Pneumatic rubber tire with a tread composed of a rubber blend of a base of at least two synthetic elastomers composed of (i) specialized isoprene/butadiene copolymer elastomer having a low Tg in a range of about -70.degree. to about -100.degree. C. and (ii) a diene based elastomer having a Tg in a range of about -5.degree. to about -30.degree. C. together with a minor amount of natural cis 1,4-polyisoprene rubber. Selection of the base of the said two synthetic elastomers having spaced apart, or spatially defined, Tg's of at least 40.degree. C. is an important feature of the tread rubber blend. Representative examples of contemplated elastomers with Tg's in a range of about -5.degree. to about -30.degree. C. are 3,4-polyisoprene elastomer, styrene/isoprene copolymer elastomer and high vinyl polybutadiene elastomers.In one aspect, the tread rubber blend is reinforced with reinforcing filler composed of carbon black or a combination of carbon black and silica accompanied by a coupling agent.