A pneumatic radial tire having a circumferentially extending equatorial plane of the tire, the tire comprising a carcass, a tread radially outward of the carcass, the carcass comprising at least one carcass reinforcing ply, opposing bead portions, and opposing sidewalls, the carcass reinforcing ply having a main portion extending between the opposing bead portions and a pair of turnup portions, each turnup portion extending from one end of the main portion, each bead portion having a bead core, and a reinforcement cavity outward of each bead core, the cavity located between the main portion and one turnup portion of the at least one reinforcing ply, the tire characterized by: the tread comprising a radially outer tread cap and a radially inner tread base radially underneath the tread cap, the tread base comprising a rubber composition comprising from 15 to 45 phr of styrene-butadiene rubber; from 20 to 50 phr of polybutadiene; and from 10 to 35 phr of natural or synthetic polyisoprene, and from 35 to 65 phr of carbon black, wherein the rolling resistance of the tire is from 1 to 10 percent lower that for an otherwise identical tire not including the tread base.