I've been reading a lot lately about the pros and cons of various break pads, and of course some of it has to do with wear and tear on the rotors. My question is, how does one determine when it's time to replace the rotor? Those babies are expensive, but on the other hand if I use soft brakes and have to change them repeatedly replacing the rotors might make more sense (cents??). I've only got about 14,000 miles so far with the stock brakes and the rotors are already somewhat scratched up, is there a check on the thickness? I don't have the manual in from of me to see if there is anything in there on that. Thanx.