i was told that the 19x20 is best for 6 piston calipers and liter bikes, and the 19x18 was typically for 4 piston calipers.Originally Posted by motobum
i have a 19x18 and both bite and feel/control are unreal. i can't imagine wanting more as it seems like it would be too much. (running stock 4 piston calipers on an f4i with vesrah rjl's)
and for what it's worth (certainly nothing to me as slow as i am), rossi and hayden both use a billet 19x18.