Tire Pressure Monitors Hate Cold Weather!
 

It has been brutally cold here in Minnesota the last few days. I had my 2008 X5 parked outside during the day when it was around -10. Started it and it told be that all four tires were low.

Previously it was reporting random tires being low. Looks like once it gets below zero, all bets are off. I did fill the tires a month ago and realize they lose pressure as the temps fall. But I do get a kick out of the TPM system, one of these days I'll really have a flat and I won't check it!

My Acura MDX never did any of this.

mine does the same thing, happened about a month ago, filled 'em up, they've been fine since.

fill them up with nitrogen, it adapts better then simple air to the temperature variations, I have an 09 x5 and i`ve filled it`s wheels with nitrogen;)

How about helium?

they won't fix the backup camera, they're not gonna give you exact numbers for each wheel. ;)

Sorry, but it doesn't. Air is mostly nitrogen.

Nitrogen expands and contracts just like air does with temperature variations.

My monitors have been good down to about -30, it hasn't been colder than that yet.

It is most likely your tire pressures that are changing, not the monitoring system. Just check your tires every month with a gauge, and you will quickly find out how much they are changing due to both time and temperature variations. An alternate subject line might have been "My TPMS saved me from driving with low tire pressures"

I wish it was that simple. My right rear goes off whenever it is cold and windy, I need to get that checked by my dealer.

I checked the tires tonight. The right rear actually had the most pressure, all were down around 3-4 psi, that makes sense with the temperature drop since I last filled them. But -- they were all within 1 psi.

I do not believe that 3-4 psi on run flats should trigger the thing. Once again, my Acura MDX did not trigger in the same conditions. It only went off when a tire was really low. My old E53 took around 8-10 psi to go off and that made sense.

I don't need the TPM to tell me it's cold outside, and no, I don't plan on checking the pressure each day when it's that cold outside. I do check them monthly.

First car this has happened on for me (and I've owned 26 cars so far).

The TPM does not measure absolute pressure. It is only capable of measuring relative pressure; ie. if your tire has lost a significant amount of air. BMW learned the hard way to stay away from absolute tire pressure devices when they used it initially in the 2002 e65 7 series. They have since changed all of their TPM to use relative pressure measurement.

FYI - for every change in 10 degrees, there is a change in 1psi in your tires. I imagine most of you that have had their TPM alert them of low air pressure have not checked their tire pressure since the summer or fall. Think about what the temp was when you last checked the air pressure.

The TPM is very useful and quite accurate. The threshold of when the TPM alerts you is dependent on how the software is written. Most of the time, the error lies with the user, not the component.

you really need to let it go rh. you're gonna give yourself an ulcer. :cool:

> The TPM does not measure absolute pressure. It is only capable of measuring relative pressure; ie. if your tire has lost a significant amount of air.


So what does it take as the baseline for the relative pressure measurement, the pressure in the tire at the time of a system reset?

Yes, which why you need to set it.

here in Montreal its been -25 to -30 celcius, and no pressure warning

BTW I repaired one of my ROF Dunlop 18-inches, in the country...service would have never found me, could not use the phone, so I had a 7$ kit,
and after lots of highway at reasonnable speed its still hold, no pressure warning either

so, yes , ROF can be repaired, this is actually the second time, on 2 diff. tires

Me too. The RF's for some reason are prone to nails. Or it's just me, when I drive the X5. :dunno:

I actually have both rears plugged. Got a nail/screw in each one. Dealership obviously said to replace the tires, but at $400 each, it's just not worth it. Nothing wrong with plugged tires, and I have ~10k on one of them.

I have no problem with a plugged tire, and repaired a runflat on the Z4 that way.

However, I would not rely on a plug that was applied from the outside. It is a risky repair. The approved method for repairing a runflat (and the safe way to repair a non RFT) is from the inside. The plugs look like a mushroom, and combine a plug with an inside patch.

My tire dealer had the manufacturer's instructions for my specific tire, I think they were Bridgestone. Different rules from each RFT manufacturer, so YMMV.

I have had no trouble with the X5 tire pressure sensor in this round of bone chilling weather. Our Hummer H3 does have sensor issues - the sevice guy says it is cold related and that the overall tire pressure in the tire fluctuates when weather changes hot to cold. I did change out the X5 Summer Air for Winter Air in the fall - don't know if this helped. :D

This morning I witnessed the first TPM warning. It was -10 degrees this morning so I understand the issue. When there is a 40 degree drop in temperature, I would expect the system to notice a problem. I checked all the tires and all except the driver front was within 1 psi. I am glad the system worked though!

I got the warning today. Got upset at first, then realized I had "four flat tires" Reset it and checked the tire pressures at home. 30 in front and 34 in back. A "freezing" 29 here today. I had my warning go off a few times in my 4.8is. Once I actually had a nail in the tire!