I am getting some new wheels they are gonna be rotas (not sure what model yet) and I have decided on either 18x7.5 or 18x8, What offset should I run? I know that a wider tire gives you more surface area and that equals more grip, what I was wondering is should I go 245's in rear? How wide can I go on a 7.5" wheel? What size tires should I go in front? The same? Thanks.