aaaah you're still running Banded Amaroks huh??Yeah there’s not much in it at all…. the sidewall on the 235 is slightly taller, but you’re talking millimetres!
Personally I always thought the 255 looked a little too big on my front banded Amarok’s (8.5” wide), but sat much better on the rears (9.5” wide) with a slight ‘stretch’. That’s why I went down to the 235 on my current setup (9.0” wide).
Hope that helps!