An air suspension system for a multi-axle vehicle has an air bag system including at least one air bag operatively associated with the vehicle wheels on selected wheel and axle sets to control relative movement between each of the selected wheels and a supporting frame structure of the vehicle. The system has an air-flow control arrangement to control the flow of air into each air bag to thereby control the relative movement of the wheels and vehicle frame structure. A pressurizing arrangement is provided to maintain a selected, predetermined pressure in the air bag system when the vehicle is at rest to thereby maintain a desired vehicle height. The pressurizing arrangement includes a valve to admit pressurized air to or exhaust air from the air bag system to maintain the predetermined vehicle height. The valve is actuated by a link associated with a rocker member connected to spaced axles of the vehicle.