Abstract: Describes a free flowing particulate composition comprising, in combination, particulate amorphous precipitated silica, e.g., in the form of granules, hydrocarbon process oil, e.g., an aromatic process oil, and organic carboxylic acid having from 2 to 30 carbon atoms, e.g., stearic acid. The hydrocarbon process oil and organic carboxylic acid are sorbed on the silica and are present in amounts sufficient to measurably improve the dispersibility of the particulate amorphous precipitated silica into an elastomer as measured by percent white area. Optionally, an organosilane coupling agent may also be present in said composition. The free flowing particulate composition of the present invention is useful in reinforcing elastomers, e.g., rubbers used in vehicle tires and the soles of athletic foot wear.

Abstract: An all season tire tread rubber blend comprises about 30 to 50 parts per hundred low vinyl polybutadiene; about 25 to 60 parts per hundred natural rubber and/or synthetic polyisoprene; and about 10 to 25 parts per hundred high styrene styrene/butadiene rubber and/or other diene polymer having a glass transition temperature of about -5.degree. to about -20.degree. C. A preferred embodiment comprises about 40 parts per hundred low vinyl solution polybutadiene, about 40 parts per hundred natural rubber, and about 20 parts per hundred high styrene solution styrene/butadiene. Tires employing the tire tread rubber of this invention exhibit improved wet and winter traction and superior abrasion resistance and treadwear without increased rolling resistance.