[atdeneve]

Wider wheels are not really just for looks and they will/should have a pronounced impact on the handling dynamics of the car. Wider wheels/tires provides a greater contact patch and therefore more traction, which the V can surely use, especially with the power it puts down even in stock form.

Greater traction in the rear decreases the amount of power oversteer / tail-out behavior, thereby allowing one to push the throttle a little more through the turns without stepping out the rear. More necessary for road courses, perhaps not as essential for autocross, although I don't think it can hurt at all (even with the wider rear setup, I'm sure you can rotate the backend if need be).