Front tire vibration and thumping sound above 20 mph

I would also swap the front tires around. Usually when a wheel bearing fails, it makes a roaring sound instead of a vibration.

no not typically. Have you checked out the tires closely for any signs of tread separation on the tires? That could be associated with the vibration above 55.

most def you need an alignment and you also need to check inner outer tie rod end and check the tires belt as well

I'd have to check your suspension. You think the tires are ok? Did you try rotating the tires to see if it made any difference?

If it's a vibration, it might be a brake pad staying in contact with the disk. Normally the pads push away when the car starts moving. (A normal condition called "runout") Try stopping your Jeep tonite by using only rear brakes. (hand brake) Don't step on the brake pedal at all. Then see if it does it in the morning. Don't step on the brake pedal in the morning till the test 20 sec's is over.

If the problem is a thump thump sound it's probably a tire flat spot from setting. Have the tires just been replaced? Could be a softer tirs material.

This sounds like a separated tire , rub your hand
around the complete surface of both front tires ,
looking for an outward bulge .
I believe this is the problem.
A tire shop can put it on the rack and spin it .
It should stand out .
Most vibrations under 40 mph are directly related to
the tire , above that is tire balance.

tires /bent rim

Vibration at 40 mph hard to diagonisis without looking at front end. Could be wheels need balancing, new wheels and rims. Loose or worn suspension items.
Bring vehicle into a tire and alignment shop. Most Sears auto center have them.
With regards to rubbing noise again hard to diagonisis without looking at the affected tire, probably a splash shield hitting the tire in reverse.
Alignment shop will find the problem.

COULD BE YOUR CV JOINTS. TIRE GUY SHOULD HAVE SPOTTED. CHECK THE RUBBER BOOTS JUST BEHIND THE HUBS. CRACKED? TAKE TO DEALER

At what speed do you feel the shake and does it only happen when you apply the brakes?