pneumatic tires
The tire design with a narrow groove and annular grooves addresses wear suppression and mold release issues by allowing the sacrificial rib to wear first, enhancing durability and flexibility.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYO TIRE CORP
- Filing Date
- 2022-08-18
- Publication Date
- 2026-05-12
AI Technical Summary
Pneumatic tires for trucks and buses experience concentrated stress at the land ends forming the ground contact surface, leading to wear, and existing sacrificial ribs improve wear suppression but compromise mold release properties.
A pneumatic tire design featuring a narrow groove dividing the shoulder land into a land main body and a sacrificial rib, with annular grooves extending from the tire sidewall, positioned radially outward and inward from the mold split, and angled at 30 degrees or less, enhancing flexibility and mold release.
The design effectively suppresses wear on the land main body by allowing the sacrificial rib to wear first, while improving mold release properties and reducing premature wear, ensuring durability and flexibility.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to pneumatic tires.
Background Art
[0002] It is known that in pneumatic tires used for trucks and buses, stress during running tends to concentrate at the land ends forming the ground contact surface, and the land is prone to wear.
[0003] Patent Document 1 discloses a pneumatic tire in which a sacrificial rib is formed on the outer side in the tire axial direction of the shoulder land by providing a groove extending from the ground contact surface toward the inner side in the tire radial direction in the shoulder land. By providing the sacrificial rib, the concentration of stress during running is dispersed, and wear of the shoulder land excluding the sacrificial rib is suppressed.
[0004] An annular groove extending from the outer surface in the tire axial direction toward the inner side in the tire axial direction is provided in the sacrificial rib. By providing the annular groove, the force applied to the sacrificial rib is dispersed.
[0005] By the way, the annular groove is provided on the outer side in the tire radial direction rather than at the split position between the tread mold forming the tread and the side mold forming the sidewall, and the mold release property of the tread mold is poor.
Prior Art Documents
Patent Documents
[0006]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0007] An object of the present disclosure is to provide a pneumatic tire capable of improving the mold release property of a tread mold while ensuring the effect of suppressing wear of a shoulder land by a sacrificial rib. [Means for solving the problem]
[0008] The pneumatic tire of this disclosure comprises a plurality of landmasses forming a contact surface, a tire sidewall surface which is the outer surface of the sidewall, and a narrow groove extending inward along the tire radial direction and continuously along the tire circumferential direction from the contact surface of the landmass that is the outermost landmass in the tire axial direction among the plurality of landmasses, wherein the landmass that is the outermost landmass in the tire axial direction among the plurality of landmasses is divided by the narrow groove into a landmass body and a sacrificial rib located further outward in the tire axial direction than the landmass body and including the end of the contact surface, wherein the sacrificial rib comprises a first annular groove extending from the tire sidewall surface along the tire radial direction and continuously along the tire circumferential direction, wherein the first annular groove is provided radially outward from the split position between the tread mold forming the tread and the side mold forming the sidewall, and the second annular groove is provided radially inward from the split position, and the inclination angle of the centerline of the first annular groove with respect to the tire radial direction is 30 degrees or less. [Brief explanation of the drawing]
[0009] [Figure 1] A tire meridian cross-sectional view showing the main parts of a pneumatic tire according to one embodiment. [Figure 2] Side view of the pneumatic tire of the same embodiment [Figure 3] Enlarged view of area III in Figure 1 [Modes for carrying out the invention]
[0010] The pneumatic tire 1 of this disclosure will be described below with reference to the drawings. In the drawings, "CD" means the circumferential direction of the tire, "AD" means the axial direction of the tire, and "RD" means the radial direction of the tire. Each drawing shows the shape of a new tire.
[0011] As shown in Figures 1 and 2, the pneumatic tire 1 (hereinafter simply referred to as "tire 1") comprises a pair of beads (not shown), sidewalls 2 extending radially outward RD1 from each bead, and a tread 3 connecting the radially outward RD1 ends of the sidewalls 2. The bead is provided with an annular bead core (not shown) made of a converging body such as steel wire covered with rubber, and a bead filler (not shown) made of hard rubber. The bead is mounted on the bead seat of the rim (not shown), and if the air pressure is a predetermined pressure (for example, the air pressure specified by JATMA), the tire is properly fitted to the rim flange by the internal pressure of the tire, and the tire 1 is fitted onto the rim.
[0012] The tire 1 comprises a toroidal carcass 4 extending from the tread 3 through the sidewall 2 to the bead. The carcass 4 is positioned between a pair of beads, and its ends are locked in place by being wound up through the bead core. An inner liner rubber 5 is provided on the inner circumference of the carcass 4 to maintain air pressure.
[0013] On the outer radial RD1 of the carcass 4, multiple belt plies 6a, 6b, 6c, 6d (four in this embodiment) and tread rubber 30 are provided sequentially from the inside to the outside of the tire radial RD to reinforce the carcass 4. The multiple belt plies 6a, 6b, 6c, 6d are provided between the carcass 4 and the tread rubber 30. Multiple belt plies 6a, 6b, 6c, 6d are provided between the contact surface 33 formed by the tread rubber 30 and the carcass 4. On the outer surface of the tread 3, multiple main grooves 31 extending along the tire circumferential direction CD and land 32 partitioned by the main grooves 31 and continuous with the tire circumferential direction CD are formed. Since the tire 1 according to this embodiment is a rib tire, the land 32 is not divided in the tire circumferential direction CD (no blocks are formed). In this embodiment, the tire 1 has two main grooves 31 formed on one side of the tire 1, and has a total of four main grooves 31. The tire 1 is not limited to the above, and may have, for example, two or three main grooves in total, or five or more main grooves.
[0014] Multiple landforms 32 are separated by main grooves 31. In this embodiment, the multiple landforms 32 are shoulder landforms 32a, quarter landforms 32b, and center landforms 32c, but are not limited to these. The number of landforms 32 can be changed as appropriate. The center landform 32c is the landform closest to the tire equatorial plane CL. The shoulder landform 32a is a landform formed in the tire axial direction AD1 further outward than the main groove 31 that is the outermost AD1 of the multiple main grooves 31. That is, the shoulder landform 32a is the landform in the tire axial direction AD1 of the multiple landforms 32. The quarter landform 32b is a landform provided between the shoulder landform 32a and the center landform 32c. Depending on the number of main grooves 31, the quarter landform 32b may be omitted.
[0015] Each of the four belt plies 6a, 6b, 6c, and 6d contains multiple steel cords arranged in parallel in a curtain-like fashion, and these are formed by covering them with rubber. Of the four belt plies 6a, 6b, 6c, and 6d, the cords of the second and third belt plies 6b and 6c, which are the second and third belt plies extending radially outward RD1 from the carcass 4, intersect each other at opposite inclinations with respect to the tire axial direction AD. The second and third belt plies 6b and 6c are the so-called main belts, and the tread rubber 30 is inserted between belt plies 6b and 6c.
[0016] The tread 3's surface 32 forms the contact surface 33. Further outward in the tire axial direction AD1 from the contact edge LE on the contact surface 33 is the tire sidewall surface 7, which is made of sidewall rubber. The tire sidewall surface 7 is the outer surface of the sidewall 2 and includes the region from the contact edge LE to the tire's maximum width (not shown). In this embodiment, the contact edge LE corresponds to the ridge line between the contact surface 33 and the tire sidewall surface 7 in a heavy-duty tire. The contact edge LE is the outermost end of the contact surface 33 in the tire axial direction AD.
[0017] The contact surface 33 refers to the surface that contacts the road surface when the tire 1 is mounted on a standard rim, filled to the standard internal pressure, placed perpendicular to a flat road surface, and subjected to the standard load. The standard rim is the rim specified for each tire in the standard system that includes the standard on which the tire is based. For JATMA, it is the standard rim; for TRA or ETRTO, it is the "Measuring Rim".
[0018] The standard internal pressure is the air pressure specified for each tire by the tire standard, which is part of the tire standard system on which the tire is based. For JATMA, it is the maximum air pressure; for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and for ETRTO, it is "INFLATION PRESSURE".
[0019] The standard load is the load specified for each tire within the standards system, including the standard on which the tire is based. For JATMA, it is the maximum load capacity; for TRA, it is the maximum value listed in the table above; and for ETRTO, it is "LOAD CAPACITY".
[0020] Figure 3 is an enlarged view of region III in Figure 1. As shown in Figures 1 and 3, the tire 1 has a narrow groove 80 that extends from the contact surface 33 of the ground 32 (shoulder ground 32a) in the radial direction RD towards the inner side RD2 of the tire. The narrow groove 80 extends continuously along the circumferential direction CD of the tire. The narrow groove 80 (including its groove bottom 80a) is located further outward AD1 in the tire axial direction than the belt end 60 that is the outermost belt end AD1 of the multiple belt plies 6a, 6b, 6c, 6d.
[0021] The land groove 80 divides the shoulder land 32a into a land main body 34 and a sacrificial rib 35. That is, among the plurality of lands 32, the land (shoulder land 32a) located most outside in the tire axial direction AD1 is divided by the land groove 80 into the land main body 34 and the sacrificial rib 35 which is located outside the land main body 34 in the tire axial direction AD1 and includes the edge (ground contact edge LE) of the ground contact surface 33. By providing the sacrificial rib 35, the sacrificial rib 35 can be worn out prior to the land main body 34, and wear of the land main body 34 can be suppressed.
[0022] The width E3 of the land groove 80 in the tire axial direction AD is preferably 2 mm or more. Thereby, when the sacrificial rib 35 is deformed, contact between the sacrificial rib 35 and the land main body 34 can be suppressed. As a result, integral behavior of the sacrificial rib 35 and the land main body 34 can be suppressed, and the wear suppression effect on the land main body 34 can be ensured. The width of the land groove 80 in the tire axial direction AD is preferably 5 mm or less. Thereby, reduction of the land width of the land main body 34 in the tire axial direction AD can be suppressed.
[0023] The groove depth of the land groove 80 is, for example, 15 mm or less. The groove depth of the land groove 80 is, for example, 80% or more and 100% or less of the depth of the main groove 31.
[0024] As shown in FIG. 3, the side wall surface 80b on the outside AD1 in the tire axial direction of the land groove 80 is preferably provided at a position within 2 mm from the ground contact edge LE. That is, the width D1 in the tire axial direction AD of the sacrificial rib 35 on the ground contact surface 33 is preferably 2 mm or less. Thereby, reduction of the land width of the land main body 34 in the tire axial direction AD can be suppressed. The width D1 is preferably 1.2 mm or more. Thereby, the rigidity of the sacrificial rib 35 can be ensured, and breakage (bending) of the sacrificial rib 35 can be suppressed. The side wall surface 80b of the land groove 80 is preferably provided, for example, outside the tire axial direction AD1 from the ground contact edge LE toward the inside AD2 in the tire axial direction by more than 20% of the land width in the tire axial direction AD of the shoulder land 32a.
[0025] The sacrificial rib 35 is located AD1 further outward in the tire axial direction than the base body 34. The sacrificial rib 35 includes the end of the contact surface 33 (contact edge LE) and extends from the contact surface 33 along the tire radial direction RD to the tire radially inward direction RD2. In this embodiment, the narrow groove 80 extends substantially parallel to the tire radial direction RD, but is not limited thereto.
[0026] The sacrificial rib 35 has at least one first annular groove 90. By providing the first annular groove 90, the sacrificial rib 35 can be made to flex, and the groove bottom of the first annular groove 90 also bears stress, so the stress acting on the groove bottom 80a of the narrow groove 80 can be distributed, and cracks in the groove bottom 80a of the narrow groove 80 can be suppressed. In addition, the ground pressure applied to the ground end LE can be reduced, and premature wear of the sacrificial rib 35 can be suppressed.
[0027] The first annular groove 90 is located radially outward RD1 of the narrow groove 80 than the groove bottom 80a. If multiple first annular grooves 90 are provided, all of the first annular grooves 90 are located radially outward RD1 of the narrow groove 80 than the groove bottom 80a.
[0028] The first annular groove 90 opens into the tire sidewall 7 and terminates within the sacrificial rib 35. The first annular groove 90 extends continuously along the tire circumferential direction CD. The first annular groove 90 is formed in an annular shape (see Figure 2). The first annular groove 90 extends along the tire radial direction RD. In this embodiment, the first annular groove 90 extends linearly along the tire radial direction RD, but is not limited to this.
[0029] The first annular groove 90 is provided at a position substantially coinciding with the center C1 of the groove depth of the narrow groove 80, but is not limited to this. The first annular groove 90 may be provided, for example, at a position RD2 radially inward of the center C1 of the groove depth of the narrow groove 80. This keeps the first annular groove 90 away from the contact surface 33 that contacts the road surface, thereby suppressing the occurrence of cracks originating from the first annular groove 90. If there are multiple first annular grooves 90, it is preferable that the first annular groove 90 located at the outermost RD1 radially inward of the tire is provided at a position substantially coinciding with the center C1 of the groove depth of the narrow groove 80, or at a position RD2 radially inward of the tire than the center C1 of the groove depth of the narrow groove 80. The center C1 is at the halfway point of the groove depth of the narrow groove 80.
[0030] In this embodiment, the first annular groove 90 extends beyond the center C1 of the groove depth of the narrow groove 80 toward the inner side RD2 in the radial direction of the tire, but is not limited to this.
[0031] The width E1 of the first annular groove 90 is preferably 2 mm or more. This allows the stress on the sacrificial rib 35 to be distributed. The width E1 of the first annular groove 90 is preferably 5 mm or less. This ensures the rigidity of the sacrificial rib 35 and ensures its durability against trauma. If multiple first annular grooves 90 are provided, the total width of the first annular grooves 90 is preferably 5 mm or less.
[0032] The first annular groove 90 is located radially outward RD1 of the tire from the splitting position MS between the tread mold (not shown) that forms the tread 3 and the side mold (not shown) that forms the sidewall 2. The splitting position MS of the tire 1 can be confirmed by the removal marks of rubber burrs that occur in the fitting gap between the tread mold and the side mold. During demolding, the tread mold moves radially outward RD1 along the tire radial direction RD, and the side mold moves axially outward AD1 along the tire axial direction AD.
[0033] The first annular groove 90 is preferably located on the tire axial side AD1 of the sacrificial rib 35, beyond the center line C4 of the tire axial side AD. This ensures the rigidity of the sacrificial rib 35.
[0034] The inclination angle θ1 of the center line C2 of the first annular groove 90 with respect to the tire radial direction RD is 0 degrees or more. This prevents a portion of the sidewall 2 from becoming thin. The inclination angle θ1 is 30 degrees or less. This improves the release properties of the tread mold. As a result, it is possible to prevent the protrusions forming the first annular groove 90 in the tread mold from breaking (bending). The inclination angle θ1 is more preferably 10 degrees or more, and more preferably 25 degrees or less. The inclination angle θ1 is the angle at which the tire is inclined toward the tire axial direction inward AD2 toward the tire radial direction inward RD2. The dimensions and angles of this disclosure are determined in an unloaded state with the tire 1 mounted on a normal rim and normal internal pressure applied.
[0035] The sacrificial rib 35 has at least one second annular groove 91. By providing the second annular groove 91, the sacrificial rib 35 can be made to flex, and the groove bottom 91a of the second annular groove 91 also bears stress, so the stress acting on the groove bottom 80a of the narrow groove 80 can be distributed, and cracks in the groove bottom 80a of the narrow groove 80 can be suppressed. In addition, the ground pressure applied to the ground end LE can be reduced, and premature wear of the sacrificial rib 35 can be suppressed.
[0036] The second annular groove 91 is located radially inward RD2 of the groove bottom 80a of the narrow groove 80. If multiple second annular grooves 91 are provided, all of them are located radially inward RD2 of the groove bottom 80a of the narrow groove 80.
[0037] The second annular groove 91 opens into the tire sidewall surface 7. The second annular groove 91 extends continuously along the tire circumferential direction CD. The second annular groove 91 is formed in an annular shape (see Figure 2). The second annular groove 91 extends along the tire axial direction AD. In this embodiment, the second annular groove 91 extends linearly along the tire axial direction AD, but is not limited to this. The second annular groove 91 is provided at RD2 radially inward of the split position MS.
[0038] It is preferable that the shortest distance D3 between the second annular groove 91 and the belt end 60 be 3 mm or more. This prevents the crack from reaching the belt ply 6b even if a crack occurs in the second annular groove 91.
[0039] The shortest distance D5 between the second annular groove 91 and the carcass 4 is preferably 3 mm or more. This prevents the crack from reaching the carcass 4 even if a crack occurs in the second annular groove 91.
[0040] The shortest distance D6 between the second annular groove 91 and the narrow groove 80 is preferably 10 mm or more. This ensures the rigidity of the base portion of the sacrificial rib 35 and prevents the sacrificial rib 35 from breaking (bending).
[0041] The width E2 of the second annular groove 91 is preferably 5 mm or more. This allows the stress on the sacrificial rib 35 to be distributed. The width E2 of the second annular groove 91 is preferably 7 mm or less. This ensures the rigidity of the sacrificial rib 35 and ensures its durability against trauma. If multiple second annular grooves 91 are provided, the total width of the second annular grooves 91 is preferably 7 mm or less.
[0042] The width E2 of the second annular groove 91 is preferably larger than the width E1 of the first annular groove 90. This ensures the rigidity of the sacrificial rib 35 while suppressing premature wear of the sacrificial rib 35.
[0043] The inclination angle θ2 of the center line C3 of the second annular groove 91 with respect to the tire axial direction AD is preferably -30 degrees or more and 30 degrees or less. This improves the release properties of the side mold. As a result, it is possible to suppress the bending of the protrusions forming the second annular groove 91 in the side mold. The inclination angle θ2 is more preferably -20 degrees or more and 20 degrees or less, and even more preferably -10 degrees or more and 10 degrees or less. Note that the inclination angle θ2 is not limited to the above, and may be less than -30 degrees or greater than 30 degrees. In the inclination angle θ2, a negative value means that it is inclined toward the inner side RD2 in the tire radial direction toward the inner side AD2 in the tire axial direction.
[0044] The inclination angle θ2 is preferably 0 degrees or greater. This allows the sacrificial rib 35 to be formed from rubber that is located further outward RD1 in the tire radial direction than the belt end 60. As a result, the sacrificial rib 35 becomes more flexible, and premature wear of the sacrificial rib 35 can be suppressed.
[0045] The second annular groove 91 (groove bottom 91a) is preferably located radially outward RD1 of the belt end 60, which is the outermost AD1 in the tire axial direction among the belt ends of the multiple belt plies 6a, 6b, 6c, 6d (see Figure 1). This allows the sacrificial rib 35 to be formed from rubber located radially outward RD1 of the belt end 60. As a result, the sacrificial rib 35 becomes more flexible, and premature wear of the sacrificial rib 35 can be suppressed. The second annular groove 91 is not limited to the above, and may, for example, be located radially inward RD2 of the belt end 60.
[0046] Preferably, the second annular groove 91 extends further inward AD2 than the side wall surface 80c of the narrow groove 80 in the tire axial direction. That is, it is preferable that the groove bottom 91a of the second annular groove 91 is located further inward AD2 than the side wall surface 80c. This allows the contact pressure at the edge of the contact surface 33 of the ground body 34 to be reduced even after the sacrificial rib 35 has worn away, thereby suppressing wear of the ground body 34. However, the groove bottom 91a of the second annular groove 91 is not limited to the above and may be located further outward AD1 in the tire axial direction than the side wall surface 80c.
[0047] In this embodiment, the groove bottom of the first annular groove 90 is formed in a straight line, and the groove bottom 91a of the second annular groove 91 is formed in a straight line, but is not limited to this. The groove bottom of the first annular groove 90 may be formed in a curved shape, for example. The same applies to the groove bottom 91a of the second annular groove 91.
[0048] As shown in Figure 1, the shortest distance D4 between the first annular groove 90 and the second annular groove 91 is preferably 10 mm or more. This ensures the rigidity of the sacrificial rib 35.
[0049] [1] As described above, the pneumatic tire 1 of this disclosure comprises a plurality of land blocks 32 that form a contact surface 33, a tire side wall surface 7 which is the outer surface of the sidewall 2, and a narrow groove 80 that extends inward along the tire radial direction RD (inner RD2) and continuously along the tire circumferential direction CD from the contact surface 33 of the land block 32a that is the outermost land block 32 in the tire axial direction AD1, and the land block 32a that is the outermost land block 32 in the tire axial direction AD1 (shoulder land block 32a) is divided by the narrow groove 80 into a land block body 34 and a sacrificial rib 35 that is located further outward in the tire axial direction AD1 than the land block body 34 and includes the end of the contact surface 33 (contact end LE), and the sacrificial rib The tire 35 includes a first annular groove 90 extending from the tire sidewall 7 along the tire radial direction RD and continuously along the tire circumferential direction CD, and a second annular groove 91 extending from the tire sidewall 7 along the tire axial direction AD and continuously along the tire circumferential direction CD. The first annular groove 90 is provided radially outward RD1 from the splitting position MS between the tread mold forming the tread 3 and the side mold forming the sidewall 2, and the second annular groove 91 is provided radially inward RD2 from the splitting position MS. The inclination angle θ1 of the center line C2 of the first annular groove 90 with respect to the tire radial direction RD is 30 degrees or less.
[0050] With this configuration, by providing the sacrificial rib 35, the sacrificial rib 35 is worn down before the main body 34, thereby suppressing wear on the main body 34. By providing the first annular groove 90 and the second annular groove 91, the sacrificial rib 35 can be made flexible, reducing the contact pressure on the contact end LE, and suppressing premature wear of the sacrificial rib 35. By setting the inclination angle θ1 to 30 degrees or less, the release properties of the tread mold can be improved. Furthermore, by providing the second annular groove 91 extending along the tire axial direction AD at RD2 radially inward of the tire from the split position MS, the second annular groove 91 can be formed in the side mold, improving the release properties of the tread mold. As a result, the wear suppression effect of the sacrificial rib 35 on the shoulder base 32a can be ensured while improving the release properties of the tread mold.
[0051] [2] In the pneumatic tire 1 according to the above embodiment [1], it is preferable that the inclination angle θ2 of the center line C3 of the second annular groove 91 with respect to the tire axial direction AD is -30 degrees or more and 30 degrees or less.
[0052] With this configuration, the release properties of the side mold can be improved. As a result, the breakage (bending) of the projection that forms the second annular groove 91 in the side mold can be suppressed.
[0053] [3] The pneumatic tire 1 according to the above embodiment [1] or [2] is preferably provided with a plurality of belt plies 6a, 6b, 6c, 6d embedded in the tread 3, and the second annular groove 91 is provided radially outward RD1 of the belt ends of the plurality of belt plies 6a, 6b, 6c, 6d, which is the belt end 60 that is the outermost AD1 in the tire axial direction.
[0054] With this configuration, the sacrificial rib 35 can be formed from rubber that is located further outward RD1 in the tire radial direction than the belt end 60. This makes the sacrificial rib 35 more flexible, and thus suppresses premature wear of the sacrificial rib 35.
[0055] [4] In the pneumatic tire 1 according to any one of the above embodiments [1] to [3], it is preferable that the second annular groove 91 extends further inward AD2 in the tire axial direction than the side wall surface 80c of the narrow groove 80 on the inner AD2 in the tire axial direction.
[0056] With this configuration, even after the sacrificial rib 35 has worn away, the ground pressure at the end of the ground contact surface 33 of the land body 34 can be reduced, thereby suppressing wear of the land body 34.
[0057] Although embodiments of this disclosure have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of this disclosure is indicated not only by the description of the embodiments above but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.
[0058] The structures adopted in each of the above embodiments can be adopted in any other embodiment. The specific configuration of each part is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of this disclosure. [Explanation of Symbols]
[0059] 1...Tire, 2...Sidewall, 3...Tread, 30...Tread rubber, 31...Main groove, 32...Surface, 32a...Shoulder surface, 32b...Quarter surface, 32c...Center surface, 33...Contact surface, 34...Surface body, 35...Sacrificial rib, 4...Carcass, 5...Inner liner rubber, 6a, 6b, 6c, 6d...Belt ply, 60...Belt end, 7...Tire sidewall, 80...Narrow groove, 80b, 80c...Sidewall, 90...First annular groove, 91...Second annular groove, LE...Contact end, MS...Split position
Claims
1. Multiple landmasses forming the contact surface, The tire sidewall, which is the outer surface of the sidewall, The device comprises a narrow groove extending inward along the tire radial direction and continuously along the tire circumferential direction from the contact surface of the land that is furthest outward in the tire axial direction among the plurality of land, Of the aforementioned plurality of landmasses, the landmass furthest outward in the tire axial direction is divided by the narrow groove into a landmass body and a sacrificial rib located further outward in the tire axial direction than the landmass body and including the edge of the contact surface. The sacrificial rib comprises a first annular groove extending from the tire sidewall surface along the tire radial direction and continuously along the tire circumferential direction, and a second annular groove extending from the tire sidewall surface along the tire axial direction and continuously along the tire circumferential direction. The first annular groove is provided radially outward of the tire from the split position between the tread mold that forms the tread and the side mold that forms the sidewall. The second annular groove is provided inward in the tire radial direction from the split position, A pneumatic tire in which the inclination angle of the center line of the first annular groove with respect to the tire's radial direction is 30 degrees or less.
2. The pneumatic tire according to claim 1, wherein the inclination angle of the center line of the second annular groove with respect to the tire axis is -30 degrees or more and 30 degrees or less.
3. The tread is equipped with multiple belt plies embedded in it. The pneumatic tire according to claim 1, wherein the second annular groove is provided radially outward of the belt end of the plurality of belt plies that is furthest outward in the tire axial direction.
4. The pneumatic tire according to any one of claims 1 to 3, wherein the second annular groove extends further inward in the tire axial direction than the side wall surface of the narrow groove on the tire axial direction side.