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01-25-2013, 06:15 PM | #1 |
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Cold weather and check tire lights
Hi All-- So the temperature drops and I get a big warning that all my tires need air, I shouldn't drive over 50F, etc...
Whats up-- is this normal? |
01-25-2013, 06:26 PM | #4 |
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Cold air is denser, molecules slow down blah blah. Essentially warm air higher pressure, cold air lower pressure. Add more air if it's going to be cold for a while, try to keep it around specs. Your tire pressure rises a little when driving after the rubber heats up too.
If you added warm air, the molecules were spaced out more, when it got cold, they crammed in closer. The colder it gets the lower the pressure goes and the TPMS I believe sense a 10% reduction, which isn't much.
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01-25-2013, 07:35 PM | #7 |
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yes it is likely to happen more when it is cold. Think about it when most things get cold they shrink. same thing happens to the air molecules. When this happens tire pressure goes down. It is easy to see a fluxuation of a few PSI with as little of a variance of 10 or more degress.
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01-25-2013, 07:57 PM | #8 |
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Ideal Gas Law
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01-25-2013, 09:16 PM | #9 | |
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Hit it right on the head. Completely normal. Although my tires are filled with nitrogen, so I'm not expecting to see these low pressure warnings. But we'll see. |
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01-25-2013, 10:47 PM | #10 |
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nitrogen also expands and contracts. you will see the warning but it might take longer. The gas is more dense if i remember right. Sylon I dont think i could do without you here to keep me straight. Oh and everytime i see your icon I think Girl 1er = cool then only to realize its just Sylon.
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01-26-2013, 02:42 AM | #11 |
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1st I hate TPMS
2nd I have those warning lights when it is cold. But I've read somewhere that it is normal to see warnings when weather gets colder because TPMS sensors measures the temp also when it changes dramatically they give you warning light "check pressure in your tires then reset" |
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01-26-2013, 04:34 AM | #12 |
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The TPMS is a "dumb" system. Meaning... when its 80'F out and you set the TPMS target pressure... and then the temp drops.... the TPMS is still looking for that higher (tire)pressure, hence the light come on.
When ever you check your tire pressure... you should ALSO reset the TPMS so it knowns the new "target" pressure. You should be checking your tire pressure every third fill up anyways. But see the problem no one does, and Congress stuck us with this crappy TPMS.
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01-26-2013, 04:39 AM | #13 |
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The funny thing is that I had maybe 100 times warning light and non of them showed the real problem.
I am really thinking to code out that system and activate European TPMS which is w/o stupid sensors |
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01-26-2013, 04:52 AM | #14 | |
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And IF your car has iDrive/Nav... you should have the european TMC channel activated so you can see real time traffic updates and news thru the iDrive.
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01-26-2013, 06:55 AM | #15 | |
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Yeah, I'm not Alessandra Ambrosio. Sorry to disappoint, lol. |
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01-26-2013, 10:54 AM | #17 |
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Given that PV=nRT, if the only change is temperature then the pressure change will be the same regardless of the type of gas filling the tire.
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01-26-2013, 11:03 AM | #18 |
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While the engine is running, scroll thru the BC using the turn signal stalk (or use the iDrive). When you scroll over to the tire TPMS icon, hit the reset button on the end of the turn signal stalk, then DRIVE the car until the reset light goes off. You can not reset the TPMS while the car is in motion. The car must be stopped. Reset then DRIVE the car for a mile or two.
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01-26-2013, 11:29 AM | #19 | |
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All I know is, I haven't had any issues since, and temps here have been as low as 6F. Maybe things will be different if we go into the negatives. Plus, it was free, so what do I care? |
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01-26-2013, 12:05 PM | #20 |
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01-26-2013, 12:38 PM | #21 |
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Are you coming to the Welt 4.0 car show? (see the sticky in the European sub forum) There will be someone there to code your car. There are lots of coder's over here who can do this for you if you can't make the show.
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01-26-2013, 12:50 PM | #22 |
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Didn't mean anything by it...
Nitrogen is a better choice for a several of reasons. Just commenting on pressure.
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