Bridgestone Corporation

Koshiro Monji

Shinichi Iwasaki

Masayuki Ohashi

Ryuji Izumoto

Kentaro Fujino

Teruo Miura

A fiber composite material in which short fibers, such as polyester short fibers, are added to a matrix, such as a cross-linked rubber matrix, is provided, wherein a heat shrinkage ratio of the short fibers is 8% or less at fiber composite material molding temperatures of 140 to 200.degree. C. Also provided is a pneumatic tire in whose tire tread the fiber composite material is used. Such pneumatic tires include pneumatic tires provided with a foamed rubber layer in a tire tread. The foamed rubber layer has an average cell diameter of 10 to 120 .mu.m and an expansion ratio of 3 to 50%. A solid phase rubber portion of the foamed rubber layer includes 5 to 55 parts by weight of carbon black, 55 to 5 parts by weight of silica, and 1 to 15 parts by weight of short fibers to 100 parts by weight of a diene-base rubber component including 70 to 20 parts by weight of natural rubber and 30 to 80 parts by weight of polybutadiene rubber. A surface of the tire tread has a hardness of 52 or less at 0.degree. C. The short fibers have a length which is from 0.5 to 3 mm and which is shorter than a minimum gap between sipes of a tire surface, a diameter of 30 to 100 .mu.m, an aspect ratio of 5 to 100, and a heat shrinkage ratio of 8% or less at 140 to 200.degree. C. On-ice performance of the pneumatic tire of the present invention is excellent.

Growing community of inventors

Tokyo, Japan

Koshiro Monji