Are TPMS numbers accurate?

All 4 sensors show consistent 2-3 psi lower than my tire pressure, measured with 2 separate gauges. Shows the same difference whether the tires are hot or cold.

They otherwise behave as expected - pressures rise with driving, and they display the same cold pressure after sitting overnight - so I don’t think they’re malfunctioning. Just not agreeing with my other gauges.

Anybody else experience this?

 

Thank you for your service Sir.

The next question is, are your tire gauges calibrated? Otherwise how does one know whether the sensors or the gauges are correct?

 

I believe there is a difference from one gauge to the next. After airing tires to desired air pressure then resetting the TPMS, then driving, we see a rise in air pressure of a couple of pounds as the tires get warmer (more so in the summer vs. the winter due to outside temp.) So if there is a difference in air gauges, give or take a couple of pounds, why couldn't there be a difference in different TPMS sensors? They are mass produced. We have one TPMS sensor that always shows 1 lb. less than the other 3. Parking one side of the 4Runner in the sun shows a difference on the TPMS when you get in and move the vehicle after a bit.

 

Our gauges at work are calibrated. TPMS seems to read 1 psi high on cold tires

 

If you mean NIST traceable with certificates, no. But I now have 3 separate (borrowed another one) gauges that agree with each other and 4 TPMS sensors that agree with each other.

so who knows which is right.

 

Yes I see those changes as well with my TPMS readout. The question is why are they all reading low compared to my manual gauges, and which value is correct.

 

Thanks - that’s one data point in favor of my TPMS numbers being correct.