Tire for heavy load

Abstract

To provide a tire 2 for a heavy load configured so that deterioration in durability caused by arrangement of a band can be suppressed and improvement in uneven wear performance can be attained.SOLUTION: A tire 2 is provided with a reinforcement layer 20 and a tread 4. The tread 4 comprises a shoulder circumferential groove. The reinforcement layer 20 comprises a belt 52 and a band 54. The belt 52 includes an inner belt ply 74 and an outer belt ply 76. The band comprises a full band 66. The full band 66 is positioned between the inner belt ply 74 and the outer belt ply 76. On an equatorial plane of the tire 2, a distance UFc between the full band 66 and the inner belt ply 74 is longer than a distance SFc between the full band 66 and the outer belt ply 76.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Tires undergo repeated deformation and recovery while in motion. Heavy-duty tires, which are subjected to large loads, undergo changes in their profile and contact patch shape. In high aspect ratio tires with an aspect ratio of 70% or more, the contact shape and profile change significantly in the crown area, which tends to wear more easily than the shoulder area.

[0003] Among the elements that make up a tire are bands. The bands include band cords that extend substantially in the circumferential direction. When a tire is in motion, the carcass tends to expand outward due to the action of internal pressure and centrifugal force. The bands can contribute to suppressing radially outward dimensional changes of the carcass, i.e., the dimensional growth of the carcass. In order to suppress changes in the profile and ground contact shape and improve resistance to uneven wear, the use of bands has been considered (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-47999 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a heavy-duty tire that can suppress a decrease in durability due to the provision of a band and achieve improved resistance to uneven wear. [Means for solving the problem]

[0006] The heavy-duty tire according to the present invention has a nominal aspect ratio of 70% or more and includes a pair of beads, a carcass spanning the pair of beads, a reinforcing layer located radially outward of the carcass, and a tread covering the reinforcing layer and in contact with the road surface. The tread has a plurality of circumferential grooves extending continuously in the circumferential direction. The plurality of circumferential grooves includes a shoulder circumferential groove located axially outermost. The reinforcing layer includes a belt including a large number of parallel belt cords and a band including a spirally wound band cord. The belt includes an inner belt ply and an outer belt ply aligned radially. The belt cords included in the inner belt ply are inclined in a direction opposite to the direction of inclination of the belt cords included in the outer belt ply. The band includes a full band located between the inner belt ply and the outer belt ply. Ends of the inner belt ply, the outer belt ply, and the full band are located axially outward of the shoulder circumferential groove. At the equatorial plane of the tire, a distance UFc between the full band and the inner belt ply is longer than a distance SFc between the full band and the outer belt ply. [Effects of the Invention]

[0007] According to the present invention, a heavy-duty tire can be obtained that can suppress the decrease in durability caused by the provision of a band and achieve improved resistance to uneven wear. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a portion of a heavy-duty tire according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a portion of the tire of FIG. 1. [Figure 3] FIG. 2 is a schematic diagram illustrating the configuration of a reinforcing layer. [Figure 4] FIG. 2 is a development view showing a part of the tread. [Figure 5] FIG. 1 is a cross-sectional view taken along the equatorial plane. [Figure 6] FIG. 10 is a cross-sectional view showing a modified example of a transverse sipe. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present invention will be described in detail based on preferred embodiments, with appropriate reference to the drawings.

[0010] The tire of the present invention is mounted on a rim. The inside of the tire is filled with air, and the internal pressure of the tire is adjusted. A tire mounted on a rim is also called a tire-rim assembly. A tire-rim assembly includes a rim and a tire mounted on the rim.

[0011] In the present invention, the 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 the standard state.

[0012] 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 of the tire's meridian cross section, which cannot be measured when the tire is mounted on a regular 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 matches the distance between the beads of the tire mounted on a regular rim. Note that the tire configuration, which cannot be confirmed when the tire is mounted on a regular rim, is confirmed on the cut surface.

[0013] A genuine rim is a rim 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 all genuine rims.

[0014] Normal tire pressure refers to the pressure specified in the standard on which the tire is based. The "maximum tire pressure" in the JATMA standard, the "maximum tire pressure" listed in the TRA standard's "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURE" and the "INFLATION PRESSURE" in the ETRTO standard are normal tire pressures.

[0015] 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 the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, and the "LOAD CAPACITY" in the ETRTO standard are normal loads.

[0016] In the present invention, the "nominal aspect ratio" is the "nominal aspect ratio" included in the "tire designation" specified in JIS D4202 "Automobile tires - designations and specifications."

[0017] In the present invention, the number of cords contained per 50 mm width of a tire element containing parallel cords is expressed as the cord density (unit: ends / 50 mm). Unless otherwise specified, the cord density is obtained on a cross section of the element obtained by cutting the element in a plane perpendicular to the longitudinal direction of the cord. Since an element containing a spirally wound cord also has a plurality of cords that appear to be parallel, the cord density can be obtained in the same manner as for a tire element containing parallel cords.

[0018] In the present invention, crosslinked rubber is obtained by pressurizing and heating a rubber composition. Crosslinked rubber is a crosslinked product of a rubber composition. A rubber composition is a material obtained by mixing raw rubber components and chemicals in a kneader such as a Banbury mixer. In crosslinked rubber, the raw rubber components are crosslinked, but in rubber compositions, the raw rubber components are not crosslinked. Crosslinked rubber is also called vulcanized rubber, and rubber compositions are also called unvulcanized rubber.

[0019] Examples of raw rubber components 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 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 raw rubber components and chemicals, the content of the selected chemicals, etc., are determined appropriately depending on the specifications of the elements to which the rubber composition is applied, such as the tread and sidewall.

[0020] In the present invention, the loss tangent (tan δ) of an element made of crosslinked rubber among elements constituting a tire is measured using a viscoelasticity spectrometer in accordance with the provisions of JIS K 6394. The measurement conditions are as follows: Initial strain = 10% Dynamic strain = ±1% Frequency = 10 Hz Mode = Decompression mode Temperature=70℃ In this measurement, a test piece (length 40 mm x width 4 mm x thickness 1 mm) is sampled from the tire. The longitudinal direction of the test piece is aligned with the circumferential direction of the tire. If it is not possible to sample a test piece from the tire, the test piece is sampled from a sheet of crosslinked rubber (hereinafter also referred to as a rubber sheet) obtained by pressing and heating the rubber composition used to form the element to be measured at a temperature of 170°C for 12 minutes. In the present invention, the loss tangent is expressed as the loss tangent at 70°C.

[0021] In the present invention, the stress at 200% elongation of an element made of crosslinked rubber among elements constituting a tire is measured in accordance with the provisions of JIS K6251 (measurement for determining tensile stress at a predetermined elongation). The stress at 200% elongation is also called 200% modulus.

[0022] In the present invention, the tread portion of a tire is the portion of the tire that comes into contact with the road surface. The bead portion is the portion of the tire that fits onto the rim. The sidewall portion is the portion of the tire that bridges between the tread portion and the bead portion. A tire has the following portions: a tread portion, a pair of bead portions, and a pair of sidewall portions. The central portion of the tread is also called the crown portion, and the edge portions of the tread are also called the shoulder portions.

[0023] [Findings that form the basis of the present invention] The belt includes a plurality of belt plies arranged in the radial direction. When a band, specifically a full band, is combined with the belt to form a reinforcing layer in order to suppress changes in the profile and ground contact shape, the full band is laminated on the belt plies. The full band tire includes a spirally wound band cord. In contrast, the belt ply includes multiple parallel belt cords. Each belt cord is independent of the others. The belt ply has less resistance to the dimensional growth of the carcass than the full band tire. The shape of the belt ply tends to change to accommodate dimensional growth. The change in the shape of the belt ply is accompanied by a change in the inclination angle of the belt cord. Distortion is likely to occur between the band cord and the belt cord. As described above, the carcass of a tire in a running state tends to expand outward due to the action of internal pressure and centrifugal force. When a full band is laminated on a belt ply, the distance between the full band and the belt ply, in other words, the distance between the band cords and the belt cords, is expected to gradually decrease. In particular, when a full band is sandwiched between two belt plies arranged radially, the distance between the band cords of the full band and the belt cords of the belt ply located inside the full band is expected to decrease significantly compared to the distance between the band cords and the belt cords of the belt ply located outside the full band. In high aspect ratio tires, the effect of internal tire pressure is stronger in the crown portion and weaker in the shoulder portion, which promotes dimensional growth in the crown portion. In high aspect ratio tires, the distance between the band cord and the belt cord in the crown portion decreases, which is expected to increase the strain generated between the band cord and the belt cord. If the distance between the band cord and the belt cord is insufficient, the band cord may come into contact with the belt cord. Depending on the degree of contact, this may result in a decrease in the adhesive strength between the full band and the belt ply, or in a decrease in the strength of the band cord or belt cord. A decrease in adhesive strength or a decrease in cord strength affects tire durability. In this case, the band, which is intended to suppress changes in the tire profile and contact shape and improve uneven wear resistance, may not be able to fully perform its function. Therefore, in order to suppress the decrease in durability caused by the provision of the band and improve resistance to uneven wear, the inventors conducted extensive research focusing on the distance between the full band and the belt ply, and have completed the present invention, which is described below.

[0024] [Outline of the embodiment of the present invention] The present invention provides a heavy-duty tire having a nominal aspect ratio of 70% or more, the tire comprising: a pair of beads; a carcass spanning the pair of beads; a reinforcing layer positioned radially outward of the carcass; and a tread covering the reinforcing layer and coming into contact with a road surface, the tread having a plurality of circumferential grooves extending continuously in the circumferential direction, the plurality of circumferential grooves including a shoulder circumferential groove positioned axially outermost, the reinforcing layer comprising a belt including a number of belt cords arranged in parallel and a band including a spirally wound band cord, the belt comprising an inner belt ply and an outer belt ply arranged radially. a heavy-duty tire including (a) a full band positioned between the inner belt ply and the outer belt ply, wherein the belt cords included in the inner belt ply have an inclination direction opposite to the inclination direction of the belt cords included in the outer belt ply, and wherein ends of the inner belt ply, the outer belt ply, and the full band are positioned axially outside the shoulder circumferential grooves, and a distance UFc between the full band and the inner belt ply is longer than a distance SFc between the full band and the outer belt ply on the equatorial plane of the tire.

[0025] The heavy-duty tire of the present invention can suppress the decrease in durability due to the provision of the band and can achieve an improvement in uneven wear resistance. The mechanism by which such effects are achieved has not been clarified, but is presumed to be as follows.

[0026] The full band located between the inner and outer belt plies suppresses changes in the tire profile and contact shape, contributing to improved resistance to uneven wear. Since the distance between the full band and the inner belt ply located inside the full band is long at the tire's equatorial plane, contact between the band cord and the belt cord in the crown portion is suppressed. This suppresses a decrease in adhesive strength and a decrease in cord strength due to contact between the band cord and the belt cord. This tire can maintain good durability. This tire can suppress the decrease in durability caused by the provision of the band, and can achieve an improvement in uneven wear resistance.

[0027] Preferably, the distance UFc between the full band and the inner belt ply at the equatorial plane of the tire is 0.6 mm or more. In this case, the band cord and the belt cord are disposed with a sufficient gap therebetween. Contact between the band cord and the belt cord is suppressed. This tire can maintain good durability.

[0028] Preferably, the distance UFs between the full band and the inner belt ply at the end of the full band is 2.5 mm or less. In this case, heat generation in the tread portion is suppressed. In this tire, an increase in rolling resistance is suppressed.

[0029] Preferably, a distance UFc between the full band and the inner belt ply at the equatorial plane of the tire is longer than a distance UFs between the full band and the inner belt ply at the end of the full band. In this case, contact between the band cord and the belt cord is effectively suppressed. This tire can maintain good durability.

[0030] Preferably, at the equatorial plane of the tire, the ratio (UFc / SFc) of the distance UFc between the full band and the inner belt ply to the distance SFc between the full band and the outer belt ply is 2.0 or more. In this case, contact between the band cords and the belt cords is effectively suppressed. This tire can maintain good durability.

[0031] Preferably, the cord density of the full band is 22 ends / 50 mm or more. In this case, the full band can effectively restrain the inner belt ply. Changes in the inclination angle of the belt cord due to dimensional growth are suppressed. Distortion occurring between the band cord and the belt cord is reduced. Contact between the band cord and the belt cord is suppressed. This tire can maintain good durability.

[0032] Preferably, the ratio of the cord density of the inner belt ply to the cord density of the full band is 0.65 or more. In this case, dimensional growth of the crown portion is effectively suppressed. The spacing between the band cords and the belt cords is appropriately maintained. Contact between the band cords and the belt cords is effectively suppressed. This tire can maintain good durability.

[0033] Preferably, the angle FU formed between the band cord of the full band and the belt cord of the inner belt ply is 10 degrees or more and 25 degrees or less, and the angle FS formed between the band cord of the full band and the belt cord of the outer belt ply is 10 degrees or more and 25 degrees or less. In this case, distortion occurring between the band cord and the belt cord of the inner belt ply and distortion occurring between the band cord and the belt cord of the outer belt ply are effectively reduced. Contact between the band cord and the belt cord is effectively suppressed. This tire can maintain good durability.

[0034] Preferably, the angle UE formed by the belt cords of the inner belt ply with respect to the equatorial plane of the tire is smaller than the angle SE formed by the belt cords of the outer belt ply with respect to the equatorial plane of the tire. In this case, the resistance of the inner belt ply, which is susceptible to the dimensional growth of the carcass, to the dimensional growth of the carcass is increased. Strain occurring between the band cords and the belt cords of the inner belt ply is effectively reduced. This tire can maintain good durability.

[0035] Preferably, the cord density of the inner belt ply is greater than the cord density of the outer belt ply. In this case, the resistance of the inner belt ply, which is susceptible to the dimensional growth of the carcass, to the dimensional growth of the carcass is increased. Strain occurring between the band cords and the belt cords of the inner belt ply is effectively reduced. This tire can maintain good durability.

[0036] Preferably, the plurality of circumferential grooves define a plurality of land portions arranged axially in the tread, and among the plurality of land portions, a land portion located on the equatorial plane of the tire or the land portion closest to the equatorial plane is a center land portion, and the center land portion has a transverse sipe crossing the center land portion, the transverse sipe having a sipe body and a tubular portion located radially inward of the sipe body, the tubular portion having a groove width wider than the groove width of the sipe body. In this case, the tire can suppress deterioration of wet performance due to wear while suppressing dimensional growth in the crown portion. This tire can maintain good wet performance while suppressing deterioration of durability and improving uneven wear resistance.

[0037] In this way, the heavy duty tire of the present invention can suppress the decrease in durability caused by the provision of the band and achieve an improvement in uneven wear resistance. This will be explained in detail below using the heavy duty tire shown in Figure 1 as an example.

[0038] [Details of the embodiment of the present invention] FIG. 1 is a cross-sectional view showing a portion of a heavy-duty tire 2 (hereinafter simply referred to as "tire 2") according to one embodiment of the present invention. This tire 2 is mounted on vehicles such as trucks and buses. The nominal aspect ratio of this tire 2 is 70% or more. In other words, this tire 2 has a nominal aspect ratio of 70% or more. This tire 2 is a high-profile tire.

[0039] Fig. 1 shows a part of a cross section (hereinafter referred to as a meridian cross section) of this tire 2 along a plane including the rotation axis of the tire 2. The tire 2 shown in Fig. 1 is a brand new tire with no running history. Fig. 2 is an enlarged cross-sectional view showing a part of the tire 2 shown in Fig. 1. Fig. 2 shows a tread portion T of the tire 2.

[0040] The direction indicated by the double-headed arrow AD is the axial direction of the tire 2. The axial direction of the tire 2 means a direction parallel to the rotation axis (not shown) of the tire 2. The direction indicated by the double-headed arrow RD is the radial direction of the tire 2. The direction perpendicular to the plane of FIG. 1 is the circumferential direction of the tire 2. A dashed line EL extending in the radial direction represents the equatorial plane of the tire 2. The direction from the equatorial plane toward the edge of the tread surface, which will be described later, is the outer side in the axial direction of the tire 2, and the direction from the edge of the tread surface toward the equatorial plane is the inner side in the axial direction of the tire 2. The direction indicated by the arrow RD1 is the radially outer side of the tire 2, and the direction indicated by the arrow RD2 is the radially inner side of the tire 2.

[0041] The tire 2 includes a tread 4 , a pair of sidewalls 6 , a pair of beads 8 , a pair of chafers 10 , a carcass 12 , a pair of cushion layers 14 , an inner liner 16 , a pair of steel fillers 18 , and a reinforcing layer 20 .

[0042] The tread 4 is located radially outward of the carcass 12. The tread 4 covers the reinforcing layer 20. The tread 4 comes into contact with the road surface. Of the outer peripheral surface 22 of the tread 4, the portion that comes into contact with the road surface is also called a tread surface 24. The tread 4 has the tread surface 24 that comes into contact with the road surface. In Fig. 1, the symbol Eq denotes the intersection of the tread surface 24 and the equatorial plane. The intersection Eq is the radially outer edge of the tire 2 and is also called the equator. When a groove, which will be described later, is located on the equatorial plane, the equator is determined based on a virtual tread surface obtained by assuming that there are no grooves on the equatorial plane.

[0043] The position indicated by the symbol TE is the edge of the tread surface 24 . In the present invention, the position on the outer surface of the tire corresponding to the axially outer edge of the contact patch obtained by applying a normal load to a tire in a normal state, setting the camber angle to 0°, and contacting the tire with a flat surface is represented as the edge of the tread surface. In the tire 2, an end TE of the tread surface 24 coincides with an end 22e of the outer circumferential surface 22.

[0044] 1, the length indicated by the double arrow WT is the width of the tread surface 24. The width WT of the tread surface 24 is the axial distance from one end TE of the tread surface 24 to the other end TE.

[0045] The tread 4 includes a base portion 26 and a cap portion 28 located radially outward of the base portion 26. The base portion 26 is made of a cross-linked rubber with low heat buildup. The cap portion 28 is made of a cross-linked rubber that takes into consideration wear resistance and grip performance. The cap portion 28 may be made of a cross-linked rubber that takes into consideration not only wear resistance and grip performance but also low heat buildup. 1, the base portion 26 covers the entire reinforcing layer 20. The cap portion 28 covers the entire base portion 26.

[0046] Grooves 30 are cut into the tread 4 of this tire 2, thereby forming a tread pattern. The tread pattern formed in the tread 4 has a plurality of circumferential grooves 32 that extend continuously in the circumferential direction. The tread 4 shown in Figure 1 has four circumferential grooves 32. These circumferential grooves 32 are aligned in the axial direction.

[0047] The four circumferential grooves 32 have a wide groove width, and a pair of groove walls of the circumferential grooves 32 do not come into contact with each other even when the tread 4 comes into contact with the road surface and deforms, and are also called circumferential main grooves. From the viewpoint of contributing to drainage performance and traction performance, the groove width of the circumferential grooves 32 is preferably 2% to 10% of the width WT of the tread surface 24.

[0048] In the present invention, of the multiple circumferential grooves cut in the tread, the circumferential groove located at the outermost position in the axial direction is a shoulder circumferential groove. A circumferential groove located on the equatorial plane is a center circumferential groove. When no circumferential groove is provided on the equatorial plane, the circumferential groove closest to the equatorial plane is the center circumferential groove. When a circumferential groove is located between the center circumferential groove and the shoulder circumferential groove, the circumferential groove located between the center circumferential groove and the shoulder circumferential groove is called a middle circumferential groove.

[0049] Of the four circumferential grooves 32 formed in the tread 4, the circumferential grooves 34 located on the outermost side in the axial direction are shoulder circumferential grooves. The circumferential groove 36 closest to the equatorial plane is the center circumferential groove. The four circumferential grooves 32 include a pair of center circumferential grooves 36 and a pair of shoulder circumferential grooves 34. The shoulder circumferential grooves 34 are located axially outward of the center circumferential grooves 36.

[0050] A plurality of circumferential grooves 32 are formed in the tread 4, and a plurality of land portions 38 are arranged in the axial direction. In other words, the tread 4 has a plurality of circumferential grooves 32. The plurality of circumferential grooves 32 form a plurality of land portions 38 in the tread 4. Four circumferential grooves 32 are formed in the tread 4 of this tire 2, forming five land portions 38. These land portions 38 are aligned in the axial direction.

[0051] In the present invention, the land portion located at the outermost position in the axial direction among the multiple land portions configured in the tread is called a shoulder land portion. A land portion located on the equatorial plane is called a center land portion. If no land portion is provided on the equatorial plane, the land portion closest to the equatorial plane is called a center land portion. If a land portion is located between a center land portion and a shoulder land portion, this land portion between the center land portion and the shoulder land portion is called a middle land portion.

[0052] As described above, the tread 4 is configured with five land portions 38. Of the five land portions 38, the land portion 40 located at the outermost position in the axial direction is the shoulder land portion. The land portion 42 located on the equatorial plane is the center land portion. The land portion 44 located between the center land portion 42 and the shoulder land portion 40 is the middle land portion. The five land portions 38 include a center land portion 42, a pair of middle land portions 44, and a pair of shoulder land portions 40. The middle land portion 44 is located axially outward of the center land portion 42. The shoulder land portions 40 are located axially outward of the middle land portions 44. The shoulder land portions 40 include the edge TE of the tread surface 24.

[0053] The axial width of the center land portion 42 is 10% to 18% of the width WT of the tread surface 24. The axial width of the middle land portion 44 is 10% to 18% of the width WT of the tread surface 24. The axial width of the shoulder land portion 40 is 15% to 25% of the width WT of the tread surface 24. The axial width of the land portion 38 is represented by the axial width of the top surface of the land portion 38 that forms part of the tread surface 24.

[0054] 1, the position indicated by the symbol BT is the groove bottom of the shoulder circumferential groove 34. In the tread portion T of this tire 2, the portion axially outward from the groove bottom BT of the shoulder circumferential groove 34 is the shoulder portion, and the portion between the groove bottoms BT of the left and right shoulder circumferential grooves 34 is the crown portion.

[0055] In the present invention, the groove bottom is the deepest position in the cross section of the groove. The distance from the line segment connecting the left and right edges that form the groove mouth to the groove is measured along the normal to this line segment. The position at which the distance from this line segment to the groove is the longest is the groove bottom. When the bottom surface including the groove bottom is composed of a plane, the center of the width of the plane that forms the bottom surface is used as the groove bottom. The groove depth of the groove is expressed as the distance from this line segment that connects the left and right edges to the groove bottom, measured along the normal to this line segment.

[0056] Each sidewall 6 is continuous with an edge of the tread 4. The sidewalls 6 are located axially outward of the carcass 12. The sidewalls 6 are made of crosslinked rubber.

[0057] Each bead 8 is located radially inward of the sidewall 6. The bead 8 is located axially inward of the chafer 10. The bead 8 includes a core 46 and an apex 48.

[0058] The core 46 extends in the circumferential direction and includes wound steel wire. The core 46 has a generally hexagonal cross-sectional shape.

[0059] The apex 48 is located radially outward of the core 46. The apex 48 includes an inner apex 48u and an outer apex 48s. The inner apex 48u is located radially outward of the core 46. The outer apex 48s is located radially outward of the inner apex 48u. The inner apex 48u is made of a hard crosslinked rubber. The outer apex 48s is made of a crosslinked rubber that is softer than the inner apex 48u.

[0060] Each chafer 10 is located axially outward of the bead 8. The chafers 10 are located radially inward of the sidewall 6. Although not shown, the chafers 10 come into contact with the rim. The chafers 10 are made of crosslinked rubber in consideration of wear resistance.

[0061] The carcass 12 is located inside the tread 4, the pair of sidewalls 6, and the pair of chafers 10. The carcass 12 bridges between the pair of beads 8.

[0062] The carcass 12 includes at least one carcass ply 50. The carcass 12 of the tire 2 is made up of one carcass ply 50. The carcass ply 50 is turned up from the inside to the outside in the axial direction at each bead 8. The carcass ply 50 includes a ply body 50a that spans between a pair of beads 8, and a pair of turned-up portions 50b that are continuous with the ply body 50a and are turned up at each bead 8.

[0063] Although not shown, the carcass ply 50 includes a number of parallel carcass cords. These carcass cords are covered with carcass topping rubber. The carcass cords are steel cords. The carcass cords intersect with the equator plane. The carcass 12 has a radial structure.

[0064] Each cushion layer 14 is located at an end 20e of the reinforcing layer 20 (specifically, the belt described below) between the reinforcing layer 20 and the carcass 12. An inner end 14ue of the cushion layer 14 is located axially inside the end 20e of the reinforcing layer 20. An outer end 14se of the cushion layer 14 is located axially outside the end 20e of the reinforcing layer 20. The cushion layer 14 is made of soft crosslinked rubber.

[0065] The inner liner 16 is located inside the carcass 12. The inner liner 16 is joined to the inner surface of the carcass 12 via insulation (not shown). The inner liner 16 forms the inner surface of the tire 2. The inner liner 16 is made of crosslinked rubber with excellent air barrier properties. The inner liner 16 maintains the internal pressure of the tire 2.

[0066] Each steel filler 18 is located in the bead portion B. The steel filler 18 is folded back around the bead 8 from the axially inner side to the axially outer side along the carcass ply 50. Although not shown, the steel filler 18 includes a number of filler cords arranged in parallel. The filler cords are steel cords.

[0067] The reinforcing layer 20 is located radially outside the carcass 12. The reinforcing layer 20 is located radially inside the tread 4. The reinforcing layer 20 is located between the tread 4 and the carcass 12. The reinforcing layer 20 includes a belt 52 and a band 54 .

[0068] Fig. 3 shows the configuration of the reinforcing layer 20. The direction indicated by the double arrow CD is the circumferential direction of the tire 2. The direction perpendicular to the paper surface of Fig. 3 is the radial direction of the tire 2. The front side of the paper surface is the radially outer side, and the back side is the radially inner side.

[0069] The belt 52 includes at least two belt plies 56 arranged in the radial direction. Each belt ply 56 is arranged such that both ends 56e thereof face each other across the equator plane. Each belt ply 56 intersects with the equator plane. The belt 52 of the tire 2 includes four belt plies 56. The four belt plies 56 are a first belt ply 56A, a second belt ply 56B, a third belt ply 56C, and a fourth belt ply 56D. The number of belt plies 56 constituting the belt 52 may be two or three.

[0070] The first belt ply 56A is the belt ply 56 located radially innermost among the four belt plies 56 that constitute the belt 52. The second belt ply 56B is located radially outer than the first belt ply 56A. The third belt ply 56C is located radially outer than the second belt ply 56B. The fourth belt ply 56D is located radially outer than the third belt ply 56C. The fourth belt ply 56D is the belt ply 56 located radially outermost among the four belt plies 56 that constitute the belt 52.

[0071] As shown in Fig. 1, a first belt ply 56A of the tire 2 is laminated on the carcass 12. A second belt ply 56B is laminated on the first belt ply 56A. A fourth belt ply 56D is laminated on a third belt ply 56C. A full band, which will be described later, is located radially inside the third belt ply 56C of the tire 2. The third belt ply 56C is laminated on the full band.

[0072] In the tire 2, the second belt ply 56B has the widest axial width, and the fourth belt ply 56D has the narrowest axial width. The first belt ply 56A and the third belt ply 56C have the same axial width, or the axial width of the first belt ply 56A is slightly wider than the axial width of the third belt ply 56C.

[0073] In the present invention, the edge of the belt is represented by the edge of the belt ply having the widest axial width among the plurality of belt plies constituting the belt. As described above, the second belt ply 56B has the widest axial width in the belt 52 of the tire 2. The end 52e of the belt 52 of the tire 2 is represented by the end 56Be of the second belt ply 56B.

[0074] For example, as shown in FIG. 2, an end 56Ae of the first belt ply 56A is located axially outward from the shoulder circumferential groove 34. An end 56Be of the second belt ply 56B is also located axially outward from the shoulder circumferential groove 34. An end 56Ce of the third belt ply 56C is also located axially outward from the shoulder circumferential groove 34. An end 56De of the fourth belt ply 56D is also located axially outward from the shoulder circumferential groove 34. In the tread portion T shown in FIG. 2, the ends 56e of all the belt plies 56 constituting the belt 52 are located axially outward from the shoulder circumferential groove 34. Note that in this tire 2, the end 56De of the fourth belt ply 56D may be disposed axially inward from the shoulder circumferential groove 34.

[0075] In FIG. 1, the length indicated by the double arrow W1 is the axial width of the first belt ply 56A. The length indicated by the double arrow W2 is the axial width of the second belt ply 56B. The length indicated by the double arrow W3 is the axial width of the third belt ply 56C. The length indicated by the double arrow W4 is the axial width of the fourth belt ply 56D. The axial width of each belt ply 56 is represented by the axial distance from one end 56e of the belt ply 56 to the other end 56e.

[0076] In this tire 2, from the viewpoint of ensuring the rigidity of the tread portion T, the ratio (W1 / WT) of the axial width W1 of the first belt ply 56A to the width WT of the tread surface 24 is preferably 0.80 or more and 0.90 or less. The ratio (W2 / WT) of the axial width W2 of the second belt ply 56B to the width WT of the tread surface 24 is preferably 0.85 or more and 0.95 or less. The ratio (W3 / WT) of the axial width W3 of the third belt ply 56C to the width WT of the tread surface 24 is preferably 0.80 or more and 0.90 or less. The axial width W4 of the fourth belt ply 56D is set appropriately depending on the specifications of the tire 2.

[0077] As shown in Fig. 3, each belt ply 56 constituting the belt 52 includes a large number of parallel belt cords 58. For ease of explanation, the belt cords 58 are shown by solid lines in Fig. 3, but the belt cords 58 are covered with a belt topping rubber 60. The belt cords 58 of the tire 2 are steel cords. The cord density of each belt ply 56 is equal to or greater than 15 ends / 50 mm and equal to or less than 30 ends / 50 mm.

[0078] In each belt ply 56, the belt cords 58 are inclined with respect to the circumferential direction. The inclination direction of the belt cords 58 included in the first belt ply 56A (hereinafter referred to as the inclination direction of the first belt cords 58A) is the same as the inclination direction of the belt cords 58 included in the second belt ply 56B (hereinafter referred to as the inclination direction of the second belt cords 58B). The inclination direction of the second belt cord 58B is opposite to the inclination direction of the belt cord 58 included in the third belt ply 56C (hereinafter referred to as the inclination direction of the third belt cord 58C). The inclination direction of the third belt cord 58C is the same as the inclination direction of the belt cord 58 included in the fourth belt ply 56D (hereinafter referred to as the inclination direction of the fourth belt cord 58D). The inclination direction of the first belt cord 58A may be opposite to the inclination direction of the second belt cord 58B. The inclination direction of the third belt cord 58C may be opposite to the inclination direction of the fourth belt cord 58D.

[0079] In Fig. 3, angle θ1 is the angle formed by the belt cords 58 of the first belt ply 56A with respect to the equatorial plane (hereinafter referred to as the inclination angle θ1 of the first belt cords 58A). Angle θ2 is the angle formed by the belt cords 58 of the second belt ply 56B with respect to the equatorial plane (hereinafter referred to as the inclination angle θ2 of the second belt cords 58B). Angle θ3 is the angle formed by the belt cords 58 of the third belt ply 56C with respect to the equatorial plane (hereinafter referred to as the inclination angle θ3 of the third belt cords 58C). Angle θ4 is the angle formed by the belt cords 58 of the fourth belt ply 56D with respect to the equatorial plane (hereinafter referred to as the inclination angle θ4 of the fourth belt cords 58D).

[0080] The inclination angle θ1 of the first belt cord 58A, the inclination angle θ2 of the second belt cord 58B, the inclination angle θ3 of the third belt cord 58C, and the inclination angle θ4 of the fourth belt cord 58D are preferably 10 degrees or more and 60 degrees or less. From the viewpoint of effectively restricting the movement of the tread portion T and obtaining a stable ground contact patch with minimal shape change, the inclination angle θ1 of the first belt cord 58A is more preferably 40 degrees or greater and 60 degrees or less. The inclination angle θ2 of the second belt cord 58B is more preferably 15 degrees or greater and 30 degrees or less, and even more preferably 15 degrees or greater and 20 degrees or less. The inclination angle θ3 of the third belt cord 58C is more preferably 15 degrees or greater and 30 degrees or less, and even more preferably 15 degrees or greater and 20 degrees or less. The inclination angle θ4 of the fourth belt cord 58D is more preferably 15 degrees or greater and 50 degrees or less.

[0081] As shown in FIG. 2 , the end 56Be of the second belt ply 56B and the end 56Ce of the third belt ply 56C are each covered with a rubber layer 62. Three more rubber layers 62 are disposed between the end 56Be of the second belt ply 56B and the end 56Ce of the third belt ply 56C, which are covered with the rubber layer 62. In the tire 2, an edge member 64 made of a total of five rubber layers 62 is configured between the end 56Be of the second belt ply 56B and the end 56Ce of the third belt ply 56C. The edge member 64 is made of crosslinked rubber. The edge member 64 contributes to maintaining the distance between the end 56Be of the second belt ply 56B and the end 56Ce of the third belt ply 56C. In the tire 2, change in the positional relationship between the end 56Be of the second belt ply 56B and the end 56Ce of the third belt ply 56C due to running is suppressed. The edge member 64 is part of the reinforcing layer 20. The reinforcing layer 20 of the tire 2 includes a pair of edge members 64 in addition to the belt 52 and the band 54 .

[0082] The band 54 includes a full band 66 and a pair of edge bands 68. The band 54 may be configured with only the full band 66 without providing the pair of edge bands 68.

[0083] The full band 66 is disposed such that both ends 66e thereof face each other across the equator plane. The ends 66e of the full band 66 are positioned axially outward of the shoulder circumferential grooves 34. The ends 66e of the full band 66 are positioned axially inward of the ends 52e of the belt 52. 1 is the axial width of the full band 66. The axial width WF of the full band 66 is the axial distance from one end 66e of the full band 66 to the other end 66e. In the tire 2, from the viewpoint of ensuring the rigidity of the tread portion T, the ratio (WF / WT) of the axial width WF of the full band 66 to the width WT of the tread surface 24 is preferably 0.70 or greater and 0.80 or less.

[0084] The pair of edge bands 68 are arranged axially spaced apart from each other across the equatorial plane. Each edge band 68 is located between the tread 4 and the full band 66. The edge bands 68 are located axially outward of the shoulder circumferential grooves 34. The edge band 68 is located radially outward from the end 66e of the full band 66. The inner end 68ue of the edge band 68 is located axially inward from the end 66e of the full band 66. The outer end 68se of the edge band 68 is located axially outward from the end 66e of the full band 66. The edge band 68 overlaps with the end 66e of the full band 66 in the radial direction. The outer end 68se of the edge band 68 is located axially inside the end 52e of the belt 52. As described above, the end 66e of the full band 66 is also located axially inside the end 52e of the belt 52. The end 52e of the belt 52 of this tire 2 is also the end 20e of the reinforcing layer 20.

[0085] As shown in Fig. 3, the full band 66 and the edge band 68 that make up the band 54 each include a spirally wound band cord 70. In Fig. 3, for ease of explanation, the band cord 70 is represented by a solid line, but the band cord 70 is covered with a band topping rubber 72.

[0086] The band cords 70 of this tire 2 are steel cords. Cords made of organic fibers (hereinafter referred to as organic fiber cords) may be used as the band cords 70. In this case, examples of the organic fibers include nylon fibers, polyester fibers, rayon fibers, and aramid fibers. The band cords 70F of the full band 66 and the band cords 70E of the edge band 68 may be the same cords or different cords. The band cords 70 used for the full band 66 and the edge band 68 are determined depending on the specifications of the tire 2.

[0087] As described above, the full band 66 includes the spirally wound band cord 70F. The full band 66 has a jointless structure. In the full band 66, the angle that the band cord 70F makes with the circumferential direction is preferably 5 degrees or less, more preferably 2 degrees or less. The band cord 70F extends substantially in the circumferential direction.

[0088] As described above, the edge band 68 includes a spirally wound band cord 70E. The edge band 68 has a jointless structure. In the edge band 68, the angle that the band cord 70E forms with the circumferential direction is preferably 5 degrees or less, and more preferably 2 degrees or less. The band cord 70E of the edge band 68 extends substantially in the circumferential direction.

[0089] The edge band 68 is located axially outward of the fourth belt ply 56D. In the tire 2, an inner end 64ue of the edge band 68 abuts against the end 56De of the fourth belt ply 56D. The edge band 68 is located radially outward of the third belt ply 56C. A narrow buffer layer, which will be described later, is located between the edge band 68 and the third belt ply 56C.

[0090] The full band 66 of the tire 2 is located between the second belt ply 56B and the third belt ply 56C. The second belt ply 56B is located radially inside the full band 66, and the third belt ply 56C is located radially outside the full band 66. As described above, the inclination direction of the belt cords 58 included in the second belt ply 56B is opposite to the inclination direction of the belt cords 58 included in the third belt ply 56C. The full band 66 is located between two belt plies 56 in which the belt cords 58 are inclined in opposite directions.

[0091] In the present invention, when a full band is positioned between two belt plies whose belt cords have inclination directions opposite to each other, the belt ply positioned radially inside the full band is called an inner belt ply, and the belt ply positioned radially inside the full band is called an outer belt ply.

[0092] In the tire 2, the full band 66 is located between the second belt ply 56B and the third belt ply 56C, and the inclination direction of the belt cords 58 included in the second belt ply 56B is opposite to the inclination direction of the belt cords 58 included in the third belt ply 56C. The second belt ply 56B is the inner belt ply 74, and the third belt ply 56C is the outer belt ply 76. If the full band 66 is located between the first belt ply 56A and the second belt ply 56B and the inclination direction of the belt cords 58 included in the first belt ply 56A is opposite to the inclination direction of the belt cords 58 included in the second belt ply 56B, the first belt ply 56A is the inner belt ply and the second belt ply 56B is the outer belt ply. If the full band 66 is located between the third belt ply 56C and the fourth belt ply 56D and the inclination direction of the belt cords 58 included in the third belt ply 56C is opposite to the inclination direction of the belt cords 58 included in the fourth belt ply 56D, the third belt ply 56C is the inner belt ply and the fourth belt ply 56D is the outer belt ply.

[0093] The belt 52 of the tire 2 includes an inner belt ply 74 and an outer belt ply 76 that are aligned in the radial direction, and the inclination direction of the belt cords 58 included in the inner belt ply 74 is opposite to the inclination direction of the belt cords 58 included in the outer belt ply 76. The band 54 includes a full band 66. The full band 66 is located between the inner belt ply 74 and the outer belt ply 76. An end 74 e of the inner belt ply 74, an end 76 e of the outer belt ply 76, and an end 66 e of the full band 66 are located axially outside the shoulder circumferential groove 34.

[0094] 2, the end 74e of the inner belt ply 74 is located axially outward of the end 66e of the full band 66. The end 76e of the outer belt ply 76 is also located axially outward of the end 66e of the full band 66. The inner belt ply 74 and the outer belt ply 76 have an axial width that is wider than the axial width WF of the full band 66.

[0095] As described above, the band cord 70F of the full band 66 extends substantially in the circumferential direction. The full band 66 suppresses dimensional growth due to the effects of tire internal pressure and centrifugal force. The full band 66 suppresses changes in profile and ground contact shape. The full band 66 can contribute to improving the uneven wear resistance of the tire 2.

[0096] An inner belt ply 74 and an outer belt ply 76 are positioned on both sides of the full band 66 in the radial direction. The inner belt ply 74 and the outer belt ply 76 suppress the force acting on the full band 66. The inclination direction of the belt cords 58 included in the inner belt ply 74 and the inclination direction of the belt cords 58 included in the outer belt ply 76 are opposite to each other, so the force acting on the full band 66 is effectively suppressed. Fluctuations in tension generated in the band cords 70F of the full band 66 are suppressed to a small level, so the full band 66 can stably perform its function.

[0097] The full band 66 of this tire 2 can effectively contribute to suppressing dimensional growth. This tire 2 can suppress changes in profile and contact shape. This tire 2 has improved uneven wear resistance.

[0098] As described above, the inner belt ply 74 is the second belt ply 56B having the widest axial width among the belt plies 56 constituting the belt 52. From the viewpoint of improving uneven wear resistance, when the belt 52 is composed of a plurality of belt plies 56 arranged in the radial direction, it is preferable that the belt ply 56 having the widest axial width among the plurality of belt plies 56 constituting the belt 52 is the inner belt ply 74.

[0099] As described above, the carcass of a tire in a running state tends to expand outward due to the action of internal pressure and centrifugal force. When a full band is laminated on a belt ply, the distance between the full band and the belt ply, in other words, the distance between the band cords and the belt cords, is expected to gradually decrease. In particular, when a full band is sandwiched between two belt plies arranged radially, the distance between the band cords of the full band and the belt cords of the belt ply located inside the full band is expected to decrease significantly compared to the distance between the band cords and the belt cords of the belt ply located outside the full band. In high aspect ratio tires, the effect of internal tire pressure is stronger in the crown portion and weaker in the shoulder portion, which promotes dimensional growth in the crown portion. In high aspect ratio tires, the distance between the band cord and the belt cord in the crown portion decreases, which is expected to increase the strain generated between the band cord and the belt cord. If the distance between the band cord and the belt cord is insufficient, the band cord and the belt cord will come into contact with each other, and depending on the degree of contact, the adhesive strength between the full band and the belt ply may be reduced, or the strength of the band cord or the belt cord may be reduced. A reduction in adhesive strength or a reduction in cord strength affects the durability of the tire.

[0100] 2, the length indicated by the double arrow UFc is the distance on the equatorial plane between the full band 66 and the inner belt ply 74. The distance UFc is expressed as the distance between the band cord 70F of the full band 66 and the belt cord 58 of the inner belt ply 74. The length indicated by the double arrow SFc is the distance on the equatorial plane between the full band 66 and the outer belt ply 76. The distance SFc is expressed as the distance between the band cord 70F of the full band 66 and the belt cord 58 of the outer belt ply 76. The length indicated by the double arrow UFs is the distance between the full band 66 and the inner belt ply 74 at the end 66e of the full band 66. The distance UFs is expressed as the distance between the band cord 70F closest to the end 66e of the full band 66 and the belt cord 58 of the inner belt ply 74. The length indicated by the double arrow SFs is the distance between the full band 66 and the outer belt ply 76 at the end 66e of the full band 66. The distance SFc is expressed as the distance between the band cord 70F closest to the end 66e of the full band 66 and the belt cord 58 of the outer belt ply 76. The distances UFc, SFc, UFs, and SFs are all inter-cord distances. These are the thicknesses of the rubber components located between the band cord 70F and the belt cord 58. The distance SFs is approximately the same as the distance SFc. In other words, the ratio of the distance SFs to the distance SFc (SFs / SFc) is equal to or greater than 0.95 and equal to or less than 1.05.

[0101] In the tire 2, the distance UFc between the full band 66 and the inner belt ply 74 is longer than the distance SFc between the full band 66 and the outer belt ply 76 on the equatorial plane. As described above, dimensional growth is promoted in the crown portion of a high aspect ratio tire. In the crown portion, the distance between the full band 66 and the inner belt ply 74 located inside the full band 66 is long. This prevents contact between the band cords 70F and the belt cords 58 in the crown portion. This prevents a decrease in the adhesive strength between the full band 66 and the inner belt ply 74 and a decrease in the strength of the band cords 70F or the belt cords 58 due to contact between the band cords 70F and the belt cords 58. This tire 2 can maintain good durability. The tire 2 can suppress a decrease in durability due to the provision of the band 54, and can achieve an improvement in uneven wear resistance.

[0102] In the tire 2, the distance UFc between the full band 66 and the inner belt ply 74 at the equatorial plane is set to 0.6 mm or more. As a result, in the tire 2, the band cord 70F and the belt cord 58 are disposed with a sufficient gap between them in the crown portion. Distortion occurring between the band cord 70F and the belt cord 58 is reduced. In the tire 2, contact between the band cord 70F and the belt cord 58 can be suppressed. The tire 2 can maintain good durability. From this viewpoint, the distance UFc is preferably 0.6 mm or more, and more preferably 0.8 mm or more. If the amount of rubber component positioned between the band cord 70F and the belt cord 58 is large, heat generation due to repeated deformation is promoted, which may result in an increase in the rolling resistance of the tire 2. From the viewpoint of suppressing an increase in rolling resistance, the distance UFc is preferably 3.0 mm or less.

[0103] The distance UFs between the full band 66 and the inner belt ply 74 at the end 66e of the full band 66 is preferably 2.5 mm or less. This makes it possible to suppress an increase in rolling resistance in the tire 2. From this viewpoint, the distance UFs is more preferably 2.0 mm or less. From the viewpoint of suppressing contact between the band cord 70F and the belt cord 58, the distance UFs is preferably 0.5 mm or more, and more preferably 0.8 mm or more.

[0104] As described above, the tire 2 is a high aspect tire. In the tire 2, strain occurring between the band cord 70F of the full band 66 and the belt cord 58 of the inner belt ply 74 tends to concentrate in the crown portion. However, in the tire 2, the distance UFc between the full band 66 and the inner belt ply 74 at the equatorial plane of the tire 2 is set to be longer than the distance UFs between the full band 66 and the inner belt ply 74 at the end 66e of the full band 66. The tire 2 can reduce distortion occurring between the band cords 70F of the full band 66 and the belt cords 58 of the inner belt ply 74 in the crown portion. The tire 2 can suppress contact between the band cords 70F and the belt cords 58. The tire 2 can maintain good durability. From this viewpoint, it is preferable that the distance UFc between the full band 66 and the inner belt ply 74 at the equatorial plane of the tire 2 be longer than the distance UFs between the full band 66 and the inner belt ply 74 at the end 66e of the full band 66. Specifically, the ratio (UFc / UFs) of the distance UFc to the distance UFs is preferably 1.05 or greater, and more preferably 1.10 or greater. From the viewpoint of suppressing heat generation in the rubber component located between the band cord 70F and the belt cord 58 and maintaining low rolling resistance, the ratio (UFc / UFs) is preferably 1.50 or less.

[0105] At the equatorial plane of the tire 2, the ratio (UFc / SFc) of the distance UFc between the full band 66 and the inner belt ply 74 to the distance SFc between the full band 66 and the outer belt ply 76 is preferably 2.0 or greater. This effectively suppresses contact between the band cord 70F and the belt cord 58. The tire 2 has good durability. From this viewpoint, the ratio (UFc / SFc) is more preferably 2.5 or greater. From the viewpoint of suppressing heat generation of the rubber component positioned between the band cord 70F and the belt cord 58 and maintaining low rolling resistance, the ratio (UFc / SFc) is preferably 3.0 or less.

[0106] In this tire 2, the distance between the band cord 70 and the belt cord 58 is controlled. The distance between the band cord 70 and the belt cord 58 is controlled by adjusting the thickness of the band topping 72 and the belt topping rubber 60, but when a relatively long distance is set, such as the distance between the full band 66 and the inner belt ply 74 of this tire 2, the distance between the band cord 70 and the belt cord 58 is preferably controlled using a buffer layer 78 made of crosslinked rubber, from the viewpoint of being able to precisely control the distance. In other words, the reinforcing layer 20 of this tire 2 preferably includes a buffer layer 78 made of crosslinked rubber.

[0107] The buffer layer 78 of the tire 2 includes a wide buffer layer 80 and a pair of narrow buffer layers 82 . The wide buffer layer 80 is positioned between the full band 66 and the inner belt ply 74. An end 80e of the wide buffer layer 80 is positioned axially between the end 66e of the full band 66 and the end 74e of the inner belt ply 74. The full band 66 is entirely laminated on the wide buffer layer 80. The wide buffer layer 80 is used to control the distance between the full band 66 and the inner belt ply 74, specifically, the above-mentioned UFc and distance UFs. Each narrow cushioning layer 82 is positioned between the edge band 68 and the outer belt ply 76. The inner end 82ue of the narrow cushioning layer 82 is positioned axially inward of the inner end 68ue of the edge band 68. The outer end 82se of the narrow cushioning layer 82 is positioned axially outward of the outer end 68se of the edge band 68. The entire edge band 68 is laminated on the narrow cushioning layer 82. The narrow cushioning layer 82 is used to control the distance between the edge band 68 and the outer belt ply 76.

[0108] As described above, the buffer layer 78 is made of cross-linked rubber. From the viewpoint that each of the wide buffer layer 80 and the narrow buffer layer 82 can contribute to reducing distortion and suppressing heat generation that occurs between the band cord 70 and the belt cord 58, the stress M at 200% elongation of the buffer layer 78 and the loss tangent LT at 70°C of the buffer layer 78 are controlled. Specifically, the ratio (M / LT) of the stress M at 200% elongation of the buffer layer 78 to the loss tangent LT at 70°C is preferably 75 or greater. This results in a buffer layer 78 that is less susceptible to distortion and heat generation. This buffer layer 78 can contribute to suppressing a decrease in durability and an increase in rolling resistance. From this perspective, the ratio (M / LT) is more preferably 80 or greater, and even more preferably 100 or greater. The higher the ratio (M / T), the better, so no upper limit is set. The ratio (M / T) is calculated using the stress M at 200% elongation in MPa (megapascals).

[0109] In this tire 2, from the viewpoint of configuring a buffer layer 78 having appropriate rigidity, the stress M at 200% elongation of the buffer layer 78 is preferably 11 MPa or more. From the viewpoint of appropriately maintaining the difference in rigidity between the buffer layer 78 and other rubber components positioned around it and suppressing a decrease in adhesive strength due to the difference in rigidity, the stress M at 200% elongation is preferably 15 MPa or less.

[0110] The cord density of the full band 66 is preferably 22 ends / 50 mm or more. This increases the restraining force of the full band 66. The full band 66 of the tire 2 can effectively restrain the inner belt ply 74. Movement of the inner belt ply 74 in the crown portion is suppressed. Distortion occurring between the band cord 70F and the belt cord 58 in the crown portion is reduced. Contact between the band cord 70F and the belt cord 58 is suppressed. The tire 2 can maintain good durability. From this viewpoint, the cord density of the full band 66 is more preferably 24 ends / 50 mm or more. From the viewpoint of effectively suppressing the effect of the full band 66 on the rigidity of the tread portion T, the cord density of the full band 66 is preferably 35 ends / 50 mm or less. Note that the density of the band cord 70E in the edge band 68 is preferably 20 ends / 50 mm or more and 35 ends / 50 mm or less.

[0111] In the present invention, the cord density of the full band 66 is represented by the number of cross sections of the band cords 70F included per 50 mm width of the full band 66 in the cross section of the full band 66 included in the meridian cross section of the tire 2. The cord density of the edge band 68 is also obtained in the same manner as the cord density of the full band 66.

[0112] The ratio of the cord density of the inner belt ply 74 to the cord density of the full band 66 is preferably 0.65 or more. This effectively suppresses dimensional growth in the crown portion. Contact between the band cords 70F and the belt cords 58 is effectively suppressed. The tire 2 can maintain good durability. From this viewpoint, the ratio of the cord density of the inner belt ply 74 to the cord density of the full band 66 is more preferably 0.75 or more. From the viewpoint of effectively suppressing the influence of the inner belt ply 74 on the rigidity of the tread portion T, this ratio is preferably 0.95 or less.

[0113] The cord density of the inner belt ply 74 is preferably greater than the cord density of the outer belt ply 76. This increases the resistance of the inner belt ply 74, which is susceptible to the dimensional growth of the carcass 12, to the dimensional growth of the carcass 12. Distortion occurring between the band cords 70F and the belt cords 58 of the inner belt ply 74 is effectively reduced. The tire 2 can maintain good durability. From this viewpoint, the ratio of the cord density of the inner belt ply 74 to the cord density of the outer belt ply 76 is more preferably 1.05 or more. From the viewpoint of effectively suppressing the effect of the inner belt ply 74 on the rigidity of the tread portion T, this ratio is more preferably 1.50 or less.

[0114] In Fig. 3, the angle indicated by the symbol FU is the angle formed between the band cord 70F of the full band 66 and the belt cord 58 of the inner belt ply 74. The angle indicated by the symbol FS is the angle formed between the band cord 70F of the full band 66 and the belt cord 58 of the outer belt ply 76.

[0115] The angle FU formed between the band cord 70F of the full band 66 and the belt cord 58 of the inner belt ply 74 is preferably equal to or greater than 10 degrees and equal to or less than 25 degrees. This effectively reduces distortion occurring between the band cord 70F and the belt cord 58. Contact between the band cord 70F and the belt cord 58 is effectively suppressed. The tire 2 can maintain good durability. From this viewpoint, the angle FU is more preferably equal to or greater than 15 degrees and equal to or less than 20 degrees.

[0116] The angle FS formed between the band cord 70F of the full band 66 and the belt cord 58 of the outer belt ply 76 is preferably 10 degrees or greater and 25 degrees or less. This effectively reduces distortion occurring between the band cord 70F and the belt cord 58. Contact between the band cord 70F and the belt cord 58 is effectively suppressed. The tire 2 can maintain good durability. From this viewpoint, the angle FS is more preferably 15 degrees or greater and 20 degrees or less.

[0117] From the viewpoint of maintaining good durability, it is more preferable that the angle FU is 10 degrees or more and 25 degrees or less, and the angle FS is 10 degrees or more and 25 degrees or less.

[0118] 3, the angle indicated by the symbol UE is the angle formed by the belt cords 58 of the inner belt ply 74 with respect to the equatorial plane. As described above, the second belt ply 56B of the tire 2 is the inner belt ply 74. This angle UE coincides with the inclination angle θ2 of the belt cords of the second belt ply 56B. The angle indicated by the symbol SE is the angle formed by the belt cords 58 of the outer belt ply 76 with respect to the equatorial plane. As described above, the third belt ply 56C of the tire 2 is the outer belt ply 76. This angle SE coincides with the inclination angle θ3 of the belt cords of the third belt ply 56C.

[0119] The angle UE that the belt cords 58 of the inner belt ply 74 make with respect to the equatorial plane is preferably smaller than the angle SE that the belt cords 58 of the outer belt ply 76 make with respect to the equatorial plane. This increases the resistance of the inner belt ply 74, which is susceptible to the dimensional growth of the carcass 12, to the dimensional growth of the carcass 12. Distortion occurring between the band cords 70F and the belt cords 58 of the inner belt ply 74 is effectively reduced. The tire 2 can maintain good durability. From this viewpoint, it is more preferable that the difference (SE-UE) between the angle SE and the angle UE is 1 degree or greater and 15 degrees or less.

[0120] In this tire 2, a relatively long distance is set between the full band 66 and the inner belt ply 74. This increases the volume of the tread portion T. The increase in volume increases the amount of heat generated in the tread portion T. A thin tread 4 may be employed to suppress an increase in rolling resistance. In this case, the groove depth of the circumferential grooves 32 provided in the tread 4 is preferably 14 mm or less. If the specifications of the tire 2 do not allow the use of a thin tread 4, the cap portion 28 is preferably made of a cross-linked rubber having a loss tangent of 0.06 or less at 70°C.

[0121] 4 is a development view showing a part of the tread 4. FIG. 4 shows a part of the tread surface 24, specifically, a part of the land surface 42s of the center land portion 42.

[0122] In the tire 2, the center land portion 42 may be provided with a transverse sipe 84 that crosses the center land portion 42. The transverse sipe 84 may also be provided in a land portion 38 other than the center land portion 42 (for example, the middle land portion 44). The transverse sipes 84 of the tire 2 extend in the axial direction. The transverse sipes 84 may extend inclined relative to the axial direction. The transverse sipe 84 connects between one center circumferential groove 36 and the other center circumferential groove 36. In other words, the transverse sipe 84 connects between the two circumferential grooves 32. Although not shown, the center land portion 42 has a plurality of transverse sipes 84. The transverse sipes 84 are aligned in the circumferential direction. The transverse sipes 84 are arranged at predetermined intervals.

[0123] 5 shows a cross section of the transverse sipe 84. The cross section of the transverse sipe 84 shown in FIG. 5 is a cross section of the transverse sipe 84 taken along a plane perpendicular to the longitudinal direction of the transverse sipe 84.

[0124] The transverse sipe 84 has a sipe body 86 and a tubular portion 88. The sipe body 86 includes a groove mouth 84M of the transverse sipe 84. The tubular portion 88 includes a groove bottom 84T of the transverse sipe 84.

[0125] As shown in Fig. 4, the sipe body 86 extends straight in the length direction of the transverse sipe 84. As shown in Fig. 5, the sipe body 86 extends straight in the depth direction of the transverse sipe 84. The length indicated by the double arrow Wp in Fig. 5 is the groove width of the sipe body 86. The sipe body 86 has a uniform groove width Wp in its depth direction. The tubular portion 88 is located radially inward of the sipe body 86. The tubular portion 88 extends in the length direction of the transverse sipe 84.

[0126] 5, a solid line LF is a boundary line between the sipe main body 86 and the tubular portion 88. The length indicated by the double-headed arrow WF is the groove width of the transverse sipe 84 measured along this boundary line LF. The boundary line LF is set at a position where the groove width WF is 1.0 mm. The groove width Wp of the outer portion of the boundary line LF, i.e., the sipe main body 86, is less than 1.0 mm. The groove width Wp of the inner portion of this boundary line LF, i.e., the tubular portion 88, is 1.0 mm or more. The groove width of the tubular portion 88 is wider than the groove width of the sipe main body 86.

[0127] The tubular portion 88 extends inward from the position of the boundary line LF. The length indicated by the double arrow WX in FIG. 5 is the maximum groove width of the tubular portion 88. The position indicated by the symbol PX in FIG. 5 is the position where the tubular portion 88 shows the maximum groove width WX (hereinafter referred to as the maximum groove width position PX). The tubular portion 74 tapers outward from the portion showing the maximum groove width WX. The tubular portion 88 tapers inward from the portion showing the maximum groove width WX.

[0128] The cross-sectional shape of the tubular portion 88 may be circular or elliptical. The tubular portion 88 may have a shape in which the portion showing the maximum groove width WX is represented by a straight line and the sipe body 86 side and the groove bottom 84T side of the straight line portion are represented by arcs, that is, a track-like cross-sectional shape.

[0129] Lateral grooves are grooves cut into the tread of a tire to improve wet performance. Lateral grooves are grooves cut into the land portion so that they cross the land portion. Lateral grooves usually have a wide groove width, so that the pair of wall surfaces do not come into contact with each other when the tire comes into contact with the road surface. Lateral grooves can contribute to improving wet performance, but they also reduce the rigidity of the land portion. As mentioned above, high aspect ratio tires promote dimensional growth in the crown portion. If lateral grooves are provided in the center land portion 42, for example, to improve wet performance, there is a risk that the tire 2 will not be able to sufficiently suppress dimensional growth, even though a full band 66 is provided to suppress dimensional growth.

[0130] However, when a transverse sipe 84 is provided in the center land portion 42, the sipe body 86 can function as an edge component. The sipe body 88 can contribute to improving wet performance. As mentioned above, the groove width Wp of the sipe body 86 is less than 1.0 mm. When a load acts on the center land portion 42 and the center land portion 42 deforms, the pair of wall surfaces 84W of the transverse sipe 84 come into contact at the sipe body 86 and support each other. This suppresses deformation of the center land portion 42. This contributes to improving uneven wear resistance.

[0131] By providing the transverse sipes 84 instead of lateral grooves in the center land portion 42, the tire 2 can improve wet performance while suppressing a decrease in rigidity of the center land portion 42. Since a decrease in rigidity of the center land portion 42 is suppressed, the full band 66 can fully demonstrate its function. The tire 2 can suppress a decrease in durability due to the provision of the band 54, and can achieve an improvement in uneven wear resistance.

[0132] The tread 4 of the tire 2 wears. As a result, the deformation allowance of the tread 4 decreases, and the rigidity of the tread 4 appears to increase. This increase in rigidity reduces wet performance. There is also concern that the wear of the tread 4 will reduce the wet performance of the tire 2.

[0133] However, the transverse sipes 84 of this tire 2 have a tubular portion 88 radially inward of the sipe body 86. The tubular portion 88 is exposed when the sipe body 86 disappears. The tubular portion 88 has a wide groove width. After the sipe body 86 disappears, the tubular portion 88 can contribute to maintaining wet performance. This tire 2 maintains good wet performance until it wears down and requires tire replacement. The tire 2 can suppress deterioration of wet performance due to wear while suppressing dimensional growth in the crown portion. The tire 2 can maintain good wet performance while suppressing deterioration of durability and improving uneven wear resistance. From this viewpoint, it is preferable that the center land portion 42 has a transverse sipe 84 that crosses the center land portion 42, the transverse sipe 84 has a sipe main body 86 and a tubular portion 88 located radially inward of the sipe main body 86, and the tubular portion 88 has a groove width wider than the groove width of the sipe main body 86.

[0134] The maximum groove width WX of the tubular portion 88 is preferably four times or more, and more preferably five times or more, the groove width Wp of the sipe main body 86. This allows the tubular portion 88 to contribute to maintaining wet performance. The maximum groove width WX of the tubular portion 88 is preferably 13 times or less, and more preferably 12 times or less, the groove width Wp of the sipe main body 86. This allows the size of the tubular portion 88 to be maintained appropriately. A decrease in rigidity of the center land zone 42 is suppressed.

[0135] As described above, the tubular portion 88 has a bottom surface that includes the groove bottom 84T of the transverse sipe 84. In the cross section shown in Figure 5, the contour of the bottom surface of the tubular portion 88 is represented by an arc that passes through the groove bottom 84T. The arrow Rb in Figure 5 indicates the radius of this arc.

[0136] The radius Rb of the arc that defines the contour of the bottom surface of the tubular portion 88 is preferably 1.5 mm or more and 3.5 mm or less. Setting the radius Rb to 1.5 mm or greater effectively suppresses the occurrence of cracks at the groove bottom 84T. From this viewpoint, it is more preferable that the radius Rb be 2.0 mm or greater. By setting the radius Rb to 3.5 mm or less, a decrease in the rigidity of the center land portion 42 caused by providing the tubular portion 88 in the transverse sipe 84 is suppressed. The rigidity of the center land portion 42 is appropriately maintained. The tire 2 can improve uneven wear resistance. From this viewpoint, it is more preferable that the radius Rb be 3.0 mm or less.

[0137] 5, the length indicated by the double arrow DA is the groove depth of the transverse sipe 84. The length indicated by the double arrow DC is the groove depth of the sipe main body 86. In the tire 2, the groove depth DA of the transverse sipes 84 is the same as the groove depth of the center circumferential groove 36, or the transverse sipes 84 are shallower than the center circumferential groove 36. Specifically, the groove depth DA of the transverse sipes 84 is 0.80 to 1.00 times the groove depth of the center circumferential groove 36.

[0138] The ratio (DC / DA) of the groove depth DC of the sipe body 86 of the transverse sipe 84 to the groove depth DA of the transverse sipe 84 is preferably 0.35 or greater and 0.80 or less. By setting the ratio (DC / DA) to 0.35 or greater, the tire 2 can expose the tubular portion 88 at an appropriate timing. The tire 2 can promote wear of the tread 4 while maintaining the rigidity of the center land portion 42. The tire 2 can maintain good uneven wear resistance. From this viewpoint, the ratio (DC / DA) is more preferably 0.40 or greater. By setting the ratio (DC / DA) to 0.80 or less, the tubular portion 88 can contribute to maintaining wet performance after the sipe main body 86 disappears. From this viewpoint, the ratio (DC / DA) is more preferably 0.75 or less.

[0139] 6 shows a modified example of a transverse sipe 84. In this transverse sipe 84, the configuration of a sipe body 86 is different from that of the transverse sipe 84 shown in FIG. The sipe body 86 of this transverse sipe 84 extends in a zigzag pattern in the depth direction. Although not shown, this sipe body 86 also extends in a zigzag pattern in the length direction. This sipe body 86 extends in a zigzag pattern in both the length direction and the depth direction. The zigzag amplitude is preferably, for example, 0.5 mm or more and 3.0 mm or less. This sipe body 86 is a three-dimensional sipe. The sipe body 86 shown in FIG. 5 is also called a two-dimensional sipe.

[0140] In this transverse sipe 84, the wall surfaces 84W also come into contact with each other and support each other when the tire 2 is running. Because the sipe body 86 is a three-dimensional sipe, when the tread 4 deforms and the wall surfaces 84W of the sipe body 86 come into close contact with each other, the wall surfaces 84W constrain each other, effectively increasing the rigidity of the center land portion 42. This tire 2 can improve wet performance while suppressing a decrease in rigidity of the center land portion 42. This tire 2 can suppress a decrease in durability due to the provision of the band 54 and achieve improved uneven wear resistance. From this perspective, when a transverse sipe 84 is provided in the center land portion 42, it is preferable that the sipe body 86 of the transverse sipe 84 extend in a zigzag pattern in the length direction and depth direction.

[0141] As is clear from the above explanation, a heavy duty tire can be obtained that can suppress the decrease in durability caused by the provision of the band and achieve an improvement in uneven wear resistance. [Industrial Applicability]

[0142] The technology described above, which can suppress the decrease in durability caused by providing a band and can achieve an improvement in uneven wear resistance, can be applied to various types of tires.

[0143] [Note] The present invention includes the following aspects.

[0144] [1] A heavy-duty tire having a nominal aspect ratio of 70% or more, a pair of beads; a carcass that spans between the pair of beads; a reinforcing layer located radially outward of the carcass; a tread covering the reinforcing layer and coming into contact with the road surface; Equipped with The tread has a plurality of circumferential grooves extending continuously in the circumferential direction, the plurality of circumferential grooves include a shoulder circumferential groove located axially outermost, The reinforcing layer includes a belt including a large number of parallel belt cords and a band including a spirally wound band cord, the belt includes an inner belt ply and an outer belt ply arranged in a radial direction; the direction of inclination of the belt cords included in the inner belt ply is opposite to the direction of inclination of the belt cords included in the outer belt ply, the band comprises a full band positioned between the inner belt ply and the outer belt ply, ends of the inner belt ply, the outer belt ply, and the full band are located axially outside the shoulder circumferential groove, A heavy-duty tire, wherein a distance UFc between the full band and the inner belt ply is longer than a distance SFc between the full band and the outer belt ply at an equatorial plane of the tire. [2] The heavy-duty tire according to the above-mentioned [1], wherein a distance UFc between the full band and the inner belt ply at the equatorial plane of the tire is 0.6 mm or more. [3] A heavy-duty tire according to either of [1] or [2] above, wherein a distance UFs between the full band and the inner belt ply at an end of the full band is 2.5 mm or less. [4] A heavy-duty tire according to any one of [1] to [3] above, wherein a distance UFc between the full band and the inner belt ply at the equatorial plane of the tire is longer than a distance UFs between the full band and the inner belt ply at an end of the full band. [5] A heavy-duty tire according to any one of the above [1] to [4], wherein, at the equatorial plane of the tire, the ratio (UFc / SFc) of the distance UFc between the full band and the inner belt ply to the distance SFc between the full band and the outer belt ply is 2.0 or more. [6] The heavy-duty tire according to any one of [1] to [5] above, wherein the cord density of the full band is 22 ends / 50 mm or more. [7] The heavy-duty tire according to any one of [1] to [6] above, wherein the ratio of the cord density of the inner belt ply to the cord density of the full band is 0.65 or more. [8] An angle FU formed between the band cord of the full band and the belt cord of the inner belt ply is 10 degrees or more and 25 degrees or less, The heavy-duty tire according to any one of the above-mentioned [1] to [7], wherein an angle FS formed between the band cord of the full band and the belt cord of the outer belt ply is 10 degrees or more and 25 degrees or less. [9] A heavy-duty tire according to any one of the above [1] to [8], wherein an angle UE formed by the belt cords of the inner belt ply with respect to the equatorial plane of the tire is smaller than an angle SE formed by the belt cords of the outer belt ply with respect to the equatorial plane of the tire.

[10] The heavy-duty tire according to any one of [1] to [8] above, wherein the cord density of the inner belt ply is greater than the cord density of the outer belt ply.

[11] The plurality of circumferential grooves define a plurality of land portions arranged in the tread in the axial direction, Among the plurality of land portions, a land portion located on the equatorial plane of the tire or a land portion closest to the equatorial plane is a center land portion, The center land portion has a transverse sipe that crosses the center land portion, The transverse sipe has a sipe body and a tubular portion located radially inward of the sipe body, The heavy-duty tire according to any one of [1] to

[10] above, wherein the tubular portion has a groove width wider than the groove width of the sipe main body. [Explanation of symbols]

[0145] 2. Tires 4. Tread 8. Bead 12. Carcass 14. Cushion layer 20. Reinforcement layer 24 Tread surface 26 Base 28 Cap part 32, 34, 36...Circumferential groove 38, 40, 42, 44... Rikubu 50···Carcass ply 50a···Ply body 50b... Folded part 52 Belt 54...Band 56, 56A, 56B, 56C, 56D, 74, 76... Belt plies 58, 58A, 58B, 58C, 58D... Belt cord 64 Edge member 66...Full Band 68···Edge band 70, 70F, 70E... Band cord 78...buffer layer 80 Wide buffer layer 82...Narrow buffer layer 84 Transverse sipes 86···Sipe body 88...Tubular part

Claims

1. A heavy-duty tire having a nominal aspect ratio of 70% or more, a pair of beads; a carcass that spans between the pair of beads; a reinforcing layer located radially outward of the carcass; a tread covering the reinforcing layer and coming into contact with the road surface; Equipped with The tread has a plurality of circumferential grooves extending continuously in the circumferential direction, the plurality of circumferential grooves include a shoulder circumferential groove located axially outermost, The reinforcing layer includes a belt including a large number of parallel belt cords and a band including a spirally wound band cord, the belt includes an inner belt ply and an outer belt ply arranged in a radial direction; the direction of inclination of the belt cords included in the inner belt ply is opposite to the direction of inclination of the belt cords included in the outer belt ply, the band comprises a full band positioned between the inner belt ply and the outer belt ply, ends of the inner belt ply, the outer belt ply, and the full band are located axially outside the shoulder circumferential groove, a distance UFc between the full band and the inner belt ply at an equatorial plane of the tire is longer than a distance SFc between the full band and the outer belt ply; Heavy duty tires.

2. a distance UFc between the full band and the inner belt ply at the equatorial plane of the tire is 0.6 mm or more; 2. The heavy duty tire according to claim 1.

3. a distance UFs between the full band and the inner belt ply at an end of the full band is 2.5 mm or less; 3. A heavy duty tire according to claim 1 or 2.

4. a distance UFc between the full band and the inner belt ply at the equatorial plane of the tire is longer than a distance UFs between the full band and the inner belt ply at an end of the full band; 3. A heavy duty tire according to claim 1 or 2.

5. a ratio (UFc / SFc) of a distance UFc between the full band and the inner belt ply to a distance SFc between the full band and the outer belt ply at an equatorial plane of the tire is 2.0 or more; 3. A heavy duty tire according to claim 1 or 2.

6. The cord density of the full band is 22 ends / 50 mm or more.

3. A heavy duty tire according to claim 1 or 2.

7. a ratio of the cord density of the inner belt ply to the cord density of the full band is 0.65 or more; 3. A heavy duty tire according to claim 1 or 2.

8. an angle FU formed between the band cord of the full band and the belt cord of the inner belt ply is 10 degrees or more and 25 degrees or less; an angle FS formed between the band cord of the full band and the belt cord of the outer belt ply is 10 degrees or more and 25 degrees or less; 3. A heavy duty tire according to claim 1 or 2.

9. an angle UE formed by the belt cord of the inner belt ply with respect to the equatorial plane of the tire is smaller than an angle SE formed by the belt cord of the outer belt ply with respect to the equatorial plane of the tire; 3. A heavy duty tire according to claim 1 or 2.

10. The cord density of the inner belt ply is greater than the cord density of the outer belt ply.

3. A heavy duty tire according to claim 1 or 2.

11. The plurality of circumferential grooves define a plurality of land portions arranged in the tread in the axial direction, Among the plurality of land portions, a land portion located on the equatorial plane of the tire or a land portion closest to the equatorial plane is a center land portion, The center land portion has a transverse sipe that crosses the center land portion, The transverse sipe has a sipe body and a tubular portion located radially inward of the sipe body, The tubular portion has a groove width wider than the groove width of the sipe body.

3. A heavy duty tire according to claim 1 or 2.

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