Just how does my Tesla MYP read the speed that I am going? Is it from a GPS, or from wheel sensors, or is it calculated from some constants such as tire size and gearing ratio?
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How Does Tesla Read MPH?
- Thread starter Vettepartz
- Start date
Mine is significantly over estimated. Probably 10%, judged against GPS readings on my phone and from those "You're going to fast!" signs that show you your speed. Is anyone else seeing faster speed displayed on their car's dash than they think they are actually going?
Please post what wheel size you are running so that others can compare. There is typically a 1-3% "acceptable" diameter difference between wheel sizes which explains some of the discrepancy. Also, are your tires new or worn out etc. Have you inflated them to rated psi? All these things will make a difference in circumference, which in turn would affect indicated speed.
PS: The same holds true of any car, not just Tesla...
PPS: From memory, my model 3 with 235/45/18 stock size seems to display a speed that's very close to radars etc.
PS: The same holds true of any car, not just Tesla...
PPS: From memory, my model 3 with 235/45/18 stock size seems to display a speed that's very close to radars etc.
My MYP reads about 8-9% faster than what a Garmin GPS reads.
The reason I asked is because back in the old days when I used to do car computer modifications to GM vehicles, there were 3 settings that determined what the speedometer was showing. One was the rear differential ratio; two was the tire diameter, and three was a correction factor which was always set to 1.000 on a stock vehicle from the factory. I wonder if the Tesla software has anything like this.
The reason I asked is because back in the old days when I used to do car computer modifications to GM vehicles, there were 3 settings that determined what the speedometer was showing. One was the rear differential ratio; two was the tire diameter, and three was a correction factor which was always set to 1.000 on a stock vehicle from the factory. I wonder if the Tesla software has anything like this.
Not sure who you're responding to but maybe me?
I have a Model Y with stock 19" Geminis. The pressure is usually a smidge low. That might be enough to change the calculated speed versus the actual speed. I'll try to ensure they're at 42 psi and run through some traps to see what they say.
I was stating that more generally since all these things affect displayed speed, if my understand of how it works is correct. Your tire dimensions, the wear of the tires, their inflation. Note that since a car is offered with multiple wheel size options, there is inevitably a difference in overall size. That means those different options could affect the displayed speed. The trick that Teslas have that others don't is that you can configure which wheels you have installed in the car's settings. That makes me think that you should definitely go and check that you have the right ones configured.
TwelveVoltMan
He'll make sparks fly round your head
All of the stock wheel/tire combos that Tesla uses are 28" in diameter (except the rear tires on the performance Y). As far as I can tell, changing the wheel size setting on a Y only changes which EPA range the vehicle displays and the image of your Y on the touch screen to match the wheel style selected. I do not believe it does anything to change how the speedometer reads.
Hi . Just wondering if you moved up to the 255/50 tyres as I’m considering for my MY? Many thanks.
