TPMS shows different pressure than pressure gauge

Snomas wrote:
I have a TST TPMS w/ 10 sensors and the never read the same as the tire actual Tire pressure gage. That's OK as long as they always read about the same when tires are cool in the AM. I have one tire extender that causes a loss of about 1psi a month. Very aggravating to have to deal w/ this problem. I just recently bought new tires and that tire was flat the next day in storage. This is my 2nd TPMS system. I'm very frustrated w/ TPMS systems & am considering to eliminate it altogether.

I recommend you keep the TPMS. Buy a new tire extender!

Someday you may pickup one of these.



And as in my case the TPMS notified me of the problem with time to pull off the highway in a safe place to investigate the problem.

I am also sure if I had continued on for 300 miles to my next overnight stop I probably would have had a catastrophic tire failure with possible great damage to the trailer as the tire was under a slide out.

I have a TST TPMS w/ 10 sensors and the never read the same as the tire actual Tire pressure gage. That's OK as long as they always read about the same when tires are cool in the AM. I have one tire extender that causes a loss of about 1psi a month. Very aggravating to have to deal w/ this problem. I just recently bought new tires and that tire was flat the next day in storage. This is my 2nd TPMS system. I'm very frustrated w/ TPMS systems & am considering to eliminate it altogether.

kmb1966 wrote:
We have the Tireminder TM66 on our Class A. We are finding that many times the sensors have a different reading than the manual tire pressure gauge. not a huge difference but enough to not know whether or not to adjust the pressure.
For example this morning our inner dual driver side read 89 on the TPMS. The manual gauge read 96psi.
So I grabbed another manual gauge and it read 96psi. Added 2 psi to the tire and both manual gauges read 98 psi, the Tireminder TPMS reads 91 psi.

Is this an acceptable variance??

ON EDIT:
I forgot to add that one of the 2 manual gauges is a TireMinder brand gauge, just like the TPMS is a TireMinder.

My TM66 reads about 5% higher than my $10 auto store tire gauge. I set my tires to 105 cold using the manual gauge, and each sensor will report between 109 and 112. I am not concerned about this difference, and, as they say, am "fat, dumb, and happy" as long as I don't get an alarm.

I have had two alarms, both of which were false and occurred shortly after pulling into a rest stop. I was told that this can happen if the tires cool down very rapidly causing a quick drop in pressure - even though the pressure doesn't go below the alarm set point.

As stated by others, inexpensive gauges are notoriously in accurate and truly accurate gauges are VERY expensive.

I have acquired several different Accu-Gage Dial type gauges over the years for 2 reasons. The have a lifetime warranty and they will recalibrate them free of charge, except for postage. I ene had them correlate all of my gauges.

They make digital gauges, but I don't know anything about them.

They are sold in many stores, but if you want a specific style check out getagauge.com

So long as you know whether each sensor is reading slightly high or low I don't know that it matters. Just keep track of it.

On my system all six sensors read exactly 3 pounds low so if I set pressure per the sensors I'm adding 3 lb extra air above what I might want if not making the adjustment.

My reference gauge is an Intercomp digital gauge which for all practical purposes has zero error. I use it to check calibration on my hand gauges that get used and abused on the road.

I bought a $40 Napa gauge one time and a couple years later the stick blew out the end so I don't know how much you have to spend to get a reliable gauge but that one sure didn't work for me.

But the key to maintaining accurate tire pressure is either having your own highly accurate calibration gauge or work with a good shop that maintains a calibration gauge of their own. I don't know that I would trust any one shop for that personally. Maybe run by two shops.

According to the Tiretraker website:

12. Why does my manual pressure gauge list slightly different pressures than the TireTraker™ TPMS?
The TireTraker™ TPMS are highly sophisticated electronic wireless tire pressure monitoring devices. Electronic systems have been proven to report much more accurate pressures that the standard tire pressure gauge. We suggest that you utilize your manual gauge to periodically check your tires, but to rely on your TireTraker™ TPMS for better accuracy.

If it still worries you then call them at 866-200-9773. The T-500 warrenty is limited lifetime.

Consider the error is just short of 10% and TireMinder list the TM66 series at +/- 2.7% I would say no, the error is is not acceptable. I would first replace the sensor battery and if the accuracy doesn't return to specification then replace the sensor.

Mine reads about 4 pounds higher than my digital tire gauge. I don't worry as long as the alarm doesn't go off. I check them a few times a day but never have to adjust. Typically the pressure rises as the temperature increases anyway. I only make adjustments if tires are cold and the pressure is lower than recommended.

My TPMS (TireMinder A1A) reads higher on all tires than my three gauges (which agree) - 65 on the six tires on the truck and 105 on the four tires on the trailer. I just set the baseline pressure on the TPMS to what the TPMS sensors read when the the tires are inflated properly per the gauges. The alarms will go off at +/- a certain percentage of what is set (and they have - saved us additional damage to the trailer when a tire took a piece of rebar).

Rob

My TPMS system is about 2 psi different than my digital pressure gauge.

But what is important all of my TPMS sensors read the same and what is even more important that I get the same readings from all tires while under way.

If any TPMS pressure has dropped more than a couple psi I pull over when convenient to investigate.

I have only had to pull over once and I found a 3/8 by 2 inch bolt in a trailer tire.

I was able to catch this before the TPMS alarmed as I watch my pressures often when under way. The pressure had not dropped to the alarm point when I noticed the tire was about 3 psi lower than the others.