TPMS Accuracy question

[Bharat]

Do the TPMS provide the pressure values accurately or is there a difference of +/- 2-3 psi?
I though i was filling 36 and 38 psi respectively, on pretty much cold tires (gas station is 500 m from my place), and the TPMS was showing 41-42 psi all around.

 

[Ozstung]

Do the TPMS provide the pressure values accurately or is there a difference of +/- 2-3 psi?
I though i was filling 36 and 38 psi respectively, on pretty much cold tires (gas station is 500 m from my place), and the TPMS was showing 41-42 psi all around.

Strange , I use the 7/11 air pumps and they match exactly my readings in the car. There was another thread in the forum where some of our US friends mentioned what you have stated. See if you can do a search on TPMS maybe.

 

[Bharat]

I did, couldn't find any proper results.
Will try filling up in another pump maybe. I see you are western Sydney. Is your 7/11 anywhere near Parra?

 

[POS VETT]

There is always a discrepancy between two systems (i.e. your car TPMS and the air pump at a gas station) and even one TPMS sensor to another (i.e. 36 psi on the left side tire is not exactly the same as 36 psi on the right). In order to have the exact same tire pressure all around (whatever that pressure is) is to use the same gauge on them. Expect to see different readings through TPMS sensors especially if the pressures were displayed to the 1/10 psi increment. There are inexpensive digital tire pressure gauges available out there, some have 1/10 psi increment, most have 5/10.

Once the tires are rolling, pressures will fluctuate independently depending on many factors.

 

[Coast GT]

My TPMS shows them between 36-38 when I start driving, but they usually show 41-42 once they heat up, there’s often one that is 1-2psi less than the others but it’s often not the same tyre I’ve even had them showing different on all 4. Not sure how accurate they are but I haven’t checked it with a gauge either

 

[Ozstung]

I did, couldn't find any proper results.
Will try filling up in another pump maybe. I see you are western Sydney. Is your 7/11 anywhere near Parra?

A bit far Emu Heights -West of Penrith. 7/11 ones you dial up the amount first and it stops when it senses the tyre pressure in the tyre. If you look carefully at the start it will tell you on the machine what you currently have in the tyre. You can then see the starting pressure matches what you have on the Stingers display.

 

[Kazz]

I have a compressor in my garage and use what I consider top quality gauges. But my dash reading does not agree with my gauges. I've heard of mediocre performance by TPMS systems before. I assume that's the issue. When I finally move to get my summer wheels and tires, I'll be looking into quality of TPMS sensors.

 

[MerlintheMad]

I will use the handheld gauge and my compressor to inflate the tires cold to 38 front 36 rear. And as soon as the TPMS readout flashes it will show c. 35, 34 or 36, 35; it varies.

 

[DrGCS3]

I have my own compressor at home and I use a non digital pressure gauge. I set mine manually to 36F and 39R. My TPMS will usually read 38F and 41R when I first start driving. I think a good idea is to use a gauge that you trust, then learn what your TPMS reads and keep it in the ballpark. I find it more useful to just look at it occasionally and make sure tires are within range of what they have been. If it says all tires are 36-40, but right front is at 30, then thank you TPMS for letting me know RF needs checked. But I won’t set the pressure based on TPMS number. I will measure that manually as I refill them.

 

[Ty Davis]

My TPMS display typically reads 2psi higher than what is actually in the tire, as verified by several other gauges.

I fill the tires with 36psi. The TPMS will read 38psi.

 

[MerlintheMad]

My TPMS display typically reads 2psi higher than what is actually in the tire, as verified by several other gauges.

I fill the tires with 36psi. The TPMS will read 38psi.

That's easily a four psi difference between TPMSs since mine typically read 2 psi low. How much of the discrepancy is the TPMS gauges and how much the interface? All four gauges are 2-3 psi low; so this makes me suspect that the "central" or controlling software is more the cause of the discrepancy than the gauges in each tire.

 

[eflyguy]

The data sent from the sensors is digital, it's not likely, otherwise every new set would need to be "calibrated" when first registered with the vehicle.

 

[washguy]

Just got a digital gauge for like 20 bills it sez 30 psi all the way around the dash sensor sez exactly the same ...old school race gauge sez 32....go figure....and I thought the ride was too stiff...now its gonna be worse when I increase to standard pressures...my aching back....getting old aint for sissies Wash

 

[Drakkon.ri]

I trust the TPMS for daily use. Not at the track. I have a digital with a 0.5 tolerance for the track.

 

[MerlintheMad]

I trust the TPMS for daily use. Not at the track. I have a digital with a 0.5 tolerance for the track.

Since my Feb 7th post, I have put on TSW "Watkins" rims and the TPMS gauges in these rims seem to be very close, within that .5 tolerance. This proves that my handheld tire gauge from O'Reilly is 3 to 4 psi too high.

 

[Wilzer]

Using compressor without drier results in water inside of tire (tyre for upside down folks). Water inside tire/tyre can produce corrosion at the tire/tyre bead and eventually gives chronic air loss. The tire boys finally admitted that's the rationale for Nitrogen as tire gas, it is very dry. So I fill my tires/tyres with SCUBA air, that is very dry, can't have water in SCUBA tank for the same reason, makes corrosion that may clog up 1st stage or produce leaks or tank failure. Scuba air is ~80% nitrogen anyway. (don't use Nitrox). You heard it here first

Sitting and waiting for blow back

 

[Todd Piefer]

How long after a tire rotation should it take for the TPMS to accurately show the pressures in the correct locations? The sticker on the door recommends 36 psi in front and 38 psi in the back so after rotating the pressures should be changed. How long before the TPMS "understands" which wheels are where?

 

[nhcowboy28]

How long after a tire rotation should it take for the TPMS to accurately show the pressures in the correct locations? The sticker on the door recommends 36 psi in front and 38 psi in the back so after rotating the pressures should be changed. How long before the TPMS "understands" which wheels are where?

Typically a mile or two.

 

[Todd Piefer]

Typically a mile or two.

So if it's been three days since the rotation and the TPMS readings still show the opposite of what I expect, would you say that the mechanic at the dealer probably just rotated the tires and didn't adjust the pressures? It's reading 38 front and 36 back on the dash.

 

[Manaz]

Do the TPMS provide the pressure values accurately or is there a difference of +/- 2-3 psi?
I though i was filling 36 and 38 psi respectively, on pretty much cold tires (gas station is 500 m from my place), and the TPMS was showing 41-42 psi all around.

Petrol station pressure gauges are known for their inaccuracy.

Get a good independent pressure gauge and see how the TPMS compare with that.

In the end, absolute accuracy isn't actually important - who cares if it reads 38psi or 42psi - what's important is consistency of reading, and the relative values (are they all the same, or is one dropping suddenly).