Tire Pressure Monitoring System Capabilities

Discussion in 'Everything Technical' started by Boo$teDB5.5, Mar 9, 2017.

  1. Boo$teDB5.5

    Boo$teDB5.5 Active Member

    So I recently just picked up some 18x8.5" et45 wheels for my 2014 GTI and I have been considering going with a 235/40 tire instead of the stock 225/40 tire to increase the contact patch area for more traction (if I wouldn't have went FWD this time I wouldn't even care). I understand that the overall diameter is increased which slightly throws off the speedometer, but with the new TPMS on the newer Volkswagens, when I hit "reset" will the computer recognize the new OD as correct and adjust the speedometer accordingly? As a side note, feel free to comment on your tire size experience on a mk6 gti. I am at stock ride height, considering eventually a cup kit so nothing more than a 1.2-1.5" drop. Does anyone think rubbing would begin on this setup?
  2. lorge1989

    lorge1989 Posting- God

    On my Sportwagen I never had TPMS sensors. And when using the button in the glovebox, which from my understanding just used the wheels speed sensor to detect OD, it never corrected the speedo, but was necessary when changing wheels. There was a small speedo adjustment that could be made manually in the cluster display on my MK6, that was used for 'snow tires'.

    I also don't think you will rub. But to make your life easier and not have a speedo error, why not just get the stock tire size in a more performance driven compound? The 10mm isn't going to do shit, you'd just be better off with a high quality tire. Running a 225/45/17 pretty slammed on coilovers, I had minimal rubbing.
  3. Boo$teDB5.5

    Boo$teDB5.5 Active Member

    Georgie, good call on the snow tire correction for any different setup in the future. As you know I already went with the 225's so I guess I won't have a problem.[​IMG][​IMG]

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  4. JKaczor

    JKaczor Well-Known Member

    If you're going to run 235's then I think a 235/35r18 would be better suited as opposed to a 40 wall. The tire pressure reset button won't adjust the speedo, it only resets the tire pressure light to calibrate to the rolling resistance of the tires (at least that's how I've come to understand it being that the tire pressure is "measured" via the ABS sensors.)

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  5. Boo$teDB5.5

    Boo$teDB5.5 Active Member

    Yeah I wanted to avoid the 35 wall with our roads around here. From the research I have done though I believe it uses the abs speed sensors to determine whether the tires are over/under inflated. I don't believe they can measure rolling resistance. The lower the pressure, the smaller the OD of the tire resulting in a faster shaft speed resulting in the speed sensor recognizing a difference from its "learned" value.

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