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TPMS vs Tire Gauge Discrepancy

Discussion in 'Model X' started by wqu06, Jul 7, 2017.

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  1. wqu06

    wqu06 Member

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    Has anyone noticed that the TPMS pressure is slightly (for me ~2 PSI) lower than manually using a tire gauge? The 20 inch tires on my Model X recommends 42 PSI and that is what I have it set to according to my tire gauge, however, the TPMS reads it at 40 PSI.
     
  2. boaterva

    boaterva Supporting Member

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    Perhaps stupid question, have you tried another tire gauge? :D You never know which is 'correct' without a standard...
     
  3. wqu06

    wqu06 Member

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    #3 wqu06, Jul 7, 2017
    Last edited: Jul 7, 2017

    This is what I used. Also used this. Both were different than the TPMS and from each other.
     
  4. aesculus

    aesculus Still Trying to Figure this All Out

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    Mine seem to be all over the map (well two of them agree) until the car is driven for about 20 miles by about 2 lbs. Then they all seem to reach the same maximum.

    It's part of my to do list to apply a highly accurate tire pressure gauge to validate against both cold and hot readings.
     
  5. boaterva

    boaterva Supporting Member

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    Those seem to be the same thing? I have no idea what the accuracy and repeatability of consumer tire gauges is. Accuracy may be a PSI or so. Repeatability may be more precise.

    But we still don't know which of any of them is 'correct', which is the problem. I might trust the electronic ones (TPMS) more. I might be incorrect. I like @aesculus 's plan. :D At least, do it once so you can trust things.
     
  6. wqu06

    wqu06 Member

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    Oops...sorry. This is the first one.

    I also did both readings in the AM when the car was parked overnight inside a garage.
     
  7. rainforest

    rainforest Member

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    Yes. I pumped my tires to 45, but car display shows 43.
     
  8. FarmerDave

    FarmerDave Supporting Member

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    As the saying goes...

    A man with a clock knows what time it is.

    A man with two clocks is never sure.
     
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  9. wqu06

    wqu06 Member

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    What PSI does everyone here inflate their tires to? The label on the car recommends 42 PSI.
     

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