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tireman9

TPMS don't work

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Good, I got your attention.

Recently there was a thread on an RV forum with a person complaining that the sensors on the toad didn't provide a warning when the brakes all locked up and all four tires quickly wore through the tire tread and all four tires suffered "Blowouts". From the numerous comments on that forum, it appears that a good number of RV owners do not have a good understanding of what TPMS can and can not do.

Here is what I wrote.:

Tire Pressure Monitor Systems do not and never were intended or designed to monitor belt separations or improper mounting or sidewall blisters or tread wear etc.
People need to stop thinking they are a cure-all to warn of every possible tire condition.
I have written on the inability of TPMS to provide advance warning of "separations".

MONITORING air pressure is their primary job and from my testing and experience working with them since 2002, they do that job quite well.

The temperature sensing an "add-on" and I have written that I wish this "feature" was not part of the package, as very few users understand the difficulties of obtaining the temperature of the critical location for high temp and IMO TPMS are of little value for monitoring tire temperature especially given they are really monitoring the temperature of the metal wheel and not of the tire radial belts.

I did a direct comparison of two TPM systems (internal vs external) and to my knowledge, this is the only such comparison I have heard about. both systems reported pressures reasonably accurately but the temperature readings were different by 20 to 30F. Not wrong, just different as the systems are measuring different areas of the tire/wheel system. Do you understand this difference? Do you know how to decide which is more important?

Bottom line. Set your TPMS for your tire pressure needs. Do not expect the TPMS to do "magic" Understand the benefits and limitations to the technology.  Go out and enjoy your RV.

IMO you are misleading yourself if you think TPMS are a substitute for competent, detailed tire inspections on an annual or more often basis.

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Excellent article Roger!

I do not monitor actual temperature reading, as you said they are not reliable nor accurate. I do monitor for any substantial difference between readings for all wheels.  I use the minimum temperature alarm setting/default setting for the TST system, 158°F. This will sound an alarm for one wheel, but long before it becomes threatening, which is my reasoning.

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I own a Tire SafeGuard TPMS with CAP sensors and it reports both psi and temps of each tire location. I only use the temp information to monitor for significant differences relative to the other tire locations. If people need to know a more accurate temperature of their tire sidewalls, wheel or hubs they should purchase an IR Temperature Gun and use it at every rest stop or fuel stop. I have been doing that since 2010 and it works flawlessly.

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I only care about TP on my TPS, all 8 of them!  Long before we had the TPS technology, I carried a small baseball wood bat & thumped my tires, especially the inside ones!  Every morning I check tire pressure with a gauge.  

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I also do hold a lot on the temperature function, I use it to compare to the others to see if something is out of the ordinary, that's it.

Here's why;  I had a situation this year in stop and go traffic down a hill, brakes were hot and I could see it on the TPMS, then someone pulled out on us once we got rolling to speed and I stood on the brakes, both rear inner duals set off over temperature alarms when I came to a stop. Me being me pulled over into a parking lot and took a temperature reading of all drive tires with my temp gun. The tires were not close to the temp reading on the inner duals on the TPMS display, the outers were!

I soon realized the TPMS sensor was getting hot from the brakes (they were located between the wheels then) and not from the actual tire. My over sized fire apparatus brake lining probably escalated the heat. I moved them back to the outer duals now for accessibility with solid extensions like I had set up before. 

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5 hours ago, jleamont said:

I soon realized the TPMS sensor was getting hot from the brakes (they were located between the wheels then) and not from the actual tire. My over sized fire apparatus brake lining probably escalated the heat. I moved them back to the outer duals now for accessibility with solid extensions like I had set up before. 

Mine did the same thing, I posted here a few months ago about it. I called my local HDT and RV service center and asked why  the high temp alarms. The owner told me not to worry is was the brakes heating up from the stop N go driving I was in at Pigeon Forge.

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On 9/11/2019 at 6:01 AM, dr4film said:

I own a Tire SafeGuard TPMS with CAP sensors and it reports both psi and temps of each tire location. I only use the temp information to monitor for significant differences relative to the other tire locations. If people need to know a more accurate temperature of their tire sidewalls, wheel or hubs they should purchase an IR Temperature Gun and use it at every rest stop or fuel stop. I have been doing that since 2010 and it works flawlessly.

Sorry but IR guns simply do not provide sufficiently focused temperature readings to be of much value.  Here is a link to my articles on IR guns and measurement of tire temperature.

IR guns are OK for measuring the temperature of materials that conduct heat i.e. metals but do not work well on insulating material such as rubber or plastic  A quick look at the thermal images collected with a good ($15,000) imager as seen in my last post will show you how critical it is to get the exact location at the bottom of a groove. 

 

TPMS temperature reading is, in reality, the temperature of the metal wheel and if your TPMS sensor is external it is low by 20F to 30F because the metal valve stem and TPM sensor is cooled by external air.

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On 9/11/2019 at 9:00 AM, manholt said:

I only care about TP on my TPS, all 8 of them!  Long before we had the TPS technology, I carried a small baseball wood bat & thumped my tires, especially the inside ones!  Every morning I check tire pressure with a gauge.  

I have seen controlled tests with a dozen professional truck drivers presented with a few tires at different inflations. While they can reliably identify a tire that has lost 50% or more pressure. the best any could do is be within 20 psi of the actual pressure.

If you have a TPMS I don't know why you check pressure with hand gauge. This increases the potential for having a valve core leak. It also gets your knees dirty. 😎

 

Here is an older blog post where I advise to not check the air in your tire and show what can happen.

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