89 9bolt rear if it matters... anyone know the the thickness a rotor should be b4 it needs replacement... i wanna measure mine. I can say on the piston side there is over a 1/8 in groove on it and the oposite side is about a 1/8 of an in.

 

Minimum tolerances will be stamped on the rotor by law. Check under the backside hat area.

 

there is nothing on the back... on the front there is a 4 diget# 2669 or somethin liek that (3's off the top of my head) how thick are the rotors supposed to be? i need help quick cause they wont let me pass emissions till it get's fixed