TPMS vs Tire Pressure Gauge

[ARD]

Which one do you trust?

Getting prepped to hit the road tomorrow and checking my tires. I know I'm a bit of a perfectionist, but I hate it when the numbers don't all match. Tire gauge agrees with separate tire inflator. TPMS is showing tire pressure lower by 3-5 psi. I know that's not a lot and as soon as I start driving the psi will increase, but just curious....which one do you all trust?

 

[mjeds]

In my experience TPMS systems are always off by about 10% off. Most systems require the vehicle/tire to be moving for 3-5 minutes before they provide an accurate read, and even then, they are usually about 10% off.

on my SUV, the OEM ones are off by 2lbs from my gauge and pump when the tires have been sitting (i.e. cold), on my gauge they show 38psi, on the TPMS of the vehicle they show 36psi,

The Lippet ones on my Travel Trailer are off by 7psi compared to my gauge, gauge shows 65psi and the lippet app shows 58psi.

also remember as the tires heat up the PSI will rise.

 

[Joe Hogan]

As mentioned above, best to check cold then verify after movement to be sure to sensors readings are current. Sensors will go to "sleep" after a certain period of inactivity, this is to save battery life.

4th paragraph

Tire Pressure Monitoring System Signal Science

A sensor is a transmitter of information that sends pressure and temperature data to the vehicle. A sensor is almost never a receiver.

www.tirereview.com

 

[Neal]

When I chatted with this long about with TST Truck (my TPMS manufacturer) he mentioned a 4% error

 

[Rich W.]

My gauge and TPMS pretty much agree with the obvious caveat that the readout on the TPMS is to the lb and the gauge is a little more of a rough approximation. I also spent a lot of time getting each side within 1lb of each other on the TPMS which is probably excessive. But if we obsess on tire pressure we’ve done the best we can, due diligence, and all that. Better too picky than not enough.

 

[DennisT]

Guess I may be a lucky one, based on the above.

My TST cap sensors have always matched what I get checking with a gauge.

Stayed that way even switching them from our class c to the superstar.

Any differences I’d believe my gauge in reality.

 

[AbdRahim]

I set the pressure to the TPMS. After a time the tires will vary by 1-2 pounds from each other. I am not ocd about it. As long as they are 97 -100 lbs, I am good. Of course that is cold. I am using TST 507. I think less fiddling with the tire valve is better.

 

[Jabber Jaw]

I too, use a TST-507 TPMS system. And I use a digital tire gauge.
Surprisingly, they agree on all (coach & toad) but two tires, the inside duals. TST is one pound lower than the digital gauge.
Guess I am lucky that they are that close. And have had both the "TST" & digital gauge for almost 4 years.
Change the sensor batteries yearly, & changed the digital gauge twice.

 

[Rich W.]

I set the pressure to the TPMS. After a time the tires will vary by 1-2 pounds from each other. I am not ocd about it. As long as they are 97 -100 lbs, I am good. Of course that is cold. I am using TST 507. I think less fiddling with the tire valve is better.

Agreed - once I have the pressures are where I want them and my TPMS is reporting consistently, there is no reason to remove the sensor and use the gauge again. I only do that if something is off, or if ‘m changing pressures (which is not often). But at that point I probably am a but obsessive about it.

 

[jbh]

PressurePro specifies +/- 3%, which I think is about average. I inflate the tires using a known-good gauge, which happens to agree with another known-good gauge. Then the TireTrakr sensors usually show +/- 2% or so. The purpose of a TPMS is to verify that your tires aren't low and to alarm at a rapid decrease in pressure or increase in temperature, not to act as an accrurate tire pressure gauge. On that note, I wasn't real thrilled about needing to drive to wake up the PressurePro sensors; when I needed to replace 10 sensors just to replace the batteries I replaced the system with TireTrakr.