I just replaced my rear tires (for the umpteenth time) and had a new experience: I replaced the Michelins (a little larger diameter than stock) with the stock AD08's. As I left the tire shop, I lost all regen and had a warning on the dash. It went away shortly after and regen started working again. When I had a chance, I found a stretch of road and retrained the car for the new tires and everything seems to be fine. It was just a major shock to coast when expecting to brake in heavy traffic.