A vehicle tire is inflated with water and is associated with one or more hollow vessels of rigid construction each containing a compartment for a gas such as air, the compartment having at least one flexible wall. The vessels have ports which admit water when the tire is compressed as in bouncing or riding over an object in the road. Some of the ports may be valved to prevent escape of water so expansion of the air, after it has been compressed by deformation of the flexible wall when the water enters the vessel, is retarded and the normal bounce of the tire is damped.