This invention is based upon the discovery that micronized solution styrene-butadiene rubber from postconsumer sources can be included in rubber formulations without severely compromising abrasion resistance. The micronized solution styrene-butadiene rubber utilized in the rubber formulations of this invention can be made by cryogenic grinding postconsumer rubber products using conventional procedures. For instance, it can be made by cryogenically grinding a tire tread containing a high level of solution styrene-butadiene rubber. The micronized solution styrene-butadiene rubber can then be blending into desired virgin rubbers and cured without significantly compromising the abrasion resistance of the rubber formulation. The rubber formulation of this invention is comprised of a natural or synthetic rubber and from 1 weight percent to 30 weight percent of a micronized rubber composition containing at least 10 weight percent solution styrene-butadiene rubber and having a particle size of 40 mesh to 200 mesh.