I also had a set of 18x7.5" wheels on my car. It had a +40mm offset and it also had 215/35/18 tires. I raised my car a little (about 1-1/2" gap between tire and fender) and I'd only rub on really hard turns or hitting bumps and/or dips on the road. Surprisingly the ride wasn't that bad (I made sure that the tire pressure was always maintained) but still not as smooth as having a 15x6.5" wheel with 205/50/15 tires.