17" or 18" wheels for track/AutoX use on Boxster S

[LuisR]

I know this has been talked over and over, but I am a new autocross driver and will be doing 2 or 3 track visits a year. I don't want to use the wheels that came with the car since they got scratched on my first autocross event. I am looking for a used set of wheels from boxsters or 993/996. I will preffer not to go with the 10" rears to avoid using thick spaces. So, I have 17" and 18" wheels offered on ebay. Which ones will be better in terms of performance??? I do know that tires will be cheaper in 17' size but since I am not autocrossing and tracking every single weekend I will not going through that many tires anyway. So, what do you guys think I should go for?? What is your experience to those that have gone either way?

Thanks

LRR

[KevinC]

Here's a link to a recent discussion on the Boxster Racing Board. A lot of us love the Kumho VictoRacers for both autocross and track events. They are not available in 18" sizes, so that's one strong reason to choose 17's. The VictoRacers have very stiff sidewalls so I wouldn't worry about any loss of steering response due to the sidewalls of the 17" tires being about 12% taller. The steering response of a softer 18" tire (like the Michelin Pilot Sport Cup) probably won't be as crisp.