Bumping this thread with my own update (btw, hi!)
tl;dr: I found some that work on 21" twin turbine wheels (YMMV - at your own risk, I guess)
I have read and understand for AWD with proper tires I don't need chains, and yet it
may be required by law, it also gives me peace of mind! Thanks to this and another thread I learned a few things:
- Normal chains would mess up the car
- Most chains only work on 19" or even 21" tires
- No all-weather tires (only all-season) were available for 265/35-21
I was sad but still tried to search as I didn't want to replace the tires for aesthetic reasons and I didn't want to store/swap the wheels given I live in PNW where I may only need traction when going to do snowsports, so.. only for a few weekends at most so it's very inconvenient to swap and very wasteful to get winter tires.
On König's website it says the
K-summit XL K55 fits, however sellers and even
their manual do NOT include the 265/35-21 measurements, so I just took a gamble and
got some from etrailer.
Now.. the problem with the lack of these tire sizes in the manual is that the chain can be configured by removing some springs (
installation video, starts at 5:40) and I didn't know how many, so I did a trial & error. Note that configuring your chain too narrow
could damage the chain and burst open potentially damaging the car, so in hindsight this was stupid, but I concluded I had to remove all 4 springs that can be safely removed, but note:
265/35-21 is not in the manual, so be careful!
At 3-springs-removed the fit was just not possible, but
at 4-springs-removed IT DOES FIT snuggly!
However I wanted reassurance so I used a
tire diameter calculator to compare my tires against the ones documented in the manual using the calculator. Based only on that, the chain seems to gain ~2.5mm diameter (~1cm circumference) for every removed spring. If I trust the calculator, my tires (265/35-21) are right in between 265/40-20 and 265/30-22 (+-1.1mm respectively)
Therefore in my testing, the König summit XL K55 does fit the rear tires for the Model S 21" twin turbine staggered tires, with the 4 springs removed configuration (265/35-21). BUT... it is
not documented in their manual, so use at your own risk!
PS - I used the 21-22mm nut clamps with the gray/medium bolt.