It is recommended to rotate tires after a specified period and as soon as one notices uneven wear on them; radial tires are preferred. When jacking the car up, don't use the parking brake but put a stopper under the wheels to prevent rolling. The entire vehicle should be raised at the same time, either by being lifted onto a hoist or by raising each corner with a jack and then lowering it on jack stands that can be placed under the frame rails. For safety purposes, have four jack stands. After rotating them, check tire pressures again and tighten the lug nuts.