Two-piece tire with improved tire tread belt and carcass

A two-piece tire assembly having a removable tread belt for installing about the circumference of a tire carcass and a tire carcass having an inflated and unloaded outer circumferential surface having an axial dimension no greater than the axial width of the removable tread belt, the two-piece tire assembly being characterized by:

• the tread belt having a rubber tread, the rubber tread having a ground-contacting tread cap and a non-ground contacting tread base, wherein the tread base underlies the tread cap, and wherein the tread base comprises a tread base rubber compound comprising, per 100 parts by weight of elastomer (phr):
• from about 80 to about 100 phr of natural rubber or synthetic polyisoprene;
• from 0 to about 20 phr of polybutadiene;
• and
• from about 30 to about 70 phr of a filler selected from silica and carbon black;
• wherein the tread belt has a pair of lateral ends each axially extending beyond the inflated unloaded carcass at the outer circumferential surface of the carcass by a distance of at least 4% of carcass width as measured at the tread belt and carcass interface and wherein the tread belt width is at best equal to or wider than the loaded deflected carcass width as measured at the outer circumference of the carcass, each lateral end of the tread belt having a plurality of circumferentially extending cords in a first reinforcement layer and being radially inwardly flexible under load;
• and
• wherein the removable tread belt has a radially outer surface having a substantially flat tread arc radius R1 between the lateral ends extending from 50% to 75% of the tread belt axial width and a smaller tread arc radius R2 extending from the first tread arc R1, the tread outer surface having a sloping surface extending from a tangency to R2 to a lateral end, the radial difference in the tread belt surface as measured at the centerline of the tread belt and each lateral end of the removable tread belt being greater than 0.3% of the outside diameter as measured by the centerline of the tread belt.