Minimum Rotor Thickness

Here is the specs System
Original
Thinnest (Refinishing)
Replacement (Discard)

JB5/JD5/JB6
31.75 mm (1.25 in)
31.25 mm (1.23 in)
30.86 mm (1.215 in)

JB7/JD7/JB8
32 mm (1.26 in)
31.25 mm (1.23 in)
30.86 mm (1.215 in)

JB8 Dual
38.10 mm (1.50 in)
37.59 mm (1.480 in)
37.21 mm (1.465 in)

JF9
36.26-36.64 mm (1.428-1.443 in)
35.1 mm (1.382 in)
34.7 mm (1.366 in)

Z56
32 mm (1.26 in)
31.25 mm (1.23 in)
30.86 mm (1.215 in)

Rotor thickness varies on this model depending on option packages but for the most part the minimum thickness is cast into the rear side of the rotor where it mounts to the hub. It should be very visible. This is your min. Thickness. If the rotor is not more than 1-1.5ml above the min spec you should replace the rotors.