Is the rougher ride due to the higher inflation pressure? I have noticed that on some of the tires used with larger diametre wheels, the pressure was as much as 80-100 psi. Assume this is due to lower sidewall height?
With the larger wheels there is kind of a double whammy in that the tire is low-profile, so you instantly lose comfort due to the lack of something to absorb the shock right at road level, along with having to alter the size of springs in order to compensate for wheel size so that they fit without rubbing onto fenders, even when wheel wells are cut out further. Having wheels that size with a low ride height means cutting the springs, and instant discomfort. Air suspension might be somewhat of a remedy, but that can be a pain to maintain. And God forbid you have a sudden leak or burst while you’re on the road.
I love my 4Runner, but for a truck, the suspension is super stiff.. It makes me miss my Delta 88.