Stock ET on Performance Model 3 .

[conv90]

I know that 2019 and 2020 are ET35mm anfd for sure ET on 2021 is 34mm.
I have a 2021.
I ask: the ET is calculated on the external side of the lip (the flat of the hub wheel) or related to the more internal machined ring?
I mean:ET is calculated by Tesla FROM Centerline
TO YELLOW surface or
TO BLUE surface ?

 

[Sam1]

Yellow. The flange is just a modification because of the rotor hat design.

 

[conv90]

Yellow. The flange is just a modification because of the rotor hat design.

I agree, my concern is IF Tesla is calculating the ET in this way for Model 3 Performance.
For sure the aftermarket rims are calculated with the yellow flat flange.
I asked because a friend of mine bought a BBS set with 36 ET on 8.5" wide rim (se basically the same stock ET) to replace the stock 2020 8.5x20 Et 35 rim.
The BBS are bigger than 64,10 (and bigger than 70.10) so for sure the ET is calulted on the yellow flat flange and he needed a center ring.
But he noticed that the wheels (expecially the rear) are tucked IN more than the original set.