As said you get the warning due to the size not being OEM, many have run the 255/55r18 size and been fine. The DWS Continental Extreme Contacts, in my experience, cup and chop very badly on IRS cars. I have not had any experience with them on a live axle though so I can not speak to that. IF you were getting a full set for the front and the rear I would advise against it, they will wear terribly in the front. The Extreme Contact DW has a better tread pattern, or the Pro Contact if you wanted to stick with Conti.