The Audi S4 features a special design of Audi factory wheels, called Avus wheels. The wheels have caps at their centres to help protect the lug nuts, which secure the wheel to the wheel hub, as well as the wheel hub assembly itself. It is a good idea to remove the centre caps from the wheels to clean the area underneath. Even though the centre caps help protect this area from the accumulation of water and dust, some dirt can still make its way inside. Fortunately, removing the centre caps is a very easy process.
Park your S4 on a level surface, leaving the transmission in gear with the emergency brake engaged, to ensure that the car will not move.
Insert the tip of the flathead screwdriver in between the centre cap and the wheel assembly. There will be a small notch on the centre cap to facilitate the insertion of the screwdriver. You can locate this tab by following the circumference of the centre cap
Pry the centre cap away from the wheel and wheel hub, which helps secure the centre cap to the wheel. Repeat steps one through three until you have removed the centre caps from the remaining wheels.
Park your S4 on a level surface, leaving the car in gear and the emergency brake engaged, then pop open the boot.
Open the tool kit that's located on the driver's side of the boot and locate the wire ring that's stored within it.
Insert the end of the wire ring into the hole that's located on the black ring at the centre of the wheel's centre cap.
Pull the wire ring firmly once you have secured it to the centre cap, to remove the cap. Repeat these steps on the remaining centre caps that you wish to remove.