Pneumatic rubber tires are conventionally prepared with a rubber tread. Such tread is often composed of a blend of rubber.
In one aspect, the rubber composite for the tread may be designed to improve the rolling resistance of the tire without unduly sacrificing its traction (skid resistance) or treadwear. Such often desirable aspect is usually difficult to obtain with a single tread rubber compound because, for example, rolling resistance reduction is typically obtained at the expense of traction and/or treadwear.
Pneumatic rubber tires have been manufactured with treads composed of butadiene/styrene copolymer, natural rubber and cis 1,4-polybutadiene rubber for such purpose where the butadiene/styrene rubber contained about 20-25 percent styrene. For example, such tread might be composed of, based on 100 parts by weight of the rubber component, about 50 parts butadiene/styrene copolymer containing about 20-25 percent styrene, about 25 parts natural cis 1,4-polyisoprene and about 25 parts cis 1,4-polybutadiene.