Preparation of silica reinforced polyisoprene-rich rubber composition and tire with component thereof

This invention relates to the preparation of a cis 1,4-polyisoprene rubber-rich rubber composition containing precipitated silica which has been pre-treated with a fatty alcohol and/or epoxidized soybean oil together with an organosilane containing polysulfide coupling agent and to tires having at least one component comprised of such rubber composition. The invention particularly relates to a process of (a) preparing a natural rubber-rich rubber composition comprised of pre-treating precipitated silica aggregates prior to blending with, or in the presence of, dry natural rubber with a fatty alcohol and/or epoxidized soybean oil to the exclusion of sulfur curative for the natural rubber, mixing an organalkoxysiloxane based polysulfide coupling agent with said dry natural rubber coincidentally with or subsequent to said precipitated silica aggregate fatty alcohol and/or epoxidized soybean oil pre-treatment to form a composite thereof, to the exclusion of sulfur curative, followed by (b) mixing the resulting rubber mixture with sulfur curative and (c) curing the resulting rubber composition.