[Perfectlap]

Very important to get the proper off set. Getting it wrong can damage your wheel bearings and those things are $500 a wheel. Avoid spacers unless you go to a Porsche specialist.
My advice, stick with Porsche Factory wheels like the legendary 18" Carrera 5 spokes voted the coolest wheels ever. If you want to fill up the wheel well get some bigger rubber like 245 up front and 275 in the rear. And add some side skirting for lowered look without having to actually lower the car.