The Yokohama Rubber Co., Ltd.

Eri Miura

Tetsuji Kawazura

Kinya Kawakami

Shingo Midorikawa

A pneumatic tire in which the cap tread portion is composed of a rubber composition comprising (i) 100 parts by weight of a diene rubber having a glass transition temperature (Tg) of not more than -45.degree. C. and (ii) not more than 65 parts by weight of carbon black having a nitrogen specific surface area (N.sub.2 SA) of not less than 140 m.sup.2 /g, a DBP oil absorption of not less than 120 ml/100 g, a .DELTA.DBP of not less than 30 ml/100 g, and a half value (.DELTA.Dst) of distribution of aggregates, measured by a centrifugal precipitation method, of not more than 50 m.mu., or a pneumatic tire in which a cap tread portion is composed of a rubber composition comprising (A) 100 parts by weight of a rubber component mainly comprising natural rubber and polybutadiene rubber and having a hardness at 0.degree. C. of not more than 60 and (B) (i) carbon black having a nitrogen specific surface area (N.sub.2 SA) of not less than 120 m.sup.2 /g and a 24M4DBP of not less than 90 ml/100 g and (ii) a silica in an amount of 5 to 40 parts by weight, with the total weight of the carbon black and silica being not more than 60 parts by weight.

Pneumatic tire including cap tread portion

Rubber compositions for automotive tire treads are made up of a selected class of base rubbers and a selected class of synthetic plasticizers in specified amounts. The plasticizer is derived from esterification of a diglycerin or an alkylene oxide adduct of a polyhydric alcohol with a selected class of higher fatty acids. Gripping performance is maintained for a prolonged period of time.

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Hiratsuka, Japan

Eri Miura