Disclosed is a pneumatic tire comprising an innerliner comprising a functionalized poly(isobutylene-co-p-methylstyrene) elastomer, at least one layered filler; and less than 8 phr of at least one processing aid; wherein the innerliner possesses a permeation coefficient of less than 200 mm·cm3/m2·day at 40° C.; and wherein the tire is selected from truck tires, airplane tires, off-the-road tires and farm tractor tires. In a preferred embodiment, the tire is formed by a process of contacting the functionalized poly(isobutylene-co-p-methylstyrene) elastomer, at least one layered filler, and at least one solvent to form an nanocomposite composition; and combining the nanocomposite composition with the at least one processing aid and a curative composition to form the innerliner, then forming the tire comprising the innerliner.