[Seattle335]

Both my cars ('11 550 and '10 M3) have been giving me false warnings once the cold set in - and I'm getting fed up of doing a walk-around just in case I really have a flat.
So, looking for a permanent solution from the physics gurus on this board - is it worth increasing the PSI during the really cold months? How about swapping out to filling up with helium or nitrogen?
Any other advice?

[The X Men]

Filling up your tires with helium Thats a good one.

Whats the tire pressure when the TPMS warning is on ?

[Silververtu]

Checking and inflating/deflating the tire pressure once a month is my permanent solution. Over the years living in Great Lakes area I found the tire pressure tends to drop about 1-2psi each month between Sept to Jan.

Most TPMS would start to warn you once the tire pressure is 25% lower than recommended so it's easy to upset the TPMS in these period of time.

[JNoSol]

Physically looking at the tires isn't going to detect if the tires are off 3-4psi. Air will expand and contract, dependant on the ambiant temp. Even Nitrogen will expanda and contract slightly.

Your TPMS will go off when the temp drops or increase dramatically, because your air pressure is off from its norm by a certain percentage. You should check your tire pressure at least once a month, no matter if you have nitro or air. You should keep the pressure close to what's recommended in your driver side door jam, no matter what time of the year it is.

[vdubturbo]

Originally Posted by JNoSol

Physically looking at the tires isn't going to detect if the tires are off 3-4psi. Air will expand and contract, dependant on the ambiant temp. Even Nitrogen will expanda and contract slightly.

Your TPMS will go off when the temp drops or increase dramatically, because your air pressure is off from its norm by a certain percentage. You should check your tire pressure at least once a month, no matter if you have nitro or air. You should keep the pressure close to what's recommended in your driver side door jam, no matter what time of the year it is.

This.

It's not TPMS you should be pissed at... it's physics

[snj1013]

More precisely, thermodynamics and the ideal gas law
http://en.wikipedia.org/wiki/Ideal_gas_law

[half man half amazin]

Yes I have noticed the same thing on all my cars every winter. Yes indeed it's annoying especially since our won't let me into sport mode while it's on.

[BMWrules7]

Originally Posted by half man half amazin

Yes I have noticed the same thing on all my cars every winter. Yes indeed it's annoying especially since our won't let me into sport mode while it's on.

Right, but it is not a problem with TPMS. Rather, it's more a akin to a tree falling in the forest.

Does the tire pressure suddenly change during seasonal temperature swings on a car that is not monitored by TPMS?

In other words, is the TPMS causing the problem or is the TPMS doing its job in reporting a low tire pressure that would have otherwise gone undetected?

Of course, silly, it is the fault of the TPMS since everyone knows a tree does not make a sound when it falls in the forest and there is no one around to hear it, right!

[The X Men]

This is a perfect example of shooting the messenger of bad news.

[jedpause]

Originally Posted by The X Men

This is a perfect example of shooting the messenger of bad news.

I agree in part, however I think the OP was raised in case his situation was fairly unique, indicating a possible sensor failure rather than and actual deflation.

[syrhee81]

Last winter I also had the TPMS light going off saying that one of my tires was low on pressure, but I found out that there really was a nail in the tire. I think I benefited from the feature vs. the annoyance in my case.

[LastFrontierBimmer]

I find this interesting because I routinely see huge fluctuations in outdoor temps, from +45 degrees to -10 degrees Fahrenheit. Yet my TMPS has not gone off once.

I set the pressure on all 4 tires to BMW-recommended levels for their size and re-set the TMPS when I installed the winter wheels & tires. I choose to run 17" wheels during the winter to combat the harsh winter road conditions. I don't however, think that would result in more stable pressures than those in your 18s.

Perhaps you are running pressure on the low end in search of better traction? This may make them more susceptible to dipping under and back over the TMPS threshold during temperature fluctuations.

[NW5er]

I always over inflate my tires just a little bit and check monthly and reset the TPMS every time I add air. The only time I heard the TPMS go off was when I got a nail in one of my tires. Then again Seattle winter isn't usually that bad. I do hate the low temperature/ice on road warning though.

[fuddman]

During the first night of our ski trip it got very cold and the TPMS came on (X5d 20"). On the "status" screen, all four wheels showed as a problem. I didn't do anything about it because, after visual inspection, the tires appeared normal. During the day, the TPMS light went out (crap! I burned my toast writing this thing). We spent 3 very cold nights there and the light never came back.

[raleedy]

Originally Posted by syrhee81

Last winter I also had the TPMS light going off saying that one of my tires was low on pressure, but I found out that there really was a nail in the tire. I think I benefited from the feature vs. the annoyance in my case.

What? You don't think a flat tire is annoying?