Brake pads should be inspected once a year or at 6,000 mile (9,662 km) intervals, whichever occurs first. Check both ends of the outboard pad, looking in at each end of the caliper; then check the lining thickness of the inboard pad, looking down through the inspection hole. On riveted pads, the lining should be more than 1⁄32 in. (0.8mm) thick above the rivet (so that the lining is thicker than the metal backing in most cases), in order to prevent the rivet from scoring the rotor. On bonded brake pads, a minimum lining thickness of 1⁄32 in. (0.8mm) above the backing plate should be used to determine necessary replacement intervals. Keep in mind that any applicable state inspection standards that are more stringent take precedence. All four rear pads MUST be replaced as a set if one shows excessive wear.