Abstract: Non-pneumatic tires are disclosed having a support structure that includes an outer reinforced annular band, a hub and a set of supports extending between the hub and radially inward from the outer reinforced annular band. The support structure is formed at least in part of a polyurethane produced from a prepolymer comprising a reaction product of an aromatic diisocyanate monomer and an active hydrogen component selected from a polyol, a polyamine or combinations thereof, the aromatic diisocyanate monomer and the active hydrogen component mixed at a ratio of NCO to isocyanate-reacting function group of at least 1.8:1, wherein the active hydrogen component has a number average molecular weight of between 1000 and 6000 and wherein the prepolymer contains no more than 10 wt % of residual aromatic diisocyanate monomer. The reaction components also include a curative.