Pneumatic tire

Abstract

To provide a pneumatic tire improved in demoldability.SOLUTION: This pneumatic tire comprises: a shoulder land 1 disposed closer to the outside of a tire axial direction AD than a shoulder main groove 40 disposed closest to the outside of the tire axial direction AD among a plurality of main grooves (40, 41); and a center land 2 disposed closer to the inside of the tire axial direction AD than the shoulder main grooves 40. The center land 2 includes a center sipe (52, 53). The shoulder land 1 includes a shoulder peripheral sipe 50 in which the extending direction of a sipe surface is 30 degrees or lower with respect to a tire circumferential direction CD. The shoulder peripheral sipe 50 extends at a sipe bottom in a depth direction S0 offset more inside the tire axial direction AD than the sipe surface on a tire meridian cross section. The shoulder peripheral sipe 50 is shallower than the center sipe (52, 53).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires.

Background Art

[0002] Pneumatic tires are manufactured by vulcanizing green tires in a vulcanization mold. The sipes on the tread surface are formed by metal blades provided in the mold. Patent Document 1 describes that the sipes of the shoulder blocks are deeper than those of the center blocks.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The reference profile of the outer surface of the tire in the tire meridian cross-section is composed of a plurality of curves. The radius of curvature of the curve located on the outer side in the tire axial direction is often relatively smaller than the radius of curvature of the curve located near the tire equator. That is, the curvature of the profile often becomes larger as it goes from the tire equator to the outer side in the tire axial direction. The sipes extend in the depth direction with the normal direction of the profile as the depth direction. When the tire is removed from the mold, the mold moves relatively in the tire diameter direction. In the tire meridian cross-section, the inclination angle of the sipes in the depth direction with respect to the tire diameter direction on the shoulder land is larger than that on the center land. Therefore, the sipes on the shoulder land are more difficult to be removed from the mold than the sipes on the center land. In particular, the demolding property of the circumferential sipes with a relatively small angle between the extending direction of the sipes surface and the tire circumferential direction tends to be poor. If the tire is forcibly removed from the mold, the blade forming the circumferential sipes will be curved, resulting in defective molding of subsequent tires.

[0005] The present disclosure provides a pneumatic tire with improved demolding properties.

Means for Solving the Problems

[0006] The pneumatic tire of the present disclosure includes a plurality of main grooves extending in the tire circumferential direction, a shoulder land disposed outside the tire axial direction of the shoulder main groove disposed most outside in the tire axial direction among the plurality of main grooves, and a center land disposed inside the tire axial direction of the shoulder main groove. The center land has a center sipe, the shoulder land has a shoulder circumferential sipe in which the extending direction of the sipe surface is 30 degrees or less with respect to the tire circumferential direction. The shoulder circumferential sipe extends in a depth direction in which the sipe bottom is offset inside the tire axial direction from the sipe surface in the tire meridian cross section, and the shoulder circumferential sipe is shallower than the center sipe.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes 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 the tread surface Tr of a pneumatic tire according to the first embodiment when the tire is new.

[0010] As shown in FIG. 1, a pneumatic tire (hereinafter, may be simply referred to as a tire) has a tread surface Tr. A plurality of main grooves (40, 41) that continuously extend in the tire circumferential direction CD are provided on the ground contact surface included in the tread surface Tr. In the first embodiment, there are three main grooves, but 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 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.

[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 within 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 values measured in a no-load state where the pneumatic tire is mounted on a regular rim and filled with a 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 a 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 based on the tire. For example, it is the standard rim in JATMA and the "Measuring Rim" in TRA and ETRTO.

[0015] The normal internal pressure is the air pressure determined for each tire in a standard system including the standards on which the tire is based. For tires for trucks and buses and light trucks, if it is JATMA, it is the maximum air pressure; if it is TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; if it is ETRTO, it is "INFLATION PRESSURE". 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 normal load is the load determined for each tire in a standard system including the standards on which the tire is based. If it is JATMA, it is the maximum load capacity; if it is TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; if it is ETRTO, it is "LOAD CAPACITY". 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 normal load is 392 N.

[0017] In this specification, the slit 30 is a groove wider than the sipe described later. The groove width of the sipe (shoulder circumferential sipe 50, shoulder axial sipe 51, center circumferential sipe 52, center axial sipe 53) is 0.3 mm or more and 1.8 mm or less. Further, the groove width of the sipe is preferably 0.8 mm or more and 1.5 mm or less. The groove width of the sipe is the width along a perpendicular line passing through two lines spaced at a constant width on the sipe surface appearing on the tread surface Tr (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 disposed outside the shoulder main groove 40 in the tire axial direction AD and a center land 2 disposed inside the shoulder main groove 40 in the tire axial direction AD. The shoulder land 1 and the center land 2 in the first embodiment are ribs that continuously extend in the tire circumferential direction CD, but are not limited thereto. At least one of the shoulder land 1 and the center land 2 may be a block divided by a slit 30.

[0019] The shoulder land 1 extends from the in-ground area Ai to the out-ground area Ao. The shoulder land 1 has a slit 30 extending in the tire axial direction AD, a shoulder circumferential sip 50, and a shoulder axial sip 51 in the in-ground area Ai. The slit 30 extends to an annular protrusion 31 formed on the side surface of the tire. The annular protrusion 31 is formed in an annular shape when viewed along the tire axial direction AD. The annular protrusion 31 is disposed at a fitting portion between a sector 75 (see FIG. 2) forming the tread of the tire and side moldings (71, 73; see FIG. 2) forming the side surface of the tire.

[0020] As shown in FIG. 1, the slit 30 extends outside the tire axial direction AD without opening into the shoulder main groove 40, extends from the in-ground area Ai to the out-ground area Ao, and extends to the annular protrusion 31.

[0021] The shoulder circumferential sipe 50 is a sipe that mainly extends in the tire circumferential direction CD, and the extending direction E0 of the sipe surface is a sipe with an angle of 30 degrees or less with respect to the tire circumferential direction CD. The sipe surface refers to the part of the sipe that appears on the tread surface Tr (tire outer surface) when the tire is new. The shoulder circumferential sipe 50 of the first embodiment has a linear part where the shape of the sipe surface is a straight line with a constant width. The extending direction E0 of the linear part is parallel to the two parallel straight lines forming the linear part of the sipe surface. The shape of the sipe surface is not limited to this. For example, the shape of the sipe surface of the shoulder circumferential sipe 50 may be a straight line with a constant width, a curve with a constant width, or a combination thereof. The extending direction of the curve part with a constant width is the tangent direction of the curve. When the shoulder circumferential sipe 50 is composed of a plurality of parts such as a straight line and a curve, each part has its own extending direction. As shown in FIG. 1, the sipe surface of the shoulder circumferential sipe 50 of the first embodiment has only a linear part extending parallel to the tire circumferential direction CD, but is not limited to this. Also, both ends of the shoulder circumferential sipe 50 of the first embodiment in the tire circumferential direction CD open to the slit 30, but are not limited to this.

[0022] The shoulder axial sipe 51 is a sipe that mainly extends in the tire axial direction AD, and the extending direction E1 of the sipe surface is a sipe with an angle exceeding 30 degrees with respect to the tire circumferential direction CD. That is, the shoulder axial sipe 51 is a sipe provided on the shoulder land 1 and is a sipe other than the above shoulder circumferential sipe 50. The shoulder axial sipe 51 of the first embodiment has a linear part where the shape of the sipe surface is a straight line with a constant width, but the linear part may not be present. The sipe surface shape of the shoulder axial sipe 51 may be a straight line with a constant width, a curve with a constant width, or a combination thereof. As shown in FIG. 1, the sip surface of the shoulder axial direction sip 51 of the first embodiment has a linear portion that linearly extends in the same direction as the extending direction of the slit 30, but is not limited thereto. Further, the shoulder axial direction sip 51 of the first embodiment opens to the shoulder circumferential direction sip 50, but is not limited thereto. The shoulder axial direction sip 51 of the first embodiment terminates within the shoulder land without opening to the shoulder main groove 40, but is not limited thereto and may open to the shoulder main groove 40.

[0023] The center land 2 has a center sip. The center sip includes a center circumferential direction sip 52 and a center axial direction sip 53.

[0024] The center circumferential direction sip 52 is a sip that mainly extends in the tire circumferential direction CD, and is a sip in which the extending direction E2 of the sip surface is 30 degrees or less with respect to the tire circumferential direction CD. The center circumferential direction sip 52 of the first embodiment has a linear portion where the shape of the sip surface is linear. The shape of the sip surface of the center circumferential direction sip 52 may be a straight line with a constant width, a curve with a constant width, or a combination thereof. As shown in FIG. 1, the sip surface of the center circumferential direction sip 52 of the first embodiment has only a linear portion that extends parallel to the tire circumferential direction CD, but is not limited thereto.

[0025] The center axial direction sip 53 is a sip that mainly extends in the tire axial direction AD, and is a sip in which the extending direction E3 of the sip surface exceeds 30 degrees with respect to the tire circumferential direction CD. The center axial direction sip 53 is a sip provided on the center land 2 and is a sip other than the center circumferential direction sip 52. The center axial direction sip 53 of the first embodiment has an arc portion where the shape of the sip surface is curved, but the arc portion may not be present. The shape of the sip surface of the center axial direction sip 53 may be a straight line with a constant width, a curve with a constant width, or a combination thereof.

[0026] As shown in FIG. 1, the center land 2 of the first embodiment has a plurality of center axis direction sipes 53. The plurality of center axis direction sipes 53 includes a first center axis direction sipe 53 disposed on one side of the tire axis direction AD of the center circumferential direction sipe 52, and a second center axis direction sipe 53 disposed on the other side of the tire axis direction AD of the center circumferential direction sipe 52. One end of the first center axis direction sipe 53 opens into the center main groove 41. The other end of the first center axis direction sipe 53 terminates near the center circumferential direction sipe 52. One end of the second center axis direction sipe 53 terminates near the center circumferential direction sipe 52. The other end of the second center axis direction sipe 53 opens into the shoulder main groove 40.

[0027] The above sipes (shoulder circumferential direction sipe 50, shoulder axis direction sipe 51, center circumferential direction sipe 52, center axis direction sipe 53) are formed by the blade 77 of the tire vulcanizing mold 7 described later. Next, the tire vulcanizing mold 7 will be briefly described.

[0028] <Tire vulcanizing mold 7> The pneumatic tire of the first embodiment is manufactured by the tire vulcanizing mold 7 shown in FIGS. 2 and 3. FIG. 2 is a cross-sectional view showing the tire vulcanizing mold 7 according to the first embodiment. FIG. 3 is a cross-sectional view of the tire vulcanizing mold 7.

[0029] As shown in FIG. 2, the tire vulcanizing mold 7 forms the outer surface of the pneumatic tire. The tire vulcanizing mold 7 includes an upper side mold 71 and a lower side mold 73 that are paired up and down, an upper bead ring 72 and a lower bead ring 74 that are paired up and down, and a plurality of sectors 75 arranged in the tire circumferential direction CD. The sector 75 is a mold for forming the tread surface Tr of the pneumatic tire. The plurality of sectors 75 are expandable and contractible in the tire radial direction RD and move outward in the tire radial direction RD1 when the mold opens. The upper side mold 71 and the upper bead ring 72 are configured to be movable relative to the lower side mold 73 and the lower bead ring 74 in the vertical direction (AD) and move upward (AD1) when the mold opens. The vertical direction (AD) coincides with the tire axial direction AD. One in the tire axial direction AD is upward (AD1), and the other in the tire axial direction AD is downward (AD2).

[0030] In FIG. 2, the bladder 76 is schematically shown by a dashed-dotted line. The bladder 76 includes an expandable and contractible rubber elastic body having a toroidal shape and is disposed on the inner surface side of the pneumatic tire to pressurize the pneumatic tire from the inside by expanding by supplying pressurized gas.

[0031] Next, the sector 75, which is a mold for forming the tread surface Tr of the pneumatic tire, will be described. As shown in FIG. 3, the sector 75 includes a mold body 750 for forming the tread surface Tr and a blade 77 for forming sipes (50, 51, 52, 53) (see FIG. 1) on the tread surface Tr. Not all the blades 77 are shown in FIG. 3. The mold body 750 is made of a soft metal such as aluminum (including aluminum alloy). The mold body 750 is provided with a tread molding surface 750A for molding the tread surface Tr. On the tread molding surface 750A, ribs 751 for molding main grooves (40, 41) (see FIG. 1) on the tread surface Tr are provided. The rib 751 is a ridge protruding from the tread molding surface 750A and extending in the tire circumferential direction CD, and is integrally formed with the mold body 750. The tread surface Tr is partitioned by the rib 751, and lands (1, 2) (see FIG. 1) are formed. The blade 77 is made of a material different from that of the mold body 750, and is preferably formed of an iron-based metal from the viewpoint of strength and the like. The blade 77 is preferably formed of stainless steel. The blade 77 is arranged so as to protrude from the tread molding surface 750A along the normal direction of the profile P shown in FIG. 4.

[0032] FIG. 4 is a cross-sectional view of the IV-IV part in FIG. 1. In FIG. 4, the bottom of the sipe projected onto the cross-section of the shoulder axial direction sipe 51 and the center axial direction sipe 53 is indicated by a dashed line. As shown in FIG. 4, the depth directions (S0, S1, S2, S3) of the respective sipes formed by the blade 77 are in the normal direction of the profile P.

[0033] The profile P is a reference surface of the outer surface of the tire, which is arranged at a position rotationally symmetric about the tire axis. The profile P is composed of a plurality of arcs with different radii of curvature in the tire meridian cross-section. Among the plurality of curves constituting the profile P, the radius of curvature of the curve located outside the tire axis direction AD is relatively smaller than the radius of curvature of the curve located near the tire equator CL. That is, the bend of the profile P becomes larger as it goes from the tire equator CL to the outside in the tire axis direction AD.

[0034] As shown in FIG. 4, due to the curvature of the profile P, the depth directions (S2, S0) of the center circumferential groove 52 and the shoulder circumferential groove 50 are respectively in the direction where the groove bottom is offset inward in the tire axial direction AD from the groove surface in the tire meridian cross-section. The depth directions (S3, S4, S1) of the center axial groove 53 and the shoulder axial groove 51 are respectively in the normal direction of the profile P in the tire meridian cross-section.

[0035] The angle θ0 of the depth direction S0 of the shoulder circumferential groove 50 with respect to the tire radial direction RD is larger than the angle θ2 of the depth direction S2 of the center circumferential groove 52 with respect to the tire radial direction RD. The shoulder circumferential groove 50 has a larger inclination with respect to the tire radial direction RD than the center circumferential groove 52. When the sector 75 (see FIGS. 2 and 3) moves in the tire radial direction RD and exits the tire, the blade 77 forming the shoulder circumferential groove 50 is more difficult to exit than the blade 77 forming the center circumferential groove 52. Similarly, the blade 77 forming the shoulder circumferential groove 50 is more difficult to exit than the blade 77 forming the center axial groove 53.

[0036] Therefore, as shown in FIG. 4, the depth D0 along the depth direction S0 of the shoulder circumferential groove 50 is shallower than the depth D2 along the depth direction (S2) of the center circumferential groove 52. Thereby, compared with the case where the shoulder circumferential groove 50 has the same depth as the center circumferential groove 52, the blade 77 forming the shoulder circumferential groove 50 is made easier to exit, and the demolding property of the shoulder circumferential groove 50 can be improved.

[0037] Similarly, the depth D0 along the depth direction S0 of the shoulder circumferential groove 50 is shallower than the depths (D3, D4) along the depth directions (S3, S4) of the center axial groove 53. Thereby, compared with the case where the shoulder circumferential groove 50 has the same depth as the center axial groove 53, the blade 77 forming the shoulder circumferential groove 50 is made easier to exit.

[0038] Furthermore, as shown in FIG. 4, the depth D0 along the depth direction S0 of the circumferential shoulder groove 50 is shallower than the depth D1 along the depth direction (S1) of the axial shoulder groove 51. This makes it easier for the blade 77 forming the circumferential shoulder groove 50 to come out compared to the case where the circumferential shoulder groove 50 has the same large depth as the axial shoulder groove 51. Also, since the axial shoulder groove 51 opens into the circumferential shoulder groove 50, the shoulder land 1 can move more easily, improving the demolding property of the circumferential shoulder groove 50.

[0039] [Second Embodiment] Hereinafter, a second embodiment of the present disclosure will be described with reference to the drawings. The same members and parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. FIG. 5 is a developed view of the tread surface Tr of the pneumatic tire according to the second embodiment when the tire is new. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5.

[0040] As shown in FIGS. 5 and 6, the shoulder land 1 of the pneumatic tire according to the second embodiment has a plurality of circumferential shoulder grooves (50, 55). The plurality of circumferential shoulder grooves include a first circumferential shoulder groove 50 and a second circumferential shoulder groove 55. The second circumferential shoulder groove 55 is located outside the first circumferential shoulder groove 50 in the tire axial direction AD. In the second embodiment, the first circumferential shoulder groove 50 is in the in-ground area Ai, and the second circumferential shoulder groove 55 is in the out-ground area Ao.

[0041] The angle θ5 of the depth direction S5 of the second circumferential shoulder groove 55 with respect to the tire radial direction RD is larger than the angle θ0 of the depth direction S0 of the first circumferential shoulder groove 50 with respect to the tire radial direction RD. When the sector 75 (see FIGS. 2 and 3) moves in the tire radial direction RD and comes out of the tire, the blade 77 forming the second circumferential shoulder groove 55 is more difficult to come out compared to the blade 77 forming the first circumferential shoulder groove 50. The depth D5 along the depth direction S5 of the second circumferential shoulder groove 55 is shallower than the depth D0 along the depth direction S0 of the first circumferential shoulder groove 50. As a result, the blade 77 forming the second circumferential shoulder groove 55 is easier to remove than when the second circumferential shoulder groove 55 has the same depth as the first circumferential shoulder groove 50.

[0042] [Modification Example] (A) In the above embodiment, both the circumferential center land groove 52 and the axial center land groove 53 are provided in the center land 2, but the present invention is not limited to this. Both the circumferential center land groove 52 and the axial center land groove 53 may not be provided in the center land 2, or at least one of the circumferential center land groove 52 and the axial center land groove 53 may be provided in the center land 2.

[0043] (B) In the above embodiment, the axial center land groove 53 opens into the shoulder main groove 40 or the center main groove 41, but the present invention is not limited to this. The axial center land groove 53 may terminate within the center land 2. The axial center land groove 53 does not open into the circumferential center land groove 52, but the axial center land groove 53 may open into the circumferential center land groove 52.

[0044] (C) In the second embodiment, the first circumferential shoulder groove 50 is arranged in the in-ground area Ai, and the second circumferential shoulder groove 55 is arranged in the out-of-ground area Ao, but the present invention is not limited to this. For example, both the first circumferential shoulder groove 50 and the second circumferential shoulder groove 55 may be arranged in the in-ground area Ai, or both the first circumferential shoulder groove 50 and the second circumferential shoulder groove 55 may be arranged in the out-of-ground area Ao.

[0045] [1] As described above, like the first and second embodiments, the pneumatic tire includes a plurality of main grooves (40, 41) extending in the tire circumferential direction CD, a shoulder land 1 disposed outside the shoulder main groove 40 which is the outermost one among the plurality of main grooves in the tire axial direction AD, and a center land 2 disposed inside the shoulder main groove 40 in the tire axial direction AD. The center land 2 has center sipes (52, 53), and the shoulder land 1 has shoulder circumferential sipes 50 in which the extending direction of the sipe surface is 30 degrees or less with respect to the tire circumferential direction CD. The shoulder circumferential sipes 50 extend in the depth direction S0 in which the sipe bottom is offset inward in the tire axial direction AD from the sipe surface in the tire meridian cross section. The shoulder circumferential sipes 50 may be shallower than the center sipes (52, 53). According to this configuration, the demolding property of the shoulder circumferential sipes 50 can be improved.

[0046] [2] The pneumatic tire according to [1] above, wherein the shoulder land 1 has shoulder axial sipes 51 in which the extending direction of the sipe surface exceeds 30 degrees with respect to the tire circumferential direction CD, the shoulder axial sipes 51 open to the shoulder circumferential sipes 50, and the shoulder circumferential sipes 50 may be shallower than the shoulder axial sipes 51. According to this configuration, the shoulder land 1 becomes more movable by the shoulder axial sipes 51 opening to the shoulder circumferential sipes 50, and the demolding property of the shoulder circumferential sipes 50 can be improved. Further, the demolding property of the shoulder circumferential sipes 50 can be improved by the shoulder circumferential sipes 50 being shallower than the shoulder axial sipes 51.

[0047] [3] The pneumatic tire according to the above [1] or [2], wherein the center sipe includes a center circumferential sipe 52 in which the extending direction of the sipe surface is 30 degrees or less with respect to the tire circumferential direction CD, and in the tire meridian cross section, the center circumferential sipe 52 extends in the depth direction S2 in which the sipe bottom is offset inward in the tire axial direction from the sipe surface. The angle θ0 of the depth direction S0 of the shoulder circumferential sipe 50 with respect to the tire radial direction RD is larger than the angle θ2 of the depth direction S2 of the center circumferential sipe 52 with respect to the tire radial direction RD, and the shoulder circumferential sipe 50 may be shallower than the center circumferential sipe 52. If the depth of the sipe is the same, since the angle θ0 of the shoulder circumferential sipe 50 is larger than the angle θ2 of the center circumferential sipe 52, the demolding property of the shoulder circumferential sipe 50 is worse than that of the center circumferential sipe 52. With the above configuration, since the shoulder circumferential sipe 50 is shallower than the center circumferential sipe 52, the demolding property of the shoulder circumferential sipe 50 can be improved.

[0048] [4] The pneumatic tire according to any one of the above [1] to [3], wherein the shoulder land 1 has a plurality of shoulder circumferential sipess, and the plurality of shoulder circumferential sipess include a first shoulder circumferential sipe 50 and a second shoulder circumferential sipe 55 located outside the first shoulder circumferential sipe 50 in the tire axial direction AD. The angle θ5 of the depth direction S5 of the second shoulder circumferential sipe 55 with respect to the tire radial direction RD is larger than the angle θ0 of the depth direction S0 of the first shoulder circumferential sipe 50 with respect to the tire radial direction RD, and the second shoulder circumferential sipe 55 may be shallower than the first shoulder circumferential sipe 50. If the depth of the sipe is the same, since the angle θ5 of the second shoulder circumferential sipe 55 is larger than the angle θ0 of the first shoulder circumferential sipe 50, the demolding property of the second shoulder circumferential sipe 55 is worse than that of the first shoulder circumferential sipe 50. With the above configuration, since the second shoulder circumferential sipe 55 is shallower than the first shoulder circumferential sipe 50, the demolding property of the second shoulder circumferential sipe 55 can be improved.

[0049] [5] The pneumatic tire according to [4] above, wherein the first shoulder circumferential groove 50 is in the in-ground contact area Ai and the second shoulder circumferential groove 55 is in the out-ground contact area Ao, may be used.

[0050] [6] The pneumatic tire according to [4] above, wherein the first shoulder circumferential groove 50 and the second shoulder circumferential groove 55 are in the in-ground contact area Ai, may be used.

[0051] 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 scope of the claims, and further includes all modifications within the meaning and scope equivalent to the scope of the claims.

[0052] 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 only the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

Description of Reference Numerals

[0053] 1: Shoulder land 2: Center land 40: Shoulder main groove 50: Shoulder circumferential groove (first shoulder circumferential groove) 51: Shoulder axial groove 52: Center circumferential groove (second shoulder circumferential groove) AD: Tire axial direction Ai: In-ground contact area Ao: Out-ground contact area CD: Tire circumferential direction RD: Tire radial direction

Claims

1. A plurality of main grooves extending in the tire circumferential direction, A shoulder land disposed axially outside the shoulder main groove that is disposed axially outermost among the plurality of main grooves, A center land disposed axially inside the shoulder main groove, and The center land has a center sipe, The shoulder land has a shoulder circumferential sipe in which the extending direction of the sipe surface is 30 degrees or less with respect to the tire circumferential direction, The shoulder circumferential sipe extends in a depth direction in which the sipe bottom is offset axially inside from the sipe surface in the tire meridian cross section, The shoulder circumferential sipe is shallower than the center sipe, a pneumatic tire.

2. The shoulder land has a shoulder axial sipe in which the extending direction of the sipe surface exceeds 30 degrees with respect to the tire circumferential direction, The shoulder axial sipe opens to the shoulder circumferential sipe, The shoulder circumferential sipe is shallower than the shoulder axial sipe, the pneumatic tire according to claim 1.

3. The center sipe includes a center circumferential sipe in which the extending direction of the sipe surface is 30 degrees or less with respect to the tire circumferential direction, The center circumferential sipe extends in a depth direction in which the sipe bottom is offset axially inside from the sipe surface in the tire meridian cross section, An angle of the shoulder circumferential sipe in the depth direction with respect to the tire radial direction is larger than an angle of the center circumferential sipe in the depth direction with respect to the tire radial direction, The shoulder circumferential sipe is shallower than the center circumferential sipe, the pneumatic tire according to claim 1 or 2.

4. The shoulder land has a plurality of the shoulder circumferential sipes, The plurality of circumferential shoulder sipes include a first circumferential shoulder sipe and a second circumferential shoulder sipe located outside the first circumferential shoulder sipe in the tire axial direction. The angle of the second circumferential shoulder sipe with respect to the tire radial direction in the depth direction is larger than the angle of the first circumferential shoulder sipe with respect to the tire radial direction in the depth direction. The second circumferential shoulder sipe is shallower than the first circumferential shoulder sipe. The pneumatic tire according to claim 1.

5. The first circumferential shoulder sipe is in the ground contact area. The second circumferential shoulder sipe is in the ground contact area. The pneumatic tire according to claim 4.

6. The first circumferential shoulder sipe and the second circumferential shoulder sipe are in the ground contact area. The pneumatic tire according to claim 4.

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