A run flat tire having a side reinforcing rubber part is disclosed. The side reinforcing rubber part is formed by a rubber composition having a ratio (M50H/M50N) of tensile stress (M50H) in 50% elongation at a measurement temperature of 100° C. to tensile stress (M50N) in 50% elongation at a measurement temperature of 23° C. of from 1.0 to 1.3. A ratio (M50H/M50F) of tensile stress (M50H) in 50% elongation at a measurement temperature of 100° C. of the rubber composition forming the side reinforcing rubber part to tensile stress (M50F) in 50% elongation at a measurement temperature of 100° C. of a rubber composition forming a bead filler is from 0.5 to 1.3.