For stability and car control, the wheels and tires must be of the correct size and in good condition. Tires must be inflated to the correct recommended air pressures, and the wheels must be in proper alignment. For maximum safety and best all-around handling, always install replacement radial tires that are of the same specifications. When possible, all four tires should be replaced at once, or at least in pairs on the front or rear. New tires do not provide maximum traction, and should be broken in gently for the first 100 miles (160 kilometers) or so. Volkswagen warns against mixing tires of different design on the same car, i.e., bias ply with radial ply.