This has been covered before.....
 

I always take notice on these 17" discussions on the 1997 because I would like to see some different wheels on my car. My indy mechanic says don't do it and I when I have researched it here and on other forums I generally find the mechanics in the know always say don't. I think if I wanted the bigger wheels I probably should have picked a different year car.

http://986forum.com/forums/performance-technical-chat/27322-18-wheels-97-a.html?highlight=1997+wheels