I just got my Tesla S P85 Wednesday with all options but the rear seats. The day I got it the roads were a bit wet from some light rain. The first time I floored it on my local two lane highway, the car oscillated some side to side under full power. Today, the roads are dry and I still feel the car swaying a bit when I stomp on it. I'm thinking it's the tires. I bought the car with the 19" setup to get more mileage.
The OEM tires (Goodyear Eagle RS-A2 - High Performance All-Season) are not rated very well. Coming from my 2012 BMW 535i, loaded with M-Sport package, sport transmission, anti-roll stabilizer bars, active steering, etc., which came with Dunlop Sport Maxx GT DSST - Max Performance Summer tires that are rated decent, but not up with the best in category, the Tesla's all out acceleration is awesome, but it doesn't feel rock stable like my BMW.
Anybody else thought about upgrading the 19" tires?