This my not be news to anyone but me, but seemed worth mentioning.
I have noticed in the "parts for sale" section many people wanting one wheel, I'm assuming to replace a damaged one or the have a full size spare.
The WHEELS are axle specific (not just the tires).
There is a FRONT and REAR designation on each.
I tried fitting a rear to the front it will NOT fit due to a Bolt on the front rotor fitting into a special indent casted only in the wheel marked front.

 

Hey bro, yeh they don't want you putting the backs on the front and visa-versa but on the 18" wheels, they are the same wheel, just the rubber is different -- 225 as opposed to 245.
The offset is the same 30mm.
As far as the bolt on the front rotors is concerned, it's there to deter using the rear tire and wheel set on the front etc., but the bolt does come off. I had to take them off to get my snows on.

Different story for the 17" front and rear wheels which are different widths.
GSM

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>