Clean the wheel rim first using a good quality rim cleaner. Place the steel retaining ring on top of the wheel trim, and press it into the slots.. Apply the cap to the wheel rim, making sure you can still easily access the air valve. Securely press the wheel trim in to the wheel rim, if the trim stands off the tyre a little, just adjust the metal brace down one notice on the inside of the hubcap and redo the steps above. In some minor cases, wheel nuts may need to be removed for optimum fitting.