TPMS question/issue

[NukeSparky]

Im in the 2nd week with my new 23 at4 and last sunday I aired down to 28 from 40 for some trail riding. After airing back up the tpms system is reading 3 psi lower compared to 2 hand gauges. Could the problem be im at 7K+ altitude and the pressure difference is off or is there something wrong with my tpms?

 

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[rick25s]

Atmospheric pressure affects them, without a doubt. Elevation is a huge factor in that. 3 psi makes no difference anyway.
Here's a good example of atmospheric pressure affecting tire pressure: Last week I put 5 psi in all my Yamaha Grizzly tires. (If you don't know anything about ATV's, that's all the air you're supposed to put in the tires, actually supposed to be 4.4 in the back and 5 in the front). Two days later, I rode around and thought they felt soft. I checked and they all had 3 psi in them. I parked it in my shed, and got side-tracked with something else. The next day, the tires felt fine. I checked them and each tire had 5.5 psi.

 

[phobby]

Typical with the sensors. That’s about as accurate as any BMW tpms will ever get to another gauge.

Every late model gm truck I’ve had the tire sensors have a mind of their own to say when the pressure was low. Three sensors could be fine at 60psi and one tire showing low at 62psi.