Thanks for the info JST.
My setup consists of an X5 18x5 spare wheel with a Continental 145/85R18 CST 17 tire from a 2018 VW Tiguan. I was looking for an older Tiguan 145/80R18 as suggested in this thread and stumbled onto the newer version which matches the overall diameter of the stock wheels at 27.7". The tire is load rated to 1929lbs and you can currently get it at Tirerack for $113. I found my spare with tire on Ebay for $70 shipped. ESC Tuning currently sells the X5 spare wheel for $83 with free shipping.
It fits on both front and rear on my 6/2016 Model S with two calipers in the rear.
Front:
View attachment 628199
Rear:
View attachment 628200