My wife's 99 Tahoe developed a bad vibration in the whole truck, including a violently shaking steering wheel from 35 to about 45 mph. This happened shortly after adding a 3 inch body lift to a truck that already has a 3 inch suspension lift. So it's lifted 6 inches with 35 BFG AT's .. old style on 15x10 rockcrawlers. Here's what I did.. 1. Checked the steering shaft extension, was loose but tightened it.. no difference. 2. Retorqued the body mount bolt's .. some were loose, helped a little bit. 3. Swapped wheels and tires from my 89 Blazer to her Tahoe,the Tahoe rides much better. But the 35's on my truck didn't make a difference. So.. could this be a steel wheel problem on an IFS truck? I've heard from 4WParts here in Austin that the steel wheels are too heavy for IFS trucks and they recommended keeping alloy wheels on the truck. So this might be tire balance problem.. or just a steel wheel "out of whack" "out of round" problem? Thanks for any input.. We've had it aligned numerous times.. and I think NTB keep's messing the truck up. Thanks in advance.