So, not to spoil your plans but I was afraid that was the answer.
The problem with upgrading the tires, wheels, or axles is that you just move the point of failure up the line. With me, I had a big bunkhouse fifth wheel with 2 x 7,000 lbs axles. I upgraded wheels, tires, and added shocks. I was running over the GVWR by 1,000 or so pounds. I was never over 14k on the axles, though. After 2.5 years of fulltiming, I buckled the frame. That was a dark day.
We were able to get everything bent back into shape and things mostly worked. But it was an important reminder that these things are flimsy at best.
2018 Ram 3500 DRW/crew cab/long bed/4x4/4.10 gears pulling a 2017 Spartan 1245 by Prime Time
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| My family and I have fulltimed since June 2015