TPMS lesson, where's my defibrillator?

**JM0397** · 05-25-2022, 01:05 PM

FYI to save anyone else a near heart attack!
I run the TireTraker TT-600 TPMS and have never had an alert in a year+

Driving on a warm, sunny day, the rig tires run up to the neighborhood of 110 degrees F and 140 lbs pressure.

Passing through Asheville, NC last weekend, it was a warm sunny day and then we crossed an apparent cold front and thunderstorm. This cooled the road down quickly. Right in the middle of the city on I-26, where it's no bueno to get off the highway, tire 1 throws a pressure and temp alert.

I needed about 10 minutes to clear town and get to a better exit, so I was watching it and pressure was steady, albeit lower than it had been, so I kept driving.
Queue tires 2 and 3 throwing an alert and I about had a heart attack before I realized the temps & pressure both dropped to around 90 degrees and 130 lbs, so 20 degrees and 10 lbs of pressure on the wet, cooler roadway, and that was a quick enough change to trigger 3x alerts.

By the time the 3rd tire threw an alert, I figured out what was going on, calmed down, and had to talk my DW off the ceiling. By the time I made it to a good exit, the alerts had cleared and everything was stable.

Good lesson: When going into a downpour after a warm, sunny day, beware the TPMS alerts!

**Hoopy Frood** · 05-25-2022, 01:28 PM

Wow, what tires are you running that you're hitting 140 psi? H-rated tires? And why did the monitor show an alert? What are your alert settings?

**Ynot4me2** · 05-25-2022, 06:30 PM

Wow that would of got our blood pumping like crazy also. It never occurred to me that a big outside temp difference and condition could make the TPMS alarm go off but it makes sense.

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**Hoopy Frood** · 05-25-2022, 06:46 PM

I still wonder about those 130-140 psi readings.

The TST system requires the pressure change to be at least 2 psi/minute, so it can happen but a 10 psi drop would have to happen in less 5 minutes. Possible I guess. But that is only for the TST system, not sure about other systems.

The Tire Tracker does seem to be a bit more sensitive to pressure changes.

**Steven@147** · 05-26-2022, 05:56 AM

If you tow long enough (miles) with one of these systems you'll run into this. We have experienced it the other way around, going from cold conditions to hot like in December crossing from Arkansas into central Texas and warm fronts. Our tires starting out 106* would run in the 118* then up to 126* just in a few miles. Hot asphalt heats them up fast.

**Hoopy Frood** · 05-26-2022, 07:10 AM

Huh. Learn something new every day.

**JM0397** · 05-26-2022, 08:43 AM

Originally Posted by Hoopy Frood

Wow, what tires are you running that you're hitting 140 psi? H-rated tires? And why did the monitor show an alert? What are your alert settings?

Tires are Roadmaster 215/75/17.5 H-rated. Cold pressure on these is 125 lbs - yes 125!, so 140 is normal operating range.
I need to check the variance alarms - I can customize those, but I have everything set to factory defaults for the time being. Knowing this can happen, I'll likely leave the alert thresholds the same - I'd rather have more sensitive than less.