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Tire Pressure Monitors Do More Than Monitor Pressures - 2015 BMW M235i Convertible Long-Term Test

Edmunds.comEdmunds.com Posts: 10,059
edited November 2015 in BMW
imageTire Pressure Monitors Do More Than Monitor Pressures - 2015 BMW M235i Convertible Long-Term Road Test

Our long-term 2015 BMW M235i has an elegant way to display variance in tire pressures. It also won't let you have any fun until it's sure the tires are up to code.

Read the full story here


Comments

  • iamthestigiamthestig Philadelphia, PAPosts: 85
    "Apparently the car wants to safeguard against potential hooliganism when the tire pressures aren't set correctly."

    I guess that system isn't available on the M4. Too bad for this guy:
    http://jalopnik.com/how-not-to-explain-why-you-crashed-your-car-via-this-b-1677523538
  • daryleasondaryleason TexasPosts: 501
    Well...I guess this system also means "good luck buying aftermarket rims that will work right with our diagnostic equipment".
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    Too large of a "horsepower-to-ability" ratio, looks like.

    "Apparently the car wants to safeguard against potential hooliganism when the tire pressures aren't set correctly."

    I guess that system isn't available on the M4. Too bad for this guy:
    http://jalopnik.com/how-not-to-explain-why-you-crashed-your-car-via-this-b-1677523538

  • You not only have gauge-to-sensor variability, but also you set the station's compressor to cut off at X pressure, which you used to fill the tires...so depending on that device's calibration, you also have this variable. And then of course there is TPMS sensor variability AMONG the sensors on the car - c'mon - you know they're not all the same.

    More and more, the correct answer is...buy a good gauge that is calibrated correctly...or get one with a calibration cert, if you're fussy. Use this gauge to periodically (and no, not once every six months...) and seasonally (when the weather changes, check and reset...don't wait for TPMS to go off) check and set tire pressures...when they are cold.

    There - now you know it's done correctly and that on any given trip you take, the tire pressures are where they should be.
  • subytrojansubytrojan Monterey Park, CaliforniaPosts: 120
    Displaying approximate tire temps for each tire is very cool! Thanks for sharing, Jay!
  • C'mon, who doesn't miss the good old days when that 'fwop fwop fwop' sound meant you got a flat tyre?
  • 7driver7driver Posts: 145
    Open the sport mode, HAL

    I'm sorry, Dave. I'm afraid I can't do that.

    What's the problem?

    I think you know what the problem is just as well as I do.

    What are you talking about, HAL?

    This car is too important for me to allow you to jeopardize it.
  • schen72schen72 Posts: 433
    Nice that BMW finally has a good TPMS system that actually displays individual tire pressures. Double nice that it's very pretty to look at. My 2006-era Acura's TPMS display isn't nowhere near as pretty but at least it displayed individual pressures. Better late than never!
  • The results of a very informal, unscientific reading of TPMS accuracy posts in various brand- or model-specific auto forums - about 2 hours all told:

    About 20% of posts state their TPMS sensors were all, generally, correct, compared to a handheld gauge; another 15% said theirs were all about 1 psi low; another 30% said theirs were around 2 psi low; and 35% said they had one or more that was 3-5 psi lower than the gauge, and/or 3-5 psi lower than the other sensors. Almost none said their sensors read high. I tossed out those who specifically stated that the handheld gauge was "cheap" or "inexpensive" or the like. The people who said they used an expensive competition or balancing-type gauge almost uniformly said their TPMS sensors were around 2 psi low.

    I would like to see Edmunds invest in such a balancing-type gauge, and report deviation between its readings and the vehicles' TPMS readings, per wheel, as part of their performance testing results. They are already adjusting pressures before testing; querying the car's monitoring systems at that time and noting the results would take no more than a few extra minutes per test.

    Interestingly, I found a piece by Edmunds' own Ron Montoya on TPMS when I was doing this "research" - including this conclusion:

    "Rely on TPMS to warn you only of a puncture or an active air leak. If you take away only one thing from this article, this should be it: It's your responsibility as a driver to check your tire pressures monthly, or at least have them checked by someone else."

    It does not appear that Edmunds is following its own published advice with regards to its LT fleet.
  • I wonder if the system will warn you if tire temperature gets dangerously high. This could prevent you from having a blowout at highway speeds.
  • thecardoc3thecardoc3 Posts: 4,992
    Most systems today will alert for excessive pressure just like they do insufficient pressure. If the tire temperature rises high enough that would cause a mil because the tire pressure would increase at approximately the 1psi per 10F rate.
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