Originally Posted by David@ApexRaceParts
The 17X9.5” ARC-8 easily supports a 255/40/17 R-compound tire. The 255 R-compound runs much wider than the stock 255 tires and this wider wheel was designed to provide the needed sidewall support. The additional support stiffens the sidewall and with less flex the tire will resist rolling over during hard cornering. This all results in sharper handling, better tire life, and a little more fun on the track! With the wide track tires a 5mm wheel spacer is required in the front to clear the strut, and about -2.8 degrees of camber for the fronts to not rub onto the fenders.
On the pre-LCI e90, you would need both a 5mm spacer and camber plates to achieve the necessary -2.8 degrees of camber in order for the front wheels to fit without rubbing onto your fenders with a 255/40/17 tire. With the 245/40/17, you would still need camber plates as it would still require a little over -2 degrees for the wheels and tires to clear your fenders properly.
Hi David, I'm gonna piggy back off of this. I am in the market for 17" Arc-8's as well. And I'm curious is there anything you offer that will give the meaty/beefy track ready look (and also be track functional) without modifying the stock sport suspension? I know the ideal setup is what you mentioned above, spacer+camber plates. But I am trying to avoid that for now. Thanks for your help!