To reduce the generation of noise in a car room during ordinary running without damaging running durability when a filled air pressure is rendered ineffective.

A belt 6 consisting of two belt layers 6a and 6b having cords crossing each other between layers is disposed on the outer peripheral side of a carcass 5 consisting of two plies 5a and 5b extending between bead cores 4. Two belt auxiliary layers 7a and 7b formed of cords extending substantially peripherally of a tire are disposed on the outer peripheral side of the belt 6, and a reinforcing rubber 9 approximately in the shape of a new moon in a radial section shape is arranged on the inner peripheral side of the carcass 5. The belt auxiliary layers 7a and 7b are formed of an organic fiber cord specified that ductility under a load of 1.4 gf/d at 50±5°C is set to 2.7% or less and ductility under a load of 0.7 gf/d at 170±5°C is set to 1.5-6.0%.