Sooo, I was right. The rims on the the truck are aftermarket replicas in 22". The spare is the OEM 20" version, with a 255/50R/20 Michelin.The stock MY10-MY12 L322 AB wheels are 20x8.5.
BTW be thankful they threw a 40 series tire on there. That should help your ride quality quite a bit on a 22.
Check your spare. Because of the towing package you should have a full size spare and nobody but me ever buyels a 5th wheel for a spare 😆