Tire size question

[RoyJ]

That was the primary reason why I switched to 24.5s.

I have a 4.11 rear end, and spin just over 2000rpm with 11R22.5s, at 60mph. With 24.5, I'm sitting at just under 2000rpm 

This probably won't matter on newer buses with a World, and even less so if you have a 10 - 12 speed ZF/Auto/UltraShift. Some of those suckers are geared for 1500rpm at 75mph!