The first thing you need to check is the wheel's bolt pattern. If the holes in your Audi wheels don't match the studs on the car's mounting hubs, they won't fit. Other considerations include the offset (the distance between the axle pad of the wheel and the imaginary centre line of the wheel) and the size of the centre bore (the hole in the middle of the wheel). If you're not sure, it's a good idea to consult a garage for expert guidance. You'll need to inform your insurance company that you've fitted aftermarket wheels, too.