Larger tires on 15" rims, 235-75R15LT etc
I note that among those Airstreamers switching to type LT tires there is great emphasis on moving to 16" rims.
There are type LT tires available in 235-75 that are smaller in diameter than the 225-75R16 tires typically advocated for LT tire conversions. While a variety of capacities are available, a 2205 pound capacity rating is available from several manufacturers. They will fit the stock 6" rims.
Given the considerable expense of replacing 5 or 7 wheels, why aren't these tires being used?