Before we bought a FW toy hauler I researched part numbers between my 06 SRW Dodge 3500 and 06 SLT dual rear wheel model. The frame, axle, wheel outer ends and springs & attachments are shared parts. The door sticker weight rating (lowest component) is the Rge E tire rating x 2 tires. I installed 19.5 wheels rated at 5000 lbs each and 19.5 tires giving me over 9000lbs rating for the pair.
I run 70psi minimum and inflate to load/inflation table pressures if the the weight exceeds what 70psi is called for.
Our 17,000lbs FW with some groceries and a part load of fresh water puts the rear axle right at the door sticker (not over) and the higher rated tires and wheels give me the spare tire/wheel capacity I want (20% - 30%).
Previously we have hauled our truck camper / enclosed trailer combination over 20,000 miles with the Rge E rear tires right on axle max without incident but this was winter travel with no temps over 75F.
I also pull other trailers as needed with this truck with combined weights up to 26,000lbs. I sometimes have to shift out of high gear when grades exceed 6% but then I guess that is why it has a "6 speed" trans...
Based on our experience I would not change a truck out to haul a 16,000lbs FW regionally - I would use the money for rv travel...
