Abstract: A tire noise reducing system comprises a wheel rim, a pneumatic tire and a noise damper disposed in the tire cavity and made from a spongy material whose total volume is in a range of from 0.4 to 20% of a volume of the tire cavity. The maximum thickness of the damper between the base end surface and the top end surface is in a range of from 1.0 to 4.5 cm. The width of the base end surface is more than the maximum thickness. The width of the damper is not increased in the direction from the base end surface to the top end surface, and each of side faces defined as extending from the edges of the base end surface to the edges of the top end surface is at least partially provided with an aslant portion inclined at an angle theta of from 30 to 75 degrees with respect to the base end surface. The damper is preferably fixed to the inside of a tread portion of the tire.