I want to get some wheel spacers to push my wheels further out but don't know what size spacers I need, what's the limit I can go don't mind if I need to roll the arches

F 18x8j et42 235x40
R 18x10j et 52 275x35

I was thinking of ET27 for the rear and ET22 for the front?

 

With just fender rolling I think you should only run a 15mm spacer in the rear. As for the front there isn't much to roll without pulling. As for the front I'd almost say 10-15mm at the most. I still think this might be a problem.

What wheels do you have?