For 1990-2009 cars

In manufacturing the brake rotor, tolerances of the braking surfaces for flatness, parallelism, and lateral runout are held very close. The maintenance of close tolerances on the shape of the braking surfaces is necessary to prevent brake roughness and brake noise.

In addition to these tolerances, the surface finish must be held to a specified range. The control of the braking surface finish is necessary to avoid pulls and erratic performance and to extend lining life.

When performing routine brake maintenance, rotors should not be refinished, unless there is a brake pulsation caused by the rotors or the rotors are excessively scored.

Scoring of the rotor surfaces not exceeding 1.5 mm (0.060 in) in depth, which may result from normal use, is not detrimental to brake operation.