I would figure with OEM 18s and 40 profile, there would have to be some suspension recalibration.

If you driven it, how does it feel vs 12-13? Or what have you read?

 

I can tell you that with my '12 sedan with 17" wheels and HFP suspension that I would not want to step up to a 18" wheel with an even thinner sidewall tire. So my guess is that Honda must have done something, because you're going to feel a difference with that large of a wheel.

I have no idea why Honda put that size tire on their new SI's. 17" wheels are plenty enough. They should have left the 18" wheel an option with summer-only tires.