While internet shopping for tires for my E350 small rig, I stumbled on
THESE "E" RATED TIRES with a load rating that is 500+ pounds more than a typical "E" rated tire. If my rig was extra heavy and I dealt with an occasional blow-out, I would surely look into one of those 3 choices. An extra 2000 pounds of tire load capability on the rear axle, and 1000 pounds on the front would be surely be something I would consider. I am sure the ride will be rougher, but for an over-loaded rig, the quality of the ride would be my least concern.
There are class C rigs built on an E450 chassis that are extra long and with multiple slide outs. These tires seem ideal for such rigs, especially ones with a shorter wheel base placing extra weight on the rear tires.