# Dumb Question, Maybe, But....



## Vistan (Mar 28, 2017)

What is the input source for the Model 3 odometer mileage? How is it adjusted in the case, for example, of changing wheel/tire overall diameter?

Vistan


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## iChris93 (Feb 3, 2017)

Vistan said:


> What is the input source for the Model 3 odometer mileage? How is it adjusted in the case, for example, of changing wheel/tire overall diameter?
> 
> Vistan


Not sure on the input, probably a wheel speed sensor that is used for ABS. I've read that when the car detects new TPMS, it will ask for tire size.


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## Vistan (Mar 28, 2017)

Bump - Still looking for a definitive answer to where the input for the odometer comes from. Now that the wheel speed sensor has been brought up, is it reasonable for speed and distance traveled to come from the same source?

Vistan


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## PNWmisty (Aug 19, 2017)

Vistan said:


> Bump - Still looking for a definitive answer to where the input for the odometer comes from. Now that the wheel speed sensor has been brought up, is it reasonable for speed and distance traveled to come from the same source?


Speed is "distance traveled per unit of time" so why wouldn't they use the same distance measurement? Can you see a potential issue that I can't?


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## Vistan (Mar 28, 2017)

PNWmisty said:


> Speed is "distance traveled per unit of time" so why wouldn't they use the same distance measurement? Can you see a potential issue that I can't?


In theory, you could count the number of revolutions a wheel of a known diameter made and then calculate the distance traveled. This would require no time input. Potential wheelspin and going around corners would affect distance measurement in small ways. If you add a time input, say revolutions per minute, then as you point out, you can calculate both distance traveled and speed. I'm still searching for the actual sensor input (ABS system, motor rpm, wheel rpm, etc.) that is used in the Model 3 to generate the odometer reading. OCD at work...

Vistan


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