I drove mine summer 20 inch set with 0,2 under inflated and it is ok, if you don't drive too sporty of course.But , I am not going to recommend this, because if you need fast and sharp reaction to avoid some situation or crash, the car will react not sharp enough, Also maybe there will be higher possibility for your wheels to be wrapped at the pot holes ??? I don't find the ride too hard with the 20s and 2,3 front, 2,5 rear bar inflated and I can guarantee you our roads here, are much worst than yours. I even had double herniated disks on my spine this summer and that was the reason I did the tyres with lower inflation, just to try the difference. There is such, but I prefer to have more stability on the road in any possible situation. Do you have sport shocks on yours? The model and the tyre maker , also makes difference. If you have run flats of any make, the ride is much harder than normal. I have Michelin Latitude Sport 3 - 20s for the summer, from the factory and now I am with Goodyear Vector All Season Gen 3 - 19s for the winter. Both , very comfortable and very good tyres for me. Maybe the 19s are like 10-15% more comfortable, but some people will not feel it for sure.
NOOOOO! Bad reason. Overinflated Stelvios handle like Sh!!. Many threads on this out thereAlthough the tire pressure is supposed to be set for 33psi front and 36psi back, I tend to fill to 35 psi in front and 38psi in back so I don't have to fill the tires as often and it rolls a little better with a little extra tire pressure.