Keep in mind...just because other people have paid for tires...it does not mean they would pass road force tests.
You can balance an egg with enough weight. It will never stop the vibration when you try driving on it, though.
I have Chinese tires on the rear of my class A and $400 per copy Michelins on the front for the exact reason you mentioned in your original post.
We no longer suffer from highway wobble as a result. (Double Coin tires are a bargain, but not always the best QC.)
Also, know RV's in general are nearly always set up to ride like a jelly fish on old, arthritic bones.
May I suggest a set of high quality, stiffer-sidewall tires along with more off-road-style shock absorbers?
The ride will slightly suffer, but the "jelly fish effect" will likely vanish...as will the 55+ wobble.
(Check the rubber that comes on a heavy-chassis step van. Look at the ply rating and how the sidewall is stiffer. Better control, safer lane changes, less wind shift when a big truck fly's by.)
The suggestions for sway-bar setup/adjustment makes sense to me. In the fleet trucks, it was standard policy to grease-needle a bit into the rubber bushings. Made them last longer and work better. (Not WD40. A tiny bit of grease till the bushing was easily moved by hand, then bolt it back to the mount.)
You will never end wind-push in that truck, but those tires and shocks will make a world of difference.
