The rear on Model S carries an average of -2.0 degrees of camber. This is normally enough to eat the inside shoulder of the rear tire (see picture below). This is a pictorial of camber showing 2 degrees of tilt of the top towards the center (negative camber). Here is a good page explaining all the normal alignment terms.
This is the drawing I did to determine the required upper arm lengthening needed to reduce camber by one degree.
Tire Degradation Numbers (this is what caused me to look into the problem in the first place)
|ViN 4288 Model S tire log|
|Rt Out||Rt Cen||Rt In||Lft In||Lft Cen||Lft Out|
|2/18/2013||Rotate A to Rear and B to Front|
You can find a drawing of the upper control arm suspension bushing here. I ended up building an eccentric bushing to put in place of one of the stock bushings to confirm the correct link length to remove 1 degree of negative camber (for a target of 0.8 to 0.9 on my car). Here is how it was done.
Here is the page for the new arms using existing bushings. This page also includes work on the ball bearing links (currently installed on my P85+ and working well).
Here is how I dealt with setting rear toe back to a reasonable number after installing the new arms. This got me close enough to get the car to an alignment shop.
This is the start of work on coil spring conversion and non-P+ upgrades to the P/S suspension and some misc. bushing work.