Since the car is already using GPS, why couldn’t it use that data to calibrate the speedometer? I understand most all speedometers typically are one or two mph optimistic, so I’m not necessarily looking for exact accuracy. I’m thinking more along the lines of when we’re making wheel/tire changes, and the speedometer reading staying consistent with its typical reading. Seems to me it should be pretty easy to do with existing hardware.
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Why can’t GPS be used to calibrate the speedometer?
- Thread starter Ray_R
- Start date
Sure, but those settings don’t account for the wide variety of tire sizes that fit on each wheel diameter. For example, is the sidewall size a 30,35,40,45,50, etc.?
Tesla could make speedometer recalibration an option under the car controls, giving the owner the ability to do it on their own.
Why would Tesla want to make it easier for people to use out of spec sized tires? Seems like a liable for them.
How so? Tires are a consumable. If an owner decides to try a different size, how could Tesla be blamed?
Right, just like it is now. They’ll potentially deny it. Just look at the tons of various threads already here about folks using non-OEM tire sizes. If anything, speedometer recalibration could prevent issues with folks going over the posted speed limits.
I’m not against your idea, I just don’t think it’s something that Tesla would ever do.
BitJam
Active Member
Good idea! I wonder if safety regulations are holding it back. There was some brouhaha when NHTSA regulations about the speedometer conflicted. They wanted FSD to slow down to zero at stop signs (making things less safe IMO) but they also want the speedometer to over-estimate the current speed so NHTSA complained that some cars were reading 1 mph at stop signs. Or something like that.
Olle
Active Member
FastEddieB
Member
Good article.
But it doesn’t seem to include GPS data among the parameters for accurately displaying speed in a Tesla:
“Unless you’re in a Tesla. The dash in every one of Elon Musk’s EVs shows a calculated speed value, computed using all available inputs (drive-motor speeds, individual wheel speeds, and inertial measurements) and then corrected using physics-based models that include motor and brake torque. Now that’s clever.”
I would imagine that with all of these inputs, the impact of wheels/tires would be included, GPS or not. I wonder if anyone has done any tests using different sized tires and measured the change in accuracy? That might be worth a Google.
SkyDog
Member
Olle
Active Member
Not always. Should be good for calibrating speedometer through average over long enough distance though.
i seem to remember my speedo reading 1 or 2 mph off vs. it seemed right on when i went to 235/60R18s... heres a couple posts about it:
Lifted Model Y Owners: Report!
Lift gets installed next week. Loving the pre lift with these wheels: Drag DR-64 is that 40 or 32 offset?
teslamotorsclub.com
Megabrode
Member
After installing tires an inch taller than stock, I asked a Tesla service advisor about speedo recalibration beyond the three available options. To my surprise, he suggested I ask Tesla to send me a software patch. I eventually decided it's not worth the hassle since A) my brain recalibrated to compensate and B) Tesla-indicated 70 mph at Waze-indicated 73 is no less accurate than multiple BMWs I've owned, which typically indicated 3 mph under 70. I'm OCD about some car issues, but not this one. No speeding tickets (yet), even though my radar detector is illegal in VA.
Anyway, I'm skeptical that Tesla would honor any such request. Maybe someone here wants to give it a try...?
Anyway, I'm skeptical that Tesla would honor any such request. Maybe someone here wants to give it a try...?
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