A pneumatic run flat tire comprising a carcass layer mounted between a pair of left and right bead portions, a belt layer disposed on an outer circumferential side of the carcass layer in a tread portion, and an inner side reinforcing rubber layer having a falcated cross-section disposed on an inner side in a tire width direction of the carcass layer in a side wall portion;
- wherein:
- the inner side reinforcing rubber layer and an outer side rubber layer positioned on an outer side in the tire width direction of the carcass layer in the side wall portion are divided into an external diameter side region, a middle region, and an internal diameter side region, which are respectively laminated in a tire radial direction such that the external diameter side region is in contact with the middle region and the middle region is in contact with the internal diameter side region;
- a dynamic elastic modulus E′10A at 60° C. of a rubber composition included in the external diameter side region of the inner side reinforcing rubber layer, a dynamic elastic modulus E′10B at 60° C. of a rubber composition included in the middle region of the inner side reinforcing rubber layer, and a dynamic elastic modulus E′10C at 60° C. of a rubber composition included in the internal diameter side region of the inner side reinforcing rubber layer are configured so as to satisfy the relationships E′10A<E′10B<E′10C and E′10A≧4.0 MPa;
- a value T10A of a tan δ at 60° C. of the rubber composition included in the external diameter side region of the inner side reinforcing rubber layer, a value T10B of a tan δ at 60° C. of the rubber composition included in the middle region of the inner side reinforcing rubber layer, and a value T10C of a tan δ at 60° C. of the rubber composition included in the internal diameter side region of the inner side reinforcing rubber layer are configured so as to satisfy the relationships T10A<T10B<T10C and T10A≦0.06;
- a dynamic elastic modulus E′20A at 60° C. of a rubber composition included in the external diameter side region of the outer side rubber layer, a dynamic elastic modulus E′20B at 60° C. of a rubber composition included in the middle region of the outer side rubber layer, and a dynamic elastic modulus E′20C at 60° C. of a rubber composition included in the internal diameter side region of the outer side rubber layer are configured so as to satisfy the relationships E′20B<E′20A≦E′20C and E′20C/E′20B≧1.6;
- and
- a ratio E′20A/E′10A of the dynamic elastic modulus E′20A at 60° C. of the rubber composition included in the external diameter side region of the outer side rubber layer to the dynamic elastic modulus E′10A at 60° C. of the rubber composition included in the external diameter side region of the inner side reinforcing rubber layer, and a ratio E′20C/E′10C of the dynamic elastic modulus E′20C at 60° C. of the rubber composition included in the internal diameter side region of the outer side rubber layer to the dynamic elastic modulus E′10C at 60° C. of the rubber composition included in the internal diameter side region of the inner side reinforcing rubber layer are configured so as to satisfy the relationships 0.6≦E′20A/E′10A≦1.0 and 0.6≦E′20C/E′10C≦1.0.