Hub Rings are used to eliminate wheel vibration issues due to the wheel centerbore being larger than the wheel hub. This could possible lead to the wheel not being centered properly so Inserting rings into the back of the wheel will reduce the inner diameter to match your vehicle properly.

Make sure to Select the proper Outer Diameter (O.D.) which matches the diameter of your wheel centerbore.
Make sure to Select the proper Inner Diameter (I.D.) which matches your vehicle hub size.