Tire with tread for combination of low temperature performance and for wet traction

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 styrene/butadiene elastomer and cis 1,4-polybutadiene rubber together with liquid styrene/butadiene polymer comprised of;

(1) about 25 to about 75 phr of a styrene/butadiene elastomer having a Tg in a range of from about −35° C. to about −5° C. and an uncured Mooney viscosity (ML1+4) 100° C. in a range of from about 60 to about 100, and

(2) about 25 to about 75 phr of high cis 1,4-polybutadiene rubber having a Tg in a range of from about −100° C. to about −109° C., a cis 1,4-isomeric content of at least about 95 percent and an uncured Mooney viscosity (ML1+4) 100° C. in a range of from about 50 to 100, together with

(3) about 3 to about 50 phr of low molecular weight liquid styrene/butadiene polymer having a number average molecular weight in a range of from about 3,000 to about 30,000 and a Tg in a range of from about −30° C. to about 0° C.,

(B) about 50 to about 250 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 polymer,

(C) about 5 to about 35 phr of traction promoting resin consisting of styrene-alphamethylstyrene resin having a softening point in a range of from about 60° C. to about 125° C. and a styrene content of from about 10 to about 30 percent, and

(D) about 10 to about 50 phr of vegetable triglyceride oil comprised of soybean oil

wherein said styrene/butadiene elastomer is a functionalized tin or silicon coupled elastomer having functional groups comprised of at least one of amine, siloxy and thiol groups reactive with hydroxyl groups on said precipitated silica.

2. The tire of claim 1 wherein said tire is sulfur cured.

3. The tire of claim 1 wherein said tread rubber composition further contains up to 25 phr of at least one additional diene based elastomer comprised of at least one of cis 1,4-polyisoprene isoprene/butadiene, styrene/isoprene, and 3,4-polyisoprene rubber.

4. The tire of claim 1 wherein said precipitated silica is a pre-formed composite of said precipitated silica and silica coupling agent.