11-21-2020, 06:57 PM | #1 |
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Tire pressure sensors
Hey there,
I've noticed than the tire pressure sensors in the car always measure 2 PSI less than direct measurements with other tools. I've performed a reset but that's still the case. Anybody noticed something similar? The concern here is to know which one to use when interpreting the recommendations from the manual. I'm using the car measurements as a reference as of now. |
11-21-2020, 07:52 PM | #3 |
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We talked about this in another thread. I think most of us agreed that tpms Is off by 0.5-1 psi. If you have another handheld gauge, perhaps you can get a third reading to see which one is off. In my case I think I was off by 0.5-1. Either way once you figure out how much tpms is off by, you're good to go.
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naitoon28.50 |
11-21-2020, 09:22 PM | #5 |
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Good to know, thanks all.
For reference, this is the other thread: https://f87.bimmerpost.com/forums/sh....php?t=1754280 Last edited by naitoon; 11-21-2020 at 10:17 PM.. Reason: Adds cross-reference to related thread. |
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DanG10444.00 |
11-21-2020, 10:58 PM | #6 |
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So, with the information in the threads here's how I would settle the question of whether to use the gauge or TPMS to set the tires to spec pressure.
I say one should not rely on the TPMS system for inflating to specification, and one should instead use a tire pressure gauge. The first reason is that TPMS was not built to be accurate, but to detect dangerous low pressure situations and warn the user. A false warning is better than no warning, and it's better for this kind of system to err on the side of under-pressure. So far, in all of the comments I read, the system was under-reading pressure, which is what we would expect from a safety (and legal) perspective. On the other hand, I've only observed reproducibility in tire pressure gauges, not in TPMS systems. The measurements from a my gauge are the same as the ones in the air pump up to 0.5 PSI. At least one person in the threads reported the same about their gauges. So, my operational takeaway for this question is that one should get a gauge, cross-check with other gauges to ensure reproducibility, and use the gauge to set the tires' pressure to specification. After setting the tires to spec, perform a TPMS reset, and count on TPMS to warn you if your tires are dangerously low, but nothing else. |
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