OK, I've searched... can't find this one.


My Low Tire alarm comes on if it's cold. First time, said RF tire was low. I checked it and it was at correct pressure. I reset the monitor. Got in the car after work, and low again (28°F outside) except this time, LF. Checked, and OK. Reset.
This morning I got in, ALL 4 were low. Checked 'em all, OK. Reset. Got in after work, RF low again. Checked it, OK.


What the heck is the deal? Or am I doing something incorrectly when resetting?? BTW, I bought the car new and it now has only 6600 miles on it. Runflats...


Any help is most appreciated.


Regards,
XLXRider - BRG Clubman...

 

Do you have caps on the valve stems?

Take soapy water and spray it on the stems to make sure the sensors/stems/valves are not leaking.

( a spray bottle, water, dish washing liquid.. Shake it up and spray it..)

 

I do not have runflats, and I have found that every fall when the weather goes cold, my TPMS acts up. It is the change of the weather. I inflate my tires to the proper pressure, and reset the system. That takes care of it.

 

it's probably not the the TPMS acting up

it is physics

without going into details, when the temp drops the pressure in the tire drops. You need to add air to keep the pressure up. When it gets warm the pressure will rise and you should check as you'll probably want to bleed some off to lower the pressure. (heat gas and it expands, cool gas and it shrinks, cool it enuf it becomes liquid)

Some parts of the world are seeing EXTREME cold so no su-prise that TPMS systems are alerting. I mean heck it is barely going to get over 70 here today.....

 

1 psi for ever 10 degrees (when filled with "air"). Nitrogen is much more stable and won't react as much with temp fluctuations.

Given what part of the country you are in... 30 degreesF to -30 degrees F is a pretty wide swing. Wide enough to trip a TPMS unit set for the 25% change mark.

 

Copied from a non-Mini forum:

 

Every cold morning the last three months without fail the TPMS is tripped, if I reset it in the warm afternoon sometimes it goes ok for a few days or until the next cold night. Add more air, reset and it is good to go for a few weeks, those runflats do not hold much air and the temperature drop is enough to condense it.

 

To all of you for verifying it is a common (non)issue. Yeah, I thought of invoking the combined gas laws to answer the question (thanx Capt_bj), but also wanted to find out if I was the Lone Ranger with this issue. See, this is the first car I've owned with all the high-tech stuff!

I'm not the only one with the issue, so will rest easier... although mebbe I oughta get that ole summer air outta mah tars. (I'm in NC.)

Regards,
XLXRider

 

something one needs to keep in the back of their head when reading ANYthing on this site

a HUGE many of MINI buyers, are buying their first 'new car'

can I proove this? NOOOO

Is it what I see from an early participant . . .

just my 2 cents

 

Just as important, if you have a fairly new Mini is to completely remove all air from the tires and replace it.

The Mini factory is in Britain, where we drive on the left of the road, so cars leave the factory with British air in their tires (well, the air goes in the tyres here, but you know what I mean).

Unbelievably those cheapskates at Mini USA do not replace the air when importing the cars and the cars will, of course, want to drive on the wrong side of the road as far as North Americans are concerned.

If you are lucky it will just want to pull to one side of the road, but in low grip conditions you could end up with a car that wants to turn like a dog chasing its own tail. The good news is that it won't try to bark while doing this.

And if you think this is bad, you want to spare a thought for Mini drivers in Australia.....

 

Really, I hear to fill the fuel tank, they have to drive up a special flip platform that inverts the car safely onto its roof.

 

How hard is it? Just put in a couple extra psi. The pressure trips at what 34 psi? Specs say 38.

Op what pressure are you running?

 

I use the chart found here to set my tire pressures for winter:
http://www.aa1car.com/library/tirepres.htm

 

Ah, but not quite that simple... the TPMS does not judge absolute psi per se, but the (perceived by the TPMS system) differential from what it was when reset. So if you have 32psi and reset the TPMS, when it senses whatever the factory differential is set at (I dunno, 3 psi or whatever) then the alert comes on. I am running the specs for the tires...


But at any rate, you guys have answered my question!


Regards,
XLXRider

 

All new Minis now come with nitrogen fill. N2 is dry, inert so helps preserve the rubber and sensors, and is more stable in temperature swings. I have N2 in all my cars. Its standard at Costco Tire Center.