| 主权项 |
1. A pneumatic rubber truck tire having a circumferential rubber tread with an outer cap rubber layer comprised of, based on parts by weight per 100 parts by weight of the tread cap rubber (phr),
(A) 100 phr of diene-based elastomers, and (B) about 40 to about 80 phr of reinforcing filler comprised of a combination of rubber reinforcing carbon black and precipitated silica (amorphous synthetic silica) comprised of:
(1) about 20 to about 40 phr of rubber reinforcing carbon black, and(2) about 20 to about 40 phr of precipitated silica, wherein said precipitated silica is used in combination with silica coupling agent having a moiety reactive with hydroxyl groups on said precipitated silica and another different moiety interactive with carbon-to-carbon double bonds of said diene-based elastomers,wherein said diene-based elastomers are comprised of:
(a) from about 30 to about 50 phr of cis 1,4-polyisoprene rubber,(b) about 25 to about 45 phr of cis 1,4-polybutadiene rubber, and(c) about 15 to about 35 phr of styrene/butadiene rubber having a Tg in a range of from about −60° C. to about −85° C., and a styrene content from about 14 to about 20 percent, wherein said styrene/butadiene rubber is comprised of:
(i) non-functionalized styrene/butadiene rubber, or(ii) functionalized styrene/butadiene rubber containing functional groups comprised of at least one of siloxy, amine and thiol groups reactive with hydroxyl groups on said precipitated silica. |
