jaymac

First question (thought I know it's been asked before). I have an '04 2.7T. I'm shopping for rear rotors and it appears there are 3 main choices: 255x10mm w/ 1558mm axle width & 47.8 height;
a 255x10mm - 53.8mm Height - w/ 1570mm Axle Width & 82mm Bearing
a 269x22mm

Can anyone say for sure which size is on my car, or do I have to physically remove the wheel and measure it? Would it be anywhere on the vehicle information sticker?

Now, as far as the diagnosis help, I dropped the car off today to get the wheels balanced and asked them to check my front rotors to see if they were warped as I've had some vibration under braking (worse under hard braking, faint under normal conditions)for a long time now. I replaced the fronts about 1 year and a half ago with Akebono ceramics and slotted discs. I've never touched the rears, but Audi quoted them @ 7 mm sometime during the fall. When I picked up the car today, they told me it was the rear rotors that were the problem. I asked him it he did a run-out test to determine that, and he said he didn't, but could tell by looking and driving it. I asked if the front rotors were fine, and he said they were. I didn't ask (and he didn't tell) if he did a runout test on the fronts to determine that. The balance feels much better now, but he said it would still feel a little off because of the rear rotors.
I don't want to go through the work and money of replacing rear discs and rotors if that might not be the problem. I have to do some more driving and diagnosing, but I believe I can feel the vibration through the steering wheel as well as the floorboards. So could poor rear rotors cause vibration through the steering wheel, or would it only come through the seats and floor board?

Thanks!
Jeremy