The Yokohama Rubber Co., Ltd.

Shinji Kawakami

Makoto Misawa

Yasuhiro Ishikawa

Yasushi Kikuchi

Ryoji Hanada

Hiroshi Hirakawa

Akinori Tokieda

Takekazu Inoue

Yoshinori Hunayama

A rubber composition for tire treads is disclosed which is designed to exhibit high resistance to skidding on wet, icy and snowy roads. A selected rubber blend of styrene-butadiene rubber and natural rubber and/or polyisoprene rubber is combined with a selected carbon black of specified specific surface areas and also with a selected softener of specified viscosity-gravity constants. The styrene-butadiene rubber consists essentially of two styrene-butadiene block copolymers each having varied styrene and vinyl contents and a specified transition temperature width, one block having a higher glass transition temperature than the other.

Rubber composition for use as a tire tread

A radial tire wherein part or the whole of the blocks present on the tread area have an angle .theta. of the direction in which the maximum shear rigidity is attained relative to the circumferential direction of the tire in the range of 40.degree..ltoreq..theta..ltoreq.75.degree., the direction in which the maximum shear rigidity of said block is attained and the direction of the cords of the outermost belt layer are opposite to each other with respect to the circumferential direction of the tire, the ratio of the maximum shear rigidity of said block to the minimum shear rigidity of said block is in the range from 1.4 to 1.8, and the total area of the block is 65% or more based on the total area of all the blocks.

Radial tire having reduced ply steer

Rubber compositions suitable for tire treads are disclosed. Starting rubbers made up of at least one SBR of -20.degree. C. to -40.degree. C. in Tg and at least one SBR of lower than -45.degree. C. in Tg are blended with specified amounts of carbon blacks having a N.sub.2 SA of more than 120 m.sup.2 /g and of softeners having a VGC of 0.90 to 0.98, whereby the compositions are provided with a storage shear modulus of less than 500 MPa at -30.degree. C. The compositions are excellent in friction performance, abrasion resistance and low-temperature resistance.

Rubber compositions for tire treads

A composite comprising a steel cords-covering rubber composition and a rubber composition which is contiguous thereto and contains a thiazole type vulcanization accelerator, at least one of these rubber compositions containing a m-cresol resin whereby they can be cured without decreasing the resulting strength of bond therebetween even after they have been left uncured in contact with each other for a considerable time.

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Hiratsuka, Japan

Shinji Kawakami