There are several ways to identify whether the BMW 21-inch 731 wheels are original. Observe the logo on the wheel hub: Original wheel hubs usually have BMW's trademark or brand logo, wheel model and other marks. If there is no mark or the mark is incorrectly positioned, it may not be the original wheel hub. Compare wheel hub styles: The original wheels of BMW vehicles have fixed styles and characteristics. If you are familiar with BMW wheel hub styles, you can compare the wheel hub styles and designs to determine whether they are original. Check the relevant documents of the wheel hub: If you obtained the relevant documents of the wheel hub when purchasing a BMW vehicle, you can determine whether it is the original wheel hub by checking the information on the document and the style and characteristics of the wheel hub.