Pneumatic tire

Abstract

To provide a pneumatic tire 1 (2) that is able to prevent deterioration of uneven wear resistance performance and wet performance as well as chipping of a block, while improving life performance and driving performance.SOLUTION: A pneumatic tire 1 (2) includes a tread 4 and a band 40 (41) located inside the tread 4 in a tire radial direction. The tread 4 has: circumferential grooves 24 including shoulder-circumferential grooves 24s and crown-circumferential grooves 24c; lateral grooves 62 including crown-lateral grooves 62c and middle-lateral grooves 62m; and blocks 26 including crown blocks 26c and middle blocks 26m. Groove depth CCD of the crown-circumferential grooves 24c and groove depth CLD of the crown-lateral grooves 62c are equal, and the band 40 (41) is present at least on an inner side of the crown-lateral grooves 62c in the tire radial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pneumatic tire. [Background technology]

[0002] Block pattern tires are known that have blocks defined by a plurality of circumferential main grooves and a plurality of lateral grooves. Block pattern tires that are mounted on drive shafts are required to have long life performance and driving performance. Increasing the groove depth of the circumferential main grooves and lateral grooves is effective in improving the long life performance and driving performance. In particular, increasing the groove depth of the circumferential main grooves and lateral grooves located on the inner side in the tire width direction effectively contributes to improving the long life performance and driving performance.

[0003] The outer diameter of the tread of a tire grows due to centrifugal force caused by running (hereinafter, sometimes simply referred to as "outer diameter growth"). When the tread groove depth is increased, the opening of the groove due to the outer diameter growth becomes larger. Therefore, the groove wall side of the block comes into contact with the ground more frequently during running. As a result, chipping of the groove wall of the block and uneven wear such as heel-and-toe wear occur.

[0004] A known method is to improve resistance to uneven wear by providing tie bars that connect blocks to grooves and increasing block rigidity. However, providing tie bars reduces the groove volume, which reduces grip performance on wet roads (hereinafter sometimes simply referred to as "wet performance"). In addition, increased block rigidity reduces driving performance.

[0005] Patent Document 1 listed below discloses a pneumatic tire that has a belt layer including a circumferential reinforcing layer, multiple circumferential main grooves, and multiple lug grooves (lateral grooves), and in which blocks on the circumferential reinforcing layer have sipes, thereby improving resistance to uneven wear. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2013-042257 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a pneumatic tire that can improve life performance and driving performance while suppressing deterioration of uneven wear resistance and wet performance, as well as block chipping. [Means for solving the problem]

[0008] A pneumatic tire according to one aspect of the present invention is a pneumatic tire including a tread and a band located on the tire radial inner side of the tread and including a band cord wound in a spiral shape. The tread has a plurality of circumferential grooves, a plurality of lateral grooves, and blocks defined by the circumferential grooves and the lateral grooves. The circumferential grooves include a pair of shoulder circumferential grooves and a pair of crown circumferential grooves located on the tire width direction inner side of the shoulder circumferential grooves. The lateral grooves include a crown lateral groove that connects the crown circumferential grooves, and a middle lateral groove that connects the shoulder circumferential groove and the crown circumferential groove. The blocks include a crown block defined by the crown circumferential groove and the crown lateral groove, and a middle block defined by the crown circumferential groove, the shoulder circumferential groove, and the middle lateral groove. The groove depth of the crown circumferential groove and the groove depth of the crown lateral groove are equal. The band is present at least on the tire radial inner side of the crown lateral groove.

[0009] Preferably, in the pneumatic tire, the band is present at least on an inner side in the tire radial direction of the crown block.

[0010] Preferably, in the pneumatic tire, the crown circumferential groove and the middle lateral groove have an equal groove depth, and the band is present at least on an inner side in the tire radial direction of the middle lateral groove.

[0011] Preferably, in the pneumatic tire, the band is present at least on an inner side in the tire radial direction of the middle block.

[0012] Preferably, in the pneumatic tire, the crown circumferential groove, the shoulder circumferential groove, and the middle lateral groove have an equal groove depth, and an outer edge of the band in the tire width direction is located at least on the inner side in the tire radial direction of the outermost side of the shoulder circumferential groove in the tire width direction.

[0013] Preferably, in the pneumatic tire, the band cord of the band located on the tire radially inner side of the crown lateral groove has a first cord density, and the band cord of the band located on the tire radially inner side from the tire widthwise outermost side of the shoulder circumferential groove to the tire widthwise outer edge of the band has a second cord density, and the first cord density is greater than the second cord density.

[0014] Preferably, in the pneumatic tire, the band has a boundary between the first cord density and the second cord density in the tire width direction.

[0015] Preferably, in the pneumatic tire, the boundary is located on an inner side in the tire radial direction of the middle block.

[0016] Preferably, in the pneumatic tire, the boundary is located on an inner side in the tire radial direction of the middle lateral groove.

[0017] Preferably, in the pneumatic tire, the first cord density is equal to or greater than 1.2 times and equal to or less than 2 times the second cord density.

[0018] Preferably, in the pneumatic tire, the crown lateral groove has a groove depth of 15 mm or greater and 30 mm or less.

[0019] Preferably, in the pneumatic tire, the number of the crown lateral grooves present on a ground contact surface of the tread when the tread contacts the ground is equal to or greater than 3 and equal to or less than 7.

[0020] Preferably, in the pneumatic tire, the lateral groove further includes a shoulder lateral groove connecting the shoulder circumferential groove and an outermost part of the tread in the tire width direction, The shoulder lateral groove has a groove bottom radius R of 2.5 mm or more.

[0021] Preferably, the pneumatic tire has an aspect ratio of 65% or less.

[0022] Preferably, in the pneumatic tire, the crown lateral groove has a groove bottom protrusion.

[0023] Preferably, the pneumatic tire is a heavy duty pneumatic tire. Effect of the Invention

[0024] According to the present invention, a pneumatic tire can be obtained that can suppress deterioration of uneven wear resistance and wet performance, as well as chipping of blocks, while improving life performance and driving performance. [Brief description of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view showing a portion of a pneumatic tire according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a development view showing a part of the tread surface of the tire of FIG. [Diagram 3] FIG. 2 is a cross-sectional view showing a portion of the tire of FIG. [Figure 4] FIG. [Diagram 5] FIG. 2 is a cross-sectional view of a middle lateral groove. [Figure 6] FIG. 4 is a cross-sectional view of a tread portion of a pneumatic tire according to another embodiment of the present invention. [Figure 7] FIG. 7 is a development view showing a part of the tread surface of the tire in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[0027] In the present invention, a state in which a tire is mounted on a standard rim, the internal pressure of the tire is adjusted to a standard internal pressure, and no load is applied to the tire is referred to as a standard state. Furthermore, unless otherwise specified, the following description will be given based on a tire that has not been worn down by running.

[0028] In the present invention, unless otherwise specified, the dimensions and angles of each part of the tire are measured in a normal state. The dimensions and angles of each part in the meridian section of the tire, which cannot be measured when the tire is mounted on a normal rim, are measured on a cut surface of the tire obtained by cutting the tire along a plane including the rotation axis. In this measurement, the tire is set so that the distance between the left and right beads is the same as the distance between the beads of the tire mounted on a normal rim. Note that the configuration of the tire that cannot be confirmed when the tire is mounted on a normal rim is confirmed on the aforementioned cut surface.

[0029] A genuine rim is a rim that is specified in the standard on which the tire is based. The "standard rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are genuine rims.

[0030] Normal tire pressure means the internal pressure specified in the standard on which the tire is based. The "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "INFLATION PRESSURE" in the ETRTO standard are normal tire pressures.

[0031] Normal load refers to the load specified in the standard on which the tire is based. The "maximum load capacity" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads.

[0032] In the present invention, the tread portion of a tire refers to a portion of the tire including a tread having a surface that comes into contact with the road surface. The tread surface is the surface of the tread that comes into contact with the road surface. The bead portion is a portion of the tire that fits onto the rim. The side portion is a portion of the tire that bridges between the tread portion and the bead portion. The tire has the following portions: a tread portion, a pair of bead portions, and a pair of side portions.

[0033] In the present invention, the crosslinked rubber is a molded product of a rubber composition obtained by pressurizing and heating the rubber composition. The rubber composition is an uncrosslinked rubber obtained by mixing a base rubber and chemicals in a kneader such as a Banbury mixer. The crosslinked rubber is also called vulcanized rubber, and the rubber composition is also called unvulcanized rubber.

[0034] Examples of the base rubber include natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), isoprene rubber (IR), ethylene propylene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and butyl rubber (IIR). Examples of the chemicals include reinforcing agents such as carbon black and silica, plasticizers such as aromatic oil, fillers such as zinc oxide, lubricants such as stearic acid, antioxidants, processing aids, sulfur, and vulcanization accelerators. The selection of the base rubber and chemicals, the content of the selected chemicals, etc. are appropriately determined depending on the specifications of each element such as the tread and sidewall to which the rubber composition is applied.

[0035] In the present invention, the number of sections of cords (number of cords) contained in a tire element containing parallel cords per 5 cm width is expressed as the cord density (unit: ends / 5 cm) contained in this element. Unless otherwise specified, the cord density is obtained in a cross section of the element obtained by cutting the element in a plane perpendicular to the length direction of the cord.

[0036] The aspect ratio of a tire is the ratio of the tire's section height to its section width obtained under normal conditions (see JATMA, etc.).

[0037] In the present invention, the groove depth is represented by the distance from the line segment connecting the opening edges of the groove to the bottom of the groove, and the groove width is the shortest length of the line segment connecting the opening edges of the groove.

[0038] [Basic configuration of the pneumatic tire of the present invention] Fig. 1 is a cross-sectional view showing a part of a pneumatic tire 1 (hereinafter, may be simply referred to as "tire 1") according to one embodiment of the present invention. Fig. 2 is a development view showing a part of the tread surface of tire 1. Tire 1 is mounted on vehicles such as trucks and buses. Tire 1 is a heavy-duty pneumatic tire.

[0039] FIG. 1 shows a part of a cross section (hereinafter, sometimes simply referred to as a "meridian cross section") of the tire 1 taken along a plane including the axis of rotation of the tire 1. In FIG. 1, the left-right direction is the width direction of the tire 1 (hereinafter, sometimes simply referred to as the "tire width direction"), and the up-down direction is the radial direction of the tire 1 (hereinafter, sometimes simply referred to as the "tire radial direction"). The direction perpendicular to the plane of FIG. 1 is the circumferential direction of the tire 1 (hereinafter, sometimes simply referred to as the "tire circumferential direction"). The dashed-dotted line CL represents the equatorial plane of the tire 1. The equatorial plane CL is located at the center of the tread 4 in the tire width direction.

[0040] The tire 1 is mounted on a rim R. The rim R is a regular rim. Air is filled inside the tire 1, and the internal pressure of the tire 1 is adjusted. The tire 1 mounted on the rim R is also called a tire-rim assembly. The tire-rim assembly includes the rim R and the tire 1 mounted on the rim R.

[0041] The tire 1 includes a tread 4 , a pair of sidewalls 6 , a pair of chafers 8 , a pair of beads 10 , a carcass 12 , a pair of steel reinforcing layers 16 , an innerliner 18 and a reinforcement portion 20 .

[0042] The tread 4 comes into contact with the road surface at the tread surface 22. In other words, the tread 4 has a tread surface 22 that comes into contact with the road surface. In FIG. 1, the symbol PC indicates the equator of the tire 1, which is the intersection point of the tread surface 22 and the equatorial plane CL. The equator PC is located on the outermost side in the tire radial direction of the tire 1. In FIG. 1, the symbol PE indicates the outer edge of the tread surface 22 in the tire width direction. The length indicated by the double arrow WT is the width of the tread surface 22. The width WT of the tread surface 22 is the distance in the tire width direction from one outer edge PE of the tread surface 22 to the other outer edge PE.

[0043] Although not shown, the tread 4 may include a base portion and a cap portion located radially outward of the base portion. In this case, both the base portion and the cap portion are made of crosslinked rubber. The cap portion is made of crosslinked rubber that takes into consideration wear resistance, low temperature characteristics, and grip performance.

[0044] As will be described later, the tread 4 has a plurality of circumferential grooves 24, a plurality of lateral grooves 62, and a plurality of blocks 26 defined by the circumferential grooves 24 and the lateral grooves 62. In Fig. 1, the crown circumferential groove 24c and the shoulder circumferential groove 24s, which are the circumferential grooves 24, are shown. Also shown are the crown block 26c, the middle block 26m, and the shoulder block 26s, which are the blocks 26.

[0045] Each sidewall 6 is continuous with an edge of the tread 4. The sidewalls 6 extend radially inward in the tire direction from the edge of the tread 4. The sidewalls 6 are located radially inward of the tread 4. The sidewalls 6 are made of crosslinked rubber that has been designed with cut resistance in mind.

[0046] Each chafer 8 is located on the inner side of the sidewall 6 in the tire radial direction. The chafers 8 contact the rim R. The chafers 8 are made of crosslinked rubber in consideration of wear resistance.

[0047] Each bead 10 is located on the inner side in the tire width direction of the chafer 8. Each bead 10 is located on the inner side in the tire radial direction of the sidewall 6. Each bead 10 includes a core 28 and an apex 30.

[0048] The core 28 extends in the circumferential direction of the tire. The core 28 includes wound steel wires. The core 28 has a generally hexagonal cross-sectional shape.

[0049] The apex 30 is located on the outer side of the core 28 in the tire radial direction. The apex 30 includes an inner apex 30u and an outer apex 30s. The inner apex 30u extends outward in the tire radial direction from the core 28. The outer apex 30s is located on the outer side of the inner apex 30u in the tire radial direction. The inner apex 30u is made of a hard crosslinked rubber. The outer apex 30s is made of a crosslinked rubber that is softer than the inner apex 30u.

[0050] The carcass 12 is located inside the tread 4, the pair of sidewalls 6, and the pair of chafers 8. The carcass 12 bridges between the first bead 10 and the second bead 10 of the pair of beads 10.

[0051] The carcass 12 includes at least one carcass ply 32. The carcass 12 of the tire 1 is made up of one carcass ply 32. The carcass ply 32 is folded back around each of the cores 28 from the inside to the outside in the tire width direction. The carcass ply 32 has a ply body 32a that spans between the first core 28 and the second core 28, and a pair of folded-back portions 32b that are continuous with the ply body 32a and are folded back around each of the cores 28 from the inside to the outside in the tire width direction.

[0052] Although not shown, the carcass ply 32 includes a number of carcass cords arranged in parallel. These carcass cords are covered with a topping rubber. Each carcass cord intersects with the equatorial plane CL. In this tire 1, the angle that the carcass cord makes with the equatorial plane CL (hereinafter, the intersecting angle of the carcass cord) is 70° or more and 90° or less. This carcass 12 has a radial structure. The carcass cords of this tire 1 are steel cords.

[0053] Each steel reinforcing layer 16 is located in the bead portion. The steel reinforcing layer 16 is folded back around the core 28 from the inner side toward the outer side in the tire width direction along the carcass ply 32. Although not shown, the steel reinforcing layer 16 includes a number of filler cords arranged in parallel. These filler cords are covered with a topping rubber. Steel cords are used as the filler cords.

[0054] The inner liner 18 is positioned inside the carcass 12. The inner liner 18 is joined to the inner surface of the carcass 12 via insulation (not shown) made of crosslinked rubber. The inner liner 18 constitutes the inner surface of the tire 1. The inner liner 18 is made of crosslinked rubber that has excellent air barrier properties. The inner liner 18 maintains the internal pressure of the tire 1.

[0055] The reinforcing portion 20 is located on the inner side in the tire radial direction of the tread 4. In the tire radial direction, the reinforcing portion 20 is located between the tread 4 and the carcass 12. The reinforcing portion 20 includes a belt 34 and a band 40.

[0056] The belt 34 includes four belt plies 38. These belt plies 38 are arranged in the tire radial direction. Each belt ply 38 is arranged such that both ends 38e face each other across the equatorial plane CL. Each belt ply 38 intersects with the equatorial plane CL. The ends 38e of each belt ply 38 are located on both sides of the equatorial plane CL.

[0057] The four belt plies 38 are a first belt ply 38A, a second belt ply 38B, a third belt ply 38C, and a fourth belt ply 38D. Of the four belt plies 38, the belt ply 38 located on the inner side in the tire radial direction is the first belt ply 38A. The second belt ply 38B is located on the outer side in the tire radial direction of the first belt ply 38A. The third belt ply 38C is located on the outer side in the tire radial direction of the second belt ply 38B. The fourth belt ply 38D is located on the outer side in the tire radial direction of the third belt ply 38C. The fourth belt ply 38D is the belt ply 38 located on the outer side in the tire radial direction of the four belt plies 38. In the tire 1 according to the embodiment of the present invention, the number of belt plies 38 may be three or more.

[0058] 1, an end 38Ae of the first belt ply 38A, an end 38Be of the second belt ply 38B, and an end 38Ce of the third belt ply 38C are located on the outer side of the shoulder circumferential groove 24s in the tire width direction. On the other hand, an end 38De of the fourth belt ply 38D is located on the inner side of the shoulder circumferential groove 24s in the tire width direction. From the viewpoint of preventing damage, the fourth belt ply 38D is disposed so that the end 38De of the fourth belt ply 38D does not overlap the shoulder circumferential groove 24s in the tire radial direction.

[0059] In the tire 1, the second belt ply 38B has the widest width, and the fourth belt ply 38D has the narrowest width. An end 38Ae of the first belt ply 38A and an end 38Ce of the third belt ply 38C are positioned between an end 38Be of the second belt ply 38B and an end 38De of the fourth belt ply 38D in the tire width direction.

[0060] The width of each belt ply 38 is the distance from a first end 38e to a second end 38e of the belt ply 38 in the tire width direction.

[0061] The band 40 is a jointless band including a band cord 48 wound in a spiral shape. The band cord 48 is covered with a topping rubber 50 (not shown). The band 40 is a full band in which the outer edges 40e are arranged to face each other across the equatorial plane CL. The band 40 intersects with the equatorial plane CL. The outer edges 40e of the band 40 are located on both sides of the equatorial plane CL. The outer edges 40e of the band 40 are located on the inner side of the shoulder circumferential grooves 24s in the tire width direction. The outer edges 40e of the band 40 are located on the outer side of the fourth belt ply 38D in the tire width direction.

[0062] [Basic tread structure] Fig. 2 is a development view showing a part of the tread surface 22 of the tire 1 of Fig. 1. As described above, the tread 4 of the tire 1 has a plurality of circumferential grooves 24, a plurality of lateral grooves 62, and a plurality of blocks 26 defined by the circumferential grooves 24 and the lateral grooves 62. Fig. 1 is a cross-sectional view taken along the X1-X1 line of Fig. 2.

[0063] In Fig. 2, the left-right direction is the tire width direction, and the up-down direction is the tire circumferential direction. The direction perpendicular to the paper surface of Fig. 2 is the tire radial direction. In Fig. 2, the position of the outer edge 40e of the band 40 is indicated by a dotted line. The length indicated by the symbol WF is the distance in the tire width direction from the equatorial plane CL to the outer edge 40e of the band 40. In Fig. 2, the double-headed arrow HWT is the distance in the tire width direction from the equatorial plane CL to the outer edge PE of the tread surface 22. The length indicated by the double-headed arrow HWT is half the width of the tread surface 22.

[0064] The tread 4 of the tire 1 has four circumferential grooves 24. The four circumferential grooves 24 are arranged in parallel in the tire width direction and extend continuously in the tire circumferential direction. Of these circumferential grooves 24, the circumferential groove 24 located on the outer side in the tire width direction is the shoulder circumferential groove 24s. The circumferential groove 24 located on the inner side in the tire width direction of the shoulder circumferential groove 24s is the crown circumferential groove 24c. The four circumferential grooves 24 of the tire 1 are composed of a pair of crown circumferential grooves 24c and a pair of shoulder circumferential grooves 24s.

[0065] The tread 4 of the tire 1 has a plurality of lateral grooves 62 arranged in parallel in the tire circumferential direction. The plurality of lateral grooves 62 include a plurality of crown lateral grooves 62c, a plurality of middle lateral grooves 62m, and a plurality of shoulder lateral grooves 62s. The crown lateral groove 62c connects a pair of crown circumferential grooves 24c. The middle lateral groove 62m connects the shoulder circumferential groove 24s and the crown circumferential groove 24c. The shoulder lateral groove 62s connects the shoulder circumferential groove 24s and the outermost side of the tread 4 in the tire width direction.

[0066] The crown lateral groove 62c has a groove bottom protrusion 72 at its groove bottom. The groove bottom protrusion 72 suppresses the opening of the crown lateral groove 62c due to outer diameter growth. This suppresses the decrease in uneven wear resistance of the tire 1 and the chipping of blocks. Furthermore, if the opening of the crown lateral groove 62c is suppressed, stones may easily become caught in the crown lateral groove 62c. The groove bottom protrusion 72 functions as a stone ejector. This improves the stone-trapping resistance of the tire 1.

[0067] One of the crown lateral grooves 62c adjacent in the tire circumferential direction is provided with one groove bottom protrusion 72 (groove bottom protrusion 72a), and the other crown lateral groove 62c is provided with two groove bottom protrusions 72 (groove bottom protrusion 72b). As shown in FIG. 2, the length GAW of the groove bottom protrusion 72a is longer than the length GBW of the groove bottom protrusion 72b. Therefore, the groove bottom protrusion 72a can suppress the opening of the crown lateral grooves 62c more than the groove bottom protrusion 72b. On the other hand, the length GBW of the groove bottom protrusion 72b is shorter than the length GAW of the groove bottom protrusion 72a. Therefore, the groove bottom protrusion 72b can suppress the deterioration of the driving performance of the tire 1 more than the groove bottom protrusion 72a. By arranging the groove bottom protrusions 72a and the groove bottom protrusions 72b alternately in the tire circumferential direction, the deterioration of the uneven wear resistance performance, the chipping of blocks, and the deterioration of the driving performance of the tire 1 are suppressed in a balanced manner.

[0068] The tread 4 of the tire 1 has a plurality of blocks 26 defined by the circumferential groove 24 and the lateral grooves 62. The plurality of blocks 26 include a plurality of crown blocks 26c, a plurality of middle blocks 26m, and a plurality of shoulder blocks 26s. The crown block 26c is a block 26 defined by the crown circumferential groove 24c and the crown lateral groove 62c. The middle block 26m is a block 26 defined by the crown circumferential groove 24c, the shoulder circumferential groove 24s, and the middle lateral groove 62m. The shoulder block 26s is a block 26 defined by the shoulder circumferential groove 24s and the shoulder lateral groove 62s.

[0069] In FIG. 2, the symbol CLO indicates the outermost position in the tire width direction of the crown lateral groove 62c. The symbol CBO indicates the outermost position in the tire width direction of the crown block 26c. The symbol MLI indicates the innermost position in the tire width direction of the middle lateral groove 62m. The symbol MLO indicates the outermost position in the tire width direction of the middle lateral groove 62m. The symbol MBO indicates the outermost position in the tire width direction of the middle block 26m. The symbol SCO indicates the outermost position in the tire width direction of the shoulder circumferential groove 24s. As shown in FIG. 2, in the tire 1, the positions CLO, CBO, MLI, MLO, MBO, and SCO are each formed to be located on a straight line in the tire circumferential direction.

[0070] 2, the tread 4 of the tire 1 is formed such that the crown circumferential groove 24c extends in a zigzag manner between positions CLO and MLI in the tire circumferential direction. Also, the tread 4 of the tire 1 is formed such that the shoulder circumferential groove 24s extends in a zigzag manner between positions MLO and SCO in the tire circumferential direction.

[0071] [Configuration of circumferential grooves, lateral grooves, and blocks] Of the lateral grooves 62, the crown lateral groove 62c and the middle lateral groove 62m are formed so as to be inclined with respect to the tire width direction of the tire 1. The inclination angle of the crown lateral groove 62c with respect to the tire width direction is 3° or more and 15° or less. The inclination angle of the middle lateral groove 62m with respect to the tire width direction is 3° or more and 15° or less. The groove width of the crown lateral groove 62c is approximately the same in a communicating region of the pair of crown circumferential grooves 24c. The groove width of the middle lateral groove 62m is approximately the same in a communicating region of the shoulder circumferential groove 24s and the crown circumferential groove 24c.

[0072] On the other hand, the shoulder lateral grooves 62s are formed to extend in the tire width direction of the tire 1. Also, the groove width of the shoulder lateral grooves 62s is formed to widen in the vicinity of the outermost side in the tire width direction of the tread 4. This improves the drainage performance of the tire 1.

[0073] The tire 1 is formed so that the intervals of the shoulder lateral grooves 62s, the middle lateral grooves 62m, and the crown lateral grooves 62c along the tire circumferential direction are substantially the same. The positions of the shoulder lateral grooves 62s and the crown lateral grooves 62c coincide with each other. Meanwhile, the positions of the middle lateral grooves 62m are shifted from the positions of the shoulder lateral grooves 62s and the crown lateral grooves 62c. The coincidence of the positions of the lateral grooves 62 means that at least a part of one lateral groove 62 and the other lateral groove 62 overlap in the tire width direction. The misalignment of the positions of the lateral grooves 62 means that one lateral groove 62 and the other lateral groove 62 do not overlap at all in the tire width direction.

[0074] In the tire 1, the innermost formation position in the tire width direction of the middle lateral groove 62m is located approximately midway between the outermost formation positions in the tire width direction of the crown lateral grooves 62c adjacent in the tire circumferential direction. Also, the outermost formation position in the tire width direction of the middle lateral groove 62m is located approximately midway between the innermost formation positions in the tire width direction of the shoulder lateral grooves 62s adjacent in the tire circumferential direction.

[0075] The crown circumferential grooves 24c are formed in a zigzag pattern with approximately the same groove width in the region between the positions CLO and MLI. The crown circumferential grooves 24c are formed so that the innermost side in the tire width direction is the outermost side in the tire width direction of the crown lateral grooves 62c. The crown circumferential grooves 24c are formed so that the outermost side in the tire width direction is the innermost side in the tire width direction of the middle lateral grooves 62m. That is, the crown circumferential grooves 24c are formed so as to be inclined with respect to the tire circumferential direction between the outermost side in the tire width direction of the crown lateral grooves 62c and the innermost side in the tire width direction of the middle lateral grooves 62m.

[0076] The shoulder circumferential grooves 24s are formed in a zigzag pattern with approximately the same groove width in the region between the positions MLO and SCO. The innermost side of the shoulder circumferential grooves 24s in the tire width direction is formed to be the outermost side of the middle lateral grooves 62m in the tire width direction. The outermost side of the shoulder circumferential grooves 24s in the tire width direction is formed to connect to the innermost side of the shoulder lateral grooves 62s in the tire width direction. That is, the shoulder circumferential grooves 24s are formed to be inclined with respect to the tire circumferential direction between the outermost side of the middle lateral grooves 62m in the tire width direction and the innermost side of the shoulder lateral grooves 62s in the tire width direction.

[0077] In the tire 1, the spacing of the crown lateral grooves 62c is set so that the number of crown lateral grooves 62c present on the tread surface 22 that contacts the ground when the tread 4 touches the ground is between 3 and 7. If the number of crown lateral grooves 62c is 3 or more, the driving performance of the tire 1 is improved. If the number of crown lateral grooves 62c is 7 or less, the band 40 can sufficiently suppress the opening of the crown lateral grooves 62c due to the growth of the outer diameter. This suppresses the deterioration of the uneven wear resistance of the tire 1 and the chipping of blocks.

[0078] As described above, in the tire 1, the intervals between the middle lateral grooves 62m and the shoulder lateral grooves 62s are substantially the same as the intervals between the crown lateral grooves 62c. Thus, the number of middle lateral grooves 62m and the number of shoulder lateral grooves 62s present on the tread surface 22 that contacts the ground when the tread 4 touches the ground are set to be 3 to 7, similar to the number of crown lateral grooves 62c. If the number of middle lateral grooves 62m is 3 or more, the driving performance of the tire 1 is further improved. If the number of middle lateral grooves 62m is 7 or less, the decrease in uneven wear resistance of the tire 1 and the chipping of blocks are further suppressed.

[0079] The shoulder block 26s is a block 26 located on the outermost side in the tire width direction. The middle block 26m is a block 26 located on the inner side in the tire width direction of the shoulder block 26s. The crown block 26c is a block 26 located on the inner side in the tire width direction of the middle block 26m. The shoulder block 26s includes an outer edge PE of the tread surface 22. The blocks 26 of the tire 1 are composed of a pair of crown blocks 26c, a pair of middle blocks 26m, and a pair of shoulder blocks 26s in the tire width direction. In the tire width direction, the crown block 26c and the middle block 26m are partitioned by the crown circumferential groove 24c. In the tire width direction, the middle block 26m and the shoulder block 26s are partitioned by the shoulder circumferential groove 24s.

[0080] The middle block 26m is defined by a plurality of middle lateral grooves 62m that are equally spaced apart. The crown block 26c is defined by a plurality of crown lateral grooves 62c that are equally spaced apart. The shoulder block 26s is defined by a plurality of shoulder lateral grooves 62s that are equally spaced apart. As shown in FIG. 2, the crown block 26c has a hexagonal shape surrounded by a pair of crown circumferential grooves 24c and a crown lateral groove 62c on the tread surface 22. The middle block 26m has a hexagonal shape surrounded by the crown circumferential groove 24c, the shoulder circumferential groove 24s, and the middle lateral groove 62m on the tread surface 22.

[0081] [Band Configuration] As described above, the band 40 includes the band cord 48 wound in a spiral shape. The band 40 has a jointless structure. The band 40 is a full band in which the outer edges 40e are disposed so as to face each other across the equatorial plane CL. In the tire 1, the band 40 is located between the second belt ply 38B and the third belt ply 38C in the tire radial direction. In the tire width direction, the outer edge 40e of the band 40 is located inside the end 38Be of the second belt ply 38B, and the outer edge 40e of the band 40 is located inside the end 38Ce of the third belt ply 38C.

[0082] The region of the tread portion where the band 40 exists in the tire radial direction is restrained by the reinforcing portion 20 including the band 40. Therefore, the outer diameter growth of the above region is suppressed. In the band 40, the angle that the band cord 48 makes with the circumferential direction is preferably 5° or less, more preferably 2° or less. The band cord 48 extends substantially in the circumferential direction.

[0083] In the tire 1, the band cord 48 is a metal cord. Specifically, the band cord 48 is a steel cord. The band cord 48 may be a cord made of organic fiber (hereinafter, organic fiber cord). In this case, examples of the organic fiber include nylon fiber, polyester fiber, rayon fiber, and aramid fiber. From the viewpoint of effectively restricting the movement of the tread portion and obtaining a ground contact surface with a stable shape, a metal cord is preferable for the band cord 48.

[0084] The density of the band cords 48 in the band 40 (hereinafter, sometimes simply referred to as "cord density") is preferably 20 ends / 5 cm or more and 35 ends / 5 cm or less. In the tire 1, the cord density is represented by the number of cross sections of the band cords 48 included per 5 cm width of the band 40 in the cross section of the band 40 included in the meridian cross section. The reinforcing portion 20 may include a plurality of bands. If the cord density is 20 ends / 5 cm or more, the outer diameter growth of the tire 1 can be effectively suppressed. Therefore, in the circumferential groove 24 and the lateral groove 62 in which the band 40 exists on the inner side in the tire radial direction, opening due to the outer diameter growth is suppressed. This suppresses a decrease in uneven wear resistance of the tire 1 and chipping of blocks. If the cord density is 35 ends / 5 cm or less, the appropriate flexibility of the tread 4 is ensured and the driving performance of the tire 1 is maintained.

[0085] 2, in the tire 1, the outer edge 40e of the band 40 is located between the position MLO and the position MBO. That is, the band 40 is present at least on the tire radially inner side of the position CLO, the position CBO, the position MLI, and the position MLO. In other words, the band 40 is present at least on the tire radially inner side of the crown lateral groove 62c, the crown block 26c, the crown circumferential groove 24c, and the middle lateral groove 62m.

[0086] The outer diameter growth is largest near the equatorial plane CL and decreases toward the outside in the tire width direction. In the tire 1, the band 40 is present on the inner side in the tire radial direction of the crown lateral groove 62c where the outer diameter growth is large. Therefore, the opening of the crown lateral groove 62c is suppressed. This suppresses the deterioration of the uneven wear resistance of the tire 1 and the chipping of the crown block 26c.

[0087] In the tire 1, the band 40 is present on the radially inner side of the crown block 26c. This improves the rigidity of the crown block 26c. This further suppresses the decrease in uneven wear resistance of the tire 1 and chipping of the crown block 26c.

[0088] In the tire 1, the band 40 is present on the radially inner side of the middle lateral groove 62m. This prevents the middle lateral groove 62m from widening. This prevents the tire 1 from suffering from a decrease in uneven wear resistance and from chipping of the middle block 26m.

[0089] As shown in Fig. 2, in the tire 1, the band 40 is not present on the tire radially inner side of the region on the tire width direction outer side of the position MBO (hereinafter, may be simply referred to as the "outer region"). That is, in the tire 1, the band 40 is not present on the tire radially inner side of the shoulder block 26s and the shoulder circumferential groove 24s. Therefore, the outer region of the tire 1 is not restrained by the band 40, and the outer diameter is easily increased by the internal pressure. Note that, hereinafter, the region on the tire width direction inner side of the position MBO may be simply referred to as the "central region".

[0090] Since a tire has a tread radius, the ground pressure on the tread surface 22 is usually the highest near the equatorial plane CL and decreases toward the outside in the tire width direction. That is, the ground pressure in the central region is higher than the ground pressure in the outer region. As described above, in the tire 1, the outer edge 40e of the band 40 is located at least on the inner side in the tire radial direction of the position MLO. Therefore, the band 40 suppresses the outer diameter growth of the central region of the tire 1. That is, in the tire 1, the outer diameter is likely to grow in the outer region and the outer diameter is unlikely to grow in the central region, so the difference between the ground pressure in the outer region and the ground pressure in the central region is likely to become small. As a result, the ground pressure on the tread surface 22 of the tire 1 is likely to be uniform. The more uniform the ground pressure on the tread surface of the tire is, the less likely uneven wear will occur. Therefore, the tire 1 has good uneven wear resistance.

[0091] The number of the shoulder lateral grooves 62s is set to be 3 to 7, the same as the crown lateral grooves 62c. When the number of the shoulder lateral grooves 62s is 3 or more, the outer diameter growth of the outer region is ensured. Therefore, the uneven wear resistance of the tire 1 is improved. When the number of the shoulder lateral grooves 62s is 7 or less, the decrease in the uneven wear resistance of the tire 1 and the chipping of blocks are further suppressed.

[0092] [Various dimensions, etc.] Fig. 3 is a cross-sectional view showing a part of the tire of Fig. 1. Fig. 3 shows a tread portion of the tire 1. The symbol CCD indicates the groove depth of the crown circumferential groove 24c. The symbol CCW indicates the groove width of the crown circumferential groove 24c. The symbol SCD indicates the groove depth of the shoulder circumferential groove 24s. The symbol SCW indicates the groove width of the shoulder circumferential groove 24s.

[0093] Fig. 4 is a cross-sectional view of the crown lateral groove 62c. Fig. 4 shows a portion of the X2-X2 cross section shown in Fig. 2 in the tread 4 of the tire 1. The symbol CLD indicates the groove depth of the crown lateral groove 62c. The symbol CLW indicates the groove width of the crown lateral groove 62c. The symbol GPH indicates the height of the groove bottom protrusion 72. The symbol GPW indicates the width of the groove bottom protrusion 72. The tire 1 is formed so that the height GPH and width GPW of the groove bottom protrusion 72a and the groove bottom protrusion 72b are approximately the same.

[0094] Fig. 5 is a cross-sectional view of the middle lateral groove 62m. Fig. 5 shows a part of the X3-X3 cross section shown in Fig. 2 in the tread 4 of the tire 1. The symbol MLD indicates the groove depth of the middle lateral groove 62m. The symbol MLW indicates the groove width of the middle lateral groove 62m.

[0095] As described above, increasing the groove depth of the circumferential grooves and lateral grooves of the tire contributes to improving the life performance, driving performance, and wet performance. In particular, increasing the groove depth of the circumferential grooves and lateral grooves located in the central region effectively contributes to improving the life performance, driving performance, and wet performance.

[0096] The tire 1 according to the embodiment of the present invention is formed so that the groove depth CCD, groove depth SCD, groove depth CLD, and groove depth MLD are equal. Therefore, the tire 1 can be formed so that the groove depths of the circumferential grooves 24 and the lateral grooves 62 located in the central region are deep. As a result, the tire 1 has excellent life performance, driving performance, and wet performance. In the tire 1, the groove depth is 15 mm or more and 30 mm or less. If the groove depth is 15 mm or more, the life performance, driving performance, and wet performance of the tire 1 are improved. If the groove depth is 30 mm or less, excessive outer diameter growth is suppressed, and the uneven wear resistance, wet performance, and block chipping resistance of the tire 1 are ensured.

[0097] Here, the groove depth being equal means that the difference between the groove depths of the circumferential groove 24 and the lateral groove 62 that communicate with each other is −5% or more and 5% or less, preferably −3% or more and 3% or less. More specifically, when the groove depth CLD is 100%, the groove depth CCD is 95% or more and 105% or less, preferably 97% or more and 103% or less of the groove depth CLD. When the groove depth MLD is 100%, the groove depth CCD is 95% or more and 105% or less, preferably 97% or more and 103% or less of the groove depth MLD. When the groove depth MLD is 100%, the groove depth SCD is 95% or more and 105% or less, preferably 97% or more and 103% or less of the groove depth MLD.

[0098] Here, increasing the groove depth may cause an increase in the growth of the outer diameter of the tire, which may lead to a decrease in uneven wear resistance and chipping of blocks. As described above, in the tire 1 according to the embodiment of the present invention, the outer edge 40e of the band 40 is formed to be located on the inner side in the tire radial direction of the central region. In other words, the band 40 suppresses the growth of the outer diameter of the tire 1 in the central region. This suppresses the decrease in uneven wear resistance of the tire 1 and the chipping of blocks. As a result, the tire 1 is capable of suppressing the decrease in uneven wear resistance and wet performance, as well as the chipping of blocks, while improving the life performance and driving performance.

[0099] In the tire 1, the groove depth CCD of the crown circumferential groove 24c and the groove depth CLD of the crown lateral groove 62c are equal. This allows the crown circumferential groove 24c and the crown lateral groove 62c to be formed deep. In addition, in the tire 1, the outer edge 40e of the band 40 is formed to be located at least on the tire radially inner side of the position CLO. That is, the tire 1 is configured such that the band 40 is present on the tire radially inner side of the crown lateral groove 62c. Therefore, the opening of the crown lateral groove 62c due to the outer diameter growth is suppressed. Therefore, the tire 1 has excellent life performance, driving performance, uneven wear resistance, wet performance, and block chipping resistance.

[0100] In the tire 1, the outer edge 40e of the band 40 is formed to be located at least radially inward of the position CBO. That is, the tire 1 is configured such that the band 40 is located radially inward of the crown block 26c. This improves the rigidity of the crown block 26c. Thus, the tire 1 has better uneven wear resistance, wet performance, and block chipping resistance.

[0101] In the tire 1, the groove depth CCD of the crown circumferential groove 24c and the groove depth MLD of the middle lateral groove 62m are equal. This allows the crown circumferential groove 24c and the middle lateral groove 62m to be formed deep. In addition, in the tire 1, the outer edge 40e of the band 40 is formed to be located at least on the inner side in the tire radial direction of the position MLO. That is, the tire 1 is configured such that the band 40 is present on the inner side in the tire radial direction of the middle lateral groove 62m. Therefore, the opening of the middle lateral groove 62m due to the outer diameter growth is suppressed. Therefore, the tire 1 has further excellent life performance, driving performance, uneven wear resistance performance, wet performance, and block chipping resistance performance.

[0102] In the tire 1, the groove width CCW of the crown circumferential groove 24c is preferably 2% to 15% of the width WT of the tread surface 22. The groove width SCW of the shoulder circumferential groove 24s is preferably 2% to 15% of the width WT of the tread surface 22. If the groove width CCW and the groove width SCW are 2% or more of the width WT, the groove volume is ensured. This improves the wet performance of the tire 1. If the groove width CCW and the groove width SCW are 15% or less of the width WT, the rigidity of the tread 4 is ensured. This improves the life performance of the tire 1.

[0103] In the tire 1, the groove width CLW of the crown lateral groove 62c is preferably 80% or more and 120% or less of the groove width CCW. The groove width MLW of the middle lateral groove 62m is preferably 80% or more and 120% or less of the groove width CCW. If the groove width CLW and the groove width MLW are 80% or more of the groove width CCW, the groove volume is ensured. This improves the wet performance of the tire 1. If the groove width CLW and the groove width MLW are 120% or less of the groove width CCW, the rigidity of the tread 4 is ensured. This improves the life performance of the tire 1.

[0104] The aspect ratio of the tire 1 is preferably 65% ​​or less. If the aspect ratio is 65% or less, the force of the internal pressure applied to the entire tread 4 can be sufficiently secured. This allows the difference in ground pressure between the outer region and the central region to be sufficiently small. This improves the uneven wear resistance of the tire 1.

[0105] The tire 1 is formed so that the radius R of the groove bottom of the shoulder lateral groove 62s is 2.5 mm or more. By making the radius R 2.5 mm or more, repeated strain at the bottom of the shoulder lateral groove 62s is suppressed. Therefore, the tire 1 is suppressed from generating tread groove cracks (hereinafter, sometimes referred to as "TGC").

[0106] The height GPH of the groove bottom protrusion 72 is preferably 15% or more and 50% or less of the groove depth CLD of the crown lateral groove 62c. The width GPW of the groove bottom protrusion 72 is preferably 20% or more and 60% or less of the groove width CLW of the crown lateral groove 62c. If the height GPH is 15% or more of the groove depth CLD and the width GPW is 20% or more of the groove width CLW, the size of the groove bottom protrusion 72 is ensured. This suppresses the opening of the crown lateral groove 62c due to the outer diameter growth and the stone bite into the crown lateral groove 62c. Therefore, the uneven wear resistance and stone bite resistance of the tire 1 are improved. If the height GPH is 50% or less of the groove depth CLD and the width GPW is 50% or less of the groove width CLW, the groove volume of the crown lateral groove 62c is ensured. Therefore, the wet performance of the tire 1 is improved.

[0107] In the tire 1, the length WF is preferably 15% or more and 85% or less of the length HWT. If the length WF is 15% or more of the length HWT, the band 40 can effectively restrain the central region of the tire 1. This ensures the uneven wear resistance, wet performance, and block chipping resistance of the tire 1. If the length WF is 85% or less of the length HWT, it ensures a state in which the outer diameter of the outer region of the tire 1 is easily allowed to grow. This makes the contact pressure of the tread surface 22 of the tire 1 uniform, and the uneven wear resistance of the tire 1 is maintained.

[0108] [Another embodiment of the pneumatic tire of the present invention] Fig. 6 is a cross-sectional view of a tread portion of a pneumatic tire 2 (hereinafter, may be simply referred to as "tire 2") according to another embodiment of the present invention. Fig. 7 is a development showing a part of the tread surface of tire 2. Fig. 6 shows the tread portion of a meridian cross section of tire 2 at the position indicated by X4-X4 in Fig. 7. Tire 2 has the same configuration as tire 1, except that band 41 is applied instead of band 40 of tire 1. Note that band 41 is a jointless band like band 40. Also, band 41 is a full band like band 40.

[0109] 6, the outer edge 41e of the band 41 of the tire 2 is located radially inward of the shoulder block 26s near the shoulder circumferential groove 24s in the tire width direction, unlike the outer edge 40e of the tire 1. That is, the tire 2 is configured such that the band 41 is located at least radially inward of the crown block 26c and the middle block 26m. This improves the rigidity of the crown block 26c and the middle block 26m. This improves the uneven wear resistance, wet performance, and block chipping resistance of the tire 2.

[0110] As shown in FIG. 7, the outer edge 41e of the band 41 of the tire 2 is located outside the position SCO in the tire width direction, unlike the outer edge 40e of the tire 1. That is, the band 40 exists at least on the inner side in the tire radial direction of the positions CLO, CBO, MLI, MLO, MBO, and SCO. In other words, the band 41 exists at least on the inner side in the tire radial direction of the crown lateral groove 62c, the crown block 26c, the crown circumferential groove 24c, the middle lateral groove 62m, the middle block 26m, and the shoulder circumferential groove 24s. In addition, the outer edge 41e of the band 41 is located near the outer side in the tire width direction of the position SCO. Therefore, as described above, the tire 2 has an outer diameter growth in the outer region. Therefore, the tire 2 has good uneven wear resistance.

[0111] The band 41 of the tire 2 is formed such that the cord density on the inner side in the tire width direction (hereinafter, may be simply referred to as the "first cord density") is higher than the cord density on the outer side in the tire width direction (hereinafter, may be simply referred to as the "second cord density") at the boundary 41b shown in Figs. 6 and 7. In the tire 2, the boundary 41b is located between the position MLI and the position MLO. The higher the cord density of the band, the stronger the binding force of the tire. The lower the cord density of the band, the weaker the binding force of the tire. In other words, the region of the band 41 having the first cord density has a stronger binding force of the tire 2 than the region of the band 41 having the second cord density. In Figs. 6 and 7, the symbol WBF indicates the length in the tire width direction from the boundary 41b to the outer edge PE of the tread surface 22.

[0112] The tire's outer diameter growth is greatest near the equatorial plane CL and decreases toward the outside in the tire width direction. In the tire 2, the band 41 having the first cord density restricts a region on the inner side in the tire width direction from the boundary 41b (hereinafter, may be simply referred to as the "first cord density region"). That is, in the tire 2, the first cord density region near the equatorial plane CL, where the outer diameter growth is particularly large, is strongly restricted in the central region. This suppresses the opening of the circumferential grooves 24 and the lateral grooves 62 located in the first cord density region of the tire 2. In addition, the rigidity of the blocks 26 located in the first cord density region of the tire 2 is improved. Therefore, the tire 2 has excellent uneven wear resistance and block chipping resistance.

[0113] The ground contact pressure of the tread surface of the tire is greatest near the equatorial plane CL and decreases toward the outside in the tire width direction. In the tire 2, the band 41 having the second cord density restrains the region from the boundary 41b to the outer edge 41e (hereinafter, may be simply referred to as the "second cord density region"). In the tire 2, the region outside the outer edge 41e in the tire width direction (hereinafter, may be simply referred to as the "shoulder region") is not restrained by the band 41. That is, the tire 2 is configured such that the first cord density region, the second cord density region, and the shoulder region are formed from the equator PC toward the outer edge PE of the tread surface 22 in the tire width direction. That is, the tire 2 is designed so that the restraining force of the band 41 decreases stepwise from the equator PC toward the outer edge PE of the tread surface 22. As a result, the ground contact pressure of the tread surface 22 in the tire 2 is more uniform. Therefore, the tire 2 has excellent uneven wear resistance.

[0114] The tire 2 is formed so that the groove depth CCD, groove depth SCD, groove depth CLD, and groove depth MLD are equal to each other, like the tire 1. Therefore, like the tire 1, the tire 2 has excellent life performance, driving performance, and wet performance. The effect of increasing the tire groove depth on the increase in outer diameter growth is greatest near the equatorial plane CL, and decreases toward the outside in the tire width direction. In the tire 2, the outer edge 41e of the band 41 is located at least on the inner side in the tire radial direction of the position SCO. This suppresses the opening of the circumferential groove 24 and the lateral groove 62 located on the inner side in the tire radial direction of the position SCO. In addition, the rigidity of the block 26 located on the inner side in the tire radial direction of the position SCO is improved. Furthermore, the tire 2 is designed so that the restraining force of the band 41 is gradually reduced in the tire width direction from the equator PC to the outer edge PE of the tread surface 22. This effectively suppresses the opening of the groove due to the outer diameter growth in the tire 2. In addition, in the tire 2, the rigidity of the block 26 is improved in a well-balanced manner. Therefore, the tire 2 has excellent life performance, driving performance, uneven wear resistance, wet performance, and block chipping resistance.

[0115] The boundary 41b is preferably located at least on the outer side in the tire width direction than the position CLO. In other words, at least the crown lateral groove 62c is preferably disposed within the first cord density region. This suppresses the opening of the crown lateral groove 62c due to the outer diameter growth. This improves the uneven wear resistance of the tire 2. Also, in the tire 2, the band 41 that is located on the outer side in the tire width direction and on the inner side in the tire radial direction than the position SCO preferably has the second cord density. This ensures the outer diameter growth in the outer region of the tire 2. Therefore, the tire 2 has excellent uneven wear resistance.

[0116] In tire 2, the length WBF is preferably 20% or more and 80% or less of the length HWT. If the length WBF is 20% or more of the length HWT, outer diameter growth in the outer region of tire 2 is ensured. Thus, uneven wear resistance of tire 2 is maintained. If the length WBF is 80% or less of the length HWT, a first cord density region is ensured. Thus, uneven wear resistance, uneven wear resistance, and block chipping resistance of tire 2 are maintained.

[0117] The boundary 41b is preferably located on the inner side in the tire radial direction of the middle block 26m. In the tire 2, the boundary 41b is located on the inner side in the tire width direction of the position MBO. This allows the band 40 to effectively restrain the central region of the tire 1 while ensuring outer diameter growth in the outer regions of the tire 2. Therefore, the tire 2 has excellent uneven wear resistance.

[0118] It is more preferable that the boundary 41b is located on the inner side in the tire radial direction of the middle lateral groove 62m. In the tire 2, the boundary 41b is located between the position MLI and the position MLO. This allows the band 40 to effectively restrain the central region of the tire 1 while further ensuring the outer diameter growth of the outer region of the tire 2. Therefore, the tire 2 has better uneven wear resistance.

[0119] The first cord density of the tire 2 is preferably 20 ends / 5 cm or more and 35 ends / 5 cm or less, similar to the band 40 of the tire 1. The first cord density of the tire 2 is preferably 1.2 times or more and 2 times or less than the second cord density. If the first cord density is 1.2 times or more than the second cord density, the difference between the binding force of the band 41 in the first cord density region and the binding force of the second cord density region is sufficiently ensured. This effectively equalizes the ground contact pressure of the tread surface 22. Therefore, the uneven wear resistance of the tire 2 is improved. If the first cord density is 2 times or less than the second cord density, the occurrence of repeated distortion and the movement of the rib at the boundary 41b are suppressed. Therefore, the TGC resistance, durability, and track wear resistance of the tire 2 are improved.

[0120] [Other variations] Tire 1 and Tire 2 have excellent life performance, driving performance, uneven wear resistance, wet performance, and block chipping resistance, and are therefore suitable for heavy-duty pneumatic tires, particularly for heavy-duty pneumatic tires mounted on drive shafts. However, the present invention is not limited to heavy-duty pneumatic tires. For example, the present invention can be applied to passenger vehicle tires.

[0121] The circumferential grooves 24 of the tires 1 and 2 are formed in a zigzag pattern in the tire circumferential direction, but the present invention is not limited to this. For example, the circumferential grooves of the present invention may be formed in a straight line or a wavy pattern in the tire circumferential direction. In addition, the lateral grooves 62 of the tires 1 and 2 are formed to be inclined with respect to the tire width direction, but the present invention is not limited to this. The lateral grooves of the present invention may be formed parallel to the tire width direction.

[0122] In the tire 2, two regions, a first cord density region and a second cord density region, are formed with the boundary 41b of the band 41 as a boundary, but the present invention is not limited thereto. For example, the band of the present invention may have a plurality of boundaries. In this case, the tire of the present invention may be formed so that the cord density is gradually decreased at each boundary from the vicinity of the equatorial plane CL toward the outer side in the tire width direction. More specifically, if a band having two boundaries is used in the tire of the present invention, a first cord density region, a second cord density region, a third cord density region, and a shoulder region may be provided from the vicinity of the equatorial plane CL toward the outer side in the tire width direction. This allows the tire restraining force of the band to be designed to be decreased in four stages. Therefore, it is possible to more flexibly respond to the influence of the outer diameter growth on the tire. Therefore, the tire life performance, driving performance, uneven wear resistance, wet performance, and block chipping resistance are improved. [Industrial Applicability]

[0123] The technology described above that can improve life performance and traction performance while suppressing deterioration in uneven wear resistance and wet performance, as well as block chipping, can be applied to various tires. [Explanation of symbols]

[0124] 1, 2... Tires 4. Tread 22 Tread surface 24...Circumferential groove 24c Crown circumferential groove 24s...Shoulder circumferential groove 26... Block 26c···Crown block 26m···Middle block 26s···Shoulder block 40, 41...Band 40e, 41e...Outer edge of band 41b...boundary 48...Band cord 62 Yokomizo 62c Crown groove 62m···Middle Yokomizo 62s···Shoulder groove 72...Groove bottom protrusion CCD: Crown circumferential groove depth SCD: Shoulder circumferential groove depth CLD: Crown lateral groove depth MLD: Middle lateral groove depth HWT: The distance from the equator to the outer edge of the tread surface. WBF: Length from the boundary to the outer edge of the tread surface

Claims

1. A pneumatic tire comprising a tread and a band located radially inward of the tread and including a spirally wound band cord, The tread has a plurality of circumferential grooves, a plurality of lateral grooves, and blocks defined by the circumferential grooves and the lateral grooves, The circumferential groove is A pair of shoulder circumferential grooves; A pair of crown circumferential grooves located on the inner side in the tire width direction than the shoulder circumferential grooves; Including, The lateral groove is a crown lateral groove connecting the pair of crown circumferential grooves; a middle lateral groove connecting the shoulder circumferential groove and the crown circumferential groove; Including, The block is a crown block defined by the crown circumferential groove and the crown lateral groove; a middle block defined by the crown circumferential groove, the shoulder circumferential groove, and the middle lateral groove; Including, a groove depth of the crown circumferential groove and a groove depth of the crown lateral groove are equal, The band is present at least on the radially inner side of the crown lateral groove. Pneumatic tires.

2. The pneumatic tire according to claim 1 , wherein the band is present at least on an inner side in the tire radial direction of the crown block.

3. a groove depth of the crown circumferential groove and a groove depth of the middle lateral groove are equal, The band is present at least on the radially inner side of the middle lateral groove. The pneumatic tire according to claim 1.

4. The pneumatic tire according to claim 3 , wherein the band is present at least on an inner side in the tire radial direction of the middle block.

5. a groove depth of the crown circumferential groove, a groove depth of the shoulder circumferential groove, and a groove depth of the middle lateral groove are equal, The outer edge of the band in the tire width direction is located at least on the inner side in the tire radial direction of the outermost side in the tire width direction of the shoulder circumferential groove. The pneumatic tire according to claim 1.

6. The band cord of the band, which is located on the tire radial direction inner side of the crown lateral groove, has a first cord density, The band cord of the band, which is present on the inner side in the tire radial direction from the outermost side in the tire width direction of the shoulder circumferential groove to the outer edge of the band in the tire width direction, has a second cord density, the first cord density is greater than the second cord density; The pneumatic tire according to claim 5.

7. The pneumatic tire according to claim 6 , wherein the band has a boundary between the first cord density and the second cord density in the tire width direction.

8. The pneumatic tire according to claim 7 , wherein the boundary is located on an inner side in the tire radial direction of the middle block.

9. The pneumatic tire according to claim 7 , wherein the boundary is located on an inner side in the tire radial direction of the middle lateral groove.

10. The pneumatic tire according to claim 6 , wherein the first cord density is 1.2 times or more and 2 times or less than the second cord density.

11. The pneumatic tire according to claim 1 , wherein the crown lateral groove has a groove depth of 15 mm or more and 30 mm or less.

12. The pneumatic tire according to claim 1 , wherein the number of the crown lateral grooves present on a contact surface of the tread when the tread contacts the ground is 3 or more and 7 or less.

13. The lateral groove further includes a shoulder lateral groove that connects the shoulder circumferential groove and an outermost portion of the tread in the tire width direction, The radius R of the groove bottom of the shoulder lateral groove is 2.5 mm or more. The pneumatic tire according to claim 1.

14. The pneumatic tire according to claim 1 , wherein the aspect ratio of the pneumatic tire is 65% or less.

15. The pneumatic tire according to claim 1 , wherein the crown lateral groove has a groove bottom protrusion.

16. The pneumatic tire according to any one of claims 1 to 14, wherein the pneumatic tire is a heavy load pneumatic tire.

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