(Otomotiv) The cap that fits over the outside of a wheel on some vehicles to keep dust and water away from the wheel bearings and brakes. Considered a decorative accessory on many cars, it's also a safety device that causes quite a racket if a lug nut falls off and tumbles around inside it
A hubcap is a metal or plastic disc that covers and protects the centre of a wheel on a car, truck, or other vehicle. a round metal cover for the centre of a wheel on a vehicle