just wondering when you should replace the rotors on a 91 integra LS. The service manual says the service limit for using a lathe is .750 inches, but is that also when they should be replaced? I measured my rear rotors at .393 inches.
your rear rotors are fine. the rears are much smaller than the fronts because the frons do most of the work. below is a list of the measurements for front and rear discs, pads and runout tests. Good luck!
rotor thickness- standard is 21mm (0.839 in) refinishing limit is 19mm (0.750 in)
runout check- mount dial indicator 10 mm away and measure run out. should be less than 0.10mm
pads- 11.5mm (0.450in) standard, 1.6mm (.060in) limit
rotor thickness- 10.0mm (0.390in)standard, refinishing limit 8.0mm (0.315 in)
Pads- 8.0mm standard (.310 in) 1.6mm (.060in) limit
Runout-mount dial indicator 10 mm away and measure run out. should be less than 0.15mm