19" and 20" wheel measurements

[MJAir23TheGoat]

I want some wider 21’s…….
Give the GT an even better stance.

 

[Pragmatic]

Related to this, does anyone know what the minimum inside diameter of a 19" wheel needs to be to clear the brake calipers?

Would like this also. I purchased older Tesla S wheels (standard 19 inch by 8 inch 40ET, pre 2016) to use as snow rims. They do not clear the caliper. I tried 5mm spacers, still had issues.. Now that the weather is nicer I will try with different spacers to see if I can get them to work.

 

[terrycs]

Related to this, does anyone know what the minimum inside diameter of a 19" wheel needs to be to clear the brake calipers?

From the inside diameter perspective, a 19" wheel should clear the brake disk & caliper assembly. I'd be more concerned about the wheel's offset and/or disk profile to clear the outside face of the factory caliper. If you are considering aftermarket 19's, the wheel design has to be designed to clear a BBK (Big Brake Kit). The wheel manufacturer should be able to tell you if their wheel will clear a BBK.

 

[Pragmatic]

The Tesla wheels (older base 19s) I tried, clear the outer face of the caliper but foul on the inner rim. That is, the wheel inner rim diameter is too small and contacts against the leading edge of the caliper.

 

[terrycs]

The Tesla wheels (older base 19s) I tried, clear the outer face of the caliper but foul on the inner rim. That is, the wheel inner rim diameter is too small and contacts against the leading edge of the caliper.

Normally a BBK manufacturer such Brembo or StopTech takes measurements and lays everything out in CAD during BBK development and can supply fitment templates to ensure wheels will clear. Since the Air already comes with BBKs, they could in theory provide such a template since the entire car is already in CAD (but good luck with that).

In case someone here has the opportunity to do so, rough measurements can be taken from the center of the hub to largest radius where interference will occur, such as to the leading edge of the caliper. For an idea of how this works, this is a picture showing such a template when StopTech did the R&D on one of my previous cars. In this case, the spare wheel would not have cleared the caliper face: