I have an '09 F-150 FX4, and just recently, put on some new XD wheels and a ProComp 6" lift kit with 35x12.50 Pro-Comp XTreme AT tires. This is where the fun began (or not):

Phase I: When I picked up the truck, it looked great and seemed to ride fine until about 50mph. Starting about 50, the truck started to vibrate and jump around like crazy. The following day, the shop rebalanced and re-aligned the wheels, but the problems continued.

Phase II: The shop took the truck back in and removed the Pro-Comp coils and shocks and replaced them with the lower end kit (stock coils with a spacer) and replaced the tires. The ride is much softer (more like stock...which I don't mind), but again, the truck vibrates and shakes like crazy over 50mph. The steering wheel shakes from side to side about a 1/4" while driving. It does stop around 70, but then the back end seems to hop around a little bit.

I have heard from some other people that these Pro-Comp tires are terrible about doing this type of thing, and even though I have now had 2 separate sets of tires, I am wondering if my tires might be the issue.

Can anyone help me out here? I love my truck, but this entire ordeal is NOT making me very happy. I have heard that the Toyo MTs are the tire to go with. Anybody else experienced this issue?

Mark

 

It sounds like you may need to beef up your driveshaft, had a buddy who had that problem of strong vibrations when doing highway speeds and its just something that may happen when you add the lift.

 

Put the coilovers back on and add a steering stabilizer. That might help the sloppyness up front.