We're home and have had a chance to really look at the tire and this is what we found:
The left side tire isn't nearly as bad but it is wearing on the inside too.
DH says they both have 90psi (max is 100) and have just over 6000 miles (not the 5000 I mentioned earlier). They are Continental tires.
We're probably going to a Ford Truck dealer in Louisville that deals with big trucks so hopefully, they'll be able to figure out what's going on.
If it's balancing, shocks or something else along those lines, it had to come from the dealer like that so I wonder if we have any recourse.