Center Cap (Wheel)
A center cap is a decorative disk on an automobile wheel that covers a central portion of the wheel. Early center caps for automobiles were small and primarily served the purpose of keeping dirt away from the spindle nut and wheel bearings of vehicles. Center caps are often found on new cars to hide the lug nuts, and/or the bearing. Center caps are a type of hubcap, the other primary type being wheel covers. Some modern center caps are retained to the wheel using spring clips, while others are retained by the wheel lugs or other threaded fasteners.
Howbeit, often a center cap will bear the logo or trademark of the maker of the automobile or the maker of the center cap, but there are custom center caps without any trademark as well. Early center caps were often chrome plated. Center caps that are found on trucks are "baby moon" center caps, that originated on Mack Trucks and are found on Freightliner Trucks.