I have an 07 Silverado Crew Cab 2wd LS, it came factory with 17 inch wheels and I just upgraded to 20 inch KMC Slide wheels. The truck has less than 5K on it but now it vibrates really bad when breaking. Anyone know what might have cause this? The wheels are torqued to 140ft/lbs. but I'm not sure if the brake caliper clips have been removed and I have hear this may cause the problem, is there any truth to that??? Could they have over tightened the lug nuts and warped the rotors???
PLEASE HELP!  

it seems highly unlikely, your rotors are warped, most of the time there would be other symptoms, to go along with the obvious vibrations, it could be the wheels, their offset, or simply the balance, the caliper pins only become a issue when the offset is wrong , get it checked out quick, you dont want those chrome wagon wheels coming off,  

Well believe it not my rotors were warped. NTB turned the rotors and it brakes fine. I would not have thought that over torquing the lugnuts or tighting them in the wrong order would have caused the rotors to warp enough to cause the problem I was having.