BigDumbOx
+1y
I just had a set of 235/30/22's mounted on an 8.5 inch wide wheel and it measured 27.5 inches tall exactly. I suppose you could go smaller, but you're going to have to have a narrower wheel. I don't think anything smaller than a 235 will fit on a standard 8.5 wide wheel.
I think Asanti makes a 7.5 inch wide wheel that would work great with a 225 though. but even then you're only saving a fraction of an inch on overall tire height. if .2 or .3 inches is gonna make or break your project, you prolly need to step down to a 21 or 20 anyway.
Ox