tire

Abstract

To provide a tire which can achieve comfort of the riding and low fuel consumption when a vehicle travels at high speed.SOLUTION: A tire 1 has a belt layer 7 and a band layer 9. The belt layer 7 includes at least one belt ply 7A. The belt ply 7A includes a belt cord 7a formed by a steel single line. The band layer 9 includes at least one band ply 9A. The band ply 9A includes a band cord 9a which is formed by organic fibers and disposed at an angle of 5° or lower with respect to a tire circumferential direction. A diameter d1 as seen in a tire radial direction a of the band cord 9a is 0.70 mm or larger.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire having a belt layer and a band layer. [Background technology]

[0002] Conventionally, tires having a belt layer and a band layer on the radially inner side of the tread portion are known. For example, the following Patent Document 1 proposes a tire in which a belt made of two or more layers contains cords, and the gauge between the cords of two adjacent layers is specified, thereby achieving both noise performance and low fuel consumption performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-177838 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in recent years, with improvements in vehicle performance and the development of infrastructure such as expressways, further improvements in ride comfort during high-speed driving and fuel efficiency have been desired even for the tire of Patent Document 1.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire that can achieve both ride comfort during high-speed driving and low fuel consumption. [Means for solving the problem]

[0006] The present invention is a tire having a belt layer and a band layer, the belt layer including at least one belt ply, the belt ply including a belt cord made of a steel solid wire, the band layer including at least one band ply, the band ply including a band cord made of organic fiber and arranged at an angle of 5° or less with respect to the tire circumferential direction, and the band cord having a diameter in the tire radial direction of 0.70 mm or more.

[0007] In the tire of the present invention, it is preferable that the band cord has a radial diameter of 1.00 mm or less.

[0008] In the tire of the present invention, the band cord is preferably a hybrid cord in which a first material and a second material different from the first material are twisted together.

[0009] In the tire of the present invention, it is preferable that the band cord includes a first cord made of a first material and a second cord made of a second material different from the first material.

[0010] In the tire of the present invention, it is preferable that the first material is a heat-shrinkable material and the second material is a non-heat-shrinkable material.

[0011] In the tire of the invention, the modulus of said second material is preferably different from the modulus of said first material.

[0012] In the tire of the present invention, it is preferable that the first material is nylon and the second material is aramid.

[0013] In the tire of the present invention, it is preferable that the band ply has 35 to 65 band cords arranged per 5 cm of ply width.

[0014] In the tire of the present invention, in the band ply, it is desirable that the product of the diameter (mm) of the band cord, the number of the band cords arranged per 5 cm of ply width (pieces), and the distance (mm) from the outer surface of the tread portion at the tire equator to the band ply is 150 or more.

[0015] In the tire of the present invention, it is desirable that the band cord has an elongation of 2.5% or more under a load of 66 N.

[0016] In the tire of the present invention, it is desirable that the band cord has an elongation of 7.0% or less when subjected to a load of 198 N.

[0017] In the tire of the present invention, it is preferable that the belt cord has a diameter in the radial direction of the tire of 0.16 to 0.50 mm.

[0018] In the tire of the present invention, it is preferable that the belt ply has 55 to 150 belt cords arranged per 5 cm of ply width.

[0019] In the tire of the present invention, in the belt ply, the product of the diameter (mm) of the belt cord in the tire radial direction and the number of the belt cords arranged per 5 cm of ply width is preferably 10-45. Effect of the Invention

[0020] In the tire of the present invention, the belt layer includes at least one belt ply, and the belt ply includes a belt cord made of a steel single wire. Even when the thickness of such a belt layer in the tire radial direction is reduced to reduce the weight of the tire, the belt cord is less likely to stretch, and the shape of the tread portion during high-speed running can be stabilized, and the rolling resistance can be reduced. In addition, since the shape of the tread portion of such a tire is stable during high-speed running, the ride comfort performance during high-speed running can also be improved.

[0021] In the tire of the present invention, the band layer includes at least one band ply, the band ply includes a band cord made of organic fiber and arranged at an angle of 5° or less with respect to the tire circumferential direction, and the band cord has a diameter in the tire radial direction of 0.70 mm or more.

[0022] Such a band layer can improve the restraint of the tread portion and reduce the deformation of the tread portion during high-speed running, thereby reducing the rolling resistance of the tire during high-speed running and improving the ride comfort. In addition, since the band layer fastens the belt cord made of a steel single wire with a band cord having a diameter of 0.70 mm or more, the fastening effect of the belt layer can be further increased. Therefore, the tire of the present invention can achieve both ride comfort and low fuel consumption performance during high-speed running. [Brief description of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view showing one embodiment of a tire of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of a belt layer and a band layer of the present embodiment. [Diagram 3] FIG. 11 is a cross-sectional view of a belt layer and a band layer according to another embodiment. [Figure 4] FIG. 2 is a schematic diagram of a band cord. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 shows a tire meridian cross section including a rotation axis of a tire 1 of this embodiment in a normal state. Here, the "normal state" refers to a state in which, in the case of a rubber pneumatic tire, the tire 1 is mounted on a normal rim, the internal pressure is adjusted to a normal pressure, and no load is applied. Unless otherwise specified below, the dimensions of each part of the tire 1 are values ​​measured in this normal state.

[0025] A "genuine rim" is a rim that is determined for each tire by a standard system that includes the standards on which tire 1 is based, for example, a "standard rim" in the case of JATMA, a "Design Rim" in the case of TRA, and a "Measuring Rim" in the case of ETRTO.

[0026] "Normal internal pressure" is the air pressure set for each tire by a standard system that includes the standard on which tire 1 is based, in the case of JATMA, it is the "maximum air pressure", in the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "INFLATION PRESSURE".

[0027] The tire 1 of this embodiment is preferably used as a passenger car tire. In this specification, a passenger car tire refers to a rubber pneumatic tire that is intended to be mounted on a four-wheeled vehicle and has a normal load of 1000 kg or less. The passenger car tire is not particularly limited as long as the normal load is 1000 kg or less, but from the viewpoint of suppressing excessive deformation in the tread portion 2, the normal load is preferably applied to a tire of 900 kg, more preferably applied to a tire of 750 kg, and even more preferably applied to a tire of 700 kg.

[0028] The "normal load" is the load that is determined for each tire by each standard in the standard system including the standard on which tire 1 is based, and is the "maximum load capacity" in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and the "LOAD CAPACITY" in the case of ETRTO.

[0029] The tire 1 is not limited to a passenger vehicle tire, but may be applied to various types of tires, such as heavy load tires, motorcycle tires, plastic tires, non-pneumatic tires that are not filled with pressurized air, and racing tires.

[0030] 1, a tire 1 of this embodiment includes a tread portion 2 extending in an annular shape, a pair of sidewall portions 3 extending on both sides of the tread portion 2, and a pair of bead portions 4 extending continuous with the sidewall portions 3. The tire 1 of this embodiment has a toroidal carcass 6 extending across between bead cores 5 of the pair of bead portions 4, and a belt layer 7 disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2 in the tire radial direction.

[0031] The tread portion 2 is desirably formed of at least one elastomer layer. The tread portion 2 may be formed, for example, of two or more elastomer layers laminated in the tire radial direction, or may have a plurality of elastomer layers in the tire axial direction.

[0032] Examples of the elastomer layer of the tread portion 2 include natural rubber, isoprene-based rubber such as isoprene rubber, butadiene rubber, styrene butadiene rubber, styrene isoprene butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, and diene rubber such as butyl rubber.

[0033] The sidewall portion 3 is desirably formed of at least one elastomer layer. The sidewall portion 3 may have, for example, two or more elastomer layers laminated in the tire axial direction, or may have a plurality of elastomer layers in the tire radial direction. The elastomer layer of the sidewall portion 3 may be, for example, the same component as the elastomer layer of the tread portion 2, or may be a different component.

[0034] The boundary surface between the elastomer layer of the tread portion 2 and the elastomer layer of the sidewall portion 3 is, for example, located radially outward from the inner end side at the outer end side in the axial direction of the tire. The boundary surface between the elastomer layer of the tread portion 2 and the elastomer layer of the sidewall portion 3 may be, for example, located radially inward from the inner end side at the outer end side in the axial direction of the tire.

[0035] The carcass 6 includes at least one carcass ply 6A, one carcass ply 6A in this embodiment. The carcass ply 6A is formed of an elastomer layer including carcass cords (not shown) arranged at an angle of 75 to 90 degrees with respect to the tire circumferential direction, for example. As the carcass cords, for example, organic fiber cords such as aromatic polyamide (aramid), rayon, polyester, etc. can be used. Here, in this specification, "A to B" means "A or more and B or less."

[0036] The carcass ply 6A includes, for example, a main body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a turn-up portion 6b continuing to the main body portion 6a and turned up around the bead core 5 from the inside in the tire axial direction to the outside. Between the main body portion 6a and the turn-up portion 6b of the carcass ply 6A, for example, a bead apex 8 extending from the bead core 5 to the outside in the tire radial direction is disposed. The bead apex 8 is formed, for example, from an elastomer layer.

[0037] The bead portion 4 may be provided with a bead reinforcing layer (not shown), for example, on the outer side in the tire axial direction of the turned-up portion 6b of the carcass 6. The bead reinforcing layer may be formed, for example, of an elastomer layer having the same component as that of the bead apex 8, or may be formed of an elastomer layer having a different component.

[0038] The bead portion 4 may be provided with a chafer (not shown), for example, on the axially outer side of the folded-up portion 6b of the carcass 6. When the bead reinforcing layer and the chafer are provided, it is preferable that the chafer be disposed axially outer than the bead reinforcing layer.

[0039] The tire 1 of this embodiment is provided with an inner liner 10 on the inside of the carcass 6. The inner liner 10 is desirably formed of an air-impermeable elastomer layer. Examples of the elastomer layer of the inner liner 10 include butyl rubber, halogenated butyl rubber, and the like. Such an inner liner 10 can maintain the air pressure filled in the tire 1.

[0040] The belt layer 7 includes at least one, and in this embodiment, two belt plies 7A and 7B. The two belt plies 7A and 7B include, for example, a first belt ply 7A located on the inner side in the tire radial direction and a second belt ply 7B located on the outer side of the first belt ply 7A. Such a belt layer 7 can increase the rigidity of the tread portion 2 and improve the steering stability performance of the tire 1 during high-speed running.

[0041] A band layer 9 including at least one band ply 9A, in this embodiment one band ply 9A, is disposed on the radially inner side of the tread portion 2. Such a band layer 9 enhances the restraint of the tread portion 2 even during high-speed running, and can achieve both ride comfort and low fuel consumption performance of the tire 1 during high-speed running.

[0042] Fig. 2 is a cross-sectional view of the belt layer 7 and the band layer 9 of this embodiment, and Fig. 3 is a cross-sectional view of the belt layer 7 and the band layer 9 of another embodiment. As shown in Fig. 2 and Fig. 3, the belt layer 7 of this embodiment includes a belt cord 7a made of a steel solid wire and an elastomer composition 7G that covers the belt cord 7a.

[0043] Such belt plies 7A, 7B are less likely to stretch than the stranded cords and can generate a large reaction force when subjected to deformation in the shear direction, thereby improving the steering stability of the tire 1 during high-speed driving.

[0044] The elastomer composition 7G of the belt plies 7A and 7B of this embodiment exhibits rubber elasticity. Examples of the elastomer composition 7G include a rubber composition and a thermoplastic elastomer composition. When the elastomer composition 7G is a rubber composition, examples of the rubber component include isoprene-based rubber, butadiene-based rubber, styrene-butadiene rubber, nitrile rubber, and butyl rubber. When the elastomer composition 7G is a thermoplastic elastomer composition, examples of the elastomer include block copolymers such as thermoplastic polyurethane, styrene-butadiene copolymer, and styrene-ethylene-butylene-styrene copolymer.

[0045] The belt cord 7a of the present embodiment is plated or ternary plated. Examples of the plating include zinc, copper, etc. Examples of the ternary plating include zinc, copper, cobalt, etc. Such a belt cord 7a has good adhesion to the elastomer composition 7G, and can generate a stress in cooperation with the belt cord 7a and the elastomer composition 7G even during high-speed running, thereby improving the steering stability of the tire 1 during high-speed running.

[0046] The belt cord 7a in Fig. 2 has a circular cross section, while the belt cord 7a in Fig. 3 has a flat cross section. In this specification, "circular" means that the ratio of the major axis to the minor axis of the cross section is less than 1.05, and "flat" means that the ratio of the major axis to the minor axis of the cross section is 1.05 or more.

[0047] The band ply 9A of this embodiment includes a band cord 9a arranged at an angle of 5° or less with respect to the tire circumferential direction, and an elastomer composition 9G that covers the band cord 9a. Here, the angle of the band cord 9a is the angle in the tire 1 in a normal state, and can be confirmed, for example, by partially peeling off the tread portion 2.

[0048] The elastomer composition 9G of the band ply 9A desirably exhibits rubber elasticity, like the elastomer composition 7G of the belt plies 7A and 7B. As the elastomer composition 9G, for example, the same one as the elastomer composition 7G can be mentioned.

[0049] The band cord 9a in Fig. 2 has a circular cross section, while the band cord 9a in Fig. 3 has a flat cross section. The band cord 9a is made of, for example, organic fibers. The band cord 9a preferably has a diameter d1 in the tire radial direction a of 0.70 mm or more.

[0050] Here, the diameter d1 of the band cord 9a in the tire radial direction a is the diameter of the cross section if the band cord 9a has a circular cross section as shown in Fig. 2. Moreover, the diameter d1 of the band cord 9a in the tire radial direction a is the diameter along the tire radial direction a if the band cord 9a has a flat cross section as shown in Fig. 3. Moreover, if the band cord 9a is made of multiple cords twisted together, the diameter d1 of the band cord 9a in the tire radial direction a is the outer diameter of an imaginary line that fills the gaps between the multiple cords.

[0051] Fig. 4 is a schematic diagram of a band cord 9a. When the band cord 9a having a flat cross section is arranged at an angle to the tire radial direction a as shown in Fig. 4, the minor axis Sd and major axis Ld of the band cord 9a having a flat cross section, whichever has a smaller angle with respect to the tire radial direction a, is set as the diameter d1 in the tire radial direction a. In Fig. 4, the angle θ1 of the minor axis Sd direction with respect to the tire radial direction a is smaller than the angle θ2 of the major axis Ld direction, so the minor axis Sd is set as the diameter d1 in the tire radial direction a.

[0052] Such a band layer 9 can improve the restraint of the tread portion 2 and reduce the deformation of the tread portion 2 during high-speed running, thereby reducing the rolling resistance of the tire 1 during high-speed running and improving the ride comfort. Therefore, the tire 1 of this embodiment can achieve both ride comfort and low fuel consumption performance during high-speed running.

[0053] 2 and 3, by setting the diameter d1 of the band cord 9a in the tire radial direction a to 0.70 mm or more, the restraint of the tread portion 2 can be reliably improved, and the tire 1 can achieve both low fuel consumption and ride comfort during high-speed running. From this viewpoint, the diameter d1 of the band cord 9a is more preferably 0.75 mm or more, and further preferably 0.80 mm or more.

[0054] The diameter d1 of the band cord 9a in the tire radial direction a is preferably 1.00 mm or less. By making the diameter d1 of the band cord 9a in the tire radial direction a 1.00 mm or less, an increase in the thickness of the tread portion 2 is suppressed, and the rolling resistance of the tire 1 during high-speed running can be reliably reduced. From this viewpoint, the diameter d1 of the band cord 9a is more preferably 0.95 mm or less, and even more preferably 0.90 mm or less.

[0055] In the band ply 9A, preferably, 35 to 65 band cords 9a are arranged per 5 cm of ply width. Here, the number n1 of arranged band cords 9a per 5 cm of ply width is the number arranged per 5 cm of ply width in a direction perpendicular to the longitudinal direction of the band cords 9a. The number n1 of arranged band cords 9a can be determined, for example, from measurements in an area including the tire equator C of the band ply 9A.

[0056] By setting the number n1 of the band cords 9a per 5 cm of ply width to 35 or more, the restraint of the tread portion 2 can be reliably improved, and the tire 1 can achieve both low fuel consumption and good ride comfort during high-speed driving. From this perspective, the number n1 of the band cords 9a is more preferably 40 or more, and even more preferably 45 or more.

[0057] By setting the number n1 of the band cords 9a per 5 cm of the ply width to 65 or less, it is possible to prevent the rigidity of the tread portion 2 from becoming excessively high, and to improve the ride comfort performance of the tire 1 during high-speed running. From this viewpoint, the number n1 of the band cords 9a is more preferably 60 or less, and further preferably 55 or less.

[0058] In the band ply 9A, the product (d1×n1) of the diameter d1 (mm) of the band cord 9a in the tire radial direction a and the number n1 (pieces) of the band cord 9a arranged per 5 cm of the ply width is preferably 25 to 60. Such a product (d1×n1) is the ratio of the band cord 9a to the width direction of the band ply 9A, and is an index related to the interval between adjacent band cords 9a.

[0059] By making the product (d1×n1) 25 or more, it is possible to reliably improve the restraining ability of the tread portion 2 and achieve both low fuel consumption performance and ride comfort performance of the tire 1 during high-speed running. From this viewpoint, the product (d1×n1) is more preferably 35 or more, and further preferably 40 or more.

[0060] By making the product (d1×n1) 60 or less, it is possible to suppress excessive rigidity and vibration caused by small intervals between the band cords 9a, and improve the ride comfort performance of the tire 1 during high-speed driving. From this viewpoint, the product (d1×n1) is more preferably 50 or less.

[0061] 1 to 3, the product (d1×n1×L1) of the above-mentioned product (d1×n1) and the distance L1 (mm) from the outer surface 2a of the tread portion 2 at the tire equator C to the band ply 9A is preferably 150 or more. Such a product (d1×n1×L1) is an index showing the restraining ability of the tread portion 2.

[0062] Here, the distance L1 is a straight-line distance from the outer surface 2a of the tread portion 2 to the band layer 9 at the tire equator C, and in the case where a groove is present on the tire equator C, the distance L1 is a straight-line distance from an imaginary line filling the groove. The distance L1 is also called the gauge of the tread portion 2, and is an index indicating the rubber thickness of the tread portion 2.

[0063] By making the product (d1×n1×L1) 150 or more, even if the gauge (distance L1) of the tread portion 2 is small, the tread portion 2 exhibits sufficient restraint during high-speed driving, and the tire 1 can achieve both ride comfort performance and low fuel consumption performance during high-speed driving. From this viewpoint, the product (d1×n1×L1) is more preferably 200 or more, and further preferably 280 or more.

[0064] The product (d1×n1×L1) is preferably 450 or less. By making the product (d1×n1×L1) 450 or less, even when the gauge (distance L1) of the tread portion 2 is large, the band layer 9 exhibits sufficient flexibility, and the tire 1 can achieve both ride comfort performance and low fuel consumption performance during high-speed driving. From this viewpoint, the product (d1×n1×L1) is more preferably 430 or less.

[0065] The elongation of the band cord 9a under a load of 66 N is preferably 2.5% or more. When the elongation of the band cord 9a under a load of 66 N is 2.5% or more, the band cord 9a can stretch even when the tire 1 is expanded during vulcanization molding, thereby suppressing contact with the belt cord 7a. From this viewpoint, the elongation of the band cord 9a under a load of 66 N is more preferably 3.0% or more, and even more preferably 3.5% or more.

[0066] The band cord 9a preferably has an elongation of 7.0% or less when loaded with 198 N. By making the band cord 9a have an elongation of 7.0% or less when loaded with 198 N, the band cord 9a exhibits sufficient restraint on the tread portion 2 when traveling at high speeds, and can achieve both ride comfort and fuel economy of the tire 1 when traveling at high speeds. From this viewpoint, the elongation at a load of 198 N is more preferably 6.5% or less, and even more preferably 6.0% or less.

[0067] The band cord 9a of the present embodiment is a hybrid cord in which a first material and a second material different from the first material are twisted together. Such a band cord 9a can provide a tire 1 suitable for achieving both ride comfort and fuel efficiency during high-speed driving due to the first material and the second material having different properties.

[0068] The modulus of the second material in this embodiment is different from that of the first material. Such band cord 9a reduces the amount of deformation of the tread portion 2 caused by an increase in internal pressure during high-speed driving by using a material with a large modulus, and can reduce input from the road surface by using a material with a small modulus. Therefore, the tire 1 can achieve both ride comfort and low fuel consumption performance during high-speed driving.

[0069] The modulus of the second material is, for example, larger than that of the first material. The modulus of the second material is preferably at least two times, more preferably at least 10 times, and even more preferably at least 30 times, the modulus of the first material. Such a band cord 9a helps the tire 1 to achieve both ride comfort and low fuel consumption performance during high-speed driving.

[0070] The first material is, for example, a heat-shrinkable material. The second material is, for example, a non-heat-shrinkable material. By including a heat-shrinkable material and a non-heat-shrinkable material, the band cord 9a can appropriately shrink due to heat generation during high-speed driving, thereby improving the restraining property during high-speed driving.

[0071] Suitable examples of the first material include aliphatic polyamide (nylon) and polyester. The nylon or polyester of the first material is preferably a bundle of filaments having a thickness of 940 dtex or more. The first material is desirably formed as one or more bundles of nylon filaments. Such a first material can exert the above-mentioned effects while suppressing costs.

[0072] The second material is preferably, for example, aromatic polyamide (aramid). The aramid of the second material is preferably a bundle of filaments having a thickness of 1100 dtex or more. The second material is preferably formed as two or more bundles of aramid filaments. Such a second material can exert the above-mentioned effects while suppressing costs.

[0073] The band cord 9a is not limited to the above-mentioned hybrid cord, and may include, for example, a first cord made of a first material and a second cord made of a second material different from the first material. Even with such a band cord 9a, it is possible to provide a cord suitable for achieving both ride comfort and low fuel consumption performance of the tire 1 during high-speed driving by using the first material and the second material having different properties.

[0074] As shown in Figures 2 and 3, the belt cords 7a are arranged at an angle of, for example, 10 to 30 degrees with respect to the tire circumferential direction. The belt cords 7a of the first belt ply 7A and the belt cords 7a of the second belt ply 7B are desirably inclined in opposite directions with respect to the tire circumferential direction. Such a belt layer 7 can increase the rigidity of the tread portion 2 in a well-balanced manner and improve the steering stability performance of the tire 1 during high-speed running. Here, the angle of the belt cords 7a is the angle in the tire 1 in a normal state, and can be confirmed, for example, by partially peeling off the tread portion 2.

[0075] The belt cord 7a preferably has a diameter d2 in the tire radial direction a of 0.16 to 0.50 mm. Here, the diameter d2 of the belt cord 7a in the tire radial direction a is the diameter of the cross section if the belt cord 7a has a circular cross section as shown in Fig. 2. Moreover, the diameter d2 of the belt cord 7a in the tire radial direction a is the diameter along the tire radial direction a if the belt cord 7a has a flat cross section as shown in Fig. 3.

[0076] Although not shown in the figures, when the belt cord 7a having a flat cross section is arranged at an angle with respect to the tire radial direction a, of the minor diameter and major diameter of the belt cord 7a having a flat cross section, the one having a smaller angle with respect to the tire radial direction a is set to the diameter d2 in the tire radial direction a (see FIG. 4).

[0077] By making the diameter d2 of the belt cord 7a in the tire radial direction a 0.16 mm or more, it is possible to reduce the amount of deformation of the tread portion 2 during high-speed running, and to reduce the rolling resistance of the tire 1 during high-speed running. From this viewpoint, the diameter d2 of the belt cord 7a is more preferably 0.18 mm or more, and further preferably 0.20 mm or more.

[0078] By setting the diameter d2 of the belt cord 7a in the tire radial direction a to 0.50 mm or less, vibrations of the tread portion 2 during high-speed running can be absorbed, and the ride comfort performance of the tire 1 during high-speed running can be improved. From this viewpoint, the diameter d2 of the belt cord 7a is more preferably 0.45 mm or less, and further preferably 0.40 mm or less.

[0079] In the belt plies 7A and 7B, preferably, 55 to 150 belt cords 7a are arranged per 5 cm of ply width. Here, the number n2 of the belt cords 7a arranged per 5 cm of ply width is the number of the belt cords 7a arranged per 5 cm of ply width in a direction perpendicular to the longitudinal direction of the belt cords 7a. The number n1 of the belt cords 7a arranged can be obtained, for example, from measurements of the belt plies 7A and 7B in an area including the tire equator C.

[0080] By setting the number n2 of the belt cords 7a per 5 cm of the ply width to 55 or more, it is possible to reduce the amount of deformation of the tread portion 2 during high-speed running, and to reduce the rolling resistance of the tire 1 during high-speed running. From this viewpoint, the number n2 of the belt cords 7a is more preferably 65 or more, and further preferably 75 or more.

[0081] By setting the number n2 of the belt cords 7a arranged per 5 cm of the ply width to 150 or less, it is possible to prevent the rigidity of the tread portion 2 from becoming excessively high, and to improve the ride comfort performance of the tire 1. From this viewpoint, the number n2 of the belt cords 7a arranged is more preferably 140 or less, and further preferably 120 or less.

[0082] In the belt plies 7A, 7B, the product (d2×n2) of the diameter d2 (mm) of the belt cord 7a in the tire radial direction a and the number n2 (pieces) of the belt cord 7a arranged per 5 cm of the ply width is preferably 10 to 45. Such a product (d2×n2) is the ratio of the belt cord 7a to the width direction of the belt plies 7A, 7B, and is an index related to the interval between adjacent belt cords 7a.

[0083] By making the product (d2×n2) 10 or more, it is possible to reliably improve the restraining ability of the tread portion 2 and achieve both low fuel consumption performance and ride comfort performance of the tire 1. From this viewpoint, the product (d2×n2) is more preferably 15 or more, and further preferably 20 or more.

[0084] By making the product (d2×n2) 45 or less, it is possible to suppress excessive stiffness and vibration caused by small intervals between the belt cords 7a, and improve the ride comfort performance of the tire 1 during high-speed driving. From this viewpoint, the product (d2×n2) is more preferably 40 or less, and further preferably 35 or less.

[0085] 1 to 3, in the belt plies 7A, 7B, the value (d2×n2 / L2) obtained by dividing the above-mentioned product (d2×n2) by the distance L2 (mm) from the outer surface 2a of the tread portion 2 at the tire equator C to the second belt ply 7B is preferably equal to or less than 6. Such a value (d2×n2 / L2) is an index showing the relationship between the deformation of the tread portion 2 on the outer side of the belt layer 7 in the tire radial direction and the product (d2×n2).

[0086] The tire 1 can achieve both steering stability and ride comfort during high-speed driving by specifying the product (d2×n2) and the distance L2 so that the value (d2×n2 / L2) is 6 or less. That is, when the product (d2×n2) is large, the distance L2 is increased to absorb vibrations transmitted to the belt plies 7A and 7B and maintain the rigidity of the belt layer 7 at a high level, and the tire 1 can achieve both steering stability and ride comfort during high-speed driving. In addition, when the product (d2×n2) is small, the distance L2 is decreased to make it easier for the belt plies 7A and 7B to generate a reaction force and improve the ability to follow the road surface, so that the tire 1 can achieve both steering stability and ride comfort during high-speed driving.

[0087] The belt cord 7a preferably contains, by mass %, 0.82 to 1.12% carbon. Such belt cord 7a has an excellent balance between strength TS and toughness, and therefore can increase the rigidity of the tread portion 2 and improve the steering stability of the tire 1 during high-speed running.

[0088] In addition to the above-mentioned carbon, the elements contained in the belt cord 7a include, for example, silicon, manganese, phosphorus, sulfur, etc. The belt cord 7a may contain, for example, by mass %, 0.15 to 0.35% silicon, 0.30 to 0.60% manganese, 0.30% or less phosphorus, and 0.30% or less sulfur.

[0089] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified in various ways. EXAMPLES

[0090] A tire having the basic structure shown in Fig. 1 was prototyped based on the specifications in Tables 1 and 2. The modulus of the first material and the modulus of the second material in Tables 1 and 2 are expressed as an index with the modulus of the first material in Comparative Example 1 being 100. Using the prototype tires, the steering stability performance, ride comfort performance, fuel efficiency performance, and durability performance during high-speed driving were tested. The common specifications and test methods are as follows.

[0091] <Common specifications> Tire size: 205 / 55R16 Air pressure: 220kPa Test vehicle: Front-wheel drive mid-size passenger car Cross-sectional shape of band cord: Circular Belt cord cross section: circular Belt cord material: Steel

[0092] <Ride comfort performance> The prototype tires were fitted to all wheels of a test vehicle, and the vehicle was driven around a test course at a speed of 100km / h. The test driver evaluated the ride comfort performance on a scale of 1 to 5 using his senses. Similar tests were conducted by 20 test drivers, and the total score was calculated. The results were expressed as an index, with the total score of Comparative Example 1 being 100, and the higher the value, the better the ride comfort performance during high-speed driving.

[0093] <Low fuel consumption performance> The prototype tires were fitted to all wheels of a test vehicle, which was then driven on a test course at 100km / h for 10 minutes, after which the accelerator was released and the distance the test vehicle traveled until it stopped was measured. The results were expressed as an index with Comparative Example 1 being 100, with a higher index indicating a greater distance the test vehicle traveled until it stopped, and therefore a smaller rolling resistance and superior fuel economy during high-speed driving.

[0094] The test results are shown in Tables 1 and 2. [Table 1] [Table 2]

[0095] As a result of the tests, it was confirmed that the tires of the examples were superior to the comparative examples in terms of ride comfort and fuel efficiency during high-speed driving, and that the overall performance, determined by the sum of the individual performance values, was also good, making it possible to achieve both ride comfort and fuel efficiency during high-speed driving. [Explanation of symbols]

[0096] 1 Tire 2 Tread section 7 Belt layer 7A Belt ply 7a Belt cord 9 Band Layer 9A Band Ply 9a Band cord

Claims

1. A tire having a belt layer and a band layer, The belt layer includes at least one belt ply, The belt ply includes a belt cord made of a steel single wire, The band layer includes at least one band ply, The band ply includes a band cord made of organic fiber and arranged at an angle of 5° or less with respect to the tire circumferential direction, The band cord has a radial diameter of 0.70 mm or more, In the band ply, the product of the diameter (mm) of the band cord, the number of the band cords arranged per 5 cm of ply width (pieces), and the distance (mm) from the outer surface of the tread portion at the tire equator to the band ply is 150 or more. tire.

2. A tire having a belt layer and a band layer, The belt layer includes at least one belt ply, The belt ply includes a belt cord made of a steel single wire, The band layer includes at least one band ply, The band ply includes a band cord made of organic fiber and arranged at an angle of 5° or less with respect to the tire circumferential direction, The band cord has a radial diameter of 0.70 mm or more and an elongation of 7.0% or less when subjected to a load of 198 N. tire.

3. The tire according to claim 1 or 2, wherein the band cord is a hybrid cord in which a first material and a second material different from the first material are twisted together.

4. A tire having a belt layer and a band layer, The belt layer includes at least one belt ply, The belt ply includes a belt cord made of a steel single wire, The band layer includes at least one band ply, The band ply includes a band cord made of organic fiber and arranged at an angle of 5° or less with respect to the tire circumferential direction, The band cord has a radial diameter of 0.70 mm or more, The band cord includes a first cord made of a first material and a second cord made of a second material different from the first material. tire.

5. the first material is a heat shrinkable material; 5. A tire according to claim 3 or 4, wherein the second material is a non-heat shrinkable material.

6. 6. Tire according to any one of claims 3 to 5, wherein the modulus of the second material is different from the modulus of the first material.

7. the first material is nylon; 7. A tire according to any one of claims 3 to 6, wherein said second material is an aramid.

8. 8. The tire according to claim 1, wherein the band ply has 35 to 65 band cords arranged per 5 cm of ply width.

9. A tire as described in any one of claims 1 to 8, wherein the band cord has a radial diameter of 1.00 mm or less.

10. The tire according to claim 1 , wherein the band cord has an elongation of 2.5% or more under a load of 66 N.

11. The tire according to any one of claims 1 to 10, wherein the belt cord has a radial diameter of 0.16 to 0.50 mm.

12. The tire according to any one of claims 1 to 11, wherein the belt ply has 55 to 150 belt cords arranged per 5 cm of ply width.

13. The tire according to any one of claims 1 to 12, wherein in the belt ply, a product of a diameter (mm) of the belt cord in the tire radial direction and an arrangement number (pieces) of the belt cord per 5 cm of a ply width is 10 to 45.

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