I have been driving a P85+ loaner all day today and was boggled at how much better the ride felt compared to our P85D. Both cars have 21" wheels and air suspension. I was trying to figure out how the car felt and drove noticeably better than our car -- until it hit me that the newer cars (ours included) are equipped with the "skinny" 245 tires on all four. I am convinced that the tires make that much of a difference and am even considering switching to the Michelin set-up (265 rear). Anyone else have similar experience or input? Did not think that the tire sizes/brands would make that much of a difference. Or is it more than just the tires that makes up for a better ride in the P85+ than the P85D?