Pneumatic tire

Abstract

To provide a pneumatic tire capable of improving uneven wear resistance performance.SOLUTION: In a shoulder land 1 and a center land 2, first combinations G1 and second combinations G2 of groove elements are alternately arranged in a tire circumferential direction CD. The shoulder land 1 includes: first slits 31 each open at both ends in a tire axial direction AD of the land; first notches 12; and first sipes 11 each separated from the first notch 12. The center land 2 includes: second slits 32 each open at both ends in the tire axial direction AD of the land; second notches 22; and second sipes 21 each separated from the second notch. The first combination G1 includes: the first slit 31; and the second notch 22 and the second sipe 21 that are continuous with the first slit 31 in the tire axial direction AD. The second combination G1 of the groove elements includes: the second slit 32; and the first notch 12 and the first sipe 11 that are continuous with the second slit 32 in the tire axial direction AD.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires.

Background Art

[0002] Patent Documents 1 to 3 disclose that the tread surface of a pneumatic tire is partitioned into a plurality of lugs by main grooves, and the lugs have slits, notches, and sipes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] While the above-mentioned slits, notches, and sipes have a function of improving desired tire performance, they may cause uneven wear in which the wear amounts at both axial ends of the lugs in the tire axial direction are different in order to make the lugs easily deformable, and there is a possibility of deteriorating the uneven wear resistance performance.

[0005] The present disclosure provides a pneumatic tire capable of improving uneven wear resistance performance.

Means for Solving the Problems

[0006] The pneumatic tire of the present disclosure includes a tread surface having a first main groove extending in the tire circumferential direction, a first land and a second land adjacent to each other in the tire axial direction with the first main groove therebetween. The first land has a first slit opening at both ends of the first land in the tire axial direction, a first notch having one end opening into the first main groove and the other end terminating within the first land, and a first sipe spaced apart from the first notch in the tire axial direction. The second land has a second slit opening at both ends of the second land in the tire axial direction, a second notch having one end opening into the first main groove and the other end terminating within the second land, and a second sipe spaced apart from the second notch in the tire axial direction. The tread surface has a first combination including the first slit, the second notch continuous with the first slit in the tire axial direction, and the second sipe, and a second combination including the second slit, the first notch continuous with the second slit in the tire axial direction, and the first sipe. The first combination and the second combination are alternately arranged in the tire circumferential direction on the tread surface.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0008] [First Embodiment] Hereinafter, the first embodiment of the present disclosure will be described with reference to the drawings.

[0009] FIG. 1 is a developed view of a tread surface Tr provided in a pneumatic tire at the time of a new tire in the first embodiment. FIG. 2 is an enlarged developed view showing half of the tread surface Tr of the first embodiment. FIG. 3 is a further enlarged developed view of the tread surface Tr of the first embodiment.

[0010] As shown in FIGS. 1 and 2, a pneumatic tire (hereinafter, may be simply referred to as a tire) has a tread surface Tr. A plurality of main grooves (40, 41) continuously extending in the tire circumferential direction CD are provided on the ground contact surface included in the tread surface Tr. The number of main grooves can be changed. The plurality of main grooves (40, 41) in the first embodiment include a shoulder main groove 40 (corresponding to the first main groove) that is the outermost in the tire axial direction AD on the ground contact surface, and a center main groove 41 that is closest to the tire equator CL. The shoulder main groove 40 in the first embodiment is a zigzag-shaped groove continuously extending in the tire circumferential direction CD. The center main groove 41 is a groove having a shape including a branch portion and a confluence portion.

[0011] The main groove is not particularly limited, but for example, it may have a groove width of 3% or more of the distance (dimension in the tire axial direction AD) between the ground contact ends LE, LE. Also, the main groove is not particularly limited, but for example, it may have a groove width of 7.0 mm or more. Also, the main groove is not particularly limited, but for example, it may be continuous in the tire circumferential direction CD and have the deepest groove depth in the tread surface Tr. A TWI (tread wear indicator) indicating the limit of use due to wear may be partially provided in the groove of the main groove.

[0012] The dimensions and the like of each part of the pneumatic tire are the values measured in a non-loaded state where the pneumatic tire is mounted on a regular rim and filled with the regular internal pressure.

[0013] The ground contact surface means the surface that contacts the road surface when the tire is vertically placed on a flat road surface and a regular load is applied in a state where the tire is rim-mounted on a regular rim and filled with the regular internal pressure. The ground contact end LE is the outermost end in the tire axial direction AD of the ground contact surface.

[0014] The regular rim is the rim defined for each tire in a standard system including the standard on which the tire is based. For example, it is the standard rim in JATMA, and it is the "Measuring Rim" in TRA and ETRTO.

[0015] The regular internal pressure is the air pressure defined for each tire in a standard system including the standard on which the tire is based. In the case of tires for trucks and buses and light trucks, it is the maximum air pressure in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and it is the "INFLATION PRESSURE" in ETRTO. In the case of passenger car tires, it is usually 180 kPa, but in the case of tires marked with Extra Load or Reinforced, it is 220 kPa.

[0016] The regular load is the load defined for each tire in a standard system including the standard on which the tire is based. It is the maximum load capacity in JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, and it is the "LOAD CAPACITY" in ETRTO. In the case of passenger car tires, it is the load corresponding to 88% of the above load. In the case of tires for racing carts, the regular load is 392 N.

[0017] In this specification, the slits (the first slit 31 and the second slit 32) are grooves that are wider than the sipe described later and extend continuously from one end of the land to the other end. The notches (the first notch 12 and the second notch 22) are grooves that are wider than the sipe described later, open at one end of the land, terminate within the land away from the other end of the land, and have a length in the tire axial direction AD that is longer than the width in the tire circumferential direction CD. The notch of the first embodiment is shallower than the main groove, but may have the same depth as the main groove. The groove width of the first part (constant-width part) of the sipe (the first sipe 11 and the second sipe 21) described later is 0.3 mm or more and 1.5 mm or less. The groove width of the sipe means the width of the first part. The width of the first part is the width along the perpendicular passing through two lines spaced at a constant width on the sipe surface appearing on the tread surface Tr (the outer surface of the tire). The two lines include straight lines and curves. The sipe may be a three-dimensional sipe having a bent portion in the depth direction or a two-dimensional sipe extending linearly in the depth direction without bending in the depth direction.

[0018] The pneumatic tire has a shoulder land 1 (corresponding to the first land) disposed outside the shoulder main groove 40 in the tire axial direction AD and a center land 2 (corresponding to the second land) disposed inside the shoulder main groove 40 in the tire axial direction AD. The shoulder land 1 and the center land 2 are adjacent to each other in the tire axial direction AD with the shoulder main groove 40 therebetween. The tread pattern shown in FIG. 1 is a tread pattern in which the shoulder land 1 and the center land 2 are point-symmetrical.

[0019] <Shoulder land 1> The shoulder land 1 in the first embodiment has a first slit 31, a first sipe 11, and a first notch 12. The shoulder land 1 is partitioned into a plurality of shoulder blocks by the first slit 31 and the main shoulder groove 40. The first slit 31 opens at both ends of the shoulder land 1 in the tire axial direction AD. Specifically, the first slit 31 opens into the main shoulder groove 40 and extends to the outer end of the shoulder land 1 in the tire axial direction AD. The shoulder land 1 has a ridge line where the outer surface (ground contact surface) in the tire radial direction of the land and the side surface of the land intersect, and this ridge line is the outer end of the shoulder land 1 in the tire axial direction AD and becomes the ground contact end LE. One end of the first notch 12 opens into the main shoulder groove 40, and the other end of the first notch 12 terminates within the shoulder land 1. The first sipe 11 is spaced apart from the first notch 12 in the tire axial direction AD. Since the first sipe 11 is spaced apart from the first notch 12, a first small land area 13, which is a part of the tread surface Tr, is disposed between the first notch 12 and the first sipe 11.

[0020] <Center land 2> The center land 2 in the first embodiment has a second slit 32, a second sipe 21, and a second notch 22. The center land 2 is partitioned into a plurality of center blocks by the second slit 32 and the main grooves (40, 41). The second slit 32 opens at both ends of the center land 2 in the tire axial direction AD. Specifically, the second slit 32 opens into the main shoulder groove 40 and the main center groove 41. One end of the second notch 22 opens into the main shoulder groove 40, and the other end of the second notch 22 terminates within the center land 2. The second sipe 21 is spaced apart from the second notch 22 in the tire axial direction AD. Since the second sipe 21 is spaced apart from the second notch 22, a second small land area 23, which is a part of the tread surface Tr, is disposed between the second notch 22 and the second sipe 21. Note that a step with a constant width such as 1.0 mm is formed along the ends of the center blocks and the shoulder blocks in the first embodiment, but it is not limited thereto. The step may not be formed at the ends of the blocks.

[0021] <Position Relationship among Sipes, Notches, and Slits> As shown in FIG. 2, the tread surface Tr has a first combination G1 of groove elements and a second combination G2 of groove elements. The first combination G1 of groove elements includes a first slit 31, a second notch 22 continuous with the first slit 31 in the tire axial direction AD, and a second sipe 21 spaced apart from the second notch 22 in the tire axial direction AD. The second combination G2 of groove elements includes a second slit 32, a first notch 12 continuous with the second slit 32 in the tire axial direction AD, and a first sipe 11 spaced apart from the first notch 12 in the tire axial direction AD. In the tread surface Tr, the first combination G1 and the second combination G2 are alternately arranged in the tire circumferential direction CD. Between the first combination G1 and the second combination G2 of groove elements, slits and sipes that do not constitute the first combination G1 and the second combination G2 of groove elements may be arranged. Thereby, in the shoulder land 1 and the center land 2 adjacent to the shoulder land 1 via the shoulder main groove 40, compared with the case where only the first combination G1 of groove elements is arranged or the case where only the second combination G2 of groove elements is arranged, uneven wear in which the wear amounts of one end and the other end in the tire axial direction of the land are different can be suppressed. In particular, since the shoulder land 1 where uneven wear is most likely to occur is included in the pattern in which the first combination G1 and the second combination G2 of groove elements are alternately arranged in the tire circumferential direction CD, the balance of the ease of deformation of each land is achieved, which is advantageous for improving the uneven wear resistance performance. It should be noted that all the notches formed in the shoulder land 1 and the center land 2 may open into the shoulder main groove 40, and the first notch 12 of the shoulder land 1 and the second notch 22 of the center land 2 may be alternately arranged in the tire circumferential direction CD. It is also possible that all of the notches formed in the shoulder land 1 and the center land 2 constitute either the first combination G1 or the second combination G2.

[0022] <Cross-sectional Shape Passing through the Second Notch 22, the Second Sipe 21, and the Second Small Land Region 23> FIG. 4 is a cross-sectional view taken along the line I-I in FIG. 1, and is a cross-sectional view in which the second notch 22, the second groove 21, and the second island region 23 appear. In the center land 2, the width of the portion 24 from the bottom (22a) of the second notch 22 through the second island region 23 to the bottom (bottom surface 21b) of the second groove 21 becomes smaller from the inner side to the outer side in the tire radial direction RD. Thereby, the rigidity of the portion 24 forming the second island region 23 can be increased to improve the uneven wear resistance. The width of the portion 24 is the width in the above cross section.

[0023] As shown in FIG. 4, the second groove 21 has a bottom surface 21b extending along the tread surface Tr and a vertical wall surface 21c extending in the depth direction from the tread surface Tr. The depth direction of the groove is the normal direction of the tread surface Tr. The bottom surface 21b is the deepest bottom. The bottom surface 21b (the end 21a close to the second island region 23) of the second groove 21 is connected to the vertical wall surface 21c via one or a plurality of curved surfaces.

[0024] In the example of FIG. 4, the second notch 22 has a vertical wall surface 22c extending in the depth direction from the tread surface Tr and a bottom surface 22b. The bottom 22a of the second notch 22 is the deepest part of the bottom surface 22b of the second notch 22. The depth direction of the notch is the normal direction of the tread surface Tr. The bottom surface 22b of the second notch 22 is inclined so that the depth becomes smaller toward the second island region 23. The bottom surface 22b of the second notch 22 is connected to the vertical wall surface 22c via a curved surface.

[0025] <Dimensions of the first island region 13 and the second island region 23> As shown in FIG. 3, it is preferable that the dimension L3 in the tire axial direction AD of the first island region 13, the dimension L2 in the tire axial direction AD of the first groove 11, and the dimension L1 in the tire axial direction AD of the first notch 12 and the second slit 32 satisfy the following relationship. The ratio of L3 to (L1 + L2 + L3) is 1% or more and 5% or less. In particular, it is preferable that the ratio is 3%. When the above ratio is 1% or more, the effect of improving the uneven wear resistance can be easily obtained. When the above ratio is 5% or less, the effect of maintaining or improving the snow traction performance and the wet grip performance can be easily obtained. The dimension L1 in the tire axial direction AD obtained by combining the first notch 12 and the second slit 32 is the distance along the tire axial direction AD between the end in the tire axial direction AD of the first notch 12 and the end in the tire axial direction AD of the second slit 32. Here, the ends in the tire axial direction AD of the first notch 12 and the second slit 32 mean the center point of the straight end when the end is a straight end, and mean the outermost side of the end when there is no straight end. The dimension L2 in the tire axial direction AD of the first sipe 11 is the distance along the tire axial direction AD between the ends of the width center in the portion with a constant width on the sipe surface. The dimension L3 in the tire axial direction AD of the first land area 13 is the distance along the tire axial direction AD between the end of the width center in the portion with a constant width on the sipe surface of the first sipe 11 and the end in the tire axial direction AD of the first notch 12.

[0026] The same applies to the second land area 23. It is preferable that the dimension L3 in the tire axial direction AD of the second land area 23, the dimension L2 in the tire axial direction AD of the second sipe 21, and the dimension L1 in the tire axial direction AD obtained by combining the second notch 22 and the first slit 31 satisfy the above relationship. The dimension L1 in the tire axial direction AD obtained by combining the second notch 22 and the first slit 31 is the distance along the tire axial direction AD between the end in the tire axial direction AD of the second notch 22 and the end in the tire axial direction AD of the first slit 31. The end in the tire axial direction AD of the second notch 22 means the center point of the straight end when the end is a straight end, and means the outermost end when there is no straight end. The end in the tire axial direction AD of the first slit 31 is the grounding end LE. The dimension L2 in the tire axial direction AD of the second sipe 21 is the distance along the tire axial direction AD between the ends of the width center in the portion with a constant width on the sipe surface. The dimension L3 in the tire axial direction AD of the second land area 23 is the distance along the tire axial direction AD between the end of the width center in the constant-width portion of the sipe surface of the second sipe 21 and the end in the tire axial direction AD of the second notch 22.

[0027] <Shape of the first sipe 11 and the second sipe 21> Figure 5A is a cross-sectional view taken along the line II-II in Figure 3. Figure 5B is a cross-sectional view taken along the line III-III in Figure 3. As shown in Figure 3, the second sipe 21 has only the first portion 51. As shown in Figures 5A and 5B, the width D1 of the sipe surface of the first portion 51 is constant. As shown in Figure 3, the first sipe 11 has the first portion 51 and the second portion 52. As shown in Figure 5B, the width D2 of the sipe surface of the second portion 52 is larger than the width D1 of the first portion 51. Since the first sipe 11 has not only the first portion 51 but also the second portion 52, the groove width increases compared to the case where the first sipe 11 has only the first portion 51, so the wet grip performance can be improved. Also, by having the second portion 52, air can easily enter when the tire deforms due to grounding, and the discharge of snow that has entered the first sipe 11 is promoted when the tire leaves the road surface. As a result, it is possible to step in with a fresh state where no snow has entered the first sipe 11, and the edge effect is easily exerted, so the snow traction performance can be improved.

[0028] As shown in Figure 5B, the second portion 52 includes a sipe portion 52a having the same width D1 as the sipe width of the first portion 51, and a pair of recesses 52b formed on both sides in the sipe width direction WD of the sipe portion 52a. The pair of recesses 52b open to the tread surface Tr and have a flat bottom surface 53 extending parallel to the direction (sipe width direction WD) orthogonal to the sipe depth direction ND of the first sipe 11, and vertical wall surfaces 56 extending in the depth direction from the tread surface Tr. The sipe depth direction ND is the normal direction of the tread surface Tr. Since the second portion 52 has the vertical wall surfaces 56, the edge effect can be improved compared to the case where the second portion 52 has an inclined surface inclined in the depth direction instead of the vertical wall surfaces 56, and the snow traction performance can be improved.

[0029] It is preferable that the width D3 of each concave portion 52b is larger than the width D1. Also, in order to achieve balance, it is preferable that the widths D3 of the pair of concave portions 52b are equal. In the first embodiment, the width D1 is 0.8 mm, the width D2 is 3.0 mm, and the width D3 is 1.1 mm. In the first embodiment, the depth D4 of the second portion 52 is 1.0 mm, but it is not limited thereto. The minimum value of the depth D4 of the second portion 52 is 0.5 mm. If the depth D4 of the second portion 52 is less than 0.5 mm, it becomes difficult to obtain the effect of improving the wet grip performance and the snow traction performance by the second portion 52.

[0030] [Examples and Comparative Examples] Examples are shown below, but the present disclosure is not limited to these examples. FIG. 6 is a plan view schematically showing the shapes of the center land 2 and the shoulder land 1 of Comparative Example 1 and Examples 1 to 6.

[0031] Comparative Example 1 In each of the blocks of the shoulder land 1 and the center land 2, notches (12, 22), small land regions (13, 23), and sipes (11, 21) are arranged in order from the outside to the inside in the tire axial direction AD. The pattern of Comparative Example 1 is a pattern in which all the notches (12, 22) are arranged so as to open at the outer ends of the lands (blocks) in the tire axial direction AD. The ratio of the above L3 to (L1 + L2 + L3) is 3%.

[0032] Example 1 In the shoulder land 1 and the center land 2, the first combination G1 and the second combination G2 of groove elements are alternately arranged in the tire circumferential direction CD. The first combination G1 of groove elements includes the first slit 31, the second notch 22, and the second sipe 21, and these are arranged in order from the outside to the inside in the tire axial direction AD. The second combination G2 of groove elements includes the first sipe 11, the first notch 12, and the second slit 32, and these are arranged in order from the outside to the inside in the tire axial direction AD. The ratio of the above L3 to (L1 + L2 + L3) is 1%.

[0033] Example 2 In Example 1, the ratio of the above L3 to (L1 + L2 + L3) is 3%. Otherwise, it is the same as Example 1.

[0034] Example 3 In Example 1, the ratio of the above L3 to (L1 + L2 + L3) is 5%. Otherwise, it is the same as Example 1.

[0035] Example 4 The first side 11 of the shoulder land 1 in Example 1 has a second part 52. Otherwise, it is the same as Example 1.

[0036] Example 5 In Example 4, the ratio of the above L3 to (L1 + L2 + L3) is 3%. Otherwise, it is the same as Example 4.

[0037] Example 6 In Example 4, the ratio of the above L3 to (L1 + L2 + L3) is 5%. Otherwise, it is the same as Example 4.

[0038] The tires of the above Examples 1 to 6 and Comparative Example 1 were manufactured and evaluated for wet grip performance, snow traction performance, and resistance to uneven wear performance. Each evaluation method is as follows.

[0039] <Wet grip performance> Each test tire was mounted on a vehicle, and with the condition of an air temperature of 25°C, at a speed of 100 km / h, the ABS was activated from the state of driving on a road surface with a water depth of 1 mm. The braking distance at this time was measured (average value of n = 10) and shown as an index with Comparative Example 1 as 100. The larger the numerical value, the shorter the braking distance, indicating better wet grip performance.

[0040] <Snow traction performance> The actual vehicle (two passengers) equipped with each test tire was driven on a snowy road, and the time from the stop state to reaching the 20 m point was measured, and the reciprocal was calculated and shown as an index with Comparative Example 1 being 100. The larger the numerical value, the shorter the time, indicating better snow traction performance.

[0041] <Abrasion resistance performance against uneven wear> Each test tire was mounted on a vehicle, and a load equivalent to four passengers (driver + three weights of 55 kg each) was loaded, and the vehicle was driven for 12,000 km. After driving, for the two inflated tires, the wear difference between the inner and outer sides of the shoulder block in the tire axial direction was measured. Then, the average value of the wear differences of the two inflated tires was obtained, and the reciprocal of the average value was made into an index. The index was shown as an index with Comparative Example 1 being 100. The larger the index, the better the abrasion resistance performance against uneven wear.

[0042] The evaluation results are shown in Table 1.

Table 1

[0043] Comparing Comparative Example 1 and Example 2, it can be understood that the first combination G1 and the second combination G2 of the groove elements are alternately arranged in the tire circumferential direction CD, thereby improving the abrasion resistance performance against uneven wear. Furthermore, it can be understood that the wet grip performance and the snow traction performance can be improved. Comparing Example 1, Example 2, and Example 3, if the ratio of the above L3 to (L1 + L2 + L3) is 1% or more and 5% or less, it can be understood that the abrasion resistance performance against uneven wear can be improved, and the wet grip performance and the snow traction performance can be maintained or improved. Comparing Example 1 and Example 4, Example 2 and Example 5, and Example 3 and Example 6, it can be understood that although the wet grip performance and the snow traction performance are improved by the first sipe 11 having the second part 52, the abrasion resistance performance against uneven wear is slightly reduced. In any case, compared with Comparative Example 1, each performance is improved.

[0044] [Modification example] (A) In the above embodiment, the second part 52 of the first sipe 11 has recesses 52b on both sides in the sipe width direction WD of the sipe part 52a, but is not limited thereto. For example, the second part 52 may have a recess 52b only on one side in the sipe width direction WD of the sipe part 52a. Further, the first sipe 11 may not have the second part 52 and may have only the first part 51.

[0045] (B) In the above embodiment, as shown in FIG. 5B, the shape of the cross section along the sipe width direction WD of the second part 52 is a bottom surface 53, a vertical wall surface extending from the tread surface Tr in the sipe depth direction ND, and one curved surface connecting the vertical wall surface and the bottom surface 53, but is not limited thereto.

[0046] (C) In the above embodiment, the second sipe 21 formed in the center land 2 opens at the inner end in the tire axial direction AD of the center land 2, but is not limited thereto. The second sipe 21 formed in the center land 2 may be terminated inside the center land 2 separated from the inner end in the tire axial direction AD of the center land 2.

[0047] (D) In the above embodiment, as shown in FIG. 4, in the center land 2, if the width of the portion 24 from the bottom 22a of the second notch 22 through the second small land region 23 to the bottom (bottom surface 21b) of the second sipe 21 decreases from the inner side to the outer side in the tire diameter direction RD, the cross-sectional shape thereof is not limited to the shape shown in FIG. 4. As a first modification example, the cross-sectional shape of the above portion 24 may be the shape shown in FIG. 7. FIG. 7 is a figure corresponding to FIG. 4 showing the first modification example. The shape of the second sipe 21 in FIG. 7 is the same as the shape of the second sipe 21 shown in FIG. 4. In the example of FIG. 7, the second notch 22 has an inclined plane 122c extending in the depth direction from the tread surface Tr. The bottom surface 22b of the second notch 22 extends along the tread surface Tr. The bottom surface 22b (the end 122a close to the second small land region 23) of the second notch 22 is connected to the inclined plane 122c via one or a plurality of curved surfaces. As a second modification example, the cross-sectional shape of the above-mentioned portion 24 may be the shape shown in FIG. 8. FIG. 8 is a figure corresponding to FIG. 4 showing the second modification example. The shape of the second notch 22 in FIG. 8 is the same as the shape of the second notch 22 shown in FIG. 4. In the example of FIG. 8, the second sipe 21 has a vertical wall surface 21c extending in the depth direction from the tread surface Tr, a bottom surface 21b extending along the tread surface Tr, and an inclined plane 21d disposed between the bottom surface 21b and the vertical wall surface 21c. The bottom surface 21b (the end 21a close to the second land area 23) of the second sipe 21 is connected to the inclined plane 21d via one or a plurality of curved surfaces. The inclined plane 21d is connected to the vertical wall surface 21c via one or a plurality of curved surfaces. As a third modification example, the cross-sectional shape of the above-mentioned portion 24 may be the shape shown in FIG. 9. FIG. 9 is a figure corresponding to FIG. 4 showing the third modification example. The shape of the second notch 22 in FIG. 9 is the same as the shape of the second notch 22 shown in FIG. 4. In the example of FIG. 9, the second sipe 21 has a bottom surface 21b extending along the tread surface Tr and an inclined plane 21d extending toward the tread surface Tr. The bottom surface 21b (the end 21a close to the second land area 23) of the second sipe 21 is connected to the inclined plane 21d via one or a plurality of curved surfaces.

[0048] [1] As described above, like the above embodiment, the pneumatic tire includes a tread surface Tr having a first main groove (40) extending in the tire circumferential direction CD, and a first land (1) and a second land (2) adjacent to each other in the tire axial direction AD with the first main groove (40) therebetween. The first land (1) has a first slit 31 opening at both ends of the first land (1) in the tire axial direction AD, a first notch 12 having one end opening into the first main groove (40) and the other end terminating within the first land (1), and a first sipe 11 spaced apart from the first notch 12 in the tire axial direction AD. The second land (2) has a second slit 32 opening at both ends of the second land (2) in the tire axial direction AD, a second notch 22 having one end opening into the first main groove (40) and the other end terminating within the second land (2), and a second sipe 21 spaced apart from the second notch 22 in the tire axial direction AD. The tread surface Tr has a first combination G1 including the first slit 31, the second notch 22 and the second sipe 21 continuous with the first slit 31 in the tire axial direction AD, and a second combination G2 including the second slit 32, the first notch 12 and the first sipe 11 continuous with the second slit 32 in the tire axial direction AD. In the tread surface Tr, the first combination G1 and the second combination G2 may be alternately arranged in the tire circumferential direction CD. According to this configuration, since the first combination G1 and the second combination G2 of the groove elements are alternately arranged in the tire circumferential direction CD, the balance of the ease of deformation of each land is achieved compared to a pattern having only the first combination G1 or a pattern having only the second combination G2, and the uneven wear resistance performance can be improved.

[0049] [2] The pneumatic tire according to [1] above, wherein the tread surface Tr has a plurality of main grooves (40, 41) extending in the tire circumferential direction CD, the first main groove (40) is included in the plurality of main grooves, and the first main groove (40) may be a shoulder main groove 40 arranged at the outermost side in the tire axial direction AD among the plurality of main grooves. According to this configuration, either the first land or the second land becomes the shoulder land 1, and the shoulder land 1 where the most uneven wear is likely to occur is included in the pattern in which the first combination G1 and the second combination G2 of the groove elements are alternately arranged in the tire circumferential direction CD, which is advantageous for improving the uneven wear resistance performance.

[0050] [3] The pneumatic tire according to the above [1] or [2], wherein the second land (2) is arranged inside the first land (1) in the tire axial direction AD, and the tread surface Tr has a small land area (second small land area 23) between the second notch 22 and the second sipe 21. In the cross section where the second notch 22, the second sipe 21, and the small land area (second small land area 23) appear, the width of the portion 24 from the bottom 22a of the second notch 22 in the second land (2), passing through the small land area (second small land area 23), and reaching the bottom (21b) of the second sipe 21 may be made smaller from the inner side to the outer side in the tire radial direction RD. According to this configuration, the rigidity of the portion 24 forming the small land area (second small land area 23) can be ensured, and the uneven wear resistance performance can be improved.

[0051] [4] The pneumatic tire according to any one of the above [1] to [3], wherein the sipe surface shape of the first sipe 11 and the second sipe 21 may include a straight portion (51) having a constant width in plan view.

[0052] As described above, the embodiments of the present disclosure have been described with reference to the drawings. However, the specific configuration should not be considered to be limited to these embodiments. The scope of the present disclosure is shown not only by the description of the above embodiments but also by the claims, and further includes all changes within the meaning and scope equivalent to the claims.

[0053] It is possible to adopt the structure employed in each of the above embodiments in any other embodiment. The specific configuration of each part is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

Explanation of Symbols

[0054] 1: Shoulder land (First land) 2: Center land (Second land) 11: First siped 12: First notch 21: Second siped 22: Second notch 23: Second small land area (Small land area) 31: First slit 32: Second slit 40: Shoulder main groove (First main groove) AD: Tire axial direction CD: Tire circumferential direction G1: First combination G2: Second combination RD: Tire radial direction Tr: Tread surface

Claims

1. A tread surface having a first main groove extending in the tire circumferential direction, and a first land and a second land adjacent to each other in the tire axial direction with the first main groove therebetween. The first land has a first slit opening at both axial ends of the first land in the tire axial direction, a first notch having one end opening into the first main groove and the other end terminating within the first land, and a first sipe spaced apart from the first notch in the tire axial direction. The second land has a second slit opening at both axial ends of the second land in the tire axial direction, a second notch having one end opening into the first main groove and the other end terminating within the second land, and a second sipe spaced apart from the second notch in the tire axial direction. The tread surface has a first combination including the first slit, the second notch and the second sipe that are axially continuous with the first slit, and a second combination including the second slit, the first notch and the first sipe that are axially continuous with the second slit. The tread surface has The first combination and the second combination are alternately arranged in the tire circumferential direction on the tread surface. A pneumatic tire.

2. The tread surface has a plurality of main grooves extending in the tire circumferential direction, and the first main groove is included in the plurality of main grooves. The first main groove is a shoulder main groove disposed at the outermost side in the tire axial direction among the plurality of main grooves. The pneumatic tire according to Claim 1.

3. The second land is disposed on the inner side in the tire axial direction than the first land. The tread surface has a small land area between the second notch and the second sipe. In a cross section where the second notch, the second sipe and the small land area appear, the width of the portion from the bottom of the second notch in the second land through the small land area to the bottom of the second sipe decreases from the inner side to the outer side in the tire radial direction. The pneumatic tire according to Claim 1 or 2.

4. The sipe surface shape of the first sipe and the second sipe includes a straight portion having a constant width in plan view. The pneumatic tire according to Claim 1 or 2. ​ ​

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