A composition well suited to forming gas barrier layers in elastomeric articles is described. The barrier layer may be incorporated into, for instance, inflatable articles that are intended to contain a gas, such as air, under pressure. For example, in one embodiment, the barrier layer may be incorporated into a tire for preventing oxygen or other gaseous components from migrating through the tire. In general, the barrier layer is made from an elastomer that is combined with permeability reducing particles, such as a silicate, and a terpene hydrocarbon resin having a relatively high glass transition temperature. The terpene hydrocarbon resin can improve the processability of the composition and, in one embodiment, can even serve to improve the permeability characteristics of the barrier layer.