If your TPMS warned on a temperature increase and not on the low pressure, then I suspect the TPM system is not programmed correctly.
The low-pressure warning threshold should correspond to the PSI at which the tire would be overloaded. One of the primary functions of a TPMS is to prevent tire damage caused by improper inflation. I trust that you understand that driving on a tire with a lower PSI than specified in the tire industry’s Load & Inflation table is detrimental to tire life. This means you’re damaging your tires as soon as you start driving if you are relying on increased tire heat to bring the PSI up to the target level.
All tire damage is irreversible and cumulative. I’m not suggesting that you’ll experience a “blowout” if you drive 5 or even 50 miles with a cold inflation set 5 PSI low. However, I am emphasizing that you are causing damage at the molecular level, which can escalate and eventually lead to a belt failure. For example, the initiation of a belt separation as small as 0.001″ can cause significant damage. For reference, the faint circles in the image show filaments of polyester as seen from the cut ends.
Once cracks like this begin, they grow over time and with each tire rotation. The growth rate increases when the tire gets hot, which happens due to higher loads or faster driving. This tire may not “fail” or come apart for several hundred or even thousands of miles, depending on the amount of heat it’s subjected to.
To protect your tires, minimize the strain on them and keep them cooler. The rate of rubber deterioration increases with temperature, and this process is even faster with older rubber.
In my opinion, your “normal” cold inflation pressure should be at least 5 psi or 10% higher than the minimum pressure required for your actual load, as specified in the tables for the heaviest loaded tire position (front or rear for a motorhome). For a trailer, tire inflation should be based on the heaviest loaded tire.
A high-pressure warning from TPMS, in my view, is largely meaningless, but it can be set to “cold inflation +25%” because undamaged tires can tolerate a significant increase in PS.
TPMS temperature reading reflects the temperature of the metal wheel, not the tire itself, since rubber is a heat insulator. The TPM sensor measures the wheel’s temperature, which is influenced by heat from the wheel hub bearings or brakes. Therefore, your TPM system can alert you to low pressure and also warn of high heat caused by bearing or brake issues.
You should read and understand your TPMS manual to learn how to set your low-pressure warning level, as different systems have different methods.
For those interested, or for anyone who doubts my statements, here’s some “light” reading:
First is a scientific paper on rubber strength versus temperature and the long-term loss of strength [pdf: copy and paste the URL in search bar]:
https://www.jsta.cl/resource?doi=j.jsta.19.6.38
And here is an informative paper on the effect of temperature on rubber tear.
Roger Marble
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I do not trust the temperature alarms. Right now, the outside air temp is 32 and the temperature reading on one sensor is 81. Air pressure reading are about what I expect.
If you have an IR gun you can check the Temperature reading of the TPMS. Get the temp of the base of the sensor and of the wheel right next to the TPM sensor, Also if you can “shoot” the hub, it would be interesting to see the results. Are your wheels steel or aluminum?
Using an IR gun is a tire and hub saver in my book…especially on hot days when you watch all the fools race down the highway pulling trailers like they are at NASCAR. A time or two popping a tire at high speeds will “learn them” about speed.
Thank you, Roger! You certainly got my attention with this particular article. Have a great week and safe travels! 🙂