I'm the new owner of a 1999 SLK230. The car currently has 17" rims, with 225 45Z R17 on the front, and 245 40Z R17 on the back. There is no spare. I believe the car originally had 16" rims. Can someone tell me what spare to buy? It seems the OEM space saver spare tire was a smaller rim size. You can see how little I understand about this, sorry!