Inspect the brake pads every 10 000 km (6,000 miles) and any time that the wheels are removed (tire rotation, etc.). Check both ends of the outer brake pad by looking in at each end of the caliper. These are the points at which the highest rate of wear normally occurs. However, at the same time, check the brake pad thickness on the inner pad to make sure that it has not worn prematurely. Some inboard brake pads have a thermal layer against the steel backing surface, integrally molded with the pad. This extra layer should not be confused with uneven inboard-outboard pad wear. Look down through the inspection hole in the top of the caliper to view the inner brake pad. Replace disc brake pads whenever the thickness of any pad is worn within 0.76 mm (0.030 in) of the steel backing surface. Replace all disc brake pads at the same time.