scca racer

2016 F-150 with 18" tires. I have noticed a 5-7 lb difference in gauge tire pressure and the dash display pressure. New industrial calibrated 100 psi gauge. I will admit I haven't checked it against my other gauges but will. Just interested in what others have observed. Are onboard tire sensor accurate??

elptxjc

For some stupid reason, most TPMS systems are calibrated to 68ºF (20ºC). That means if you inflated your tires to 35 psi at 98º, your TPMS would read 32, since every 10ºF change in ambient temperature is equal to about 1 psi of pressure (35@98ºF=32@68ºF). And that was exactly what my truck showed when I adjusted tire pressures to 35 psi at 100ºF a few days ago. Your differences seem excessive for July, and if that's the case with all 4 sensors, and they weren't like that before, my guess is batteries must be getting low, and affecting accuracy. At any rate, as long as you don't get a TPMS warning light when tire pressures are correct, I'd just memorize the difference, and not worry about it. But keep in mind with that much difference, you must be pretty close to triggering a TPMS warning light, so check tire pressures often. Finally, when you have to change a sensor, change all 4, since the others would surely fail shortly thereafter. Hope this helps.

AreaMan

On my '18 three are dead on, one reads 1 psi high. Might have just gotten lucky.

291433

mine is too. anytime ive had to air them up it was dead on when i checked them.

todd92

Mine are accurate at any temperature. Not sure what wheel size or tire size has to do with it.

Wicked ace

That is the NIST test standard. What it really means is the equipment used to calibrate is standardized at 68 deg F to a tolerance "not to exceed" (.0025% ??) to laboratory equipment held by NIST.
The TPMS sensors aren't held at 68 deg for calibration. I.E.The OP's gauge output was compared to a calibrated piece of test equipment certified in a test lab.

Kingofwylietx

It could be the sensors or your gauge.
You say the gauge is calibrated, but how do you know your new gauge is calibrated? Did you get a certificate of calibration showing actual gauge readings at various test points compared to an NIST traceable test standard? Even new gauges can be outside the stated accuracy....some more than others.

Check your gauge against one you know is accurate, if you have one.
Outside that, I’d tend to trust the gauge more than the sensors...unless it’s an el cheapo.




My TPMS doesn’t exhibit the characteristics you are describing. How would you test that? Tire pressures change with ambient temperature because air expands as it gets warmer. See link: https://www.discounttire.com/learn/a...mperature-flux. Also, driving the vehicle will increase the pressure. There are other factors that also effect pressure readings.

idrive

iTrader: (3)

Regardless of temperature, which set of tires I'm running, when I've checked the TPMS against a pressure gauge they have matched. I've used the one from my buds repair shop at least 7-8 times over the last four years.

scca racer

That’s what I was looking for—-real world experience. Was just wondering.

doug97gxe

mine is off