The Toyo Rubber Industry Co., Ltd.

Takuya Okazaki

Masanori Kan

Tatsuo Sakashita

Keijiro Oda

Masahide Nishihata

Yukitoshi Morishita

Toyohiko Asada

A carcass rubber composition for tires comprising a polymer blend of diene synthetic elastomer and natural rubber. Said diene synthetic elastomer contains a solution polymerization star shaped SBR, preferably, in the ratio of 20-50 percent. 1, 2 structure in the butadiene unit is preferably less than 50 percent. The styrene content is preferably 10-20 percent.

Composition for carcass of tire

An automotive tire tread having a low rolling resistance including a cap tread rubber and a base tread rubber wherein the value of the loss tangent of the cap tread rubber is not more than 0.24 and the value of the resilience of the cap tread rubber is more than 60%. In addition, the value of the loss tangent of the base tread rubber should be less than that of the cap tread rubber.

Tire tread having low rolling resistance

A rubber composition for a side wall of tires comprising a polymer blend of 20-100 parts by weight of solution polymerization star shaped SBR and 80-0 parts by weight of natural rubber and/or diene synthetic rubber. The glass transition temperature (Tg) of said star shaped SBR is preferably less than -50.degree. C. Styrene content in said star shaped SBR is preferably less than 20% parts by weight.

Rubber composition for side wall of tire

A pneumatic radial-ply tire having a tread constructed of at least two kinds of rubber which is capable of attaining both braking performance and rolling resistance. The tread portion is constructed so that the tread center zone is comprised of a rubber having a low hysteresis loss and the tread side zones adjacent to the center zone on both sides thereof or the outer layers of them are each comprised of a rubber having a high hysteresis loss; the tread center zone and the tread side zones are disposed in parallel to each other in the circumferential direction or the tread side zones are each disposed adjoining to the tread center zone and in a superposing manner.

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Toyonaka, Japan

Takuya Okazaki