Hub rings vary in millimeters and using the correct ring is critical to ensure proper function. You will need the diameter (mm) of the wheel center bore and the vehicle hub (mm). The hub ring will fill the space between the larger center bore of wheel and the smaller hub bore of your vehicle. This creates another point of stability for the wheel aside from just your lug nuts.
For example: If the center bore of the wheel is 72mm and your vehicle hub bore is 56.10, you would need a 72mm to 56.10mm hub centric ring. If you are unsure, your local dealer can assist you in ordering the correct hub rings for you.