Center caps that are found on trucks are "baby moon" center caps, that originated on Mack Trucks and are most popular and commonly found on Freightliner Trucks.
World Trade Center | center | Kennedy Space Center | Walker Art Center | Woodrow Wilson International Center for Scholars | Marshall Space Flight Center | Cap (sport) | Rockefeller Center | Lyndon B. Johnson Space Center | Goddard Space Flight Center | cap | Georgia World Congress Center | Staples Center | Lincoln Center for the Performing Arts | Tanglewood Music Center | National Center for Biotechnology Information | John F. Kennedy Center for the Performing Arts | Center for Constitutional Rights | cap (sports) | Georgetown University Law Center | Art Center College of Design | Southern Poverty Law Center | George C. Marshall European Center for Security Studies | Beth Israel Deaconess Medical Center | University of Pittsburgh Medical Center | Prudential Center | Painted Bride Art Center | National Center for Atmospheric Research | Langley Research Center | German Aerospace Center |