This invention relates to the preparation of a silica reinforced elastomer via preparation of a silica-elastomer masterbatch as a composite of synthetic silica and an emulsion polymerization prepared synthetic elastomer. Such masterbatch is prepared by introducing such silica and a silane into a latex of the synthetic elastomer and recovering the composite thereof The invention further includes a rubber composition of at least two elastomers wherein at least one of said elastomers is such masterbatched composite. A tire having a component of such rubber composition, particularly a tire tread, is specifically contemplated.