Chiming in to reciprocate with all the help I’ve garnered through this thread and forum.
Stock 2021 Model 3 Performance w/ 20” Uberturbine wheels and suspension:
1. Stock summer Pirellis (2345/35/20) were too stretched for me plus the car will be my daily through northeast weather.
2. Switched to 255/35/20 Conti DWS 06 Plus since I’ve had very good experience with the non-plus version on other vehicles. Switched the software wheel configuration in the car to the “track package” set from Tesla, which runs 245/35/20 wheels.
3. Tried 15-, 18-, and 8-mm spacers in the rear to get the wheels close if not flush with the rear fender (the last one was a slip on while the former 2 were studded). Confirming with Model+’s post that 15 mm studded spacers work with Uberturbines (at least mine; manufactured mid/late 2021).
4. My opinion is that 7-mm (+/- 2 mm) spacers work best to get the
rim flush with the rear fender; tire brand and size will dictate overall fit/preference. My experience is Michelin has the most “vertical” tire wall followed by Continental and lastly Pirelli; other brands I’ve tried fall somewhere in between these extremes.
5. Use of slip-on spacers beyond 5 mm may result in less than ideal wheel securement (not enough thread engagement). Since the Performance version of the Model 3 utilizes a thinner brake rotor hat, which results in an effectively longer hub/wheel stud by 3 or 5 mm (needs to be verified), slip-on spacers up to 5 mm should be fine. In my case, I utilized extended-shank wheel nuts to remedy this.
6. Front wheels with replacement tires mentioned above did not require spacers to be flush with front fenders. Tried 3-mm spacers and it was too much to the extent of the rear with 15-mm spacers; didn’t even bother with the 5-mm spacers.
Stock 2021 Model Y LR w/ 20” Induction wheels and suspension:
1. Rear (and possibly front as well) wheels do not accept 15-mm studded wheel spacers; the stock hub/wheel studs interfere with the rim pockets. I ended up using the 18-mm studded wheel spacers with a slight poke in the rear but I didn’t mind it with the Model Y; looks nice in my opinion for an SUV-style vehicle.
2. Front setup is with a 5-mm slip-on spacer utilizing the extended-shank wheel nuts. Could possibly look better with a 7- or even an 8-mm spacer to match the rear but I couldn’t be bothered at this time.
Photos to support above text:
Rear wheel with spacer.
Rear wheel with 8-mm slip-on spacer.
Front wheel with no spacer (in hindsight, not the best photo since background cabinetry is black).
Front wheel with 3-mm slip on spacer. Again, not the best shot given black background reference.
Reference image of the Conti tires; don’t have the Pirellis for comparison.