I swapped out the stock Continental tires for Continental Terrain Contact A/T tires at the dealer when new. The A/T's have a rim guard molded into the two ply sidewalls to prevent damage to the wheels. Our first demo Passport had curb rash on one of the front wheels! In 4500 miles I'm very happy with the tire change, and mileage does not seem to be affected. The road to my house has been a muddy mess this spring, with mud holes in multiple locations. So far I'm impressed with how the tires, and the Passport, has been able to negotiate through. (Bad enough to drag bottom on several occasions)