Center cap

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Center cap (also called centercap) is a decorative disk on a wheel that covers the wheel’s central area. Its main job is to keep dirt away from the axle nut and bearings and to hide the lug nuts or bearings. Center caps are a type of hubcap; other type is wheel covers. They can be attached with spring clips or by the wheel lugs or other fasteners. Early caps were either very small or very large, and they date back to carts and wagons before becoming common on cars. From the 1950s to the 1970s many were made of stainless steel, while the rest of the wheel was often wood or metal pieces. Today center caps can be metal or plastic and are used with aluminum alloy or styled steel wheels. Some full wheel covers have removable center caps that hide the lug nuts. Many caps feature the car maker’s logo or the cap maker’s logo, though plain caps exist too. On trucks, center caps are often called 'baby moon' caps; the term comes from Mack Trucks and is still used on some Freightliner models.