Jim,
The guy is full of sheet! 265-70-19.5 lrG will net you iir 5000-5500 per tire. Iirc their is a 285 too. Closer to 5500 yet! Granted you would have to go to a 10 lug setup to have "EASY" access to tires. Those are 33-35" or so in diam. A 245 shy of 5000 iirc, is 32.5", 225s 31.5", 4100?!?!? Lbs capacity in lr g. Should go outside like at my IHC...
So assuming you can build a 10-11k RA, 6K FA, talking class 4 truck with singles. If you can get an 8' put on it, great rig for the 12' slide campers, larger 5W setups.
It can be done now. I can see where rim manufactures in typical 8 lug class 3 sizes could be screwed. This would not, nor should it be a 35 series or smaller gvw. It's solid 45 series truck.
Marty