The present invention relates to a modified crumb rubber particle having carbon to silicon bonds created by the reaction of the unsaturation in the crumb rubber particle and silicon hydride, with or without the use of a catalyst. Bound silicon content ranges from about 0.1% to 10% by weight. The silicon-modified crumb rubber can be used as is or a reinforcing filler in formulations. Typically the silicon-modified crumb rubber is used in up to 25% by weight of the total rubber present in virgin rubber compositions.