FWIW we have a 2010 Fuzion. It came with 235/80R-16 ST tires rated at 3450 lbs. These tires were mounted on Dexter 7,000 lb. axles that had been derated to 6800 lbs. so the tires would equal the rating.
It's very possible the OP has 7,000 lb. rated axles and those wheels, as ours were, could be rated to 110 psi. To state positively that his wheels are only rated to 80 psi may be leaping to conclusions until they have been checked. My wheels with the same size tires were rated to 110 psi, and they were also on a year older Keystone.