I've said this before....actually a lot of programs don't even require that you send Step scores. They can likely guesstimate by the residency you are in, though. I would say that for a mid-tier program that actually cares about board scores, they might be looking for 220's or better...a picky program might look for 230 or 240, but that would probably be the pickier ones. Publications, where you did residency, and your LOR's trump USMLE scores in general.