[RockyMtnRay]

Originally Posted by mjlaupp

re: RMR picture #4.
I have had at least 4 tires loose pressure due to a cracked valve stem over the last 15 years. 2 were on a minivan with extra long stems to extend past full wire wheel covers. The other 2 were on an Isuzu Trooper II. These had heavy chrome plated valve caps installed. All of the failures were at or just outboard of the valve stem hole in the wheel. I don't know if they failed due to age or constant flexing. Suggest adding a valve stem check on a regular basis.
Mike

Ah...you've identified the achilles heel of this system...flexing/stress on the rubber valve stems from the extra weight on the end of the stems.

Although a visual/manual valve stem check is certainly a good idea, these pressure sensors will automatically detect (and warn if it gets large enough) any pressure loss due to cracked valve stems. So I'm not at all concerned that the kind of pressure loss you had will go undetected. Kind of a dual edged sword...the sensors may accelerate deterioration of the rubber stems but they'll also immediately send a warning if the deterioration results in a significant pressure loss.

That being said, if/when a rubber valve stem does crack and start leaking, it could be a serious problem. My stems are currently in excellent condition...zero weathering and the rubber is very supple. And I've got only 2 more trips this year...around 800 miles total...I'd be really surprised if these stems couldn't last at least that long. Nonetheless, I'm planning on replacing the rubber stems with metal ones at the beginning of next year's towing season.