...ahhh, the 225/50-16s are the same diameter as the 205/55-16s, in fact I remember them both were original to the first 911 C4.
-----Added 5/11/2009 at 08:30:24-----
If you haven't found the limit of the Blizzaks then do yourself a favor and get yourself an 80,000 mile warranty tire, Pep Boys...