Patent ID: 6465560
Filing Date: 2002-10-15
Classification: B60C,C08L

Abstract:
A pneumatic rubber tire having a circumferential rubber tread where said tread is a rubber composition comprised of, based on 100 parts by weight of the tread rubber,(A) conjugated diene-based elastomers comprised of (1) from 55 to about 85 phr of cis 1,4-polybutadiene rubber having a Tg within a range of about âˆ’95Â° C. to about âˆ’105Â° C.; (2) from about 15 to 45 phr of at least one elastomeric styrene/butadiene copolymer rubber having a bound styrene content in a range of about 30 to about 55 percent selected from one of (i) emulsion polymerization prepared styrene/butadiene copolymer having a Tg within a range of âˆ’15Â° C. to âˆ’45Â° C.; or (ii) organic solution polymerization prepared tin coupled styrene/butadiene copolymer having a Tg within a range of âˆ’55Â° C. to âˆ’25Â° C.; (3) a range of from 0 to about 15 phr of a medium vinyl polybutadiene having a vinyl content in a range of about 45 to about 70 and a Tg in a range of about âˆ’55Â° C. to about âˆ’35Â° C.; wherein the Tg of said cis 1,4-polybutadiene elastomer is at least 50Â° C. lower than the Tg of the said styrene/butadiene rubber and tin coupled styrene/butadiene rubber; and (4) a range of from zero to about 15 phr of cis 1,4-polyisoprene rubber having a Tg in a range of about âˆ’65Â° C. to about âˆ’70Â° C. (B) about 60 to about 110 phr of reinforcing filler comprised of amorphous silica; and (C) a coupling agent having a moiety reactive with hydroxyl groups contained on the surface of said silica and another moiety interactive with at least one of said diene-based elastomers.