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Model 3 TPMS off by 3-5 PSI?

JeffK

Well-Known Member
Apr 27, 2016
6,997
6,650
Indianapolis
Does anyone know if there is any variance in other car brands? I just received my car a week or so ago. It was held up a couple of days due to faulty sensor.
It's not the car brand, it'd be the supplier. If it's the same supplier as Model S, I believe the newer ones are from Continental (I could be wrong). If anyone knows for sure, please post.
 
Last edited:

rtanov

Member
Jan 4, 2018
113
137
Cincinnati, OH
Does anyone know if there is any variance in other car brands? I just received my car a week or so ago. It was held up a couple of days due to faulty sensor.
My i3 is off by 1-2 psi but I like it more because it also shows the temperature (I know that P & T are directly correlated in the ideal gas law but still find this useful), and gives the warning when the pressure is really low instead of at the pressure I find best for the car as in the Model 3.
 

GregD60

Member
Mar 24, 2016
344
337
Colorado
When I had my car in for service for five days I didn’t even bring it up since they made a big deal about not doing anything “extra” due to their backlog.

Supposedly V9 lowered the level where TPMS will throw faults, however I am still on V8 (service didn’t do firmware update on my car while they had it) so no way for me to verify.

People rave about the great service at the Broadway S.C. but frankly I haven’t been that impressed.
I'm on V9, and the tire pressure warning came on at 38 PSI. Also, the placard on my car shows the recommended pressure as 42 PSI.
 

voip-ninja

Give me some sugar baby
Mar 15, 2012
4,121
4,691
Colorado
I'm on V9, and the tire pressure warning came on at 38 PSI. Also, the placard on my car shows the recommended pressure as 42 PSI.

My car came from Tesla with tires set at nearly 50 PSI. The car handled pretty rough due to the tires being overinflated. Per Elon Musk you should set the tires at 45 PSI for range or 39 PSI for comfort. I am unable to set my tires at 39 PSI for comfort since the crap TPMS monitoring system on the Model 3 considers real PSI of 39, which it reads as 36 PSI as being dangerously low and puts the car into alarm.
 

GregD60

Member
Mar 24, 2016
344
337
Colorado
My car came from Tesla with tires set at nearly 50 PSI. The car handled pretty rough due to the tires being overinflated. Per Elon Musk you should set the tires at 45 PSI for range or 39 PSI for comfort. I am unable to set my tires at 39 PSI for comfort since the crap TPMS monitoring system on the Model 3 considers real PSI of 39, which it reads as 36 PSI as being dangerously low and puts the car into alarm.
It is pretty silly how tight Tesla has made the low pressure warning. 3 or 4 PSI at the 40 PSI range really isn't going to make a difference from a safety standpoint. They should set the low pressure warning so that it doesn't come on until at least 8 PSI less than the recommended inflation pressure. Since Tesla is now officially recommending 42 PSI on the placard, I think 34 PSI or preferably 32 PSI would be more reasonable choices.
 
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voip-ninja

Give me some sugar baby
Mar 15, 2012
4,121
4,691
Colorado
It is pretty silly how tight Tesla has made the low pressure warning. 3 or 4 PSI at the 40 PSI range really isn't going to make a difference from a safety standpoint. They should set the low pressure warning so that it doesn't come on until at least 8 PSI less than the recommended inflation pressure. Since Tesla is now officially recommending 42 PSI on the placard, I think 34 PSI or preferably 32 PSI would be more reasonable choices.

Someone previously reported that when the warning comes on is regulated and determined by a certain offset (20%?) from what the placard says. Realize that older cars had door placards advising 45psi (I believe mine says 45).

Even then though Tesla should be able to lower it. Tesla should also be able to easily fix this problem in software as far as altitude offset.
 

GoodOmens

Member
May 30, 2018
97
47
Memphis
It's not the software but the sensor. I'm curious if just refilling them to a proper level (45PSI) and having a tire shop reset the sensors would recalibrate them.

Might try one of those cheapo TPMS devices on Amazon, but unsure which ones the Tesla sensors use.
 

miimura

Well-Known Member
Aug 21, 2013
5,989
5,567
Los Altos, CA
It is pretty silly how tight Tesla has made the low pressure warning. 3 or 4 PSI at the 40 PSI range really isn't going to make a difference from a safety standpoint. They should set the low pressure warning so that it doesn't come on until at least 8 PSI less than the recommended inflation pressure. Since Tesla is now officially recommending 42 PSI on the placard, I think 34 PSI or preferably 32 PSI would be more reasonable choices.
I agree. The warning should be at 32 psi. Our car is throwing pressure warnings as the pressures dither down to 36-37 psi. I gave up on trying to run at 38 psi for comfort and pumped them up to 40 psi according to the car, 41 psi on my analog gauge.
 

voip-ninja

Give me some sugar baby
Mar 15, 2012
4,121
4,691
Colorado
It's not the software but the sensor. I'm curious if just refilling them to a proper level (45PSI) and having a tire shop reset the sensors would recalibrate them.

Might try one of those cheapo TPMS devices on Amazon, but unsure which ones the Tesla sensors use.

That's not going to solve the problem.
 

kwest2

Member
Apr 28, 2017
253
251
Boston, MA
I brought this up to Tesla Service and he said going from 45 at purchase 7mo ago to 37 in the cold is "normal". And that they'd fill them up when I take my car in for other issues.

Uh.
 

miimura

Well-Known Member
Aug 21, 2013
5,989
5,567
Los Altos, CA
I brought this up to Tesla Service and he said going from 45 at purchase 7mo ago to 37 in the cold is "normal". And that they'd fill them up when I take my car in for other issues.

Uh.
That is perfectly normal. Just because the reading goes down over time and temperature doesn't mean that there's a leak. The original complaint in this thread is the readings differing from an external gauge.
 

tensoneu

Member
May 15, 2018
16
4
New York
I brought this up to Tesla Service and he said going from 45 at purchase 7mo ago to 37 in the cold is "normal". And that they'd fill them up when I take my car in for other issues.

Uh.

This is normal in cold weather. Unless you have your car filled with Nitrogen where pressure wouldn't be affected much.
 

miimura

Well-Known Member
Aug 21, 2013
5,989
5,567
Los Altos, CA
This is normal in cold weather. Unless you have your car filled with Nitrogen where pressure wouldn't be affected much.
Nitrogen is the largest component of earth's atmosphere, so it still behaves like air and it will lose pressure with temperature pretty much the same way. Nitrogen is a slightly larger molecule than oxygen so it will not escape as easily through the rubber.
 

Tardis5

Member
Dec 4, 2018
11
2
New jersey
So this thread is all about the TPMS issue misreading, but has anyone heard of an issue with one tire losing up to 10 psi overnight? I have been to SC 4 times and they have neve3r found an issue. They have replaced the tire and put in new stem. I was told the third time that they replaced the wheel, but now told that wasnt done. They just went through the same exercise of testing the tire and found no issue. Any suggestions?
 

SomeJoe7777

Marginally-Known Member
Mar 28, 2015
2,165
5,533
Houston, TX
So this thread is all about the TPMS issue misreading, but has anyone heard of an issue with one tire losing up to 10 psi overnight? I have been to SC 4 times and they have neve3r found an issue. They have replaced the tire and put in new stem. I was told the third time that they replaced the wheel, but now told that wasnt done. They just went through the same exercise of testing the tire and found no issue. Any suggestions?

Might be a crack in the wheel. Take it to an independent tire shop like Discount Tire (also known as America's Tire in some locations in the US), they have a tank they can dunk the entire tire/wheel in and look for bubbles. Just make sure they know how to jack up the car correctly (place jack at the exact jack point, don't hit the battery).
 

Uncle Paul

Well-Known Member
Nov 1, 2013
6,105
6,607
Canyon Lake,CA
This must be as frustrating for Tesla as for owners.
The tire pressure monitoring system is a Federally mandated item. By law, Tesla must install them. The purpose is to increase fuel economy by monitoring low tire pressures. Obviously low tire pressures in a Tesla will not negatively effect the amount of gas used : >)

Altitude effects all these readings, and I am not sure the sensors can be recalibrated by Tesla. The only thing I think they could do is reduce the pressure amount that triggers a warning, but even then they might be running afoul of Federal regulations.

It is a bit analogous to how normally aspirated ICE vehicles produce significantly less horsepower and torque at higher altitudes. There is nothing the ICE manufacturers can do even though they rate their motors output significantly higher than their high altitude customers will experience.

A 3 minute egg takes longer to boil at altitude as well, but they may still call it a 3 minuted egg.
 

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