They started out as high priced LARGE chrome wheels with an additional disc on the outside. The disc spun independently of the wheel, so when the car/truck came to a stop, the wheels looked like they were still spinning. These wheels cost a great deal of money, thousands a piece. Then came add-on spinners to place over your existing dubs, reducing the cost to a mere several hundred per wheel. Not to be left out of this craze the po’ folks demanded a low price alternative. Ever accommodating, car aftermarket manufacturers came through, we now have chrome-like plastic hub caps that are spinners, available at a Wal-Mart near you.
Saw some cheapo ones on a POS green Hyundai this afternoon (one spinning, the other not, on the side we could see.) Donna summed it up perfectly, “They are like baseball cards in the spokes of a bicycle, for adults.”