What would the offset need to be on a set of 18 X 8.5" wheels with 245/40 tires on the sedan without rubbing the suspension arm.

 

You should be good with a 35-40mm offset. Stay more toward 35mm to be safe. I'm looking into 19x8 front and 19x9 rear, the fronts would be a 40mm offset and the rear would have to be a 35mm. I'm thinking about just doing the 19x8's all the way around. It also depends if you have the sport package or not. If not a 40mm offset on 18x8.5 would be fine.

 

Thanks, for the response haYanNoize. I just purchased the ADR M-Sports in titanium silver 18 X 8.5 35mm offset (only offset available) from Wheel Max because the sales guy guaranteed the 35mm offset would fit like a glove. Just had them mounted yesterday and they do. I'll try to post some picks this weekend. Oh yea, damn they look good!