18 Vs 17 Inch rims?

[CamaroPat]

17" vs. 18" wheels. If you're after a look, go for whatever looks right to you. As far as performance is concerned, there is no benefit to running 18" wheels instead of 17's. The larger the outer diameter of your tire, the more leverage aforementioned tire will apply against your brakes. Since your front wheels do 70%+ of your braking, there is little sense in increasing the diameter of your rotor in the rear to counteract the additional resistance you will experience with a larger tire. Just test carefully with a proportioning valve. From a purely functional standpoint, the best reason to install larger diameter wheels is to allow for the installation of larger diameter brake rotors, which then have increased leverage and ability to stop the wheel. The increase in unsprung and rotational mass from a 17 to an 18 is negligible for street use. You can maintain the same outer diameter tire running 17's or 18's, just by reducing the aspect ratio, but at the limits of adhesion, a shorter sidewall tire will act more twitchy, the ride will be stiffer and there is an increased risk of damaging your wheels when you encounter pot holes, etc. due to the reduced cushioning effect of the tire.