Hubcaps are used to cover lug nuts holding 'hub' of wheel on axle. Those hubcaps are usually bolted on and smaller than 6" in diameter. Later designs that covered completely metal wheel are called "wheel covers." The terms are now interchangeable. In today’s usage, hubcap can be used as a more generic term covering everything from center caps (covering only lug nuts) to wheel covers that hide whole wheel rim.
Parts Train's Hubcaps are either made of plastic or metal. Most customers prefer plastic as it performs better as a wheel cover due to its lighter weight. Metal hubcaps are heavier and tend to come off due to centrifugal force. And they cost a lot more. Mazda custom chrome hubcaps give styled steel or alloy wheels a “high-end” chrome look and are an inexpensive alternative to chromed alloy wheels that may cost up to 20 times as much.
There are Mazda hubcaps that are ABS plastic and triple chrome plated. A major quality of this material is that when it is scratched, it does not degrade further with time and exposure to sun, weather, and salt. Even after some years, scratch will look same as it did first day. Whereas chromed metal, steel or alloy, will react with oxygen and salt, and will rust, pit, scale, or flake after it has been scratched.
Hubcaps come off due to broken clips, faulty installation, or damage from contact with a curb. Sometimes impact from a big pothole or speed bump can knock off a hubcap. Spinning Hubcaps are also available at Partstrain. It is made of a high quality, tough and lightweight, triple-chrome plated ABS plastic with metal retaining clips for a better-fit and superior retention. The rotating outer plate attaches to inner portion by an encased bearing. Spinning hubcaps look just as good and are much more economical than spinning rims.