JCkicks300

Hey guys, I was looking into buying new wheels for my IS300. Now, I want some lip on my wheels but I know with the IS there isn't much space for wide wheels. Currently Im running 18x9.5 +30 all around with 215/40/18 in the front and 225/40/18 in the rear. I was thinking of doing 18x9 in the fronts and 18x10 in the rear (if possible). Now, I would like to know what is the offsets I could use with these sizes that would allow me to have at least 3" lips in the rear if even possible that is. Even if I can't have a 3" lip in the rear with a 10 width wheel, whats the offset id need for a 10 wide wheel in order to have no rubbing? All fenders are rolled as well.

Before you guys ask me to search and to look around let me just say that I have searched and tried to figure out the sizes I can pull off but I haven't found much help to be honest. any help would be greatly appreciated. Thanks!