Enzo250GTO said:
chas,
If you look in this section or do a search for topics started by "enjoythemusic" you'll find that he (Steven) has upgraded his wheels and tires on his 308.
Have done various upgrades from after market Italian Etoile 16-inch rims (7 front / 8 rear) to now 17-inch Kinesis semi-custom (8 front and 9 rear). Would avoid 18 UNLESS you REALLY have redone your suspension to something like Nick's dual-adjustable and height adjustable shocks and uprate the springs.
My recent rim/tire upgrade has been wonderful with EXCELLENT results as seen at:
http://ferrarichat.com/forum/showthread.php?t=30912
The car now can habndle about a full G of lateral traction (yes, i repeated the test and used the appropriate test instruments).
Nick sells the shocks/springs (go 300 lbs front, 250 lbs rear) and avoid his rims IMHO as seen at:
http://www.nicksforzaferrari.com/forzaferrariwebsite1005.htm
For suspension discussion see:
http://ferrarichat.com/forum/showthread.php?t=11581&highlight=rochlin+suspension
Hope this helps. Seriously, AVOID 18-inchers as you leave TOO LITTLE rim and odds are they will be damaged by the road in short order. Also, the Mich Pilot Sport PS2 has a softer sidewall and this is a PLUS for tuning IMHO as i can easily stiffen the custom suspension bits accordingly yet the ride 'comfort' is good when it is set for such for daily drives, yet TIGHT AND FIRM when set for track driving as well. LOVE the dual adjustable suspension
Only changing out the rims... i would say stick with 17 or, frankly, don't bother and save your money. If you want to truly explore the possibilities you really need to dump the lackluster Koni stock rubbish from the 80's. Technology has LONG left it behind (with all due respect and apologies accordingly).