The original factory warranty is hitch to bumper - but there are a couple issues here. I know our dealer has a very large service department, but they don't mount/balance tires or align axles - they just don't have the equipment. I think that is true of many dealers. And the other issue is proving to FR that the alignment is the root cause of the wear.
By all means, ask your dealer about this. Maybe they can check it or maybe they have a recommended shop that can properly check this. Hopefully, that is enough to get the ball rolling.
If not, you may have to be persistent and find a good commercial trailer shop yourself. If they check the alignment and find its off, they should be able to document that for you to submit to the dealer. If the dealer doesn't help, you could contact FR directly for remedy / reimbursement.
We had some tire issues, and our dealer had to sub-contract the work, but they were very good about submitting the info to FR and it was approved as a warranty issue repair. We never had to pay out of pocket or deal with the tire shop.
Hopefully you have a similar experience. You certainly need to resolve it before you put new tires on. Might take some persistence on your part, but if they really are off, seems like it should be a warranty item.
2005 F-150 FX4
2013 Rockwood Roo 23 IKSS