Quote:
	
	
		
			
				
					Originally Posted by  schoir
					 
				 
				Here it is, from TSB #4407, dated March 4, 1997:  " Eighteen inch wheels are not approved for use on Boxsters.  Use of eighteen inch wheels on Boxsters under severe conditions may result in structural failures of the body and/or suspension". 
I guess the key here is "under severe conditions".
 
This caution was removed when the frame was reinforced in later years, but I guess that must be in another TSB.    
Regards, Maurice.  
			
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This is similar to the info that I've read also, even though I use 18" wheels in the summer on my 97 w/o issues, but my driving style probably wouldn't be described as  a severe condition.  The PCA Boxster Tech advisor also wrote in his column that using 18" on the street would "probably" not be a problem, however using 18" (or even 17" R-compound tires) on the track may lead to trouble.