Internal vs. external TPMS temperature test results for warm weather


RV Tire Safety
with RV tire expert Roger Marble

Previously I posted the test results for my comparison of internal versus external sensor TPM systems. The weather was cool (“How accurate is your TPMS – Part two”) to cold (“More on internal vs. external TPMS temperature reporting”) back in March. Now I can report the results with the ambient temperature in the upper 80s.

All temperatures are in degrees Fahrenheit.

Internal System:

RF 102   LF 104   RRO 104   RRI 111   LRI 111   LRO 102

External System:

RF 73   LF 75   RRO 71   RRI 71   LRI 82   LRO 80

I was driving 65 mph with cruise on a level stretch of Interstate. The sun was fully on the left side of the RV.

Difference between Internal and External:

 RF 29   LF 29   RRO 33   RRI 40   LRI 29   LRO 22

These results tend to match the previous runs with the internal reporting about 30 F hotter than the external sensors.

Again I do not consider the results of a comparison between the temperature readings to be “meaningful” in the sense that the internal sensor numbers are useless.

Suggestion:  If you have an external sensor TPMS I would continue to use that system. Just be aware that the temperature readings are probably in the range of 27 to 40 F cooler than the temperature readings your friend would be getting with their internal sensor system. If you are concerned, you could change your High-Temperature warning level with your external sensor system from the factory 158° F to about 145° F.  Just be aware that if in Phoenix or Death Valley or other location where the ambient temperature exceeds 120° F,  you may get a high temp warning. If you do, just pay attention to the pressure readings to be sure you are not losing any air pressure.

Since tire temperature is also a function of load and speed, you might bump up the High-Pressure warning level 5° F until you are not getting a warning simply because it is hot outside.  Of course, it might also help to slow down a bit as that will also result in lower tire temperature.

Bottom Line: There is a difference between temperature readings based on sensor location. BUT this does not automatically make one type of system better or worse than another. As I said in this post, I am not a fan of TPMS temperature readings no matter which type sensor you run.

Read more from Roger Marble on his blog at




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