Speedometer wrong after changing tires? How to fix?

[metroplex]

I believe the only tire/wheel setting that would have an impact are those Zero-G 20" wheels as they come with 245/35R20. Just so happens to be about 1.4% difference in diameter, I plan to test it out.

i remember my 88 mustang i had to go to a speed shop and buy a few different speedo gears and swap them out till i got it dialed in with the right gear. later on my 2006 mustang i was able to just quickly program my new tire size and the car auto corrected the speedo itself.

But tesla doesn't want us fiddling around in the software

Yes my 2000 Crown Vic was the same way, needed different speedo gears to get it close. Had to do it whenever the rear axle ratio was changed or tires were changed to non-standard size. Starting around 2005 is when almost all Fords switched over to an electronic VSS and you can go into the PCM to change tire circumference (car doesn't correct it, still needs correct input). Later on when Ford switched to MS-CAN/HS-CAN, the Body Control Module has a setting for tire size and I found out that using FORScan, you can go in and change a few hex digits to match your new tire size and bingo presto.
Don't get me wrong, I won't be buying a new Ford/GM as I am really impressed with Tesla and the Model 3 Long Range. There's just a lot of nit noid things that Ford/GM had already done years and years ago that I wish I could do in the Tesla.

 

[Midnightsun]

On my wife’s previous car it bugged me the Speedo was off by 3kph so when it came time to change tires I simply installed tires with a slightly bigger diameter. Turned out to read perfectly after the swap. Cars reading a few km over is the norm by the way. Motorcycles,quads and snowmobiles are way off, usually in the 10% + range.

 

[metroplex]

Looks like changing the wheel/tire to the 20" Zero-G setting didn't do anything. Speedometer was still 1 mph faster than actual speed.