[P.K.]

I am asking if anyone has found a smaller diameter wheel that fits the i8?
I want to autocross the car and would like to put either 18" or even 17" on with some sticky tires. Yes I realize the speedometer will read fast by whatever rolling diameter percentage I change. The vehicle speed is (I assume) created by the ICU based on wheel sensor input. I am prepared to sacrifice accurate speed reading for the advantage of decreased angular momentum, increased, acceleration, lower centre of gravity, and easier braking, for the short time the wheels/tires will be deployed. Oddly enough, the i8 has a 5 on 112 bolt pattern rather than the popular BMW 5 on 120. That said, there are lots of Mercedes, Audi and even VW wheels that have the same bolt pattern and offset. Actual experience would be be more appreciated than an out of the gate don't do it.

[Obioban]

The sidewall starts to get pretty silly for 17s or 18s-- the i8 has crazy large total rolling diameter. 19s seem like a pretty good size setup theoretically, but tire choices are pretty limited...

[stressdoc]

I think brake clearance becomes an issue.