Lateral Runout
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1990 Pontiac Bonneville, 1990 Oldsmobile Ninety-Eight, 1990 Oldsmobile Eighty-Eight, 1990 Cadillac Fleetwood, and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Raise and support vehicle. Mark relationship of wheel to hub and remove wheel. Reinstall 2 lug nuts to retain rotor to hub. Clamp a dial indicator to caliper so it contacts rotor at a point about 1/2 inch from outer edge. Turn rotor one full revolution. Check indicator reading. If reading exceeds specification, refinish or replace rotor.