A self-supporting pneumatic tire, capable of continued operation during under-inflation conditions, has at least one insert located in each tire sidewall. Forming the interior surface of the self-supporting tire is a stiffening layer of material having characteristics similar to that of the insert. In the tread region of the tire, and radially inward of the innermost carcass layer, and possibly in the interior bead region of the tire, is a partial inner liner layer of the bromobutyl rubber.