Method of preparing a self-sealing pneumatic tire

A method of preparing a self-sealing pneumatic tire which comprises (A) building a green, unvulcanized rubber tire construction;

• said construction comprised of tread, spaced beads, connecting sidewalls and supporting structure and having an adherent unvulcanized rubber layer containing a heat activatable, gas liberating blowing agent on its inner surface, (B) shaping, molding and heating said tire construction under pressure to substantially simultaneously both covulcanize said construction and adherent layer and activate said blowing agent to cause its decomposition to form a gaseous product and (C) releasing said pressure to allow expansion of said gaseous product and provide a pneumatic tire having an integral, thin gauge, covulcanized, resilient rubber closed cell structure on its inner surface with said closed cells containing a gas under a greater than atmospheric pressure.