Tire having tread portion with rubber to control wear

Abstract

A tire comprising a pair of beads; a carcass ply having ends, each ends anchored to a respective bead; at least one belt ply extending circumferentially around the tire and disposed radially outward of the carcass ply; and a tread portion disposed radially outward of the belt ply. The tread portion has a plurality of tread ribs or blocks and at least one groove disposed between adjacent tread ribs or blocks. In one aspect of the invention, the tread portion is formed from first and second rubber portions. The second rubber portion has a hysteresis value greater than the first rubber portion and a modulus value less than first rubber portion. In another aspect of the present invention, the tread portion is formed from a first and second tread compound. The hysteresis value of the second tread compound is greater than the hysteresis value of the first tread compound and the modulus value of the first tread compound is less than the modulus value of the second tread compound. In another aspect of the present invention, the tread portion is formed from a rubber with a modulus of between approximately 2 and 3 N/mm2, and a tan δ value of between approximately 0.2 and 0.4 under normal operating conditions. The present invention reduces the maximum longitudinal contact stress, maximum lateral contact stress, and the maximum normal contact stress on the tread layer relative to conventional tires, hence increasing the robustness of the tire with respect to tread wear.

Dependencies are inferred from the claim text.