Need Help with Fitment, Widebody

Hey Guys. Im doing a liberty walk on my e92. I haven't seen much information about wheels. I have a set of BBS LM's 19inch 19x8.5 and 9.5. I am getting a custom 3 piece set up for them. I just don't know what size to get. Was thinking about 10.5 and 12.5. But not sure about offsets.. Anyone have any experience or can help me? Thanks in advance!

See Post #2 here: http://www.m3post.com/forums/showthread.php?t=1184930