Abstract: This invention relates to the preparation of an elastomer which contains a dispersion of a reinforcing system formed in situ within an elastomer host by the interaction of a telechelic hydroxy and/or alkoxy terminated polysiloxane and a reticulating agent having a moiety comprised of at least two alkoxy groups. The invention further includes a rubber composition of at least two elastomers wherein one of said elastomers is a pre-formed composite of elastomer and the in situ formed reinforcement system. A tire having a component of such rubber composition, particularly a tire tread, is specifically contemplated.