Hi, could someone please tell me what offset I can get away with please? I currently have 17" Devonports which I think are ET55 (may be wrong) and I'm interested in some 18"s which are ET37. So I believe the lower the number the more sticky out they are? Sorry as I know its a question that has been asked before I just wanted to know on these two differences. Many thanks in advance. Also mine is lowered 30mm, not that should make much difference.