To provide sufficient run flat durability, to improve the cord cut resistance of a carcass ply and to make a tire lightweight by specifying the gauge of an inner liner rubber at the hump section of the tire and the oxygen partial pressure of the gas filled in the assembly.

The gauge Gi of an inner liner rubber 8 measured on the normal line VL drawn to the outside surface of an outside ply 6-2 from the hump section H of a tire 1 is set to 1.3 mm or below. The oxygen partial pressure of the pressure gas filled in an assembly of the tire 1 and a rim 15 is set to 15% or below. The oxygen quantity infiltrating into the constituting members of the tire 1 can be decreased, and the weight of the tire 1 can be reduced when the thickness of the inner liner rubber 8 is set to 1.3 mm or below. The heat quantity of the inner liner rubber 8 during a flat travel can be sharply decreased, and run flat durability can be improved.