I have a 1988 ford f150 2wd I just put some mickey thompson baja belted on my truck they were slightly used they have about 50% tread left my problem is when I go about 40mph my front driver side tire shakes real bad like the rim is going to come off. I had them balanced and rotated yesturday but my truck still shakes my truck has new wheel bearings new shocks everything was inspected and nothing looks broken, torn or any other signs that a part is damaged so what can be causing this problem.

 

My brothers truck had the same problem. We did all the things you have done (wheel bearings balance tires) It turns out to be the steering stabilizer shock. It looked fine but after we installed the new one the problem was gone. Hope that does the trick for you Good Luck.

 

Adding a new stiff damper is a cover up to a problem, should be able
to run without one. It helps reduce steering wheel kickback not control
a out of balance tire or tires, a small amount of axial imbalance it will dampen.
On used tires they have worn round and now you remounted them,
does the tread spin still spin true? If not rotate on rim to find the best
position then rebalance.
Dynamic balance done on a machine not a static bubble balancer?
A vertical (horizontal axle) balancer will only do radial balance not axial.
Drum/disc assembly in balance?
Tire delaminating and making a wop wop sound and shakes differently between cold and at operating temperature, bad tire?
Same result if wheels swapped left right?
Years ago when they balanced on the vehicle they used a "shoe"
the box with motor to rotate the wheel.
If you can locate one and have the wheel spun on the truck you will see the
problem if it's not round, radial or axial imbalance.
This is the reason why I purchased an old shoe, to locate a so called
balanced wheel. Between a static balance (horizontal axle) and the shoe I haven't had a balance problem the last 20 years, turbine smooth.
Even new tires will wear round and go out of balance slightly which I correct.
After paying $12 a wheel plus watching the crap way they centered wheels
I decided to do my own. Sorry off topic a bit.
Maybe there's a reason PO wanted to get rid of them.
JMO's.