First, I cleaned all oil, brake dust, etc from the wheels, particularly where the cover will "bite" the wheel. Then I scratched the wheels where the covers will "bite" with a screwdriver, because the paint is glossy smooth. Then I cleaned the wheel covers, particularly at the "teeth". Hope they stay put. Will not likely help mileage, as they weigh 28 oz compared to the original plastic at 14 oz. I lost one original and had to do something. Originals were scraped, too, so I figured I couldn't go too far wrong replacing them. I like the space age look! What do you think?