I mic'd a new (from PP/not OEM) rear rotor last nite and found they are a tad bit shy of the OEM. Haynes lists the OEM at .374" which I verified off the old rotor's outer rim. You know the part that never gets turned unless you specify that you want it turned, also.
However, the new one mic'd .365". Hmmmm. Does anyone remember the min amount that you can take off an undamaged rotor?