Abstract: Tandem wheels are carried on arms trailing from a hinge point to a vehicle chassis. The forward wheel trailing arm extends rearwardly of the wheel to termination under an air bag. The rear wheel trailing arm extends forwardly of chassis hinge point to termination on the top side of the same air bag associated with the forward trailing arm. The distance from each hinge point to the air bag is identical, and the distance from each wheel center to the associated hinge point is identical. A mechanical linkage measures the height of the air bag and either supplies additional air to or vents air from the bag, as required, to restore the bag to a predetermined height.