Hey, just been to the Porsche center with a Cayman S from my buddy, he bought a set of 19″ turbo wheels, and he wanted to buy winter tyres for it, tell him, in the winter there are only 18″ registered…. What please???????? Is that so, or what is this nonsense, and if so what can you do? So I only know, 19″ registered, then no matter what tires are on it. Can anyone help? Thanks already