Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Accuracy of TPMS?

COrental

Member
Jun 24, 2014
30
5
Denver, CO
I checked the TPMS display today and all 4 sensors were reading about 5 psi lower than the reading on what I think is a pretty good quality gauge. Has anyone else compared their readings?
 

CHG-ON

Still in love after all these miles
Jun 24, 2014
3,079
636
Santa Cruz Mountains, USA
I just corrected my pressure two days ago. The fronts show as right on, the rears looked a pound or two low. That's all. I'll get them all perfect tomorrow when the tires are cold and then test. I think I have a good gauge, but have now way of truly confirming that.
 

Law&Disorder

Member
Mar 18, 2015
139
3
Long Island, NY
I posted on another thread about the new vehicle status app displaying tire pressure about 4-5 psi low compared with a good quality tire gauge. It's going to become a problem for those of us in climates that are going to be getting colder soon. Should be an easy fix with the next software upgrade.
 

Barry

Active Member
Aug 9, 2013
1,833
1,426
Colorado
I posted on another thread about the new vehicle status app displaying tire pressure about 4-5 psi low compared with a good quality tire gauge. It's going to become a problem for those of us in climates that are going to be getting colder soon. Should be an easy fix with the next software upgrade.
I just had my tires rotated and the tech added a few lbs of pressure, to 50, as measured by his digianl inline gauge (at Firestone). TPMS shows 48, so not too bad.
DOn't foget the tire pressure changes about 1 PSI for every 10 degrees F, if you're not checking both ways at the same time.
 

JPP

Active Member
Feb 4, 2013
3,059
1,287
SF Bay Area, CA
FWIW I compared pressures on my wife's S70D in the status display with the FOBO Plus readings--within 1/2 PSI (close enough for government work, maybe not Mil Spec...).
 

thimel

Member
Feb 27, 2015
605
470
I set all 4 of my tires to 50 PSI with an accurate guage. First TPMS readings were 50, 49, 49, 49. Difference is quite small in my opinion and could be either my guage or the TPMS.
 

gzerninplatz

Member
Aug 24, 2014
329
125
Portland OR
My Fobo, hand-held gauge, and TPMS pressures are the same, mostly - sometimes shows a pound different, but that could be just a smidgeon either side of the breakpoints....
 

green1

Active Member
Mar 25, 2014
4,548
1,121
Calgary, Alberta, Canada
I'm uncertain, I have 3 cheap gauges I don't trust much, but they all agree exactly at 45psi while the car says all the tires are 40psi.
On the one side, I trust the fancy TPMS more than any of those gauges, but at the same time, the other 3 all agree despite being horribly cheap gauges, I'm not sure which to believe...
 

AWDtsla

Active Member
Mar 3, 2013
4,264
3,959
NE
3-5psi high reading here. Will have to confirm with a 3rd pressure gauge, but I've not known my existing inflation gauge to be off by that much before. Is there re-calibration for the TPMS pressure?
 

boonedocks

MS LR Blk/Blk 19” OD-1/1/21 RN#1143376 NO Del Date
May 1, 2015
2,784
4,196
Gainesville GA
Have 21" setup and have the rear tires at 1.5 lbs higher (tpg) than the front and the on-board show same. Once the tires are warmed up they are mostly the same psi as the fronts are a little warmer than the rear.
 

AWDtsla

Active Member
Mar 3, 2013
4,264
3,959
NE
Also seeing markedly higher reading from TPMS

I had to recalibrate my filler gauge, the TPMS and a handheld digital gauge are within 0.5 psi, unless that is a coincidence, but the digital gauge zero's before measurement so it's probably OK.
 

AudubonB

One can NOT induce accuracy with precision!
Mar 24, 2013
8,130
27,352
Few of us have the equipment necessary to determine the accuracy of our gauges; I do what AWDTsla does, but the naked truth is that all such devices could be equally wrong.

Nevertheless -
Creating a device to respond to relative gas pressures is not, as it's fun to say in these forums, rocket science. As such, if one has three or even two pressure gauges that agree with each other, there is an excellent chance they are correct.

All of this brings to mind Joe Pesci's and Marisa Tomei's characters in My Cousin Vinny:

Lisa: [sighs] If you will look in the manual, you will see that this particular model faucet requires a range of 10 to 16 foot-pounds of torque. I routinely twist the maximum allowable torquage.
Vinny Gambini: Well, how could you be sure you used 16 foot-pounds of torque?
Lisa: Because I used a Craftsman model 1019 Laboratory Edition Signature Series torque wrench. The kind used by Caltech high energy physicists. And NASA engineers.
Vinny Gambini: Well, in that case, how can you be sure THAT's accurate?
Lisa: Because a split second before the torque wrench was applied to the faucet handle, it had been calibrated by top members of the state AND federal Department of Weights and Measures... to be dead on balls accurate!
[She rips a page out of a magazine and hands it to him]
Lisa: Here's the certificate of validation.
Vinny Gambini: Dead on balls accurate?
Lisa: It's an industry term.
Vinny Gambini: [tosses paper away] I guess the ****** thing is broken.
 

green1

Active Member
Mar 25, 2014
4,548
1,121
Calgary, Alberta, Canada
Creating a device to respond to relative gas pressures is not, as it's fun to say in these forums, rocket science. As such, if one has three or even two pressure gauges that agree with each other, there is an excellent chance they are correct.
But here's the rub, three cheap analog gauges (2 of the simple pen style slide-out ones, and one that is part of the filling assembly on my air compressor) all agree at one number, the 4 TPMS sensors all agree at a different number 5psi different...

I'm inclined to believe the TPMS, but it does lead one to think...
 

CHG-ON

Still in love after all these miles
Jun 24, 2014
3,079
636
Santa Cruz Mountains, USA
I have read that some see their TPMS reading a few pounds less than their tire gauge. So I did the most simple test. I filled my tires to exactly the spec for my car, very carefully, with what I think is an accurate gauge (according to tons of Amazon reviews...). 38 front, 40 rear. I then drove just far enough to get the sensors to report (less than 1/4 mi) on a very cool day with no sun on the road and slowly. They gave the exact same reading as my gauge. I was actually quite surprised. However, when I bled my tires dry in order to put AlloyGators on, the alarm did not go off until they were essentially completely flat. So I don't trust their ability to warn me that I am low, only that I am flat, which is WAAAAY too late. What's up with that? My '06 Acura would warn after a 10% drop in pressure. So I check the widget regularly. I will say that the tires don't seem to lose pressure except when the temp changes significantly. I expected that they would.
 

jerry33

(S85-3/2/13 traded in) X LR: F2611##-3/27/20
Mar 8, 2012
19,705
22,701
Texas
So I check the widget regularly. I will say that the tires don't seem to lose pressure except when the temp changes significantly. I expected that they would.

Modern tires with oxygen-tight butyl tubeless liners don't lose pressure unless the liner is damaged or there is a leak somewhere else (wheel or valve).
 

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top