| 主权项 |
1. A pneumatic tire having a circumferential rubber tread of a rubber composition comprised of, based on parts by weight per 100 parts by weight elastomer (phr):
(A) 100 phr of conjugated diene-based elastomers, exclusive of elastomers containing styrene, comprised of;
(1) about 25 to about 75 phr of a high vinyl polybutadiene rubber having a Tg in a range of from about −40° C. to about −10° C. and an isomeric vinyl 1,2-content in a range of from about 70 to about 85 percent,(2) about 75 to about 25 phr of a low vinyl polybutadiene rubber having a Tg in a range of from about −108° C. to about −90° C. and an isomeric vinyl 1,2-content in a range of from about 0 to about 15 percent,provided that the ratio of said low vinyl to high vinyl polybutadienes is at least 1/1,
(B) about 80 to about 200 phr of rubber reinforcing filler comprised of a combination of precipitated silica and rubber reinforcing carbon black in a ratio of precipitated silica to rubber reinforcing carbon black of at least 9/1, together with silica coupling agent having a moiety reactive with hydroxyl groups on said precipitated silica and another different moiety interactive with said diene-based elastomers, and (C) about 10 to about 60 phr of a traction promoting resin selected from at least one of styrene-alphamethylstyrene resin, coumarone-indene resin, petroleum hydrocarbon resin, terpene polymer, terpene phenol resin and rosin derived resins and copolymers, wherein such resins have a softening point (ASTM E28) in a range of from about 60° C. to about 150° C. |
