I know this has been posted before but I already went through the usual fixes. New rotors , NAPA Premium Ultras and new pads. The wheels were torqued not air gunned. The balancing was checked. 18" after market rims with 275/65/18 Hankook RF10s. The vibration is real bad at 45 mph and it pulses at slow speed. Since the new rotors and pads it has improved but not gone. I found this posted on another thread; The factory puts on two copper keepers over the lug nuts to help with installing the rotor. These keepers are two per wheel, they are smashed in when the wheel is set with an impact gun. Did you pull them off when you replaced the wheels. I was told by a trusted GM mechanic that those can make aftermarket wheels wobble. I assume they mean the copper rings they put over the studs to hold the rotor on. Has anyone else heard of this. By the way the truck is an 07 Silverado NBS ext cab LT2 Z71 with discs up front and drums in the rear. I am at the end of my rope!!!! Any help would be soooo appreciated!!