The present invention relates to the preparation of rubber compositions for tire tread and tire sidewall component applications. A tire is provided having tread of such composition designed for relatively heavy loads such as, for example, truck tires. A tire having a sidewall of such composition is also provided. Such tire component rubber compositions are of rubber compositions reinforced with precipitated silica and selected carbon black in specified amounts and prepared with a prescribed order of addition to the rubber composition and composed of elastomers as a specific combination of high trans styrene-butadiene rubber with natural or synthetic cis 1,4-polyisoprene rubber and cis 1,4-polybutadiene rubber.