BTW is a hubcap (wheel cover), that is installed on top of the tire and the wheel, alloy or steel, giving the impression of a bigger wheel (20 inches, R20) and a low profile tire.

 BTW has a built in sport brake that looks and feel real. The caliper is stationary while everything else rotates with the wheel on the car.

 With a universal fit system and easy installation, the size of your wheel don't matter. Because it is installed on top of the tire, if your TIRE is bigger than 25 inches diameter (63 cm), it should work with your wheels.
Works with most wheels R14, R15 and up to R20.