Bridgestone Corporation

Kazuo Oshima

Shizuo Iwasaki

Tomohisa Nishikawa

Kenji Matsuo

Kazuomi Kobayashi

Kozo Sasaki

A pneumatic tire for a passenger car having a pair of bead portions, a toroidal carcass portion extending over both bead portions, at least two belt layers provided in a crown portion of the carcass, a tread portion positioned at an outer peripheral side of the belt layer, and side wall portions provided at the right and left sides of the tread portion, and which further includes a steel cord as a reinforcing material for reinforcing at least one layer of the carcass portion and the belt layer. The steel cord is formed by plying a plurality of filaments each having a strand diameter of 0.125 to 0.275 mm, and has an inflection point on an S&mdash;S curve. A reduction rate of a diameter of the steel cord under a load stress which is one third of breaking strength in comparison with a no load condition is equal to or more than 20%.

Pneumatic tire for passenger cars including specified steel cord

A low rolling resistance pneumatic radial tire having an improved appearance comprises a carcass composed of a single rubberized carcass ply containing cords therein. The carcass ply cord is a high tenacity vinylon cord having characteristics after vulcanization represented by the following equations: ##EQU1## Further, the carcass ply has the number of overlapped cords of not more than 15 at the shoulder portion in its joint portion.

Low rolling resistance pneumatic radial tires having an improved

A pneumatic radial tire having a low noise and an improved cornering stability has a belt structure of at least two belt layers composed of at least one layer containing cords each obtained by twisting organic fibers and at least one layer containing steel cords, at least one of the organic fiber cord layers being interposed between the steel cord layer and a tread at a state that both transversely outermost end portions are folded inward. This organic fiber cord is a cord obtained by twisting high strength, high modulus polyvinyl alcohol fibers and has particular twisting coefficient and strength. The tire further satisfies a particular relation between a height of a turnup portion of a carcass ply around a bead portion and a tensile stress at 50% elongation of a bead filler rubber reinforcing the bead portion at room temperature.

Pneumatic radial tire having a folded belt including a polyvinyl alcohol

A pneumatic radial tire having improved cornering stability, service durability and rolling resistance is provided by using high-elasticity, high-strength vinylon fiber having specified elongation and strength as a cord material for at least one belt layer in a belt composed of at least two belt layers. Particularly, noise level can be reduced without damaging other tire performances by combining at least one layer of high-elasticity, high-strength vinylon fiber cords with at least one layer of steel cords as a belt of the tire.

Pneumatic radial tires with a folded belt and high strength vinylon

Nylon cords having a yarn strength of not less than 12 g/d are subjected to a stretch heating treatment under specified conditions before the dipping and then dipped in a dipping solution having a particular composition, whereby the strength and adhesion force of the resulting dipped cords are considerably improved for use in large size tires.

Adhesive treatment for nylon cords

A pneumatic tire is reinforced with cords made of polyvinyl alcohol based fibers, and meets the following requirements:

Growing community of inventors

Higashiyamato, Japan

Kazuo Oshima