I run 20x8.5 +35 on my Model Y with 255/40R20 tires. No issues so far.
Don't know much about technical stuff on how wheel width and offset affects handling/stability, so I am not going to offer my 2 cents bout that.
Had a conversation about TST 19s vs Stock 19s few months ago, and here was my opinion:
The Y is designed with 19x9.5 wheels +45 mm offset. Ideally, use that since Tesla engineered the Y with this set up.
Outside of these specs maybe affecting handling, suspension, etc - I can't tell if for good or bad way.
If you go with TSV 19x9.5 +35, see A.
If you go with TSV 19x8.5 +35, see C.
Just sub TST with TSV when looking at the diagram, same NNx8.5 +35 spec.
Basically the +35 offset on 8.5 width will get the edge of the rim/wheel almost the same place as 9.5 +45 (stock 19s).
I am actually looking into getting 19x8.5 +35 TSV for my Model Y as well.
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