Groover, you missed the part of my quote that said “same OD”.
Seems a bunch of confused folks trying to prove me wrong. Rather than conjecture, compare the same DIAMETER and load range (E or XL or whatever) in different rim sizes. Yes to get the same diameter the tires will have a different aspect ratio.
And the larger rim with lower aspect ratio and same diameter will lose to the smaller rim and taller aspect ratio. Same width.
That said, with today’s truck tires in the 32-35” diameter range, there are plenty of high load rating options in 20” rims and moderate widths.
Extremely wide tires don’t necessarily have the same ratings. Like wider than 12”, in general.