Anyone know of a suitable 18" space saver wheel, doesn't have to be BMW? As I don't plan on using it (fingers crossed) I would rather pick up a second hand/fleabay one.
Never assume.
Unless you have facelift 3.0si brakes then a 17" fits.
Take a look inside your rim and see the space.
Rolling radius is near the same as a highe profile tye is used.