Ride Harshness
 

Our base 2016 Cayenne has 20” wheels with low profile tires (& springs), and our local roads are always in bad shape. I assume finding some 18” wheels with a higher profile tire would improve the ride and perhaps save a rim from the northern Illinois potholes. Has anyone noticed a noticeable difference in switching to the smaller diameter wheel? I figured getting some all season (or winter) tires might make sense.

A smaller diameter wheel and larger sidewall ratio will greatly improve your ride quality, I find anything over 19" and any sidewall under 40 doesn't offer much compliance on small imperfections on the road. With an SUV you should be able to fit something in the 50-65 sidewall range without modification.

Yep ^ I run 18" wheels in the winter, 19's in the summer. Good choice, especially on steel springs. Hard cornering feels a bit more squishy, less crisp, but hey, trade offs.

I‘ll search for 18“ wheels. We just had the car loaded down with 5 people and the ride was much better with the load.