Abstract: A flexible, homogeneous rubbery product comprising a matrix of a rubber selected from the group consisting of natural and synthetic elastomer in which there is uniformly dispersed at least 5% by weight based on the weight of the elastomer of a crystalline polyolefin whose molecular weight is equal to or greater than 500,000. A substantial proportion of the polyolefin is in the condition or form of fine particles which are drawn out in the form of elongated fibrils having a diameter smaller than 5 microns. This product exhibits a very high resistance to elongation in at least one direction.

Abstract: A safety tire comprising a tread (11), spaced beads (12) and sidewalls connecting the beads to the sides of the tread by forming under the tread a central inflatable chamber, each sidewall comprising an outside wall convex towards the outside and an inside partition convex towards the inside delimiting between each other lateral chambers distinct from the central inflatable chamber, characterized in that said lateral chambers are filled with a flexible cellular material rendering the sidewalls suitable to support the load of the wheel with a limited sagging of the tire in case of the deflating of the central chamber.