I can almost guarantee you that it's the wheels / tires not being properly balanced. In fact, I'd bet dollars to donuts that's what it is.
Often times with larger tires like this, if the person at the shop doesn't have that much experience with them, it can sometimes take 2-3 balance attempts to get it right.
Before you go down a rabbit hole of trying to figure it out, have the tires balanced and inspected by another shop. Again, I would bet that's your issue. I've seen this same thing happen so many times with Jeeps, and 9 out of 10 times it's a balancing issue.