The Yokohama Rubber Co., Ltd.

Tokusen Industry Co., Ltd.

Shinya Harikae

Masatoshi Kuriyama

Eiichi Iida

Masatoshi Shimizu

Takamitsu Chaya

Noritaka Morioka

Makoto Ozaki

In a pneumatic tire including a carcass layer mounted between a pair of bead portions and a belt reinforcing layer disposed on an outer circumferential side of the carcass layer, the carcass layer is formed of a carcass cord made of an organic fiber cord, an elongation at break of the carcass cord is set to 20% or more, an elongation under a load of 1.5 cN/dtex of the carcass cord in sidewall portions is set to from 5.0% to 8.0%, the belt reinforcing layer is formed of a cover cord made of an organic fiber cord, and a tensile strength of the cover cord per width of 50 mm at a 3.0% elongation is set to from 2.8 kN to 4.0 kN.

Pneumatic tire

A pneumatic tire is provided that can achieve performance that is equivalent to or higher than that of known tires while allowing weight reduction of bead cores by using, for the bead cores, a composite cord. A pneumatic tire includes annular bead cores () embedded in bead portions (), and a carcass layer () locked on the bead cores (). Each of the bead cores () includes a cable bead structure in which a composite cord () is spirally wound around an annular core body (), the composite cord including a core wire () formed of carbon fibers and a plurality of siding wires () formed of glass fibers disposed around the core wire ().

A pneumatic tire has two carcass layers including carcass cords are laid between a pair of bead portions, bead cores and bead fillers are disposed in the bead portions, and at least two belt layers are disposed on the outer circumferential side of the carcass layers, the tire being characterized in that both ends of the inner carcass layer are folded back from the tire inner side to the tire outer side around the bead cores, and the ends of the folded back portions of the inner carcass layer are disposed between the innermost belt layer and the outer carcass layer, while both ends of the outer carcass layer are disposed so as to pass between a main portion of the inner carcass layer and the bead fillers, and both ends of the outer carcass layer terminate at the bead portions without being folded back around the bead cores.

Pneumatic Tire

A belt cover layer is provided on an outer circumferential side of a belt layer. The belt cover layer is constituted by a band-like member in which steel cords are embedded in rubber. Adjacent revolution portions of the band-like member are wound spirally in a tire circumferential direction so as not to contact each other in a region of at least 50% of a belt width centered on a tire equator. A load-strain curve of the steel cords has an inflection point in a strain region of 1% to 3.5%. An average elastic modulus when the steel cords are subjected to a load from 50 N to 100 N is from 25 GPa to 100 GPa.

Pneumatic radial tire for use on passenger cars

Provided is a pneumatic radial tire including a main belt layer and at least one circumferential-direction reinforcement layer, which are provided in the tread portion. The main belt layer includes two belt layers in which steel cords are disposed in a manner that the steel cords of a first one of the two belt layers intersect the steel cords of a second one of the two belt layers. In the circumferential-direction reinforcement layer, steel cords are disposed in a substantial tire circumferential direction. The ratio Wo/Wm of the width Wo of the circumferential-direction reinforcement layer to the maximum width Wm of the main belt layer is 0.5 to 0.9. The ratio Ee/Ec of the reinforcement-cord elastic modulus Ee of the steel cords in the edge portions of the circumferential-direction reinforcement layer to the reinforcement-cord elastic modulus Ec of the steel cords in the center portion of the circumferential-direction reinforcement layer is not less than (0.85&#x2212;0.5 Wo/Wm) and not more than 0.8.

Pneumatic radial tire

Disclosed is a pneumatic radial tire having improved flat spot resistance without sacrificing its high-speed durability, when a belt auxiliary reinforcement layer thereof is constituted of a hybrid fiber cord including a general-purpose nylon as a low-elastic fiber yarn. In the pneumatic radial tire, the belt auxiliary reinforcement layer is formed by winding an organic fiber cord around the outer periphery of belt layers in the tire circumferential direction. The organic fiber cord constituting the belt auxiliary reinforcement layer is obtained by twisting a highly-elastic fiber yarn with an elastic modulus of 10000 MPa or more and a low-elastic fiber yarn made of nylon 46.

There is provided a pneumatic tire capable of improving high-speed durability and noise characteristics. The pneumatic tire has a belt-reinforcing structureradially outwardly of belt pliesand, the belt-reinforcing structurehaving organic fiber cords n spirally wound in the circumferential direction T of the tire. The belt-reinforcing structurehas an end reinforcement layerB disposed radially outwardly of each end region BE of the belt pliesand. The end reinforcement layerB has a two-layer structure in which its organic fiber cord nb formed of a hybrid cord is spirally wound from the axially inner side of the tire toward the axially outer side of the tire, is turned in an opposite direction at an edgeof the belt-reinforcing structure and is spirally wound from the axially outer side of the tire toward the axially inner side of the tire, and in which the opposite edges of the organic fiber cord nb are away inwardly in the axial direction of the tire from the edgeof the belt-reinforcing structure.

Provided is a pneumatic radial tire: that includes a circumferential-direction reinforcement layer having a width increased with fatigue break of the circumferential-direction reinforcement layer being suppressed at edge portions thereof; and that suppresses separation in each of cross belt layers at edge portions thereof. A pneumatic radial tire according to the present invention is a pneumatic tire including: at least two cross belt layers disposed on an outer circumferential side of a carcass layer in a tread portion; and at least one circumferential-direction reinforcement layer disposed between these cross belt layers, a width of the circumferential-direction reinforcement layer being smaller than that of each cross belt layer. The pneumatic radial tire is configured so that: the cross belt layers are separated away from each other at outer sides respectively of end positions, in a width direction, of the circumferential-direction reinforcement layer; the circumferential-direction reinforcement layer includes steel cords of two types which differ in elongation at break; and the steel cord having relatively small elongation at break is disposed in a center portion of the circumferential-direction reinforcement layer, whereas the steel cord having relatively large elongation at break is disposed in each of outer side portions of the circumferential-direction reinforcement layer.

A tire/wheel assembly, wherein bent parts () bent outward are formed at the leg end parts of an annular shell (), an inclination angle (&#x3b1;) of a line segment Lextending from the axially outer end (P) of the bent part () through the apex (P) of a hump () on a rim relative to a direction perpendicular to a tire axis is set to within &#xb1;5&#xb0; in a cross section orthogonal to the circumferential direction of the annular shell (), the area () of the annular shell equal to the height (B) of at least 35% of the height (A) from the radially inner end of the annular shell is formed linearly, the inclination angle (&#x3b1;) of an extension line (L) along the inner surface of the linear area () relative to the direction perpendicular to the tire axis is 15 to 30&#xb0; in axial inner side, and the extension line (L) passes between the apex (P) of the hump () and the toe tip (P) of a tire bead part.

Tire/wheel assembly

Disclosed are a tire/wheel assembly and a run-flat support member which are designed to be lightened without losing durability during run-flat traveling. The tire/wheel assembly is constituted as follows: a pneumatic tire is fit to a wheel rim; and the run-flat support member constituted of a circular shell and elastic rings is inserted into a cavity of the pneumatic tire. The circular shell has a support surface thereof extended toward the periphery of the pneumatic tire and leg portions along each side of the support surface. The elastic rings support the leg portions of the circular shell on the rim. In the tire/wheel assembly, contact portions and noncontact portions for the circular shell are alternately formed on the elastic rings in a shell circumferential direction.

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Hiratsuka, Japan

Shinya Harikae