Abstract: The present invention provides an elastomeric composition processable in a curable, filled rubber formulation. The composition comprises a halogenated interpolymer of a C4 to C7 isoolefin and from 3 to 20 weight percent alkylstyrene and comprising from 0.2 to 2 mole percent haloalkylstyrene, a Mooney viscosity less than 27, a number average molecular weight less than 270,000, a weight average molecular weight less than 470,000, a z-average molecular weight less than 700,000, and a branching index (g?) from 0.4 to 1.1. Also disclosed are a method of making a cured, filled rubber article, comprising compounding the elastomeric composition with filler and curative, processing the compounded composition to form a shape of the article, and curing the composition to obtain the article in the formed shape, as well as a tire comprising an innerliner made by the method.