Tyre noise reducing system

A tyre noise reducing system comprises a wheel rim (3a), a pneumatic tyre (2) to be mounted on the wheel rim and a noise damper (5/6) to be disposed in an annular tyre cavity enclosed by the wheel rim and the pneumatic tyre mounted thereon, wherein the noise damper is made of a multi-cellular material whose volume S2 is in a range of not less than 0.4 % of the volume S1 of said annular tyre cavity. Preferably, the specific gravity of the damper is set in a range of from 0.005 to 0.06.