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Fender skirts are implemented for both aesthetic and aerodynamic reasons. Rather than air flowing into and being trapped in the rear wheel well, it flows smoothly over the bodywork. They are generally detachable to allow for tire changes and installation of snow chains.
Automakers have also experimented with integral front wheel fender skirts, as on the 1949–1954 Nash “Airflyte” models and the compact 1950–1954 Nash Rambler, but with success limited by the fact that the front wheels must pivot for steering, extending out from the side of the vehicle slightly. The 1955 Ford Thunderbird introduced rear “fender shields” as a type of fender skirts with an edge molding and a gravel shield. In General Motors parts accessories books, fender skirts are known as fender shields.