JP2019094006A - tire - Google Patents

Abstract

To provide a tire capable of achieving excellent steering stability while controlling uneven wear on a crown land part.SOLUTION: A tire has a tread part 2 which is designated in an orientation of attachment to a vehicle and which is formed with a pattern asymmetrical with respect to a tire equator. The tread part 2 comprises: an outer shoulder main groove 3A; an outer crown main groove 4A; an inner crown main groove 4B; an outer crown land part 8A and a center crown land part 8C. The outer crown land part 8A is provided with first outer crown sipes 26 and second outer crown sipes 27. The center crown land part 8C is provided with first center crown sipes 45 and second center crown sipes 46. The second outer crown sipes 27 are arranged to smoothly continue to the first center crown sipes 46 through the outer crown main groove 4A.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire having a crown sipe.

  Patent Document 1 below proposes providing a shoulder sipe extending in the axial direction of the tire on the shoulder land portion in order to suppress uneven wear of the shoulder land portion of the pneumatic tire.

JP, 2016-13820, A

  However, in recent years, along with the enhancement of the performance of vehicles, not only the improvement of the wear resistance performance but also the improvement of the steering stability are also required. As a result of various experiments, the inventors obtained the finding that the steering stability can be improved while maintaining the wear resistance of the crown land by improving the crown sipes disposed on the crown land.

  The present invention has been made in view of the above-described actual situation, and its main object is to provide a tire capable of exhibiting excellent steering stability while suppressing uneven wear of a crown land portion.

  The present invention is a tire having a tread portion in which a direction of mounting on a vehicle is specified and in which an asymmetric pattern is formed with respect to a tire equator, and the tread portion extends continuously in the tire circumferential direction. An outer shoulder main groove, an outer crown main groove continuously extending in the tire circumferential direction adjacent to the outer shoulder main groove, and an inner crown main groove extending continuously in the tire circumferential direction adjacent to the outer crown main groove An outer crown land section divided between the outer shoulder main groove and the outer crown main groove, and a central crown land section divided between the outer crown main groove and the inner crown main groove A first outer crown sipe completely traversing the outer crown land and a direction from the outer crown main groove toward the outer shoulder main groove; A second outer crown sipe extending in the outer crown land and terminating in the outer crown land, the first crown crown sipes completely crossing the middle crown land in the middle crown land, and A second central crown sipe extending from the inner crown main groove toward the outer crown main groove and terminating in the central crown land portion is provided, the second outer crown sipe being the outer crown main groove Through the first central crown sipes.

  In the tire according to the present invention, in the tread portion, an inner shoulder main groove continuously extending in the tire circumferential direction adjacent to the inner crown main groove, and between the inner shoulder main groove and the inner crown main groove The inner crown land portion extends from the inner shoulder main groove to the inner crown main groove with a width of 1.5 mm or more, and an inner end within the inner crown land portion And a first inner crown sipe having a width of less than 1.5 mm extending from the inner end of each of the crown lug grooves to the inner main crown groove, wherein the first inner crown sipes It is preferable that each be disposed so as to be smoothly continuous with the second central crown sipe via the inner crown main groove.

  In the tire according to the present invention, the inner crown land portion may have a plurality of width less than 1.5 mm having an inner end extending from the inner shoulder main groove toward the inner crown main groove and having an inner end in the inner crown land portion. 2 It is desirable to have an inner crown sipe.

  In the tire according to the present invention, in the inner crown land portion, a plurality of first members extending from the inner crown main groove toward the inner shoulder main groove and having an outer end in the inner crown land portion have a width of less than 1.5 mm It is desirable to have 3 inner crown sipes.

  In the tire according to the present invention, it is preferable that the third inner crown sipes be disposed so as to be smoothly continuous with the first central crown sipes via the inner crown main groove.

  In the tire according to the present invention, at least one sipe wall and a tread contact surface such that the width of the first outer crown sipe gradually increases toward the outer crown main groove at the communication portion with the outer crown main groove. It is desirable to be chamfered.

  In the tire according to the present invention, at least one of the sipe wall and the tread contact surface so that the first central crown sipe has a width gradually increasing toward the outer crown main groove at the communication portion with the outer crown main groove. It is desirable to be chamfered.

  In the tire according to the present invention, the first outer crown sipe is chamfered at one side in the tire circumferential direction at the communication portion with the outer crown main groove, and the first central crown sipe is the outer side It is desirable that the sipe wall on the other side in the tire circumferential direction be chamfered at the communication portion with the crown main groove.

  The present invention is a tire having a tread portion in which the direction of mounting on a vehicle is specified and in which an asymmetric pattern is formed with respect to the tire equator. The tread portion of the tire according to the present invention includes an outer shoulder main groove continuously extending in the tire circumferential direction, an outer crown main groove continuously extending in the tire circumferential direction adjacent to the outer shoulder main groove, and an outer crown main groove An inner crown main groove continuously extending in the circumferential direction of the tire, an outer crown land section divided between the outer shoulder main groove and the outer crown main groove, and an outer crown main groove and an inner crown main groove And a central crown land section separated by an interval. Since such tires tend to exert a relatively large contact pressure on the outer crown land portion and the central crown land portion during straight running and turning, the sipes disposed on these land portions are resistant to deflection. A large contribution to wear and steering stability.

  The outer crown land portion of the tire according to the present invention extends from the outer crown main groove toward the outer shoulder main groove and terminates in the outer crown land portion, and a first outer crown sipe completely crossing the outer crown land portion. A second outer crown sipe is provided. The first outer crown sipes and the second outer crown sipes relieve the strain at the time of contact of the outer crown land portion and suppress its uneven wear. In addition, the second outer crown sipes, together with the first outer crown sipes, further reduce the rigidity on the side of the outer crown main groove of the outer crown land portion. Therefore, the outer crown land portion can easily follow the road surface even in the initial state of turning, for example, in which the ground contact pressure is not sufficiently increased, so that excellent initial responsiveness can be obtained.

  On the other hand, because the second outer crown sipe terminates in the outer crown land, the outer crown land has high stiffness on the side of the outer shoulder major groove. Accordingly, the outer crown land portion can exert a large cornering force, for example, in the middle stage of cornering in which a sufficient contact load is applied to the tire, and thus can improve the steering stability.

  The central crown land portion of the tire according to the present invention extends from the inner crown main groove toward the outer crown main groove from the inner crown main groove and terminates in the central crown land portion completely crossing the central crown land portion. A second central crown sipe is provided. Such a central crown land portion can exert the same function as the above-mentioned outer crown land portion and can enhance steering stability. Moreover, in the present invention, since the second outer crown sipes are arranged to be smoothly continuous with the first central crown sipes via the outer crown main groove, the first outer crown sipes and the first central crown sipes are arranged. Is easier to open, and the rigidity on the side of the outer crown main groove of the outer crown land portion and the center crown land portion is more relaxed, so that an even better initial response can be obtained.

It is an expanded view of a tread part of a tire of one embodiment of the present invention. It is the sectional view on the AA line of FIG. It is an enlarged view of the outer crown land part of FIG. 1, and a center crown land part. FIG. 4 is an enlarged view of the second outer crown sipes and the first central crown sipes of FIG. 3; (A) is the BB sectional drawing of FIG. 3, (b) is the CC sectional view shown in FIG. (A) is a cross-sectional view taken along the line E-E of FIG. 3, (b) is a cross-sectional view taken along the line F-F of FIG. 3, (c) is a cross-sectional view taken along the line G-G of FIG. . (A) is a cross-sectional view taken along the line K-K in FIG. 3, (b) is a cross-sectional view taken along the line L-L in FIG. 3, and (c) is a cross-sectional view taken along the line M-M in FIG. . It is an enlarged view of the inner crown land part of FIG. (A) is a cross-sectional view taken along the line HH in FIG. 8, (b) is a cross-sectional view taken along the line I-I in FIG. 8, and (c) is a cross-sectional view taken along the line JJ in FIG. . It is an enlarged view of the outer side shoulder land part of FIG. It is an enlarged view of the inside shoulder land part of FIG. It is the DD sectional view taken on the line of FIG. It is an enlarged view of the outer crown land part of a comparative example, and a center crown land part.

Hereinafter, an embodiment of the present invention will be described based on 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 can be used, for example, in various tires such as pneumatic tires for passenger cars and heavy loads, and non-pneumatic tires in which the inside of the tire is not filled with pressurized air. The tire 1 of the present embodiment is suitably used, for example, as a pneumatic tire for a passenger car.

  As shown in FIG. 1, the tire 1 of the present embodiment has a tread portion 2 in which the direction of attachment to a vehicle is specified and in which a pattern of asymmetry with respect to the tire equator is formed. The tread portion 2 has, for example, a first tread end Te1 located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and a second tread end Te2 located on the inner side of the vehicle when the vehicle is mounted. The direction of attachment to the vehicle is displayed, for example, in the side wall (not shown) as characters or symbols.

  In the case of a pneumatic tire, each tread end Te1 and Te2 is a contact position on the outermost side in the axial direction of the tire when a normal load is applied to the tire 1 in a normal state and the flat surface is grounded at a camber angle of 0 °. The normal state is a state in which the tire is rim-assembled on a normal rim, filled with a normal internal pressure, and unloaded. In the present specification, unless otherwise noted, the dimensions and the like of each part of the tire are values measured in the normal state.

  The “regular rim” is a rim that defines the standard for each tire in the standard system including the standard on which the tire is based, for example, “standard rim” for JATMA, “Design Rim” for ETRA, and “TRA” for TRA If it is, it is "Measuring Rim".

  The “normal internal pressure” is the air pressure specified by each standard in the standard system including the standard on which the tire is based, and in the case of JATMA, the “maximum air pressure”; in the case of TRA, the table “TIRE LOAD LIMITS AT The maximum value described in VARIOUS COLD INFlation PRESSURES, and in the case of ETRTO, it is “INFLATION PRESSURE”.

  "Normal load" is the load defined by each standard in the standard system including the standard on which the tire is based, and if it is JATMA, "maximum load capacity", if it is TRA, the table "TIRE LOAD LIMITS At the time of ETRTO, it is "LOAD CAPACITY".

  The tread portion 2 of the present embodiment is provided with, for example, a main groove continuously extending in the tire circumferential direction. The main groove is adjacent to the shoulder main groove 3 provided between, for example, the first tread end Te1 and the tire equator C, or between the second tread end Te2 and the tire equator C, and the shoulder main groove 3 And a crown main groove 4.

  The shoulder main groove 3 of this embodiment is an outer shoulder main groove 3A provided between the first tread end Te1 and the tire equator C, and an inner side provided between the second tread end Te2 and the tire equator C. And a shoulder main groove 3B.

  The shoulder main groove 3 desirably has a distance L1a from the tire equator C to the groove center line of 0.20 to 0.30 times the tread width TW, for example. The tread width TW is a distance in the tire axial direction from the first tread end Te1 to the second tread end Te2 in the normal state.

  The crown main groove 4 includes an outer crown main groove 4A and an inner crown main groove 4B. The outer crown main groove 4A is provided between the tire equator C and the outer shoulder main groove 3A. The inner crown main groove 4B is provided between the tire equator C and the inner shoulder main groove 3B.

  The crown main groove 4 preferably has a distance L1b from the tire equator C to the groove center line of 0.05 to 0.15 times the tread width TW, for example.

  The groove width W1a of the outer crown main groove 4A and the groove width W1b of the inner crown main groove 4B are desirably larger than, for example, the groove width W1c of the outer shoulder main groove 3A and the groove width W1d of the inner shoulder main groove 3B. Specifically, the groove width W1a of the outer crown main groove 4A and the groove width W1b of the inner crown main groove 4B are preferably 1.25 to 1.35 times the groove width W1b of the outer shoulder main groove 3A. This provides excellent wet performance.

  The groove width W1d of the inner shoulder main groove 3B is desirably, for example, larger than the groove width W1c of the outer shoulder main groove 3A. Specifically, the groove width W1d of the inner shoulder main groove 3B is preferably 1.20 to 1.28 times the groove width W1c of the outer shoulder main groove 3A.

  The groove width W1a of the outer crown main groove 4A, the groove width W1b of the inner crown main groove 4B, and the groove width W1c of the outer shoulder main groove 3A and the inner shoulder in order to enhance the steering stability and wet performance on dry road The groove width W1d of the main groove 3B is desirably, for example, 2.5% to 5.0% of the tread width TW. In addition, when the dimension of a groove | channel is shown by this specification, the dimension which does not contain a chamfer is shown.

  FIG. 2 is a cross-sectional view taken along the line A-A of FIG. As shown in FIG. 2, the groove depth D1a of the outer crown main groove 4A, the groove depth D1b of the inner crown main groove 4B, the groove depth D1c of the outer shoulder main groove 3A, and the groove depth of the inner shoulder main groove 3B. It is desirable that D1d be, for example, 6.0 to 12.0 mm.

  As shown in FIG. 1, the tread portion 2 of the present embodiment has an outer shoulder land portion 7A, an inner shoulder land portion 7B, an outer crown land portion 8A, and an inner crown land portion 8B by the above-described main groove. , Central crown land portion 8C. The outer shoulder land portion 7A is divided between the first tread end Te1 and the outer shoulder main groove 3A. The inner shoulder land portion 7B is divided between the second tread end Te2 and the inner shoulder main groove 3B. The outer crown land portion 8A is divided between the outer shoulder main groove 3A and the outer crown main groove 4A. The inner crown land portion 8B is divided between the inner shoulder main groove 3B and the inner crown main groove 4B. The central crown land portion 8C is divided between the outer crown main groove 4A and the inner crown main groove 4B.

  FIG. 3 shows an enlarged view of the outer crown land portion 8A and the center crown land portion 8C. As shown in FIG. 3, the outer crown land portion 8 </ b> A is provided with a first outer crown sipes 26 and a second outer crown sipes 27. As used herein, "sipe" is a cut less than 1.5 mm in width.

  The first outer crown sipes 26 completely cross the outer crown land 8A. The second outer crown sipes 27 extend from the outer crown main groove 4A toward the outer shoulder main groove 3A and terminate in the outer crown land portion 8A. The first outer crown sipes 26 and the second outer crown sipes relieve the strain at the time of contact of the outer crown land portion 8A and suppress its uneven wear. Further, the second outer crown sipes 27 together with the first outer crown sipes 26 further reduce the rigidity on the side of the outer crown main groove 4A of the outer crown land portion 8A. For this reason, the outer crown land portion 8A can easily follow the road surface even in the initial state of turning, for example, in which the ground contact pressure is not sufficiently increased, so that excellent initial responsiveness can be obtained.

  On the other hand, since the second outer crown sipes 27 end in the outer crown land portion 8A, the outer crown land portion 8A has high rigidity on the side of the outer shoulder main groove 3A. Therefore, the outer crown land portion 8A can exert a large cornering force, for example, in the middle stage of cornering in which a sufficient ground contact load acts on the tire, and thus can improve the steering stability.

  The central crown land portion 8C is provided with a first central crown sipe 45 and a second central crown sipe 46. The first central crown sipe 45 completely crosses the central crown land 8C. The second central crown sipe 46 extends from the inner crown main groove 4B toward the outer crown main groove 4A and terminates in the central crown land 8C. Such a central crown land portion 8C can exert the same function as the above-mentioned outer crown land portion 8A, and can enhance steering stability.

  An enlarged view of the second outer crown sipes 27 and the first central crown sipes 45 is shown in FIG. As shown in FIG. 4, in the present invention, the second outer crown sipes 27 are arranged to be smoothly continuous with the first central crown sipes 45 via the outer crown main grooves 4A. Note that "the sipes are provided in a smoothly continuous position" means the shortest in the tire circumferential direction of at least a first region 32a virtually extending one sipe and a second region 32b virtually extending the other sipe. Including the aspect whose separation distance is less than 1.0 mm. In the present embodiment, the first area 32 a and the second area 32 b intersect at least in part (that is, the shortest separation distance = 0). In a more desirable aspect, the first region 32a intersects the end of the other sipe, and the second region 32b intersects the end of the one sipe.

  In the present invention, the arrangement of the sipes described above facilitates the opening of the first outer crown sipes 26 and the first central crown sipes 45, and the rigidity of the outer crown land portion 8A and the outer crown main groove 4A of the center crown land portion 8C. Is further mitigated, so that a better initial response can be obtained.

  As shown in FIG. 3, the first outer crown sipe 26 includes, for example, a fine sipe portion 22 and a thick sipe portion 23 having a larger width than the fine sipe portion 22. The thick sipe portion 23 communicates with, for example, the outer shoulder main groove 3A. The fine sipe portion 22 has, for example, a width of 0.4 to 0.8 mm. The width of the thick sipe portion 23 is, for example, preferably 1.50 to 1.80 times, more preferably 1.60 to 1.70 times the width of the thin sipe portion 22, specifically, 0.8 It is desirable to have a width of ~ 1.2 mm.

  The thick sipe portion 23 can further reduce the rigidity of the land portion around it compared to the fine sipe portion 22. On the other hand, in the outer crown land portion 8A, the load on the outer shoulder main groove 3A is more varied than the outer crown main groove 4A on traveling, and the uneven load tends to easily occur due to minute slippage of the contact surface. There is. In the present embodiment, by providing the thick sipe portion 23 in this region, the land portion around it can easily follow the road surface, and the above-mentioned minute slippage can be suppressed, which further suppresses uneven wear of the outer crown land portion 8A. can do.

  In addition, in the outer crown land portion 8A, the land portion around the thick sipe portion 23 can easily follow the road surface even in the initial state of turning, for example, in which the ground contact load is not sufficiently increased. Can.

  Furthermore, in the outer crown land portion 8A, the land portion around the narrow sipe portion 22 is disposed closer to the outer crown main groove 4A than the narrow sipe portion 22 and has higher rigidity than the land portion around the thick sipe portion 23. In order to provide it, a large cornering force can be exerted, which in turn can improve the steering stability.

  The BB sectional drawing of the thick sipe part 23 of FIG. 3 is shown by Fig.5 (a). In FIG.5 (b), the CC sectional view taken on the line of the fine sipe part 22 is shown. As shown in FIGS. 5A and 5B, it is desirable that the depth d1 of the thick sipe portion 23 be larger than the depth d2 of the thin sipe portion 22. Specifically, the depth d1 of the thick sipe portion 23 is preferably 1.03 times or more, more preferably 1.06 times or more, and preferably 1.15 times or less the depth d2 of the fine sipe portion 22 More preferably, it is 1.12 times or less. The depths d1 and d2 correspond to, for example, the distance along the depth direction of the sipe from the tread surface of the land portion to the bottom of the sipe.

  As shown in FIGS. 3 and 5 (a), the outer crown land 8A is provided with a narrow groove 24 having a groove width of 1.5 mm or more and a groove depth of 2.0 mm or less. The portion 23 preferably extends inward in the tire radial direction from the groove bottom of the narrow groove portion 24. The depth d3 of the narrow groove portion 24 is, for example, 1.0 to 2.0 mm. Such thin groove portion 24 and thick sipe portion 23 can further enhance uneven wear resistance.

  As shown in FIG. 3, the narrow groove portion 24 is in contact with at least one groove wall and the tread so that the groove width gradually increases toward the outer shoulder main groove 3A, for example, in the communication portion with the outer shoulder main groove 3A. It is desirable to be chamfered between the ground and the ground. The narrow groove portion 24 provided in the outer crown land portion 8A has a chamfer 25 on one groove wall.

  The axial length L9 of the thick sipe portion 23 is preferably 0.30 to 0.40 times the width W7 of the outer crown land portion 8A, for example.

  The fine sipes 22 communicate with the outer crown main groove 4A, for example. It is desirable that the axial length L10 of the fine sipe portion 22 be larger than the axial length L9 of the thick sipe portion 23. The length L10 of the fine sipes 22 is, for example, 1.60 to 1.80 times the length L9 of the thick sipes 23. With such a thick sipe portion 23 and a fine sipe portion 22, a large cornering force can be obtained while exhibiting excellent initial response.

  The fine sipe portion 22 is, for example, chamfered between at least one sipe wall and the tread contact surface so as to gradually increase in width toward the outer crown main groove 4A at the communication portion with the crown main groove. Is desirable. In the present embodiment, the chamfered portion 28 is provided on the sipe wall on the opposite side (the lower side in FIG. 3) to the chamfered portion 25 provided on the groove wall of the narrow groove portion 24. Such a chamfered portion 28 can reduce air column resonance noise of the outer crown main groove 4A, and thus can improve noise performance.

  FIG. 6A is a cross-sectional view of the first outer crown sipes 26 of FIG. 3 taken along the line E-E. As shown in FIG. 6 (a), the first outer crown sipes 26 include, for example, a first sipe portion 26a on the outer shoulder main groove 3A side and a second sipe portion 26b on the outer crown main groove 4 side. It is. The second sipe portion 26 b has, for example, a smaller depth than the first sipe portion 26 a. The depth d5 of the second sipe portion 26b is, for example, 0.45 to 0.55 times the depth d4 of the first sipe portion 26a. Such first outer crown sipes 26 can maintain the rigidity of the outer crown land portion 8A on the tire equator C side while enhancing the initial responsiveness, and can exhibit further excellent steering stability.

  As shown in FIG. 3, the axial length L11 of the second outer crown sipes 27 is, for example, 0.35 to 0.55 times the axial width W7 of the outer crown land portion 8A. Desirably, it is 0.42-0.48 times. Further, it is desirable that the discontinuous end 29 of the second outer crown sipes 27 be positioned closer to the crown main groove 4 than the end portion of the thick sipe portion 23 of the first outer crown sipes 26 on the crown main groove 4 side. Such second outer crown sipes 27 can suppress an excessive decrease in rigidity of the outer crown land portion 8A and provide a large cornering force.

  FIG. 6 (b) shows a cross-sectional view taken along line F-F orthogonal to the second outer crown sipes 27 of FIG. 3. As shown in FIG. 6 (b), it is desirable that the second outer crown sipes 27 have, for example, an opening 30 whose width extends outward in the tire radial direction. In the present embodiment, the opening 30 is formed by the sipe wall 31 on one side in the tire circumferential direction of the second outer crown sipe 27 being inclined. In the second outer crown sipes 27, for example, the sipe walls 31 on both sides may be inclined. Also, the second outer crown sipes 27 may be provided, for example, at the groove bottom of the above-mentioned narrow groove portion.

  FIG. 6C shows a cross-sectional view along line G-G along the second outer crown sipes 27 of FIG. 3. As shown in FIG. 6C, it is desirable that the second outer crown sipes 27 include a first sipe portion 27a on the discontinuous end 29 side and a second sipe portion 27b on the crown main groove 4 side. The second sipe portion 27b has, for example, a smaller depth than the first sipe portion 27a. The depth d7 of the second sipe portion 27b is preferably, for example, 0.45 to 0.55 times the depth d6 of the first sipe portion 27a. Such second outer crown sipes 27 can prevent the side of the crown main groove 4 from being excessively opened, and can improve uneven wear resistance and steering stability.

  As shown in FIG. 3, the first central crown sipes 45 are inclined, for example, with respect to the tire axial direction. The angle θ3 of the first central crown sipes 45 with respect to the tire axial direction is preferably, for example, 10 to 30 °.

  The first central crown sipe 45 is chamfered between at least one sipe wall and the tread contact surface so as to gradually increase in width toward the outer crown main groove 4A at the communication portion with the outer crown main groove 4A Is desirable. Similarly, at least one of the sipe wall and the tread contact surface has a width gradually increasing toward the inner crown main groove 4B in the communication with the inner crown main groove 4B. It is desirable to be chamfered. The chamfered portion 48 provided on the side of the inner crown main groove 4B of the first central crown sipe 45 is preferably provided on the opposite side to the chamfered portion 47 on the outer crown main groove 4A side.

  In a further desirable aspect, the first outer crown sipe 26 is chamfered at one side (the lower side in FIG. 3) in the tire circumferential direction at the communication portion with the outer crown main groove 4A, and the first central crown The sipe wall of the other side (upper side in FIG. 3) of the tire circumferential direction is chamfered at the communication portion with the outer crown main groove 4A. Thus, air column resonance noise of the outer crown main groove 4A can be reduced.

  FIG. 7A shows a cross-sectional view of the first central crown sipe 45 of FIG. 3 taken along the line K-K. As shown in FIG. 7 (a), the first central crown sipe 45 includes a first sipe 45a on the outer crown main groove 4A side, a second sipe 45b on the inner crown main groove 4B side, and a first sipe. It is desirable to include a third sipe portion 45c between the portion 45a and the second sipe portion 45b.

  The depth d12 of the first sipe portion 45a and the depth d13 of the second sipe portion 45b are, for example, 0.60 to 0.75 times the groove depth D1a (shown in FIG. 2) of the outer crown main groove 4A. Is desirable. The third sipe portion 45c has, for example, a depth d14 smaller than the first sipe portion 45a and the second sipe portion 45b. The depth d14 of the third sipe portion 45c is, for example, 0.40 to 0.60 times the depth d12 of the first sipe portion 45a. Such a first central crown sipe 45 can enhance steering stability and uneven wear resistance in a well-balanced manner.

  As shown in FIG. 3, the axial length L17 of the second central crown sipe 46 is, for example, 0.40 to 0.60 times the axial width W8 of the central crown land portion 8C. Is desirable. The second central crown sipes 46 of this embodiment, for example, terminate in the land portion without straddling the tire equator C.

  FIG. 7 (b) shows a cross-sectional view along the line L-L orthogonal to the second central crown sipes 46 of FIG. 3. As shown in FIG. 7 (b), the second central crown sipes 46 preferably have, for example, openings 49 whose width extends outward in the tire radial direction. In the present embodiment, the opening 49 is formed by the sipe wall 50 on one side in the tire circumferential direction of the second central crown sipe 46 being inclined. In the second central crown sipes 46, for example, the sipe walls 50 on both sides may be inclined. In addition, the second central crown sipes 46 may be provided, for example, at the groove bottom of the above-mentioned narrow groove portion.

  As shown in FIG. 3, in the present embodiment, the inclined sipe wall 31 of the second outer crown sipe 27 is disposed on one side (lower side in FIG. 3) of the tire circumferential direction, and the second central crown sipe 46 Preferably, the inclined sipe wall 50 is disposed on the other side (upper side in FIG. 3) in the tire circumferential direction.

  FIG. 7C shows a cross-sectional view taken along the line M-M along the second central crown sipes 46 of FIG. 3. As shown in FIG. 7C, the second central crown sipe 46 desirably includes a first sipe portion 46a on the end side and a second sipe portion 46b on the inner crown main groove 4B side. The second sipe portion 46b has, for example, a smaller depth than the first sipe portion 46a. The depth d16 of the second sipe portion 46b is desirably, for example, 0.30 to 0.40 times the depth d15 of the first sipe portion 46a. Such a second central crown sipe 46 can suppress excessive opening of the side of the inner crown main groove 4B, and can improve uneven wear resistance and steering stability.

  FIG. 8 shows an enlarged view of the inner crown land portion 8B of the present embodiment. As shown in FIG. 8, the inner crown land portion 8B is provided with a plurality of crown lug grooves 34 having a width of 1.5 mm or more and a plurality of inner crown sipes 35 having a width of less than 1.5 mm. ing.

  The crown lug groove 34 extends from the inner shoulder main groove 3B to the side of the crown main groove 4 and has an inner end in the inner crown land portion 8B. The crown lug groove 34 cooperates with, for example, the inner shoulder main groove 3B to enhance drainage near the inner crown land portion 8B.

  The inner crown sipes 35 include, for example, a first inner crown sipe 36, a second inner crown sipe 37 and a third inner crown sipe 38. The first inner crown sipes 36 extend from the respective inner ends of the crown lug grooves 34 to the inner crown main groove 4B. The second inner crown sipes 37 extend from the inner shoulder main groove 3B to the side of the crown main groove 4 and have an inner end in the inner crown land portion 8B. The third inner crown sipe 38 extends from the inner crown main groove 4B to the side of the inner shoulder main groove 3B and has an outer end within the inner crown land 8B. These sipes provide frictional force on the wet road surface with their respective edges. In addition, since a relatively large contact pressure acts on the inner crown land portion 8B, the wet performance is significantly enhanced by the action of these grooves and sipes.

  Since the first inner crown sipes 36, the second inner crown sipes 37 and the third inner crown sipes 38 have a width of less than 1.5 mm, they hardly generate pumping noise when grounded. Furthermore, since the first inner crown sipes 36, the second inner crown sipes 37 and the third inner crown sipes 38 moderately reduce the rigidity of the inner crown land portion 8B, the impact sound when the land portion is in contact with the ground can be reduced. Therefore, excellent noise performance can be obtained.

  It is desirable that the axial length L12 of the crown lug groove 34 be larger than the axial length L13 of the second inner crown sipes 37, for example. As a result, the frequency band between the hitting sound when the edge of the crown lug groove 34 contacts the ground and the hitting sound when the edge of the second inner crown sipe 37 contacts the ground is dispersed, and thus the noise performance is enhanced. Further, the crown lug groove 34, which is longer than the sipes, can also be expected to have high drainage performance.

  In order to further enhance the above-mentioned effects, the length L12 of the crown lug groove 34 is preferably 105% or more, more preferably 108% or more, of the axial length L13 of the second inner crown sipes 37. Preferably it is 120% or less, more preferably 114% or less.

  The crown lug grooves 34 are inclined, for example, with respect to the tire axial direction. For example, it is desirable that the groove width of the crown lug groove 34 be gradually reduced toward the inner crown main groove 4B.

  The crown lug groove 34 is chamfered between at least one groove wall and the tread contact surface so that, for example, the groove width gradually increases toward the inner shoulder main groove 3B at the communication portion with the inner shoulder main groove 3B. Is desirable. In the present embodiment, a chamfered portion 39 is provided on one groove wall of the crown lug groove 34. In a desirable mode, a chamfer 39 of the crown lug groove 34 is provided on the same side of the chamfer 28 (shown in FIG. 3) provided in the fine sipe 22 of the first outer crown sipes 26 in the tire circumferential direction. Such a crown lug groove 34 can suppress the generation of a standing wave in the inner shoulder main groove 3B while improving the partial wear resistance, and can reduce air column resonance noise.

  The circumferential length L14 of the chamfered portion 39 of the crown lug groove 34 is desirably, for example, 0.15 to 0.30 times the one pitch length P1 of the crown lug groove 34. Thereby, the wet performance and the noise performance can be enhanced in a well-balanced manner.

  The first inner crown sipes 36 are inclined, for example, in the same direction as the crown lug grooves 34. In the present embodiment, one edge of the first inner crown sipes 36 extends smoothly and continuously with the edge of the crown lug groove 34.

  For example, the first inner crown sipes 36 are chamfered between at least one sipe wall and the tread contact surface so that the width gradually increases toward the crown main groove 4 in the communication portion with the crown main groove 4 Is desirable. It is desirable that the first inner crown sipes 36 have chamfers 40, for example, on the side opposite to the chamfers 39 of the crown lug grooves 34 in the tire circumferential direction. This makes it easy to disperse the frequency band between the hitting sound when one edge of the first inner crown sipes 36 and the crown lug groove 34 contacts the road surface and the hitting sound when the other edge contacts the road surface. , Noise performance is enhanced.

  FIG. 9A shows a cross-sectional view of the crown lug groove 34 and the first inner crown sipe 36 of FIG. 8 taken along the line H-H. As shown in FIG. 9A, the first inner crown sipe 36 includes a first sipe portion 36a on the crown main groove 4 side and a second sipe portion 36b on the crown lug groove 34 side. desirable.

  The first sipe portion 36 a has, for example, the same depth d 8 as the depth d 14 of the crown lug groove 34. The second sipe portion 36b preferably has a depth d9 smaller than, for example, the first sipe portion 36a. The depth d9 of the second sipe portion 36b is, for example, 0.40 to 0.60 times the depth d8 of the first sipe portion 36a. Such a first inner crown sipe 36 makes it easy to appropriately deform the side of the crown main groove 4 of the inner crown land portion 8B, and can suppress generation of a standing wave in the crown main groove 4, so the crown main The column resonance noise of the groove 4 can be reduced.

  As shown in FIG. 8, the second inner crown sipes 37 and the third inner crown sipes 38 are each disconnected without crossing the center position of the inner crown land portion 8 </ b> B in the tire axial direction. The second inner crown sipes 37 and the third inner crown sipes 38 according to this embodiment have, for example, a smaller axial length than the first inner crown sipes 36. The axial axial length L13 of the second inner crown sipes 37 and the axial axial length L16 of the third inner crown sipes 38 are respectively the axial axial length L15 of the first inner crown sipes 36. Preferably, it is 0.60 to 0.75.

  The second inner crown sipes 37 and the third inner crown sipes 38 are preferably inclined in the same direction as the first inner crown sipes 36 with respect to the tire axial direction, for example. The angle θ1 of the second inner crown sipes 37 with respect to the tire axial direction is desirably, for example, 0 to 20 °. The angle θ2 of the third inner crown sipes 38 with respect to the tire axial direction is desirably larger than the above angle θ1, and is, for example, 20 to 40 °. Such second inner crown sipes 37 and third inner crown sipes 38 serve to whiten noise when the respective edges contact the road surface.

  In FIG.9 (b), the II sectional view orthogonal to the 2nd inner crown sipe 37 of FIG. 8 is shown. As shown in FIG. 9 (b), it is desirable that the second inner crown sipes 37 have, for example, an opening 41 whose width extends outward in the tire radial direction. In the present embodiment, the opening 41 is formed by the sipe wall 42 on one side in the tire circumferential direction of the second inner crown sipe 37 being inclined. In the opening 41 of the present embodiment, for example, the sipe wall 42 (shown in FIG. 3) of the opening 49 of the second central crown sipe 46 and the sipe wall 42 on the same side in the tire circumferential direction are formed to be inclined. ing. In the second inner crown sipes 37, for example, the sipe walls 42 on both sides may be inclined. Further, the second inner crown sipes 37 may be provided, for example, at the groove bottom of the above-mentioned narrow groove portion. The third inner crown sipes 38 have, for example, the same cross-sectional shape as the second inner crown sipes 37 described above.

  FIG. 9C is a cross-sectional view of the second inner crown sipes 37 and the third inner crown sipes 38 of FIG. 6 taken along the line JJ. As shown in FIG. 9C, the second inner crown sipes 37 extend at a constant depth and gradually decrease in depth near the inner end. The third inner crown sipe 38 includes a first sipe portion 38 a on the second inner crown sipe 37 side and a second sipe portion 38 b on the crown main groove 4 side. The first sipe portion 38a has, for example, the same depth d10 as the depth d15 of the second inner crown sipe 37. The second sipe portion 38 b has, for example, a depth d11 smaller than that of the first sipe portion 38 a. The depth d11 of the second sipe portion 38b is preferably, for example, 0.45 to 0.55 times the depth d10 of the first sipe portion 38a. Such second inner crown sipes 37 and third inner crown sipes 38 in combination with the above-described first inner crown sipes 36 can improve the wet performance and the noise performance in a well-balanced manner.

  As shown in FIG. 1, in a more desirable aspect, the third inner crown sipes 38 are disposed so as to be smoothly continuous with the first central crown sipes 45 via the inner crown main grooves 4B. This makes it easier for the land portion around the sipe to follow the road surface, and the initial responsiveness is enhanced.

  As shown in FIG. 2, it is desirable that both the inner edge 43a on the side of the inner crown main groove 4B of the inner crown land portion 8B and the outer edge 43b on the side of the inner shoulder main groove 3B be chamfered. It is desirable that both the inner edge 43a on the side of the outer crown main groove 4A of the outer crown land portion 8A and the outer edge 43b on the side of the outer shoulder main groove 3A be chamfered. Similarly, it is desirable that each edge 43c of the central crown land portion 8C be chamfered. Such land portions can mitigate the hitting noise when the edge contacts the road surface.

  The inner crown land portion 8B and the outer crown land portion 8A desirably have a tread radius of curvature R1 of 560 mm or less. Specifically, it is desirable that the curvature radius R1 be 400 to 500 mm. As a result, the contact pressure acting on the inner crown land portion 8B and the outer crown land portion 8A is enhanced, while the contact pressure acting on the outer shoulder land portion 7A and the inner shoulder land portion 7B is relaxed, and each shoulder land portion 7A, Sound when 7B rolls can be reduced.

  In FIG. 10, as an example of the shoulder land portion 7, an enlarged view of the outer shoulder land portion 7A is shown. As shown in FIG. 10, the shoulder land portion 7A is provided with a shoulder sipe 10 extending in the tire axial direction. Further, in the present specification, a shoulder sipe provided in the outer shoulder land portion 7A may be referred to as an outer shoulder sipe. The shoulder sipe 10 relieves the strain at the time of contact with the shoulder land portion 7A and suppresses its uneven wear.

  The shoulder sipe 10 of the present embodiment extends from the shoulder main groove 3A to the first tread end Te1. However, the present invention is not limited to such an aspect, and one or both ends of the shoulder sipe 10 may be interrupted in the shoulder land portion 7A.

  The shoulder sipe 10 includes a narrow sipe portion 11 and a thick sipe portion 12 which is wider than the narrow sipe portion 11. The dimensions of the thin sipe portion 22 and the thick sipe portion 23 of the outer crown sipe 21 described above can be applied to the thin sipe portion 11 and the thick sipe portion 12 of the shoulder sipe 10.

  The thick sipe portion 12 can further reduce the rigidity of the land portion around it compared to the fine sipe portion 11. For this reason, the land portion around the thick sipe portion 12 can easily follow the road surface, for example, even in the initial state of turning when the ground contact load is not sufficiently increased, and excellent initial responsiveness can be obtained.

  The thick sipe portion 12 of the present invention is disposed on the side of the shoulder main groove 3A. At the shoulder main groove 3A side of the shoulder land portion 7A, a ground contact load that is larger than the tread end Te1 side tends to act at the initial stage of turning. Therefore, by providing the thick sipe portion 12 in this region, the initial responsiveness is significantly improved.

  In addition, the land portion around the narrow sipe portion 11 is disposed closer to the tread end Te1 than the thick sipe portion 12 and provides higher rigidity than the land portion around the thick sipe portion 12, for example, sufficient for a tire It is possible to exert a large cornering force in the middle stage of turning under the influence of the ground contact load, and thus to improve the steering stability.

  It is desirable that the thick sipe portion 12 communicate with, for example, the shoulder main groove 3A. The axial length L2 of the thick sipe portion 12 is preferably, for example, 0.15 to 0.30 times the width W2 of the shoulder land portion 7A. Such a thick sipe portion 12 can enhance the resistance to uneven wear and steering stability in a well-balanced manner.

  It is desirable that the fine sipes 11 communicate with the first tread end Te1, for example. Further, it is desirable that the axial length L3 of the fine sipe portion 11 be larger than the axial length L2 of the thick sipe portion 12. Specifically, the length L3 of the thin sipe portion 11 is preferably 3.0 to 4.5 times the length L2 of the thick sipe portion 12, for example.

  In the shoulder land portion 7A, for example, the narrow groove portion 13 similar to the narrow groove portion 24 (shown in FIG. 3) provided in the outer crown land portion 8A is provided, and the thick sipe portion 12 is a groove of the narrow groove portion 13 It is desirable that the tire extends radially inward from the bottom. Such thin groove portion 13 and thick sipe portion 12 can further enhance uneven wear resistance.

  The narrow groove portion 13 extends, for example, outward in the tire axial direction from the shoulder main groove 3A, and terminates between the outer end in the tire axial direction of the thick sipe portion 12 and the first tread end Te1. desirable. The axial length L4 of the narrow groove portion 13 is preferably 1.5 to 2.5 times the axial length L2 of the thick sipe portion 12, for example.

  Between the outer end of the thick sipe portion 12 and the outer end of the narrow groove portion 13, the narrow sipe portion 11 preferably extends inward in the tire radial direction from the groove bottom of the narrow groove portion 13. Further, in the region between the outer end of the narrow groove portion 13 and the first tread end Te1, the narrow sipe portion 11 desirably extends with a constant width from the bottom to the tread surface.

  It is desirable that the narrow groove portion 13 be chamfered between at least one groove wall and the tread contact surface so that the groove width gradually increases toward the shoulder main groove 3A at the communication portion with the shoulder main groove 3A. . In the narrow groove portion 13 of the present embodiment, for example, only one groove wall (the lower groove wall in FIG. 10) has a chamfered portion 14. Such a fine groove portion 13 can reduce air column resonance noise in the outer shoulder main groove 3A while enhancing resistance to uneven wear.

  In the present embodiment, as shown in FIG. 1, the narrow groove portion 13 provided in the outer shoulder land portion 7A has a chamfered portion 14 on the groove wall on one side (lower side in FIG. 1) of the tire circumferential direction. The narrow groove portion 24 provided in the outer crown land portion 8A has a chamfer 25 on the groove wall on the other side (upper side in FIG. 1) of the tire circumferential direction. The chamfered portion 25 provided in the outer crown land portion 8A has a chamfered length in the tire circumferential direction larger than the chamfered portion 14 provided in the outer shoulder land portion 7A. Such an arrangement of the narrow groove portion 24 can improve the resistance to uneven wear, can suppress the generation of standing waves in the outer shoulder main groove 3A, and can reduce air column resonance noise.

  The first outer crown sipes 26 preferably have a positional deviation between the outer shoulder sipes 10 in the outer shoulder main groove 3A and the tire circumferential direction of 1.0 mm or less. In the present embodiment, the outer shoulder sipe 10 is disposed to be continuous with the first outer crown sipe 26 via the outer shoulder main groove 3A, and in the preferred embodiment, the outer shoulder sipe 10 is configured to have the shoulder main groove 3A And a portion continuous with the first outer crown sipes 26 in a straight line. The arrangement of such sipes can make the surrounding land portion follow the road more easily, and can further enhance the initial responsiveness.

  As shown in FIG. 10, in the shoulder land portion 7A of the present embodiment, a plurality of shoulder sipes 10 are arranged at intervals in the tire circumferential direction, and between the shoulder sipes 10 adjacent in the tire circumferential direction, Shoulder lug grooves 15 are arranged. In the present specification, the shoulder lug groove 15 provided in the outer shoulder land portion 7A may be referred to as an outer shoulder lug groove.

  For example, the shoulder lug groove 15 extends inward in the tire axial direction from the first tread end Te1 and terminates without communicating with the shoulder main groove 3A. Such shoulder lug grooves 15 can enhance the wet performance while maintaining the rigidity of the shoulder land portion 7A.

  It is preferable that the tire axial inner end 15 a of the shoulder lug groove 15 be located on the tire axial direction outer side than the tire axial outer end 12 a of the thick sipe portion 12. The axial length L5 of the shoulder lug groove 15 is preferably 0.60 to 0.75 times the axial width W2 of the shoulder land portion 7A, for example.

  In order to exert sufficient drainage performance, the groove width W3 of the shoulder lug groove 15 is preferably 1.5 to 2.5 times the groove width W4 of the narrow groove portion 13, for example.

  FIG. 11 is an enlarged view of the inner shoulder land portion 7B as a view showing another example of the shoulder land portion 7. As shown in FIG. 11, the inner shoulder land portion 7 </ b> B is provided with, for example, a plurality of inner shoulder lug grooves 16. For example, the inner shoulder lug groove 16 extends inward in the axial direction of the tire from the second tread end Te2 and terminates without communicating with the inner shoulder main groove 3B.

  The axial length L6 of the inner shoulder lug groove 16 is preferably, for example, 0.70 to 0.80 times the axial width W5 of the inner shoulder land portion 7B. Such an inner shoulder lug groove 16 can enhance steering stability and wet performance in a well-balanced manner.

  The axial distance L7 from the inner end of the inner shoulder lug groove 16 to the inner shoulder main groove 3B is, for example, the distance L8 from the inner end of the outer shoulder lug groove 15 to the outer shoulder main groove 3A (shown in FIG. 11) It is desirable to be smaller.

  The inner shoulder lug groove 16 has, for example, a groove width W6 greater than 2 mm. The groove width W6 of the inner shoulder lug groove 16 is preferably 0.40 to 0.60 times the groove width W1c (shown in FIG. 1) of the inner shoulder main groove 3B, for example.

  The inner shoulder land portion 7B is provided with an inner shoulder sipe 18 between a connection sipe 17 extending from the inner shoulder lug groove 16 to the inner shoulder main groove 3B and an inner shoulder lug groove 16 adjacent in the tire circumferential direction. .

  The connecting sipes 17 extend inward in the tire radial direction from the groove bottom of the narrow groove portion 19 having a groove width of 1.5 mm or more and a groove depth of 2.0 mm or less, for example. The connection sipes 17 have, for example, a width of 0.4 to 0.8 mm. The dimension of the narrow groove part 19 can apply the dimension of the narrow groove part 13 distribute | arranged to the outer side shoulder land part 7A, for example.

  In FIG. 12, the DD sectional view taken on the line of connection sipes 17 of FIG. 11 is shown. As shown in FIG. 12, the connection sipe 17 includes, for example, a first sipe portion 17a on the inner side shoulder lug groove 16 side and a second sipe portion 17b on the inner side shoulder main groove 3B side. The second sipe portion 17 b has, for example, a smaller depth than the first sipe portion 17 a. The depth d13 of the second sipe portion 17b is preferably 0.35 to 0.55 times the depth d12 of the first sipe portion 17a. Such a connection sipe 17 can suppress the excessive opening of the side of the inner shoulder main groove 3B while improving the initial responsiveness, and can also improve the uneven wear resistance.

  As shown in FIG. 11, the inner shoulder sipe 18 extends, for example, along the inner shoulder lug groove 16. The inner shoulder sipe 18 has, for example, both ends interrupted in the inner shoulder land portion 7B. Such an inside shoulder sipe 18 makes it possible to make the land part follow the road surface while suppressing an excessive decrease in the rigidity of the land part, and thus can exhibit excellent steering stability and initial responsiveness.

  The inner shoulder sipes 18, for example, extend inward in the tire radial direction from the groove bottom of the narrow groove portion, like the connection sipes 17 described above.

  As shown in FIG. 1, the land ratio Lr1 of the region between the tire equator C and the first tread end Te1 is from the land ratio of the land ratio Lr2 of the region between the tire equator C and the second tread end Te2. Is also desirable. Specifically, the land ratio Lr1 is preferably 1.05 to 1.10 times the land ratio Lr2. As a result, the response at the time of steering can be made linear, and excellent steering stability can be exhibited. In the present specification, the “land ratio” is the ratio Sb / Sa of the actual total ground area Sb to the total area Sa of the virtual ground plane where all the grooves and sipes are completely filled.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention can be changed and carried out in various modes, without being limited to the above-mentioned specific embodiment.

A tire of size 215 / 60R16 having the basic pattern of FIG. 1 was prototyped based on the specifications of Table 1. As a comparative example, as shown in FIG. 13, the second outer crown sipes c provided in the outer crown land portion a and the first central crown sipes d provided in the central crown land portion b are smoothly continuous. A tire which is misaligned in the tire circumferential direction was produced on a trial basis. The tread portion of the comparative example tire is substantially the same as the tread portion shown in FIG. 1 except for the points described above. The steering stability of each test tire and the uneven wear resistance of the crown land were tested. The common specification and test method of each test tire are as follows.
Mounting rim: 16 × 6.5J
Tire internal pressure: front wheel 250kPa, rear wheel 230kPa
Test vehicle: Four-wheel drive, displacement 1500cc
Tire installation position: All wheels The test method is as follows.

Steering stability
The steering stability including the initial response when traveling on a dry road surface with the above test vehicle was evaluated by the driver's sense. A result is a score which sets a comparative example to 100, and it shows that steering stability is excellent, so that a numerical value is large.

<Uneven wear resistance>
A wear energy measurement device was used to measure the wear energy of the outer crown land and the center crown land. The result is an index based on the abrasion energy of the comparative example being 100. The smaller the numerical value, the smaller the abrasion energy and the better the uneven wear resistance.
The results of the test are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples had excellent steering stability and that the uneven wear resistance of the crown land portion was enhanced.

2 tread portion 3A outer shoulder main groove 4A outer crown main groove 4B inner crown main groove 8A outer crown land portion 8C central crown land portion 26 first outer crown sipes 27 second outer crown sipes 45 first central crown sipes 46 second center Crown sipes

Claims (8)

What is claimed is: 1. A tire having a tread portion in which a direction of mounting on a vehicle is specified, and a pattern of asymmetrical with respect to the tire equator is formed,
The tread portion includes an outer shoulder main groove continuously extending in the tire circumferential direction, an outer crown main groove continuously extending in the tire circumferential direction adjacent to the outer shoulder main groove, and an outer crown main groove adjacent to the outer crown main groove Inner crown main groove continuously extending in the circumferential direction of the tire, an outer crown land portion divided between the outer shoulder main groove and the outer crown main groove, the outer crown main groove and the inner crown main groove And a central crown land section separated by
The outer crown land portion includes a first outer crown sipe completely crossing the outer crown land portion, and extends from the outer crown main groove toward the outer shoulder main groove and terminates in the outer crown land portion A second outer crown sipe is provided,
The central crown land portion includes a first central crown sipe completely crossing the central crown land portion, and extends from the inner crown main groove toward the outer crown main groove and terminates in the central crown land portion A second central crown sipe is provided,
The second outer crown sipe is disposed so as to be smoothly continuous with the first central crown sipe via the outer crown main groove;
tire. The tread portion includes an inner shoulder main groove continuously extending in the circumferential direction of the tire adjacent to the inner crown main groove, and an inner crown land divided between the inner shoulder main groove and the inner crown main groove. Including
The inner crown land portion is
A plurality of crown lug grooves having a width of 1.5 mm or more and extending from the inner shoulder main groove to the side of the inner crown main groove and having an inner end in the inner crown land portion;
A first inner crown sipe having a width of less than 1.5 mm extending from the inner end of each of the crown lug grooves to the inner crown main groove;
The tire according to claim 1, wherein each of the first inner crown sipes is disposed to be smoothly continuous with the second central crown sipes via the inner crown main groove.   The inner crown land portion is provided with a plurality of second inner crown sipes having a width of less than 1.5 mm having an inner end extending from the inner shoulder main groove to the side of the inner crown main groove and having an inner end in the inner crown land portion. The tire according to claim 2, which is   The inner crown land portion is provided with a plurality of third inner crown sipes having a width of less than 1.5 mm, having an outer end extending from the inner crown main groove to the side of the inner shoulder main groove and having an outer end in the inner crown land portion. The tire according to claim 2 or 3, which is   The tire according to claim 4, wherein the third inner crown sipes are disposed to be smoothly continuous with the first central crown sipes via the inner crown main groove.   The first outer crown sipe is chamfered between at least one sipe wall and the tread contact surface so as to gradually increase in width toward the outer crown main groove at the communication portion with the outer crown main groove A tire according to any one of the preceding claims.   The first central crown sipe is chamfered between at least one sipe wall and the tread contact surface so as to gradually increase in width toward the outer crown main groove at the communication portion with the outer crown main groove The tire according to claim 6. The first outer crown sipe is chamfered at one side in the tire circumferential direction at a portion where the first outer crown sipe communicates with the outer crown main groove,
The tire according to claim 7, wherein the first central crown sipe is chamfered at a sipe wall on the other side in the tire circumferential direction at a communication portion with the outer crown main groove.

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