Loosen the wheel lug nuts, raise the vehicle and support it securely on jackstands, remove the wheel and install the lug nuts to hold the disc in place against the hub flange. If the lug nuts don't contact the disc when screwed on all the way, install washers under them. Release the parking brake if checking the rear disc. Remove the 
Brake Caliper, suspend the caliper out of the way with a piece of wire and remove the two caliper mounting bracket-to-steering knuckle bolts or, on rear calipers, the bracket-to-knuckle bolts and remove the mounting bracket. Visually inspect the disc surface for score marks and other damage, and check disc runout with a dial indicator. If pulsating has been noticed during application of the brakes, suspect disc runout. Remove the lug nuts which were installed to hold the disc in place, or remove the two disc retaining screws and remove the disc from the hub. Place the disc in position over the threaded studs, install the disc retaining screws and tighten them securely, install the caliper mounting bracket and caliper, tightening the bolts, install the wheel, then lower the vehicle to the ground. Tighten the lug nuts, depress the brake pedal a few times to bring the brake pads into contact with the disc and check the operation of the brakes carefully before driving the vehicle.