mounted on the vehicle, an inner tread end that becomes the inside of the vehicle when mounted on the vehicle, four circumferential grooves that continuously extend in the tire circumferential direction between the outer tread end and the inner tread end, and five land portions divided by the four circumferential grooves. The four circumferential grooves include an inner shoulder circumferential groove arranged on the innermost tread end side among the circumferential grooves. The five land portions include an inner shoulder land portion arranged on the outer side in the tire axial direction of the inner shoulder circumferential groove. The inner shoulder land portion is the smallest among the five land portions in terms of the width in the tire axial direction of the ground contact surface. A plurality of inner shoulder transverse grooves and a plurality of inner shoulder sipes are provided in the inner shoulder land portion. The inner shoulder transverse grooves extend from the inner end spaced apart in the tire axial direction from the inner shoulder circumferential groove to a position beyond the inner tread end. The inner shoulder sipes extend from the inner shoulder circumferential groove to a position beyond the inner tread end.

[0007] In the tire of the present invention, it is desirable that each of the inner shoulder sipes has chamfered portions formed at both side sipes edges.

[0008] In the tire of the present invention, it is desirable that the five land portions are formed to be larger as they are located closer to the outer tread end side in terms of the width in the tire axial direction of the ground contact surface.

[0009] In the tire of the present invention, the land portions include a crown land portion arranged on the tire equator. It is desirable that the width in the tire axial direction of the ground contact surface of the inner shoulder land portion is 90% or more of the width in the tire axial direction of the ground contact surface of the crown land portion.

[0010] In the tire of the present invention, it is desirable that the center position in the tire axial direction of the crown land portion is located on the outer tread end side of the tire equator.

[0011] In the tire of the present invention, it is desirable that the maximum groove width of the inner shoulder circumferential groove is 55 to 70% of the tire axial width of the ground contact surface of the inner shoulder land portion.

[0012] In the tire of the present invention, the five land portions include an inner middle land portion adjacent to the inner shoulder land portion via the inner shoulder circumferential groove, and it is desirable that a plurality of inner middle transverse grooves that completely cross the inner middle land portion in the tire axial direction are provided in the inner middle land portion.

[0013] In the tire of the present invention, it is desirable that the circumferential distance between the end of the inner middle transverse groove on the inner shoulder circumferential groove side and the end of the inner shoulder sidewall on the inner shoulder circumferential groove side is 15% or less of the circumferential distance from the inner shoulder transverse groove to the inner shoulder sidewall at the inner tread end.

[0014] In the tire of the present invention, the five land portions include an inner middle land portion adjacent to the inner shoulder land portion via the inner shoulder circumferential groove, and a plurality of inner middle sidewalls are provided in the inner middle land portion, and it is desirable that each of the inner middle sidewalls extends in the tire axial direction from the inner shoulder circumferential groove and is interrupted within the inner middle land portion.

[0015] In the tire of the present invention, it is desirable that the tire axial length of each of the inner middle sidewalls is 30% to 70% of the tire axial width of the ground contact surface of the inner middle land portion.

[0016] In the tire of the present invention, it is desirable that each of the inner middle sidewalls has chamfered portions formed at each of the sidewall edges on both sides.

[0017] In the tire of the present invention, it is desirable that the maximum depth of the chamfered portion of the inner middle sidewall is smaller than the maximum depth of the chamfered portion of the inner shoulder sidewall.

[0018] In the tire of the present invention, it is desirable that the maximum opening width of the inner middle size is smaller than the maximum opening width of the inner shoulder size.

Advantages of the Invention

[0019] By adopting the above configuration, the tire of the present invention can improve the noise performance and braking performance while maintaining the wet performance.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment is suitably used, for example, as a pneumatic tire for a passenger car. However, the present invention is not limited to such a mode and may be applied to a pneumatic tire for heavy loads or a non-pneumatic tire in which the inside of the tire is not filled with pressurized air.

[0022] As shown in FIG. 1, the tire 1 of the present invention has a tread portion 2 with a specified mounting direction on the vehicle. The tread portion 2 has an outer tread end To that becomes the outer side of the vehicle when the tire 1 is mounted on the vehicle, and an inner tread end Ti that becomes the inner side of the vehicle when the tire 1 is mounted on the vehicle. The mounting direction on the vehicle is indicated, for example, by letters or symbols on a sidewall portion (not shown).

[0023] The outer tread end To and the inner tread end Ti respectively correspond to the outermost grounding positions in the tire axial direction when 50% of the normal load is applied to the tire 1 in the normal state and the tire is grounded on a plane at a camber angle of 0°.

[0024] The "normal state" means that in the case of a pneumatic tire with various standards defined, the tire is rim - assembled on a normal rim and filled with a normal internal pressure, and moreover, it is in a non - loaded state. In the case of a tire without various defined standards or a non - pneumatic tire, the "normal state" means a standard use state according to the purpose of use of the tire, which is a state where the tire is not mounted on a vehicle and is non - loaded. In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the above - mentioned normal state.

[0025] The "normal rim" is the rim defined for each tire in a standard system including the standards on which the tire is based. For example, in JATMA, it is the "standard rim", in TRA, it is the "Design Rim", and in ETRTO, it is the "Measuring Rim".

[0026] The "normal internal pressure" is the air pressure defined for each tire in a standard system including the standards on which the tire is based. In JATMA, it is the "maximum air pressure", in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in ETRTO, it is the "INFLATION PRESSURE".

[0027] "Normal load" means, in the case of a pneumatic tire for which various standards are defined, the load defined for each tire in the standard system including the standards on which the tire is based. For JATMA, it is the "maximum load capacity"; for TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; for ETRTO, it is "LOAD CAPACITY". In the case of a tire for which no various standards are defined or a non-pneumatic tire, the "normal load" refers to the load acting on one tire in the standard mounting state of the tire. The "standard mounting state" refers to a state in which the tire is mounted on a standard vehicle according to the purpose of use of the tire and the vehicle is stationary on a flat road surface in a state where it can run.

[0028] The tread portion 2 includes four circumferential grooves 3 that continuously extend in the tire circumferential direction between the outer tread end To and the inner tread end Ti, and five land portions 4 divided by the four circumferential grooves 3.

[0029] The circumferential grooves 3 include an inner shoulder circumferential groove 5 arranged on the innermost inner tread end Ti side among the four circumferential grooves 3. Further, the circumferential grooves 3 include an inner crown circumferential groove 6, an outer shoulder circumferential groove 7, and an outer crown circumferential groove 8. The inner crown circumferential groove 6 is provided between the tire equator C and the inner shoulder circumferential groove 5. The outer shoulder circumferential groove 7 is arranged on the outermost outer tread end To side among the four circumferential grooves 3. The outer crown circumferential groove 8 is arranged between the outer shoulder circumferential groove 7 and the tire equator C.

[0030] The tire axial distance L1 from the tire equator C to the groove center line of the outer shoulder circumferential groove 7 or the inner shoulder circumferential groove 5 is desirably, for example, 25% to 35% of the tread width TW. The tire axial distance L2 from the tire equator C to the groove center line of the outer crown circumferential groove 8 or the inner crown circumferential groove 6 is desirably, for example, 5% to 15% of the tread width TW. Note that the tread width TW is the tire axial distance from the outer tread end To to the inner tread end Ti in the normal state.

[0031] Each circumferential groove 3 of the present embodiment extends linearly in parallel with the tire circumferential direction, for example. Each circumferential groove 3 may extend in a wavy shape, for example.

[0032] The circumferential groove 3 of the present embodiment has a groove width of 3.0 mm or more. The groove width W1 of each circumferential groove 3 is desirably, for example, 2.0% to 8.0% of the tread width TW. In the present embodiment, the outer shoulder circumferential groove 7 has the smallest groove width among the four circumferential grooves 3. However, the present invention is not limited to such a mode. The depth of each circumferential groove 3 is, for example, 5 to 10 mm in the case of a pneumatic tire for a passenger car.

[0033] The five land portions 4 include the inner shoulder land portion 11 disposed outside the inner shoulder circumferential groove 5 in the tire axial direction. Further, the five land portions 4 include the outer shoulder land portion 12, the outer middle land portion 13, the crown land portion 14, and the inner middle land portion 15. The outer shoulder land portion 12 is disposed outside the outer shoulder circumferential groove 7 in the tire axial direction. The outer middle land portion 13 is partitioned between the outer shoulder circumferential groove 7 and the outer crown circumferential groove 8. The crown land portion 14 is partitioned between the outer crown circumferential groove 8 and the inner crown circumferential groove 6. The inner middle land portion 15 is partitioned between the inner shoulder circumferential groove 5 and the inner crown circumferential groove 6.

[0034] Fig. 2 shows an enlarged view of the ground contact surface shape of the tread portion 2 when it contacts the ground. Note that this ground contact surface shape is the shape of the ground contact surface in the 50% load state where the normal tire 1 is loaded with 50% of the normal load and grounded on a flat surface at a camber angle of 0°. As shown in Fig. 2, in the present invention, the inner shoulder land portion 11 is the smallest among the five land portions 4 in terms of the width of the ground contact surface in the tire axial direction.

[0035] Fig. 3 shows an enlarged view of the inner shoulder land portion 11 and the inner middle land portion 15. As shown in Fig. 3, the inner shoulder land portion 11 is provided with a plurality of inner shoulder transverse grooves 16 and a plurality of inner shoulder sipes 17.

[0036] The inner shoulder transverse groove 16 extends from the inner end 16a which is at a distance in the tire axial direction from the inner shoulder circumferential groove 5 to a position beyond the inner tread end Ti. Further, the inner shoulder sipe 17 extends from the inner shoulder circumferential groove 5 to a position beyond the inner tread end Ti.

[0037] In this specification, a "sipe" refers to a cut element having a small width, and the width between two inner walls facing each other is 1.5 mm or less. The width of the sipe is preferably 0.5 to 1.5 mm. A chamfered portion having a width exceeding 1.5 mm may be continuous with the opening of the sipe. Also, a flask bottom having a width exceeding 1.5 mm may be continuous with the bottom of the sipe.

[0038] By adopting the above configuration, the tire of the present invention can improve the noise performance and braking performance while maintaining the wet performance. The following mechanism is speculated as the reason.

[0039] As shown in FIGS. 2 and 3, in the present invention, since the width of the grounding surface of the inner shoulder land portion 11 is small, when driving on a wet road, the inner shoulder land portion 11 can easily cut through the water film on the wet road surface, and the wet performance is maintained. Also, such an inner shoulder land portion 11 can be expected to reduce the impact sound when grounding. Further, since the inner shoulder transverse groove 16 does not communicate with the inner shoulder circumferential groove 5, the pumping sound is small, and further improvement in noise performance can be expected.

[0040] On the other hand, the inventors have found that the combination of the inner shoulder land portion 11 with a small grounding surface width and the inner shoulder transverse groove 16 that does not communicate with the inner shoulder circumferential groove 5 tends to cause distortion when the grounding surface touches the ground, resulting in uneven ground pressure and deteriorating braking performance.

[0041] To address such a problem, as described above, in the present invention, an inner shoulder siped portion 17 is provided on the inner shoulder land portion 11. Thereby, the above-described distortion of the grounding surface is reduced, the ground pressure is equalized, and excellent braking performance can be obtained. It is presumed that the tire of the present invention can improve the noise performance and the braking performance while maintaining the wet performance by the above mechanism.

[0042] FIG. 4 shows a cross-sectional view taken along line A-A of FIG. 3. As shown in FIG. 4, in a more desirable embodiment, in the present embodiment, each of the inner shoulder siped portions 17 has chamfered portions 18 formed at each of the siped edges on both sides. Thereby, the above-described distortion of the grounding surface is further reduced, and even better performance can be obtained. However, the present invention is not limited to such an embodiment, and the inner shoulder siped portion 17 may have, for example, an edge where the grounding surface of the land portion and the siped wall extending in the tire radial direction intersect substantially at a right angle.

[0043] Hereinafter, a more detailed configuration of the present embodiment will be described. Note that each configuration described below shows a specific aspect of the present embodiment. Therefore, it goes without saying that the present invention can exhibit the above-described effects even if it does not have the configurations described below. Further, even if any one of the configurations described below is applied alone to the tire of the present invention having the above-described characteristics, an improvement in performance corresponding to each configuration can be expected. Furthermore, when some of the configurations described below are applied in combination, a composite improvement in performance corresponding to each configuration can be expected.

[0044] As shown in FIG. 2, it is desirable that the five land portions 4 of the tread portion 2 are formed larger in the tire axial direction width of the ground contact surface as the land portion 4 located closer to the outer tread end To side. Such a tire 1 has a larger rigidity in the land portion closer to the outer tread end To. For this reason, even when the center of the ground contact surface moves to the outer tread end To side by steering, the feel of steering is stable, and a cornering force is generated linearly with respect to an increase in the steering angle. Thereby, excellent steering stability and ride comfort are obtained.

[0045] Specifically, it is desirable that the tire axial direction width Wis of the ground contact surface of the inner shoulder land portion 11 is 90% or more, more desirably 90% to 99%, of the tire axial direction width Wc of the ground contact surface of the crown land portion 14. Similarly, it is desirable that the tire axial direction width Wim of the ground contact surface of the inner middle land portion 15 is 90% to 99% of the width Wc of the crown land portion 14.

[0046] It is desirable that the tire axial direction width Wom of the ground contact surface of the outer middle land portion 13 is 101% to 107% of the width Wc of the crown land portion 14. It is desirable that the tire axial direction width Wos of the ground contact surface of the outer shoulder land portion 12 is 114% to 124% of the width Wc of the crown land portion 14. Such a tire 1 of the present embodiment exhibits excellent initial responsiveness and steering stability by, for example, the front wheels and the rear wheels exerting a well-balanced cornering force when mounted on all the wheels of a vehicle.

[0047] As shown in FIG. 3, it is desirable that the maximum groove width W2 of the inner shoulder circumferential groove 5 is 55 to 70% of the tire axial width Wis of the ground contact surface of the inner shoulder land portion 11. Such an inner shoulder circumferential groove 5 improves wet performance and noise performance in a well-balanced manner.

[0048] The inner shoulder transverse groove 16 extends, for example, at an angle of 10° or less with respect to the tire axial direction. Further, the inner shoulder transverse groove 16 crosses, for example, the center position in the tire axial direction of the ground contact surface of the inner shoulder land portion 11. There are no sipe or other grooves arranged between the inner end 16a of the inner shoulder transverse groove 16 and the inner shoulder circumferential groove 5. The tire axial length L3 of the inner shoulder transverse groove 16 is, for example, 70% to 85% of the width Wis of the ground contact surface of the inner shoulder land portion 11.

[0049] The inner shoulder sipe 17 extends, for example, along the inner shoulder transverse groove 16. The angular difference between the inner shoulder sipe 17 and the inner shoulder transverse groove 16 is 5° or less, and in this embodiment, they extend in parallel.

[0050] As shown in FIG. 4, the depth d1 of the inner shoulder sipe 17 is, for example, 3.0 to 5.0 mm. The chamfered portion 18 of the inner shoulder sipe 17 includes, for example, an inclined surface 18a inclined at an angle θ1 of 30 to 60° with respect to the sipe depth direction. The depth d2 of the chamfered portion 18 is, for example, 0.5 to 2.0 mm. The width W3 of the chamfered portion 18 in the tread plan view is, for example, 2.0 to 4.0 mm. Such a chamfered portion 18 reliably improves braking performance.

[0051] As shown in FIG. 3, a plurality of inner middle transverse grooves 20 are provided in the inner middle land portion 15. The inner middle transverse grooves 20 completely cross the inner middle land portion 15 in the tire axial direction. Such inner middle transverse grooves 20 help improve wet performance. However, the present invention is not limited to such an embodiment, and as will be described later, only sipes may be provided in the inner middle land portion 15.

[0052] The inner middle transverse groove 20 extends linearly, for example, with a constant groove width W5. The groove width W5 of the inner middle transverse groove 20 is smaller than the maximum groove width W4 of the inner shoulder transverse groove 16 within the grounding surface of the inner shoulder land portion 11, and is desirably 30% to 50% of the groove width W4.

[0053] The inner middle transverse groove 20 is inclined, for example, with respect to the tire axial direction. In each figure of this specification, the inner middle transverse groove 20 is inclined downward to the right, and hereinafter, such an inclination direction may be referred to as "inclined in the first direction with respect to the tire axial direction". The angle θ2 of the inner middle transverse groove 20 with respect to the tire axial direction is larger than the angle of the inner shoulder transverse groove 16 with respect to the tire axial direction, and is, for example, 15 to 45°. Such an inner middle transverse groove 20 provides frictional force in the tire axial direction during wet running.

[0054] The circumferential pitch length of one pitch of the plurality of inner middle transverse grooves 20 is, for example, 80% to 120% of the circumferential pitch length of one pitch of the plurality of inner shoulder sipes 17, and in a preferred embodiment, these are the same.

[0055] The distance L5 in the tire circumferential direction between the end on the inner shoulder circumferential groove 5 side of the inner middle transverse groove 20 (which is the end of the groove center line of the inner middle transverse groove 20) and the end on the inner shoulder circumferential groove 5 side of the inner shoulder sipe (which is the end of the sipe center line of the inner shoulder sipe 17) is 15% or less of the distance L4 in the tire circumferential direction from the inner shoulder transverse groove 16 to the inner shoulder sipe 17 at the inner tread end Ti. Note that the distance L4 means the distance between the groove center line of the inner shoulder transverse groove 16 and the sipe center line of the inner shoulder sipe 17 on the inner tread end Ti. Thereby, it is possible to prevent the pitch sounds of the inner middle transverse groove 20 and the inner shoulder transverse groove 16 from overlapping, and it is possible to achieve uniformization of the contact pressure between the inner shoulder land portion 11 and the inner middle land portion 15.

[0056] FIG. 5 shows an enlarged view of the crown land portion 14, the outer middle land portion 13, and the outer shoulder land portion 12. As shown in FIG. 5, the center position of the crown land portion 14 in the tire axial direction is located on the outer tread end To side with respect to the tire equator C. The width Wco in the tire axial direction of the outer ground contact surface 14a of the crown land portion 14 is larger than the width Wci in the tire axial direction of the inner ground contact surface 14b of the crown land portion 14. Specifically, the width Wco is 51% to 55% of the width Wc in the tire axial direction of the ground contact surface of the crown land portion 14. Thereby, while suppressing uneven wear of the crown land portion 14, the handling stability is improved. Note that the outer ground contact surface 14a means the ground contact surface on the outer tread end To side with respect to the tire equator C of the crown land portion 14. The inner ground contact surface 14b means the ground contact surface on the inner tread end Ti side with respect to the tire equator C of the crown land portion 14.

[0057] A plurality of outer crown sipes 21 and a plurality of inner crown sipes 22 are provided in the crown land portion 14. The outer crown sipes 21 extend from the outer crown circumferential groove 8 and are interrupted within the crown land portion 14. The inner crown sipes 22 extend from the inner crown circumferential groove 6 and are interrupted within the crown land portion 14.

[0058] It is desirable that the outer crown sipes 21 and the inner crown sipes 22 do not cross the tire equator C and the center position of the crown land portion 14 in the tire axial direction, respectively. The length L10 in the tire axial direction of the outer crown sipes 21 and the inner crown sipes 22 is, for example, 20% to 40% of the width Wc of the ground contact surface of the crown land portion 14.

[0059] The outer crown side rib 21 and the inner crown side rib 22 are each inclined in the first direction with respect to the tire axial direction. The angles of the outer crown side rib 21 and the inner crown side rib 22 with respect to the tire axial direction are, for example, 15 to 45°. In a desirable embodiment, the outer crown side rib 21 and the inner crown side rib 22 are arranged in parallel, and in a more desirable embodiment, they are arranged in parallel with the inner middle lateral groove 20 (shown in FIG. 3). Such outer crown side rib 21 and inner crown side rib 22 are helpful for suppressing uneven wear of the crown land portion 14 and the inner middle land portion 15.

[0060] In a tread plan view, it is desirable that the region where the outer crown side rib 21 is extended in parallel in its length direction overlaps with the inner crown side rib 22. Also, as shown in FIG. 1, it is desirable that the end of the inner crown side rib 22 on the inner crown circumferential groove 6 side is displaced in the tire circumferential direction with respect to the end of the inner middle lateral groove 20 on the inner crown circumferential groove 6 side. Such an arrangement of the outer crown side rib 21 and the inner crown side rib 22 can white-noise the pitch noise of each side rib and improve the noise performance.

[0061] As shown in FIG. 3, it is desirable that each of the outer crown side rib 21 and the inner crown side rib 22 has a chamfered portion 23 formed at each of the side rib edges on both sides. This chamfered portion 23 includes an inclined surface similar to the chamfered portion 18 of the inner shoulder side rib 17 (shown in FIG. 4). Also, the depth and width of this chamfered portion 23 are each 1.0 to 3.0 mm.

[0062] A plurality of outer middle lateral grooves 24 are provided in the outer middle land portion 13. The outer middle lateral grooves 24 completely cross the outer middle land portion 13 in the tire axial direction. Such outer middle lateral grooves 24 are helpful for improving wet performance.

[0063] The outer middle transverse groove 24 is inclined, for example, with respect to the tire axis direction. The outer middle transverse groove 24 is inclined, for example, in a second direction opposite to the first direction with respect to the tire axis direction. The maximum angle θ3 of the outer middle transverse groove 24 with respect to the tire axis direction is, for example, 40 to 50°. Such an outer middle transverse groove 24 can enhance the turning performance on a wet road surface.

[0064] The outer middle transverse groove 24 of the present embodiment is curved in an S shape by including a portion curved in a direction convex toward one side in the tire circumferential direction and a portion curved in a direction convex toward the other side in the tire circumferential direction. Such an outer middle transverse groove 24 can further enhance the wet performance.

[0065] The distance L6 in the tire circumferential direction between the end of the outer middle transverse groove 24 on the side of the outer crown circumferential groove 8 and the end of the outer crown sipe 21 on the side of the outer crown circumferential groove 8 is preferably 15% or less of the pitch length P1 in the tire circumferential direction of the outer crown sipe 21. Such an arrangement of the outer middle transverse groove 24 helps to equalize the contact pressures of the outer middle land portion 13 and the crown land portion 14.

[0066] A plurality of outer shoulder transverse grooves 30 and a plurality of outer shoulder sipers 31 are provided in the outer shoulder land portion 12. The outer shoulder transverse grooves 30 and the outer shoulder sipers 31 each completely cross the outer shoulder land portion 12 in the tire axis direction.

[0067] The outer shoulder transverse grooves 30 and the outer shoulder sipers 31 are arranged, for example, at an angle of 10° or less with respect to the tire axis direction, and in a preferred embodiment, they are arranged in parallel. Such outer shoulder transverse grooves 30 and outer shoulder sipers 31 help to enhance the braking performance.

[0068] The circumferential distance L8 of the tire in the circumferential direction between the end on the circumferential groove 7 side of the outer shoulder of the outer shoulder size 31 and the end on the circumferential groove 7 side of the outer middle transverse groove 24 is preferably 15% or less of the circumferential distance L7 of the tire in the circumferential direction from the outer shoulder transverse groove 30 to the outer shoulder size 31 at the outer tread end To. Thereby, it is possible to prevent the pitch sounds of the outer middle transverse groove 24 and the outer shoulder transverse groove 30 from overlapping, and it is possible to make the contact pressure uniform between the outer shoulder land portion 12 and the outer middle land portion 13.

[0069] The outer shoulder transverse groove 30 preferably has, for example, the edges of the groove formed by the chamfered portions 32. Further, it is desirable that the width of this chamfered portion 32 continuously decreases toward the outer tread end To side in a plan view of the tread. Thereby, the contact pressure of the outer shoulder land portion 12 is made uniform, and the braking performance is further improved.

[0070] The outer shoulder size 31 preferably has each of the size edges on both sides formed by the chamfered portions 33. Further, the outer shoulder size 31 has substantially the same cross-sectional shape as the inner shoulder size 17. Therefore, the configuration of the inner shoulder size 17 described above can be applied to the cross-sectional shape of the outer shoulder size 31.

[0071] Hereinafter, other embodiments of the present invention will be described. In the drawings showing other embodiments, the elements already described are given the same reference numerals as those described above, and the above-described configuration can be applied.

[0072] FIG. 6 shows an enlarged view of the inner shoulder land portion 11 and the inner middle land portion 15 of another embodiment. As shown in FIG. 6, in this embodiment, a plurality of inner middle sizes 25 are provided in the inner middle land portion 15. Note that the other land portions of this embodiment have the same configuration as those of the above-described embodiment, and the description thereof is omitted here.

[0073] Each of the inner middle sipes 25 extends in the tire axial direction from the inner shoulder circumferential groove 5 and is interrupted within the inner middle land portion 15. The axial length L9 of the inner middle sipes 25 is, for example, 30% to 70% of the width Wim of the inner middle land portion 15. Such inner middle sipes 25 help to enhance the wet performance and noise performance in a well-balanced manner.

[0074] The inner middle sipes 25 are inclined in the first direction with respect to the tire axial direction. The angle of the inner middle sipes 25 with respect to the tire axial direction is, for example, 15 to 45°.

[0075] Each of the side edges of the inner middle sipes 25 is formed with a chamfered portion. The chamfered portion 34 of the inner middle sipes 25 is substantially the same as the chamfered portion 23 (shown in FIG. 5) of the outer crown sipes 21 and the inner crown sipes 22 described above. Also, it is desirable that the maximum depth of the chamfered portion 33 of the inner middle sipes 25 is smaller than the maximum depth of the chamfered portion 18 of the inner shoulder sipes 17. Also, it is desirable that the maximum opening width of the inner middle sipes 25 is smaller than the maximum opening width of the inner shoulder sipes 17. Such inner middle sipes 25 can equalize the contact pressure of the inner middle land portion 15 and further enhance the braking performance.

[0076] As described above, the tire according to an embodiment of the present invention has been described in detail. However, the present invention is not limited to the above specific embodiments and can be implemented with various modifications.

Example

[0077] A tire of size 235 / 55R19 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1. Also, as a reference tire (reference tire) for comparing various performances, a tire was prototyped in which the width of each land portion of the tread portion was the same as that shown in FIG. 1, and no grooves and sipes were provided in each land portion. As a comparative example, as shown in FIG. 7, a tire was prototyped in which an inner shoulder cross groove b and an inner shoulder sipe c were provided in the inner shoulder land portion a. The inner shoulder sipe c of the comparative example does not communicate with the inner shoulder circumferential groove d and does not include a chamfered portion. The tire of the comparative example has substantially the same pattern as that shown in FIG. 1 except for the above matters. The wet performance, noise performance, and braking performance of each test tire were tested. The common specifications and test methods of each test tire are as follows. Mounting rim: 19×7.0J Tire internal pressure: 230 kPa Test vehicle: 2000 cc displacement, four-wheel drive vehicle Tire mounting position: all wheels

[0078] <Wet performance> The wet performance when the test vehicle travels on a wet road surface was evaluated by the driver's sensory evaluation. The results are shown in a score with the wet performance of the tire of the comparative example being 100, and the larger the numerical value, the better the wet performance.

[0079] <Noise performance> The test vehicle was driven on a dry road surface at 40 to 100 km / h, and the maximum sound pressure of the noise inside the vehicle at this time was measured. The results are shown in an index with the sound pressure reduction amount, which is the difference from the sound pressure of the reference tire, being 100 for the sound pressure reduction amount of the comparative example. The larger this index, the smaller the maximum sound pressure of the noise, indicating that excellent noise performance is exhibited.

[0080] <Braking performance> The braking distance was measured when the test vehicle suddenly braked from 100 km / h on a dry road surface. The result is shown as an index with the improvement amount of the braking distance, which is the difference from the braking distance of the reference tire, with the improvement amount of the braking distance in the comparative example set to 100. The larger this index, the greater the improvement amount of the braking distance, indicating excellent braking performance. The test results are shown in Table 1.

[0081]

Table 1

[0082] As a result of the test, it was confirmed that the tires of the examples had improved noise performance and braking performance while maintaining wet performance.

Explanation of symbols

[0083] 2 Tread portion 3 Circumferential groove 4 Land portion 5 Inner shoulder circumferential groove 11 Inner shoulder land portion 16 Inner shoulder transverse groove 17 Inner shoulder sipe 18 Chamfered portion To Outer tread end Ti Inner tread end

Claims

1. A tire having a tread portion with a specified mounting orientation on a vehicle, wherein the tread portion includes an outer tread edge that becomes the outside of the vehicle when mounted on the vehicle, an inner tread edge that becomes the inside of the vehicle when mounted on the vehicle, four circumferential grooves that continuously extend in the tire circumferential direction between the outer tread edge and the inner tread edge, and five land portions divided by the four circumferential grooves, the four circumferential grooves include an inner shoulder circumferential groove disposed on the innermost tread edge side among the circumferential grooves, the five land portions include an inner shoulder land portion disposed outside the inner shoulder circumferential groove in the tire axial direction and an inner middle land portion adjacent to the inner shoulder land portion via the inner shoulder circumferential groove, the inner shoulder land portion is the smallest among the five land portions in terms of the width in the tire axial direction of the ground contact surface, a plurality of inner shoulder lateral grooves and a plurality of inner shoulder sipes are provided in the inner shoulder land portion, the inner shoulder lateral grooves extend from an inner end spaced apart from the inner shoulder circumferential groove in the tire axial direction to a position beyond the inner tread edge, the inner shoulder sipes extend to a position beyond the inner tread edge from the inner shoulder circumferential groove, each of the inner shoulder sipes has chamfered portions formed at respective sipes edges on both sides, a plurality of inner middle sipes are provided in the inner middle land portion, each of the inner middle sipes extends in the tire axial direction from the inner shoulder circumferential groove and is interrupted within the inner middle land portion, each of the inner middle sipes has chamfered portions formed at respective sipes edges on both sides, the maximum depth of the chamfered portion of the inner middle sipes is smaller than the maximum depth of the chamfered portion of the inner shoulder sipes, a tire.

2. The tire according to claim 1, wherein the maximum opening width of the inner middle sipes is smaller than the maximum opening width of the inner shoulder sipes.

3. A tire having a tread portion with a specified mounting orientation on a vehicle, wherein the tread portion includes an outer tread edge that becomes the outside of the vehicle when mounted on the vehicle, an inner tread edge that becomes the inside of the vehicle when mounted on the vehicle, four circumferential grooves that continuously extend in the tire circumferential direction between the outer tread edge and the inner tread edge, and five land portions divided by the four circumferential grooves, The four circumferential grooves include an inner shoulder circumferential groove arranged closest to the inner tread end among the circumferential grooves. The five land portions include an inner shoulder land portion arranged on the outer side in the tire axial direction of the inner shoulder circumferential groove, and an inner middle land portion adjacent to the inner shoulder land portion via the inner shoulder circumferential groove. The width of the inner shoulder land portion in the tire axial direction of the ground contact surface is the smallest among the five land portions. A plurality of inner shoulder transverse grooves and a plurality of inner shoulder sipes are provided in the inner shoulder land portion. The inner shoulder transverse grooves extend from the inner end spaced apart from the inner shoulder circumferential groove in the tire axial direction to a position beyond the inner tread end. The inner shoulder sipes extend from the inner shoulder circumferential groove to a position beyond the inner tread end. A plurality of inner middle sipes are provided in the inner middle land portion. Each of the inner middle sipes extends in the tire axial direction from the inner shoulder circumferential groove and is interrupted within the inner middle land portion. Each of the inner middle sipes has chamfered portions formed at both side sipe edges. The maximum opening width of the inner middle sipes is smaller than the maximum opening width of the inner shoulder sipes. Tire.

4. The tire according to claim 3, wherein each of the inner shoulder sipes has chamfered portions formed at both side sipe edges.

5. The tire according to any one of claims 1 to 4, wherein the length of each of the inner middle sipes in the tire axial direction is 30% to 70% of the width of the ground contact surface of the inner middle land portion in the tire axial direction.

6. The tire according to any one of claims 1 to 5, wherein the five land portions are formed larger toward the land portion located on the outer tread end side with respect to the width of the ground contact surface in the tire axial direction.

7. The land portion includes a crown land portion arranged on the tire equator. The tire according to any one of claims 1 to 6, wherein the width of the ground contact surface of the inner shoulder land portion in the tire axial direction is 90% or more of the width of the ground contact surface of the crown land portion in the tire axial direction.

8. The tire according to claim 7, wherein the center position of the crown land portion in the tire axial direction is located on the outer tread end side of the tire equator. **Claim 9**: The maximum groove width of the inner shoulder circumferential groove is 55 to 70% of the width in the tire axial direction of the grounding surface of the inner shoulder land portion, for the tire according to any one of claims 1 to 8.

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