RV Tire Safety
with RV tire expert Roger Marble
As a tire engineer, I see little reason to present the temperature of the tire pressure monitoring system’s (TPMS) sensor. IMO, this extra information has some problems:
1. Tires fail from low inflation primarily due to air leaks (puncture, cut or valve problems) but not from just getting hot. You only get a tire hot from running too fast and/or running too low air pressure. The sensor is not actually reading the temperature of the critical location in the tire, as the hottest location is internal to the tire construction and measurement of that location can only be accomplished with a needle probe as done by race tire engineers ( I did do that as part of my job once upon a time).
2. The temperature number is distracting and is actually the temperature of the sensor, not the tire, and the sensor is cooler than the wheel.
3. The TPMS temperature reading is significantly (25 F to maybe 50 F) different, i.e. lower, than the tire temperature for most applications. More on this temperature difference in a future post. While it is possible for a sensor to report a dragging brake or failing wheel bearing, an IR hand gauge is a better tool to use if that is your concern, as the hub will be hotter than the wheel and provide an earlier warning.
Read more from Roger Marble on his blog at RVtiresafety.net.
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As much as absolute temperature readings, it is often the difference between tires that provide some indication that there is an issue that needs to be looked into. If one tire is significantly higher than others, and even if it hasn’t reached alarm levels, it indicates that there is something that needs to be looked at. I would caution however that you should not rely on your TPMS to alert you to something like a failed bearing because unless it has caused the wheel to drag (unlikely) the prevalence of aluminum wheels which do not conduct heat well means you can have a red hot bearing and the outside of the rim is still cool to the touch (I have experienced exactly this situation).
My TPMS system alerted me to high temperatures which upon pulling over I discovered that my break-away cable had been pulled and that I was driving with trailer brakes activated. Had I not observed the high temperatures, I likely wouldn’t have pulled over to make the discovery.