Continuing my series on TPMS. Last time I covered temperature reports when it was moderate to just cool outside. This report is different. On my way South to GA from OH it got downright cold.
I stopped for the night in KY and in the morning I obtained these readings.
RF 30 LF 32 RRO 32 RRI 32 LRI 30 LRO 32
RF 32 LF 32 RRO 32 RRI 32 LRI 32 LRO 32
As expected the temperature numbers were essentially the same. To me this confirms that the sensors can report ambient temperature if given sufficient time to cool to ambient temp.
After about an hour running down I-75 I observed these temperatures when the outside temperature was in the 40's.
RF 86 LF 83 RRO 85 RRI 86 LRI 80 LRO 80
RF 48 LF 48 RRO 46 RRI 44 LRI 57 LRO 55
These numbers clearly show that the external sensors are reporting significantly cooler temperatures than the internal sensors. With cooler ambient the difference internal to external is greater than when the temperatures were warmer. I previously suggested that people running external semsor TPMS might consider adjusting theit high temperature warning level down by 10°F to 15°F. While the above might suggest lowering from 158°F to maybe 135°F I am not sure if this would be too cool for people that are traveling when the abmient is above 85°F.
For now you might just want to be aware of this difference. I am hoping that later this summer when I am traveling I will be able to get measurements when the ambient is above 85°F.