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Which to trust: the TPMS, or tire gauges?

Discussion in 'Prime Technical Discussion' started by Scott_R, Oct 15, 2024 at 2:57 PM.

  1. Scott_R

    Scott_R Member

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    Almost immediately after buying my 2024 Prime I noticed that the Toyota reported the tire PSI as 31 PSI. I went out and checked them with 2 tire gauges, and they reported ~2 PSI lower, not quite 29. I attached a tire inflator (i.e., a compressor made for tires and not a general purpose compressor) and its gauge reported the same.
    I inflated to the numbers given on the door sticker (35 front, 33 rear) and now the app reports 37 PSI front, 35 rear.

    I'm leaning to trusting the gauges, since at least 2 (plus the tire inflator) reported the same numbers, but should I instead believe the TPMS?

    tires1a.jpg tires3.jpg tires4.jpg
     
    #1 Scott_R, Oct 15, 2024 at 2:57 PM
    douglasjre and bisco like this.
  2. bisco

    bisco cookie crumbler

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    trust the gauges. most apps aren't good enough to be trustworthy
     
    #2 bisco, Oct 15, 2024 at 8:40 PM
  3. fuzzy1

    fuzzy1 Senior Member

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    I would suspect that they start with similar accuracies or tolerances. But the TPMS sensors should not be degrading from mechanical abuse in glove boxes and other places they are tossed.

    Consensus among multiple units (more than 2) would probably be a reasonable guide. If at least 3 TPMS sensors are reading the same, compared to an external gauge, I'd go with them.
     
    #3 fuzzy1, Oct 15, 2024 at 9:05 PM
  4. douglasjre

    douglasjre Senior Member

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    Where r the gauges made
     
    #4 douglasjre, Oct 16, 2024 at 3:21 AM
  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Either could be off a bit, due to manufacturing variation. I’ve got several gauges; most read about the same, while one is invariably about 3 PSI higher. The higher one happens to be my preferred (due to ease-of-use, easy-to-read), so I taped a bit of masking tape on it, with a note to remind me about the 3 PSI overshoot.
     
    #5 Mendel Leisk, Oct 16, 2024 at 6:36 AM
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