In a previous post you said the standard wheel offset was 50mm front & rear. Want to put 18 x 8 1/2 front & 91/2 rear Racing Hart M5's very similar to your C5's. Dealer may have mistakenly or on purpose sold me 17 offset for both front & rear since they had them in stock. Obvviously had terrible rubbing problem. Dazz/RH says that 39mm for front & 44 rear,but that seems in conflict with what you say. What offsets for your C5's? Is ideal offset 50mm? Any wheel bearing or other negative issues with above 39 & 44 offsets recommended by RH? BTW mine is 95 NA if that makes any difference. Tires are Pirelli P7000SS 235-18-40 front & 255-18-235 rear. Originally wanted C5's,but was told they were discontinued. didn't want to do that if they ever needed replacement. Yours or others expertise & help would be greatly appreciated! Thanks! Sorry about long post. Car parked until issue resolved.