For 1990-2009 cars

Caution: Refer to Brake Dust Caution in the Preface section.

1. Clean the brake pad lining contact surface of the brake rotor with denatured alcohol or an equivalent brake cleaner.
2. Using a micrometer calibrated in ten-thousands of an inch, measure and record the lowest thickness of the brake rotor at 4 or more points, equally spaced around the rotor.

Ensure that the measurements are only taken within the brake pad lining contact area and that the micrometer is positioned the same distance from the outside edge of the rotor for each measurement.

3. Compare the lowest thickness measurement recorded to the following specifications:

Specification
Brake rotor discard thickness 25.6 mm (1.00 in).

4. If the lowest thickness measurement of the brake rotor is above the brake rotor discard thickness 25.6 mm (1.00 in); the rotor may be able to be refinished, depending upon surface and wear conditions which may be present.
5. If the lowest thickness measurement of the brake rotor is at or below the discard thickness specification 25.6 mm (1.00 in); the rotor requires replacement.