I took delivery of a Model S Performance in early March. I immediately switched over the to 19" wheels and snow tires because winter was not over in Vermont yet. Five weeks later I remounted the 21" wheels in my own garage, using the factory recommended torque spec of 140N.m. (103 lb/ft). (See important update below.) After the 21" wheels had been on the car for about a week, I began to noticed a subtle deterioration in crispness of the handling. There seemed to be more lateral slop. I started to wonder if the dampers were "settling in" or something. My car has about 3K miles on it. This turn of events inspired me to start thinking about a Performance Plus upgrade. Then today I tried something: I pulled out the torque wrench and checked the lug nuts again. To my surprise and horror, every single one of them needed tightening. Some took nearly a quarter of a turn. When I took the car out afterward, the suspension felt crisp and new again. Word to the wise... re-torque your wheels often! Even if you don't change your own wheels, a torque wrench is a good thing to have around.