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[WPG D33Z]

Originally Posted by Dackelone

Its been well known that the metal valve stem nuts(E in the photo bellow!) tend to loosen with miles. Use an 1/4 ratchet, 11mm deep socket to just snug them up - they require very LOW torque something like 4Nm. Also once they are tight check your tire pressures AND RESET your TPMS. You do this with the car running(but stopped) and use the BC or iDrive menu settings to reset it. The TPMS system is a "dumb" system... everytime you "reset" the system you are giving the TPMS a new "target" pressure to look for. IF you do not do this you can get false warnings with your TPMS.

If you live in a cold climate replace the metal valve caps with rubber ones.

[bmw1racer]

Originally Posted by WPG D33Z

If you live in a cold climate replace the metal valve caps with rubber ones.

You shouldn't have metal caps to begin with: There have been stories of metal valve caps seizing with the valve stems due to galvanic corrosion...

[MightyMouseTech]

All it takes is one winter in the salt belt with metal valve caps, and you will be replacing all the TPMS sensors soon.

[maxdriver]

Any idea as to how many pounds of pressure that the tire is low before the warning comes on?!!

I used to check my tires regularly, but with the BMW sensor I wrongly ASSumed that after a deficit of a 2-3 lbs the sensor would kick in.

I too recently had the warning go off on my front left tire. I checked it and it was 10lbs low...so was the left front!....both rears were down 5 lbs....

I have a portable compressor and will be checking regularly in the future...!

Sounds like the BMW sensor system is a joke...

[gregthegr8]

Originally Posted by maxdriver

Any idea as to how many pounds of pressure that the tire is low before the warning comes on?!!

I used to check my tires regularly, but with the BMW sensor I wrongly ASSumed that after a deficit of a 2-3 lbs the sensor would kick in.

I too recently had the warning go off on my front left tire. I checked it and it was 10lbs low...so was the left front!....both rears were down 5 lbs....

I have a portable compressor and will be checking regularly in the future...!

Sounds like the BMW sensor system is a joke...

I can't find it right now but I remember it's a pretty high threshold. The TPMS warning doesn't go off either when it falls 25% below whatever it was last reset to, or maybe it's when it falls to 25% of whatever it was last set to. So, it's not only a major drop until it will go off, but supposedly our cars are notorious for slowly leaking out air from the TPMS as Dackel informed of us.

For example, I checked mine this past weekend, and after 5 weeks, each tire was down about 2-3 PSI when taken after the car had sat overnight and was about the same outside temperature. So, especially on our cars, check 'em, and check 'em often.

[rdano]

Originally Posted by maxdriver

Any idea as to how many pounds of pressure that the tire is low before the warning comes on?!!

I used to check my tires regularly, but with the BMW sensor I wrongly ASSumed that after a deficit of a 2-3 lbs the sensor would kick in.

I too recently had the warning go off on my front left tire. I checked it and it was 10lbs low...so was the left front!....both rears were down 5 lbs....

I have a portable compressor and will be checking regularly in the future...!

Sounds like the BMW sensor system is a joke...

I'm having the similar problem. It took me 4 times to put air in the FRONT LEFT tire in a week. I checked it if there's something that causing this leak, but I couldn't find one physically. Every time I would set it to 36-38 PSI, and reset the TPMS, it will drop down to 20 PSI the next day.

I finally got tired of it, and took it to the dealer yesterday, and they said it's cause by the weather changes. I told her that this has been happening for a week now, and she said it's normal LOL. She claimed that everything is ok, and told me to come back if it happens again.

This is really annoying especially it's going to be cold soon. I can't imagine myself putting air in every morning before I leave just to make sure it doesn't throw that warning. This TPMS sensor sucks, and it's a surprised why it only happens to one tire, which is the FRONT LEFT tire. Anyone else having the same issue?

Originally Posted by gregthegr8

I can't find it right now but I remember it's a pretty high threshold. The TPMS warning doesn't go off either when it falls 25% below whatever it was last reset to, or maybe it's when it falls to 25% of whatever it was last set to. So, it's not only a major drop until it will go off, but supposedly our cars are notorious for slowly leaking out air from the TPMS as Dackel informed of us.

For example, I checked mine this past weekend, and after 5 weeks, each tire was down about 2-3 PSI when taken after the car had sat overnight and was about the same outside temperature. So, especially on our cars, check 'em, and check 'em often.

Mine drop from 38 PSI to 20 PSI overnight, and the dealer couldn't explain why. They claimed it's because of the weather changes. With this situation, I just wanna purchased another set of wheels and call it a day. Gill suggested I should get a TPMS installed on my winter wheels, but if this continue to happen, I'm not getting it. What's the point of having a TPMS if it's not functioning properly and have to pay extra $230 to get it installed.

[maxdriver]

WOW...I will be checking mine again tomorrow.

[gregthegr8]

A lot of it has to do with weather changes too since the temperature will have a big impact on the pressure readings. Warmer the temperature - higher the readings and vice versa. PSI readings will also go up as you drive and the tire and air in there warms up.

The rule of thumb is every 10 degree drop in temperature will lower your psi by 1 degree. So, take that into account as if the last time you reset it you filled it up and it was 90 degrees out in summer, and are checking when it's 35 degrees now in the morning, will be a huge difference. You'll see a bigger impact too if your car sits outside at night.

You also might want to try having your tires filled with nitrogen, too as it's a more stable gas, bigger molecules, less crap in there, and will hold a set PSI much better. Problem is it's harder to do yourself at home.

Signed,

Mr. Wizard

[maxdriver]

Originally Posted by gregthegr8

A lot of it has to do with weather changes too since the temperature will have a big impact on the pressure readings. Warmer the temperature - higher the readings and vice versa. PSI readings will also go up as you drive and the tire and air in there warms up.

The rule of thumb is every 10 degree drop in temperature will lower your psi by 1 degree. So, take that into account as if the last time you reset it you filled it up and it was 90 degrees out in summer, and are checking when it's 35 degrees now in the morning, will be a huge difference. You'll see a bigger impact too if your car sits outside at night.

You also might want to try having your tires filled with nitrogen, too as it's a more stable gas, bigger molecules, less crap in there, and will hold a set PSI much better. Problem is it's harder to do yourself at home.


Signed,

Mr. Wizard

Thanks for the info. I personally was aware of what you posted. My issue is how much pressure the tires lost before the sensor went off. Surprised that it takes such a drop before the notification. I've also never had runflats before and I could not tell any difference in how the tire looked with the reduced air pressure...

[Dackelone]

Originally Posted by rdano

Mine drop from 38 PSI to 20 PSI overnight, and the dealer couldn't explain why. They claimed it's because of the weather changes. With this situation, I just wanna purchased another set of wheels and call it a day. Gill suggested I should get a TPMS installed on my winter wheels, but if this continue to happen, I'm not getting it. What's the point of having a TPMS if it's not functioning properly and have to pay extra $230 to get it installed.

Instead of a second set of TPMS sensors you could have your car coded to EU tpms specs. The EU cars use the car's ABS sensors to detect a deflated tire. the US system is better I think, but the EU system is less error prone. Once your car is coded to EU system you simply unplug the TPMS pc in the rr wheel well.

Also very common is for the metal valve stem nuts(a 11mm nut) to loosen over time. They need very LOW torque. 4Nm(four!) I think. Cracked alloy wheels or damage tire sidewall damage is also very common.


Everyone SHOULD be checking their tires every two or three fillups. But hardly anyone does that. Well... except over here were we have Autobahns were tire performance is important(!) and gas costs $9 per gallon! Then people check their tire pressures!


Dack