I have had my Model X 90D with 20 inch wheels and Continental tires for 3 months and 3000 miles. The ride quality is very rough and I am wondering if anyone has had any luck in dealing with this issue. The ride didn't seem particularly harsh for our first road trip of a 1000 miles from the Bay Area to Oregon. When we returned my wife noticed that she couldn't rest her head on the passenger head rest without it getting bounced around uncomfortably. Now she is reluctant to ride in the car because there seems to be very little in the way of shock absorption from bumps in the road. I have to agree that the ride is very harsh and not particularly pleasant. I took the car to the service center and they checked it out and a service manager rode in it with me. Nothing out of the ordinary was found. I compared it with a demo Model X - not a huge difference. He didn't have any suggestions to improve the ride other than take a few psi out of the tires. I had a 2013 Model S with Continental shocks for 3 years - the ride was great and very smooth. Vastly different from my Model X. Any suggestions?