On my 68 S-clone,I run 28/29 in the 235/60-14 frts and 24 in the 295/50-15s. This is for even treadwear. Very nice ride.
Bit soft on the turns, til the suspension takes a set on the bump stops. The sidewall roll-over isnt too bad.Once in a while, I pump the fronts up to 32 and go have some fun. But the current tires arent sticky enough to make much of a difference.
At 22 the rear feels odd on turns.The front rides nice at nearly any pressure. Modern radials are awesome.
"how much do you think the air pressure contributes to ride quality?
..say 32 psi to 26 psi? "
Not nearly as much as Lightweight wheels, and decent shocks.When a rear goes down on my car I can tell almost right away. But until the fronts are down to 20-24, I dont notice the fronts going soft.So I'm assuming that means not much change in ride quality from 29 down to 24.
When I had skinnier tires on the back, I noticed ride quality more easily.