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			I have a second set of rims with snow tires for the winter.  I am not an expert on rim/tire sizing, however if the cup wheels are the regular Porsche 17" size, I would recommend going as narrow as possible.  When I replace my snow tires later this year I will be going for 205/50/17 and 225/45/17.
 Here is a PDF that will help:
 
				__________________1999 Ocean Blue Metallic Boxster - blueboxster.com
 
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