Tire

Abstract

The present application provides a tire (2) capable of ensuring required block drop resistance and off-road performance, and reducing pattern noise. The tire (2) includes a tread (4). At least two circumferential grooves (36) are engraved in the tread (4), constituting at least three lands (38) arranged in the axial direction. The land (38) located on the outer side in the axial direction among the at least three lands (38) is a shoulder land (38s). The shoulder land (38s) includes a plurality of shoulder blocks (52) arranged in the circumferential direction. The shoulder land (38s) is divided into a ground contact zone (ZC) from the equatorial plane side to a ground end (PE), and a non-ground contact zone (ZNC) from the ground end (PE) to an end (PT) of the tread (4). The shoulder blocks (52) in the ground contact zone (ZC) are engraved with a plurality of first pits (62) in a cylindrical shape.

Description

TECHNICAL FIELD

[0001] The present application relates to a tire. BACKGROUND

[0002] A sport utility vehicle (SUV) travels not only on a paved road but also on an uneven ground. An SUV tire adopts a tread in which a plurality of blocks are formed by cutting circumferential grooves and transverse grooves. In view of urban travel, the tire is required to have excellent quietness.

[0003] When a tire contacts a road surface, it hits the road surface. At this time, a sound (hereinafter, referred to as a pattern noise) is generated. A large pattern noise increases an outside noise of a vehicle. In order to improve the quietness of a tire, a study on reducing the pattern noise has been made (for example, Patent Literature 1).

[0004] [Patent Literature]

[0005] [Patent Literature]

[0006] [Patent Literature 1] Japanese Patent Laid-Open No. 2004-58839 SUMMARY

[0007] [Problems to be Solved by the Invention]

[0008] A thick tread can moderate an input at the time of contacting a road surface. The thick tread contributes to a reduction in the pattern noise. However, the thick tread increases the mass or the rolling resistance of the tire.

[0009] After grooves are cut in a tread, an input at the time of contacting a road surface is moderated. The grooves contribute to a reduction in the pattern noise. However, the grooves become a starting point of cracking, and there is a concern that the block drop resistance is reduced at the time of traveling on a bad road.

[0010] When a groove volume of an axial groove is reduced, the pattern noise is reduced. However, in the case, there is a concern that an off-road performance such as a mud performance or a locking performance is reduced.

[0011] In an SUV tire, it is difficult to have the quietness, the block drop resistance, and the off-road performance in a good balance. The industry demands a technology capable of securing a required block drop resistance and off-road performance and reducing the pattern noise.

[0012] The present application was made in view of such a situation, and an object thereof is to provide a tire capable of securing a required block drop resistance and off-road performance and reducing a pattern noise.

[0013] [Technical Means to Solve the Problems]

[0014] A tire of an embodiment of the present application includes a tread that contacts a road surface. At least two circumferential grooves are formed in the tread, forming at least three land portions arranged in the axial direction. A land portion located on the outer side in the axial direction among the at least three land portions is a shoulder land portion. The shoulder land portion includes a plurality of shoulder blocks arranged in the circumferential direction. The shoulder land portion is divided into a ground contact region from the equatorial plane side to the ground contact end, and a non-ground contact region from the ground contact end to the end of the tread. The shoulder blocks in the ground contact region are formed with a plurality of first depressions that are cylindrical.

[0015] Preferably, in the tire, the diameter of the first depressions is 2 mm or more and 5 mm or less. The ratio of the depth of the first depressions to the groove depth of the circumferential grooves is 25% or more and 65% or less.

[0016] Preferably, in the tire, the plurality of first depressions are arranged at intervals from the equatorial plane side toward the end of the tread. The ratio of the interval of the first depressions to the width of the shoulder blocks is 0.10 or more and 0.20 or less.

[0017] Preferably, in the tire, the angle formed by the wall surface of the first depressions with respect to the center line of the first depressions is 0° or more and 30° or less.

[0018] Preferably, in the tire, a shoulder reinforcement portion extending in the circumferential direction is provided between the shoulder blocks and the end of the tread in the non-ground contact region, and a plurality of second depressions that are cylindrical are formed in the shoulder reinforcement portion.

[0019] Preferably, in the tire, the diameter of the second depressions is 2 mm or more and 5 mm or less. The ratio of the depth of the second depressions to the groove depth of the circumferential grooves is 5% or more and 15% or less.

[0020] Preferably, in the tire, the plurality of second depressions are arranged at intervals in the circumferential direction. The interval of the second depressions is 5.0 mm or more and 10.0 mm or less.

[0021] Preferably, in the tire, the angle formed by the wall surface of the second depressions with respect to the center line of the second depressions is 0° or more and 30° or less.

[0022] Preferably, in the tire, the ratio of the radial distance from the ground contact end to the end of the tread to the cross-sectional height is 5% or more and 15% or less.

[0023] A tire of other embodiments of the present application includes a tread that contacts a road surface. At least two circumferential grooves are engraved in the tread, constituting at least three land portions arranged in an axial direction. A land portion located on an outer side in the axial direction among the at least three land portions is a shoulder land portion. The shoulder land portion includes a plurality of shoulder blocks arranged in a circumferential direction. The shoulder land portion is divided into a ground contact region from an equatorial plane side to a ground contact end, and a non-ground contact region from the ground contact end to an end of the tread. Between the shoulder blocks and the end of the tread in the non-ground contact region, a shoulder reinforcing portion extending in the circumferential direction is provided, and a plurality of second depressions in a cylindrical shape are engraved in the shoulder reinforcing portion.

[0024] [Effects of the Invention]

[0025] According to the present application, a tire that can ensure required chunking resistance and off-road performance and reduce pattern noise can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a cross-sectional view showing a portion of a tire of an embodiment of the present application.

[0027] Figure 2 is an expanded view showing a tread surface of a tire.

[0028] Figure 3 is a perspective view showing a portion of a tread.

[0029] Figure 4 is a cross-sectional view of a first depression.

[0030] Figure 5 is a cross-sectional view of a second depression.

[0031] [Legend of Reference Numerals]

[0032] 2: tire

[0033] 4: tread

[0034] 24: tread surface

[0035] 36, 36s, 36m: circumferential groove

[0036] 38, 38s, 38m, 38c: land portion

[0037] 52: shoulder block

[0038] 60: depression

[0039] 62: first depression

[0040] 64: shoulder reinforcing portion

[0041] 66: second depression

[0042] 76: third depression DETAILED DESCRIPTION

[0043] Hereinafter, the present application will be described in detail based on preferred embodiments with appropriate reference to the accompanying drawings.

[0044] In the present disclosure, a state in which a tire is assembled to a regular rim, the internal pressure of the tire is adjusted to a regular internal pressure, and no load is applied to the tire is referred to as a regular state. In the present application, the dimensions and angles of each part of the tire are measured in the regular state, unless otherwise specified.

[0045] The regular rim means a rim determined in a specification to which the tire conforms. The "standard rim" contained in the application rim under the specification of The Japan Automobile Tire Manufacturers Association, Inc. (JATMA), the "design rim" under the specification of Tire and Rim Association (TRA), and the "measuring rim" under the specification of European Tyre Rim Technical Organization (ETRTO) are the regular rim.

[0046] The regular internal pressure means an internal pressure determined in a specification to which the tire conforms. The "maximum air pressure" under the specification of JATMA, the "maximum" disclosed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" under the specification of TRA, and the "inflation pressure" under the specification of ETRTO are the regular internal pressure. In the case where the tire is used for a passenger car, the regular internal pressure is 180 kPa, unless otherwise specified.

[0047] The regular load means a load determined in a specification to which the tire conforms. The "maximum load capacity" under the specification of JATMA, the "maximum" disclosed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" under the specification of TRA, and the "load capacity" under the specification of ETRTO are the regular load. In the case where the tire is used for a passenger car, the regular load is a load corresponding to 88% of the load, unless otherwise specified.

[0048] In this disclosure, the load index (LI), for example as specified in the JATMA specification, is an index that represents the maximum mass of load permissible on a tire under specified conditions, i.e., the maximum load capacity.

[0049] Figure 1 This illustrates an example of an air-filled tire 2 (hereinafter referred to as tire 2) according to an embodiment of the present invention. The tire 2 is mounted on a passenger vehicle. More specifically, the tire 2 is mounted on SUVs (Sport Utility Vehicles) and other vehicles designed for driving not only on paved roads but also on uneven surfaces. Figure 1 In the process, tire 2 is assembled onto rim R. Rim R is a standard rim. Tire 2 is filled with air, and its internal pressure is adjusted to the standard internal pressure.

[0050] Figure 1 This represents a portion of the cross-section of tire 2 along the plane containing the axis of rotation of tire 2. Figure 1 In the diagram, the left-right direction represents the axial direction of tire 2, and the up-down direction represents the radial direction of tire 2. Perpendicular to... Figure 1 The orientation of the paper is the circumferential direction of tire 2. Figure 1 In the diagram, the dashed line CL represents the equatorial plane of tire 2.

[0051] exist Figure 1 In the diagram, the solid line BBL extending along the axial direction is the bead base line. The bead base line is the line that specifies the rim diameter R of the wheel rim (refer to JATMA, etc.).

[0052] The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of cinch liner 8, a pair of beads 10, a carcass 12, a belt 14, a band 16, a pair of bead wraps 18, a pair of fillers 20, and an inner liner 22. In the tire 2, the sidewalls 6, cinch liner 8, beads 10, carcass 12, belt 14, band 16, bead wraps 18, fillers 20, and inner liner 22 are constructed using technology commonly used in SUV tires. Detailed descriptions of these components are omitted.

[0053] The outer surface of the tread 4, i.e., the tread surface 24, is in contact with the road surface. Figure 1 In the diagram, the symbol PE indicates a specific location on the tread surface 24. The specific location PE corresponds to the outermost point in the tire 2 that is in contact with the road surface in the axial direction. In the tire 2, the specific location PE is the contact point. The contact point PE is a position on the outer surface of the tire 2 corresponding to the outermost point in the tire 2 that is in contact with the road surface in the axial direction.

[0054] The ground contact surface for specifying the ground contact end PE is obtained, for example, using a ground contact surface shape measuring device (not shown). The ground contact surface is obtained in the device in a state where the tire 2 is assembled to the rim R, the internal pressure of the tire 2 is adjusted to 230 kPa, the camber angle of the tire 2 is set to 0°, the tire 2 is contacted with a flat road surface, and a load corresponding to 70% of the mass indicated by the load index is applied as a longitudinal load.

[0055] The tread 4 includes a tread body 26 and a pair of wing portions 28. The tread body 26 includes a base layer 30 and a crown band layer 32.

[0056] The base layer 30 is laminated to the steel belt 16. The base layer 30 contains a crosslinked rubber having low heat generation. The crown band layer 32 is located radially outward of the base layer 30. The crown band layer 32 covers the entire base layer 30. The crown band layer 32 contains a crosslinked rubber that takes into account wear resistance and grip performance. An outer surface of the crown band layer 32 forms a part of the tread surface 24.

[0057] Each wing portion 28 is located radially outward of the tread body 26 in the axial direction. In the tire 2, the tread body 26 is joined to the sidewall 6 with the wing portion 28 interposed therebetween. The wing portion 28 contains a crosslinked rubber that takes into account adhesion.

[0058] In the tire 2, the tread surface 24 includes the outer surface of the crown band layer 32 and the outer surface of the wing portion 28. In Figure 1 In the tire 2, the tread surface 24 includes the outer surface of the crown band layer 32 and the outer surface of the wing portion 28. In

[0059] In the tire 2, the tread surface 24 includes the outer surface of the crown band layer 32 and the outer surface of the wing portion 28. In Figure 1 In the tire 2, the tread surface 24 includes the outer surface of the crown band layer 32 and the outer surface of the wing portion 28. In Figure 1 In the tire 2, the tread surface 24 includes the outer surface of the crown band layer 32 and the outer surface of the wing portion 28. In

[0060] Figure 2 A part of the tread surface 24 is indicated by a double-headed arrow HS. In Figure 2 In the tire 2, the axial direction is the left-right direction, and the circumferential direction is the up-down direction. A direction perpendicular to the paper surface is the radial direction of the tire 2. Figure 2 In the tire 2, the axial direction is the left-right direction, and the circumferential direction is the up-down direction. A direction perpendicular to the paper surface is the radial direction of the tire 2.

[0061] The tire 2 has a tread 4. The tread 4 is provided with grooves 34. The grooves 34 constitute a tread pattern. The tread 4 is provided with at least two circumferential grooves 36 extending in the circumferential direction as the grooves 34 constituting the tread pattern. Thus, the tread 4 is provided with at least three lands 38 arranged in the axial direction. In the tire 2, four circumferential grooves 36 are provided in the tread 4, and the tread 4 is provided with five lands 38. Further, the grooves 34 constituting the tread pattern, in which the groove width is 2.0 mm or less, are referred to as sipes.

[0062] In the tire 2, the four circumferential grooves 36 are continuous in the circumferential direction, respectively. As shown in FIG. 1, the circumferential grooves 36 extend in a curved manner. The circumferential grooves 36 can be constituted in a zigzag manner or in a straight line manner. Figure 2

[0063] In the tire 2, the circumferential grooves 36 located on the outer side in the axial direction among the four circumferential grooves 36 are shoulder circumferential grooves 36s. The circumferential grooves 36 located on the inner side of the shoulder circumferential grooves 36s are intermediate circumferential grooves 36m. In the tire 2, the four circumferential grooves 36 include a pair of intermediate circumferential grooves 36m arranged across the equatorial surface, and a pair of shoulder circumferential grooves 36s located on the outer side of the intermediate circumferential grooves 36m, respectively.

[0064] In the tire 2, the circumferential grooves 36 located on the outer side in the axial direction among the four circumferential grooves 36 are shoulder circumferential grooves 36s. The circumferential grooves 36 located on the inner side of the shoulder circumferential grooves 36s are intermediate circumferential grooves 36m. In the tire 2, the four circumferential grooves 36 include a pair of intermediate circumferential grooves 36m arranged across the equatorial surface, and a pair of shoulder circumferential grooves 36s located on the outer side of the intermediate circumferential grooves 36m, respectively. Figure 2 In the tire 2, the circumferential grooves 36 located on the outer side in the axial direction among the four circumferential grooves 36 are shoulder circumferential grooves 36s. The circumferential grooves 36 located on the inner side of the shoulder circumferential grooves 36s are intermediate circumferential grooves 36m. In the tire 2, the four circumferential grooves 36 include a pair of intermediate circumferential grooves 36m arranged across the equatorial surface, and a pair of shoulder circumferential grooves 36s located on the outer side of the intermediate circumferential grooves 36m, respectively.

[0065] In the tire 2, the circumferential grooves 36 located on the outer side in the axial direction among the four circumferential grooves 36 are shoulder circumferential grooves 36s. The circumferential grooves 36 located on the inner side of the shoulder circumferential grooves 36s are intermediate circumferential grooves 36m. In the tire 2, the four circumferential grooves 36 include a pair of intermediate circumferential grooves 36m arranged across the equatorial surface, and a pair of shoulder circumferential grooves 36s located on the outer side of the intermediate circumferential grooves 36m, respectively.

[0066] Figure 1 In the tire 2, the circumferential grooves 36 located on the outer side in the axial direction among the four circumferential grooves 36 are shoulder circumferential grooves 36s. The circumferential grooves 36 located on the inner side of the shoulder circumferential grooves 36s are intermediate circumferential grooves 36m. In the tire 2, the four circumferential grooves 36 include a pair of intermediate circumferential grooves 36m arranged across the equatorial surface, and a pair of shoulder circumferential grooves 36s located on the outer side of the intermediate circumferential grooves 36m, respectively.

[0067] ​​In the tire 2, the ratio of the groove depth DM of the intermediate circumferential groove 36m to the ground contact width WE (DM / WE) is preferably 0.040 or more and preferably 0.085 or less from the viewpoint of ensuring the drainability and having the rigidity of the tread 4. The ratio of the groove depth DS of the shoulder circumferential groove 36s to the ground contact width WE (DS / WE) is preferably 0.040 or more and preferably 0.085 or less from the same viewpoint.

[0068] In the tire 2, the land portion 38 located on the outer side in the axial direction among the five land portions 38 is the shoulder land portion 38s. The land portion 38 located on the inner side of the shoulder land portion 38s is the intermediate land portion 38m. The land portion 38 located on the inner side of the intermediate land portion 38m is the center land portion 38c. In the tire 2, the center land portion 38c is located on the equatorial plane between the two intermediate circumferential grooves 36m. The intermediate land portion 38m is located between the intermediate circumferential groove 36m and the shoulder circumferential groove 36s. The shoulder land portion 38s is located on the outer side of the shoulder circumferential groove 36s in the axial direction and includes the ground end PE. The five land portions 38 include the center land portion 38c, a pair of intermediate land portions 38m, and a pair of shoulder land portions 38s.

[0069] In the tire 2, the land portion 38 located on the outer side in the axial direction among the five land portions 38 is the shoulder land portion 38s. The land portion 38 located on the inner side of the shoulder land portion 38s is the intermediate land portion 38m. The land portion 38 located on the inner side of the intermediate land portion 38m is the center land portion 38c. In the tire 2, the center land portion 38c is located on the equatorial plane between the two intermediate circumferential grooves 36m. The intermediate land portion 38m is located between the intermediate circumferential groove 36m and the shoulder circumferential groove 36s. The shoulder land portion 38s is located on the outer side of the shoulder circumferential groove 36s in the axial direction and includes the ground end PE. The five land portions 38 include the center land portion 38c, a pair of intermediate land portions 38m, and a pair of shoulder land portions 38s. Figure 2 In the tire 2, the land portion 38 located on the outer side in the axial direction among the five land portions 38 is the shoulder land portion 38s. The land portion 38 located on the inner side of the shoulder land portion 38s is the intermediate land portion 38m. The land portion 38 located on the inner side of the intermediate land portion 38m is the center land portion 38c. In the tire 2, the center land portion 38c is located on the equatorial plane between the two intermediate circumferential grooves 36m. The intermediate land portion 38m is located between the intermediate circumferential groove 36m and the shoulder circumferential groove 36s. The shoulder land portion 38s is located on the outer side of the shoulder circumferential groove 36s in the axial direction and includes the ground end PE. The five land portions 38 include the center land portion 38c, a pair of intermediate land portions 38m, and a pair of shoulder land portions 38s.

[0070] In the tire 2, the ratio of the groove depth DM of the intermediate circumferential groove 36m to the ground contact width WE (DM / WE) is preferably 0.040 or more and preferably 0.085 or less from the viewpoint of ensuring the drainability and having the rigidity of the tread 4. The ratio of the groove depth DS of the shoulder circumferential groove 36s to the ground contact width WE (DS / WE) is preferably 0.040 or more and preferably 0.085 or less from the same viewpoint.

[0071] A plurality of transverse grooves (hereinafter referred to as center transverse grooves 40) are formed in the center land portion 38c of the tire 2 as the grooves 34 constituting the tread pattern. The center transverse grooves 40 are arranged at intervals in the circumferential direction. Each of the center transverse grooves 40 has ends in the center land portion 38c. The ends are located on the equatorial plane, and the center transverse grooves 40 connect the ends with the intermediate circumferential grooves 36m. As shown in Fig. 1, the center transverse grooves 40 provided on one side of the center land portion 38c are alternately arranged in the circumferential direction with the center transverse grooves 40 provided on the other side. The groove width and the groove depth of the center transverse grooves 40 are appropriately determined in consideration of the specifications of the tire 2. Figure 2

[0072] A plurality of transverse grooves (hereinafter referred to as intermediate transverse grooves 42) are formed in the intermediate land portion 38m of the tire 2 as the grooves 34 constituting the tread pattern. The intermediate transverse grooves 42 are arranged at intervals in the circumferential direction. Each of the intermediate transverse grooves 42 connects the intermediate circumferential grooves 36m with the shoulder circumferential grooves 36s. The groove width and the groove depth of the intermediate transverse grooves 42 are appropriately determined in consideration of the specifications of the tire 2.

[0073] The intermediate transverse grooves 42 span the intermediate land portion 38m. A plurality of blocks (hereinafter referred to as intermediate blocks 44) are formed by forming a plurality of intermediate transverse grooves 42 in the intermediate land portion 38m. The intermediate land portion 38m includes a plurality of intermediate blocks 44 arranged in the circumferential direction.

[0074] An open sipe 46 and two end sipes 48 are formed in the intermediate block 44 of the tire 2 as the grooves 34 (in detail, sipes) constituting the tread pattern. In the tire 2, the groove width of the open sipe 46 and the end sipes 48 is 1.0 mm or less.

[0075] The open sipe 46 connects the intermediate circumferential grooves 36m with the shoulder circumferential grooves 36s. The two end sipes 48 are arranged across the open sipe 46. Each of the end sipes 48 has ends in the intermediate block 44. One of the end sipes 48 connects the ends with the intermediate circumferential grooves 36m. The other of the end sipes 48 connects the ends with the shoulder circumferential grooves 36s.

[0076] A plurality of transverse grooves (hereinafter referred to as shoulder transverse grooves 50) are formed in the shoulder land portion 38s of the tire 2 as the grooves 34 constituting the tread pattern. The shoulder transverse grooves 50 are arranged at intervals in the circumferential direction. Each of the shoulder transverse grooves 50 extends from the shoulder circumferential grooves 36s toward the end portion PT of the tread 4. The groove width and the groove depth of the shoulder transverse grooves 50 are appropriately determined in consideration of the specifications of the tire 2.

[0077] The shoulder transverse grooves 50 span the shoulder land portion 38s. A plurality of blocks (hereinafter referred to as shoulder blocks 52) are formed by forming a plurality of shoulder transverse grooves 50 in the shoulder land portion 38s. The shoulder land portion 38s includes a plurality of shoulder blocks 52 arranged in the circumferential direction.

[0078] In the tire 2, as shown in Fig. 1, the shoulder transverse grooves 50 provided on one side of the shoulder land portion 38s are alternately arranged in the circumferential direction with the shoulder transverse grooves 50 provided on the other side.​Figure 2 As shown, multiple longitudinal grooves 54 are engraved on the outer axial portion of the shoulder block 52 as grooves 34 forming the tread pattern. The longitudinal grooves 54 are spaced apart along the circumferential direction. Each longitudinal groove 54 connects the ends of two shoulder transverse grooves 50 to each other. In the shoulder land portion 38s of the tire 2, shoulder blocks 52 with longitudinal grooves 54 and shoulder blocks 52 without longitudinal grooves 54 are alternately arranged along the circumferential direction. The groove width and groove depth of the longitudinal grooves 54 are appropriately determined considering the specifications of the tire 2.

[0079] The tire shoulder block 52 is engraved with wide grooves 56 as grooves 34 (more specifically, grooves) forming the tread pattern. The width of the wide grooves 56 is wider than the width of the open grooves 46 and the terminating grooves 48 described above.

[0080] The wide groove 56 has an end within the shoulder block 52. The wide groove 56 connects the end to the circumferential groove 36s of the shoulder. In the shoulder block 52 of the tire 2, a recess 58 is further engraved on the outer side of the wide groove 56. The wide groove 56 connects to the recess 58 at its end.

[0081] Figure 3 The tire 2 has a shoulder block 52 with multiple cylindrical recesses 60. These recesses 60 are circular holes that extend inward from the outer surface of the shoulder block 52.

[0082] The tire 2 has ten recesses 60 etched into its shoulder block 52. There is no particular limitation on the number of recesses 60 on the tire 2's shoulder block 52. The number of recesses 60 is appropriately determined considering the size of the shoulder block 52 and the impact of the recesses 60 on performance.

[0083] In the tire 2, there are no particular restrictions on the arrangement of the multiple pits 60 as long as they are distributed on the outer surface of the shoulder block 52.

[0084] In the tire 2, two rows of pits, comprising five pits 60, are formed. For example... Figure 3 As shown, two rows of pits are arranged with a wide groove 56 between them. In the tire 2, five pits 60 in each row are spaced apart from the equatorial side (more specifically, the side of the shoulder circumferential groove 36s) toward the end PT of the tread 4.

[0085] In the tire 2, the number of rows of the rows of the depressions provided in the shoulder block 52 and the number of the depressions 60 included in one row of the rows of the depressions are appropriately determined in consideration of the size of the shoulder block 52 and the influence of providing the depressions 60 on the performance. In the tire 2, the number of rows of the rows of the depressions provided in the shoulder block 52 is preferably one row or more and preferably three rows or less from the viewpoint of exerting the effect of providing the depressions 60. More preferably, the number of rows of the rows of the depressions is two rows. The number of the depressions 60 included in one row of the rows of the depressions is preferably five or more and preferably ten or less.

[0086] As described above, the shoulder land portion 38s includes the ground edge portion PE. As shown in FIG. 2, the shoulder land portion 38s is divided into the ground contact zone ZC from the equatorial plane side to the ground edge portion PE and the non-ground contact zone ZNC from the ground edge portion PE to the end portion PT of the tread. Figure 2

[0087] As shown in FIG. 2, a plurality of depressions 60 (specifically, six depressions 60) are provided in the shoulder block 52 in the ground contact zone ZC. In the tire 2, the depressions 60 provided in the ground contact zone ZC are first depressions 62. Figure 2

[0088] The rigidity of the shoulder block 52 has an influence on the generation of the pattern noise. In the tire 2, the shoulder block 52 in the ground contact zone ZC is engraved with a plurality of the first depressions 62 which are cylindrical. The rigidity of the shoulder block 52 is appropriately lowered, and thus the impact at the time when the tread 4 hits the road surface can be suppressed. The input at the time of contacting the road surface is moderated, and thus the pattern noise is reduced. In the tire 2, the improvement in quietness is achieved.

[0089] In the tire 2, the tread 4 does not need to be thickened in order to reduce the pattern noise. Furthermore, the first depressions 62 contribute to the reduction in the mass of the tread 4. In the tire 2, the weight reduction and the reduction in the rolling resistance are achieved.

[0090] In the tire 2, the first depressions 62 are cylindrical, and thus are less likely to become the starting point of the cracking as in the case of the grooves. In the tire 2, the generation of the cracking as confirmed in the case where the grooves are added can be suppressed even when the first depressions 62 are provided in the shoulder block 52. In the tire 2, the good block drop resistance can be maintained despite the provision of the first depressions 62 in the shoulder block 52.

[0091] The first depressions 62 are so-called holes, and thus contribute to the removal of mud in the travel on the bad road such as a muddy field. In the tire 2, the good mud performance can be obtained. When the stone road surface composed of rock plates is traveled on, the shoulder block 52 whose rigidity is moderately reduced by the first depressions 62 can sufficiently grip the rocks. The tire 2 can stably travel on the stone road surface. In the tire 2, the good locking performance can be obtained. The off-road performance of the tire 2 is excellent.

[0092] ​​The tire 2 can ensure the required block resistance and off-road performance, and reduce the pattern noise. Furthermore, the required block resistance and off-road performance mean a degree that can be permitted to the same extent as the existing tire.

[0093] In the tire 2, a shoulder reinforcing portion 64 is between the shoulder block 52 and the end portion PT of the tread 4 in the non-contact region ZNC. In the tire 2, the radially inner end of the shoulder reinforcing portion 64 is the end portion PT of the tread 4. The radially outer end of the shoulder reinforcing portion 64 is the axially outer end of the shoulder block 52. The shoulder reinforcing portion 64 extends along the circumferential direction.

[0094] In the tire 2, a plurality of cylindrical concaves (hereinafter, second concaves 66) are engraved in the shoulder reinforcing portion 64. These second concaves 66 are arranged at intervals along the circumferential direction. In the tire 2, a row of concaves including the plurality of second concaves 66 is arranged in the circumferential direction. A plurality of rows of concaves can be formed in the shoulder reinforcing portion 64.

[0095] The second concaves 66 provided in the shoulder reinforcing portion 64 reduce the rigidity of the shoulder land portion 38s. In the tire 2, the second concaves 66 contribute to the suppression of the impact when the tread 4 hits the road surface. The input at the time of contact with the road surface is moderated, and thus the pattern noise is reduced. In the tire 2, an improvement in quietness is achieved.

[0096] In the tire 2, the tread 4 does not need to be thickened in order to reduce the pattern noise. Furthermore, the second concaves 66 contribute to the reduction in the mass of the tread 4. In the tire 2, a reduction in weight and a reduction in rolling resistance are achieved.

[0097] In the tire 2, the second concaves 66 are cylindrical, and thus are less likely to become the starting point of a crack. Even if the tire 2 is driven on a bad road with the shoulder reinforcing portion 64 in contact with the bad road, the generation of a crack starting from the second concaves 66 can be suppressed. In the tire 2, a good block resistance can be maintained despite the provision of the second concaves 66 in the shoulder reinforcing portion 64.

[0098] The second concaves 66 are so-called holes, and thus contribute to the removal of mud when the shoulder reinforcing portion 64 is in contact with the bad road. The second concaves 66 contribute to an improvement in the mud performance. The second concaves 66 contribute to a reduction in the rigidity of the shoulder land portion 38s, and thus the shoulder land portion 38s can sufficiently grip the rocks even in a state in which the shoulder reinforcing portion 64 is in contact with the stone road surface. The tire 2 can stably travel on the stone road surface. The second concaves 66 contribute to an improvement in the locking performance. The second concaves 66 contribute to an improvement in the off-road performance.

[0099] In the tire 2, by forming the plurality of second depressions 66 in the shoulder reinforcing portion 64, it is possible to ensure the required block resistance and off-road performance, and reduce the pattern noise. In this regard, in the tire 2, it is preferable that the plurality of second depressions 66 be formed in the shoulder reinforcing portion 64 in a cylindrical shape.

[0100] In Figure 1 the tire 2, the plurality of first depressions 62 are formed in the shoulder block 52 in the ground contact region ZC, and the plurality of second depressions 66 are formed in the shoulder reinforcing portion 64 in the non-ground contact region ZNC. In the tire 2, it is also possible that the plurality of first depressions 62 be formed in the shoulder block 52 in the ground contact region ZC, and the second depressions 66 not be formed in the shoulder reinforcing portion 64. It is also possible that the first depressions 62 not be formed in the shoulder block 52 in the ground contact region ZC, and the plurality of second depressions 66 be formed in the shoulder reinforcing portion 64 in the non-ground contact region ZNC. In this regard, it is more preferable that the plurality of first depressions 62 be formed in the shoulder block 52 in the ground contact region ZC, and the plurality of second depressions 66 be formed in the shoulder reinforcing portion 64 in the non-ground contact region ZNC, as shown in Figure 2 and Figure 3 the tire 2, the plurality of first depressions 62 are formed in the shoulder block 52 in the ground contact region ZC, and the plurality of second depressions 66 are formed in the shoulder reinforcing portion 64 in the non-ground contact region ZNC. In the tire 2, it is also possible that the plurality of first depressions 62 be formed in the shoulder block 52 in the ground contact region ZC, and the second depressions 66 not be formed in the shoulder reinforcing portion 64. It is also possible that the first depressions 62 not be formed in the shoulder block 52 in the ground contact region ZC, and the plurality of second depressions 66 be formed in the shoulder reinforcing portion 64 in the non-ground contact region ZNC. In this regard, it is more preferable that the plurality of first depressions 62 be formed in the shoulder block 52 in the ground contact region ZC, and the plurality of second depressions 66 be formed in the shoulder reinforcing portion 64 in the non-ground contact region ZNC, as shown in

[0101] In Figure 1 the tire 2, the radial distance HB is measured in the normal state.

[0102] In the tire 2, in regard to the second depressions 66 formed in the shoulder reinforcing portion 64, the ratio of the radial distance HB to the cross-sectional height HS (HB / HS) is preferably 5% or more, and preferably 15% or less, from the viewpoint that the second depressions 66 can effectively contribute to the ensuring of the required block resistance and off-road performance, and the reduction of the pattern noise.

[0103] In Figure 2 the tire 2, the axial distance WB indicates the axial distance from the inner end to the outer end of the shoulder block 52. In the tire 2, the axial distance WB is the width of the shoulder block 52. The double-headed arrow SI indicates the interval of the first depressions 62. The interval SI is indicated by the shortest distance between adjacent first depressions 62. The double-headed arrow S2 indicates the interval of the second depressions 66. The interval S2 is indicated by the shortest distance between adjacent second depressions 66. The width WB, the interval SI, and the interval S2 are measured in the developed view of the tread surface 24.

[0104] In the tire 2, from the viewpoint of ensuring the required resistance to tread blockage, the ratio (S1 / WB) of the spacing S1 of the first indentation 62 to the width WB of the shoulder block 52 is preferably 0.10 or more, more preferably 0.13 or more. From the viewpoint of ensuring the required off-road performance and reducing tread noise, the ratio (S1 / WB) is preferably 0.20 or less, more preferably 0.17 or less.

[0105] In the tire 2, from the viewpoint of ensuring the required resistance to tread blockage, the spacing S2 of the second pit 66 is preferably 5.0 mm or more, more preferably 6.5 mm or more. From the viewpoint of ensuring the required off-road performance and reducing tread noise, the spacing S2 is preferably 10.0 mm or less, more preferably 8.5 mm or less.

[0106] Figure 4 This represents the cross-section of the first recess 62. The dashed line C1 is the centerline of the first recess 62. (Example) Figure 4 As shown, the first recess 62 faces the bottom 68 and tapers at the front end. The first recess 62 can be configured as a cylinder. Figure 4 In this context, angle θ1 is the angle formed by the wall 70 of the first recess 62 relative to the centerline C1. In the tire 2, angle θ1 is set within a range of 0° to 30°.

[0107] exist Figure 4 In the diagram, double arrow A1 represents the diameter of the first recess 62. In the tire 2, diameter A1 is represented by the diameter of the opening edge of the first recess 62. Double arrow D1 represents the depth of the first recess 62. Depth D1 is represented by the distance from the opening edge of the first recess 62 to the bottom 68.

[0108] In the tire 2, the diameter A1 of the first pit 62 is preferably 2 mm or more, and preferably 5 mm or less. By setting the diameter A1 to 2 mm or more, the first pit 62 effectively helps to ensure the required off-road performance and reduce tread noise. From this perspective, the diameter A1 is more preferably 3 mm or more. By setting the diameter A1 to 5 mm or less, the first pit 62 effectively helps to ensure the required resistance to sharding. From this perspective, the diameter A1 is more preferably 4 mm or less.

[0109] In the tire 2, the ratio (D1 / DS) of the depth D1 of the first dimple 62 relative to the groove depth DS of the circumferential groove 36, specifically relative to the groove depth DS of the shoulder circumferential groove 36s dividing the shoulder land portion 38s, is preferably 25% or more, and preferably 65% ​​or less. By setting the ratio (D1 / DS) to 25% or more, the first dimple 62 effectively helps ensure the required off-road performance and reduce tread noise. From this perspective, the ratio (D1 / DS) is more preferably 30% or more, and even more preferably 35% or more. By setting the ratio (D1 / DS) to 65% or less, the first dimple 62 effectively helps ensure the required resistance to tread blockage. From this perspective, the ratio (D1 / DS) is more preferably 60% or less, and even more preferably 55% or less.

[0110] From the viewpoint that the first recess 62 can more effectively help ensure the required resistance to slugging and off-road performance, as well as reduce tread noise, it is preferable that the diameter A1 of the first recess 62 is more than 2 mm and less than 5 mm, and the ratio (D1 / DS) of the depth D1 of the first recess 62 to the groove depth DS of the shoulder circumferential groove 36s is more than 25% and less than 65%.

[0111] Figure 5 This represents the cross-section of the second recess 66. The dashed line C2 is the centerline of the second recess 66. (Example) Figure 5 As shown, the second recess 66 faces the bottom 72 and tapers at the front end. The second recess 66 can be cylindrical. Figure 5 In this context, angle θ2 is the angle formed by the wall 74 of the second recess 66 relative to the centerline C2. In the tire 2, angle θ2 is set within a range of 0° to 30°.

[0112] exist Figure 5 In the diagram, double arrow A2 represents the diameter of the second recess 66. In the tire 2, diameter A2 is represented by the diameter of the opening edge of the second recess 66. Double arrow D2 represents the depth of the second recess 66. Depth D2 is represented by the distance from the opening edge of the second recess 66 to the bottom 72.

[0113] In the tire 2, the diameter A2 of the second dimple 66 is preferably 2 mm or more, and preferably 5 mm or less. By setting the diameter A2 to 2 mm or more, the second dimple 66 effectively helps ensure the required off-road performance and reduce tread noise. From this perspective, the diameter A2 is more preferably 3 mm or more. By setting the diameter A2 to 5 mm or less, the second dimple 66 effectively helps ensure the required resistance to sharding. From this perspective, the diameter A2 is more preferably 4 mm or less.

[0114] In the tire 2, the ratio (D2 / DS) of the depth D2 of the second dimple 66 relative to the groove depth DS of the circumferential groove 36, specifically relative to the groove depth DS of the shoulder circumferential groove 36s dividing the shoulder land portion 38s, is preferably 5% or more, and preferably 15% or less. By setting the ratio (D2 / DS) to 5% or more, the second dimple 66 effectively helps ensure the required off-road performance and reduce tread noise. From this perspective, the ratio (D2 / DS) is more preferably 8% or more. By setting the ratio (D2 / DS) to 15% or less, the second dimple 66 effectively helps ensure the required resistance to tread blockage. From this perspective, the ratio (D2 / DS) is more preferably 12% or less.

[0115] From the viewpoint that the second recess 66 can more effectively help ensure the required resistance to scratching and off-road performance, as well as reduce tread noise, it is preferable that the diameter A2 of the second recess 66 is more than 2 mm and less than 5 mm, and the ratio (D2 / DS) of the depth D2 of the second recess 66 to the groove depth DS of the shoulder circumferential groove 36s is more than 5% and less than 15%.

[0116] like Figure 2 As shown, in the tire 2, a plurality of recesses 60 are also provided between the contact area ZC and the shoulder reinforcement 64.

[0117] The contact patch shape of tire 2 in driving conditions varies depending on the situation. Depending on the circumstances, the contact patch end may be located further outward than the reference contact patch end PE. In this case, of the plurality of recesses 60 located between the contact patch area ZC and the shoulder reinforcement 64, the recess 60 on the ZC side is included in the contact patch surface. This recess 60 functions as a first recess 62. During off-road driving, the radially outer portion of the shoulder reinforcement 64 also contacts the road surface. In this case, of the plurality of recesses 60 located between the ZC and the shoulder reinforcement 64, the recess 60 on the shoulder reinforcement 64 side functions as a second recess 66.

[0118] In the tire 2, the plurality of recesses 60 located between the contact patch ZC and the shoulder reinforcement 64 also more effectively help ensure the required block resistance and off-road performance, as well as reduce tread noise. From this perspective, it is preferable that a plurality of cylindrical recesses 60 (hereinafter referred to as the third recess 76) are also etched on the shoulder block 52 between the contact patch ZC and the shoulder reinforcement 64. In this case, since the third recess 76 is etched on the shoulder block 52, the third recess 76 is constructed with the same specifications as the first recess 62.

[0119] As explained above, according to the present application, a tire 2 capable of ensuring the required block resistance and off-road performance and reducing the pattern noise can be obtained. The tire 2 exerts an especially remarkable effect when used as a tire for an SUV.

[0120] [Example]

[0121] The present application will be explained in further detail below by way of examples, but the present application is not limited only to the examples.

[0122] [Example 1]

[0123] An SUV tire (tire size = 265 / 65R18) including the basic structure shown in Fig. 1 and including the specifications shown in Table 1 below was obtained. Figures 1-3

[0124] In the example 1, the shoulder blocks and the shoulder reinforcement portion were engraved with recesses. This case is indicated by "D" in the tread column of Table 1.

[0125] The diameter of the recesses engraved in the shoulder blocks was 3.5 mm, the ratio of the depth of the recesses to the groove depth DS of the shoulder circumferential groove was 45%, and the ratio of the interval of the recesses to the width WB of the shoulder blocks was 0.13. The recesses included in the contact area ZC in the recesses engraved in the shoulder blocks were first recesses, and therefore the diameter Al of the first recesses was 3.5 mm, the ratio (D1 / DS) of the depth D1 of the first recesses to the groove depth DS of the shoulder circumferential groove was 45%, and the ratio (S1 / WB) of the interval S1 of the first recesses to the width WB of the shoulder blocks was 0.13.

[0126] The diameter A2 of the recesses engraved in the shoulder reinforcement portion, i.e., second recesses, was 3.5 mm, the ratio (D2 / DS) of the depth D2 of the second recesses to the groove depth DS of the shoulder circumferential groove was 10%, and the interval S2 of the second recesses was 7.5 mm.

[0127] [Comparative Example 1]

[0128] The tire of comparative example 1 was obtained in the same manner as in example 1 except that recesses were not engraved in the shoulder blocks and the shoulder reinforcement portion.

[0129] [Comparative Example 2]

[0130] The tread was formed so as to have a thickness 1 mm greater than the thickness of the tread of comparative example 1, and the tire of comparative example 2 was obtained in the same manner as in comparative example 1 except for this. The use of the thick tread is indicated by "T" in the tread column of Table 1 below. Comparative example 2 is a tire that uses the thick tread as a countermeasure against pattern noise.

[0131] [Comparative Example 3]

[0132] ​The tire of Comparative Example 3 was obtained in the same manner as in Comparative Example 1, except that the grooves were not engraved in the shoulder blocks. The tire face in which the grooves were engraved in the shoulder blocks is indicated by "S" in the tire face column of Table 1 below. Comparative Example 3 is a tire in which the tire face in which the grooves were engraved in the shoulder blocks was used as a countermeasure against pattern noise.

[0133] [Example 2]

[0134] The tire of Example 2 was obtained in the same manner as in Example 1, except that the depressions were not engraved in the shoulder reinforcing portion.

[0135] [Example 3]

[0136] The tire of Example 3 was obtained in the same manner as in Example 1, except that the depressions were not engraved in the shoulder blocks.

[0137] [Examples 4 to 5]

[0138] The outer diameter of the depressions engraved in the shoulder blocks and the shoulder reinforcing portion was changed, and the diameter Al of the first depressions and the diameter A2 of the second depressions were set as shown in Table 2 below, and otherwise the tire of Examples 4 to 5 was obtained in the same manner as in Example 1.

[0139] [Examples 6 to 7]

[0140] The depth of the depressions engraved in the shoulder blocks and the shoulder reinforcing portion was changed, and the ratio (D1 / DS) and the ratio (D2 / DS) were set as shown in Table 2 below, and otherwise the tire of Examples 6 to 7 was obtained in the same manner as in Example 1.

[0141] [Examples 8 to 9]

[0142] The number of depressions engraved in the shoulder reinforcing portion was adjusted, and the interval S2 of the second depressions was set as shown in Table 3 below, and otherwise the tire of Examples 8 to 9 was obtained in the same manner as in Example 1.

[0143] [Examples 10 to 11]

[0144] The number of depressions engraved in the shoulder blocks was adjusted, and the ratio (S1 / WB) was set as shown in Table 3 below, and otherwise the tire of Examples 10 to 11 was obtained in the same manner as in Example 1.

[0145] [Riding Performance]

[0146] The test tire was assembled on a rim (size = 8.0J), and the internal pressure of the tire was adjusted to 230 kPa by filling air. The tire was mounted on a test vehicle (SUV), and the test vehicle was driven by a driver on a test course including dry asphalt road surface, muddy road surface, and stone road surface. The occurrence of pattern noise on the dry asphalt road surface was confirmed as quietness. Functional evaluation related to the degree of occurrence of traction on the muddy road surface and the stone road surface was performed as off-road performance. These results are shown in Tables 1 to 3 below as indices. The larger the value in quietness, the lower the pattern noise. The larger the value in off-road performance, the better the traction.

[0147] [Chip resistance]

[0148] The appearance of the tire after the end of the above-described driving performance evaluation was observed, and the occurrence of chipping was confirmed. The results are shown in Tables 1 to 3 below as indices. The larger the value, the more chipping occurrence was suppressed. In the evaluation, even if the index is less than 100, as long as it is 95 or more, reduction in chip resistance performance is recognized to be suppressed.

[0149] [Overall performance]

[0150] The sum of quietness, off-road performance, and chip resistance performance is shown in Tables 1 to 3 below as overall performance. The larger the value, the better.

[0151] [Table 1]

[0152]

[0153] [Table 2]

[0154] [Table 3]

[0155] As shown in Tables 1 to 3, in the examples, compared with the comparative examples, it was possible to ensure the required chip resistance performance and off-road performance, and reduce pattern noise. Comparative Example 2 had performance equivalent to the examples in quietness, off-road performance, and chip resistance performance. However, in the comparative example 2, an increase in rolling resistance was confirmed due to the use of a thick tread. In contrast, in the examples, a decrease in rolling resistance was also confirmed. The superiority of the present application was known from the above evaluation results.

[0156] [Industrial applicability]

[0157] The technology described above, which ensures the required chip resistance performance and off-road performance and reduces pattern noise, can also be applied to various tires.

Claims

1. A tire comprising a tread which comes into contact with a road surface, characterized in that, at least two circumferential grooves are engraved in the tread, constituting at least three land portions arranged in the axial direction, a land portion located on the outer side in the axial direction among the at least three land portions is a shoulder land portion, the shoulder land portion comprises a plurality of shoulder blocks arranged in the circumferential direction, the shoulder land portion is divided into a ground region from the equatorial plane side to a ground end, and a non-ground region from the ground end to an end of the tread, the shoulder blocks in the ground region are engraved with a plurality of first depressions in a cylindrical shape, a diameter of the first depressions is 3 mm or more and 4 mm or less, a ratio of a depth of the first depressions to a groove depth of the circumferential grooves is 35% or more and 55% or less, a shoulder reinforcement portion extending in the circumferential direction is provided between the shoulder blocks and the end of the tread in the non-ground region, the shoulder reinforcement portion is engraved with a plurality of second depressions in a cylindrical shape, a diameter of the second depressions is 3 mm or more and 4 mm or less, a ratio of a depth of the second depressions to the groove depth of the circumferential grooves is 8% or more and 12% or less, the plurality of second depressions are arranged at intervals in the circumferential direction, an interval of the second depressions is 6.5 mm or more and 8.5 mm or less.

2. Tyre according to Claim 1, characterized in that, the plurality of first depressions are arranged at intervals from the equatorial plane side toward the end of the tread, a ratio of the interval of the first depressions to a width of the shoulder blocks is 0.10 or more and 0.20 or less.

3. The tire according to claim 1, characterized in that, an angle formed by a wall surface of the first depressions with respect to a center line of the first depressions is 0° or more and 30° or less.

4. The tire according to claim 1, characterized in that, an angle formed by a wall surface of the second depressions with respect to a center line of the second depressions is 0° or more and 30° or less.

5. The tire according to claim 1, characterized in that, a ratio of a radial distance from the ground end to the end of the tread with respect to a cross-sectional height is 5% or more and 15% or less.

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