[lichenlt]

how are you guys making sure the pressure are the same on both sides? Do you go by the TPMS or a separate mechanical/digital gauge?

I took my car to Costco yesterday and the technician helped me adjust the pressures on all four tires. Since the tires were warm when I got there, we decided to go with 34/40psi, but today the tire pressures are totally out of whack. The difference between the rear tires is as big as 3psi. I might need to drive to the nearest gas station and adjust them again but the air pump at the gas station doesn't have an accurate pressure gauge, I'll be relying on the TPMS while the car is sitting still, which isn't very accurate or instantaneous in reflecting the pressure changes.

[overcoil]

You can always use a bicycle pump to inflate your tires; fast, easy & the air is probably drier then from most business's compressors.

Worth having your own tire pressure gauge, some of the digital gauges that TireRack or even BMW Accessories sells are very accurate.

[2msport]

Typically I use a digital pressure gauge. Not expensive from your local auto shop. To be honest, the TPMS page is kind of useless. It doesn't show what the actual tire PSI is... Just whether its green or red. I'm also curious at what PSI does the system tell you its low.?

lickenlt: Tires don't usually warm up at the same rate due to: sunlight hitting the tires, weight and balance of the car while driving, and how you drive (more left or right turns or wheel spin) At Costco if your tires were different temperatures when you went to fill them, you equalized the pressure but NOT the temp. Later when your tires cooled, the number of air molecules were not the same so you resulted in less pressure in the tires that started with a higher temp.

One way I eliminate this problem is I overfill my tires and the next morning let air out until the PSI is the same (before driving anywhere). The key is to do this before the sun directly hits your tires or park your car in the garage overnight.

[alz0rz]

Originally Posted by G228msport

Typically I use a digital pressure gauge. Not expensive from your local auto shop. To be honest, the TPMS page is kind of useless. It doesn't show what the actual tire PSI is... Just whether its green or red. I'm also curious at what PSI does the system tell you its low.?

lickenlt: Tires don't usually warm up at the same rate due to: sunlight hitting the tires, weight and balance of the car while driving, and how you drive (more left or right turns or wheel spin) At Costco if your tires were different temperatures when you went to fill them, you equalized the pressure but NOT the temp. Later when your tires cooled, the number of air molecules were not the same so you resulted in less pressure in the tires that started with a higher temp.

One way I eliminate this problem is I overfill my tires and the next morning let air out until the PSI is the same (before driving anywhere). The key is to do this before the sun directly hits your tires or park your car in the garage overnight.

The TPMS page shows the actual psi in each tire..

[2msport]

Originally Posted by alz0rz

The TPMS page shows the actual psi in each tire..

Ok I could have sworn thats the case, and even remember seeing a picture somewhere. But mine doesn't... Is there something I have to do to see it other than going to settings, vehicle info, tire pressure?

[lichenlt]

Originally Posted by G228msport

Ok I could have sworn thats the case, and even remember seeing a picture somewhere. But mine doesn't... Is there something I have to do to see it other than going to settings, vehicle info, tire pressure?

That's interesting, mine shows exact psi. Did you get the Tech pkg?

[tccox]

Originally Posted by G228msport

Ok I could have sworn thats the case, and even remember seeing a picture somewhere. But mine doesn't... Is there something I have to do to see it other than going to settings, vehicle info, tire pressure?

I understand that feature was coded out for USA cars

[pikcachu]

what's coded out is temperature.... pressure is standard

[lichenlt]

Originally Posted by pikcachu

what's coded out is temperature.... pressure is standard

your front pressures seem to be way too high LOL

[2msport]

Originally Posted by lichenlt

That's interesting, mine shows exact psi. Did you get the Tech pkg?

No I didn't which I suspected had something to do with it. Now I have a reason to have someone code my car. So useful to have that feature. Stupid BMW.

[pikcachu]

Originally Posted by lichenlt

your front pressures seem to be way too high LOL

wasn't really a pic of my car though but probably somebody just went for some twisties :-D

[pikcachu]

Originally Posted by G228msport

No I didn't which I suspected had something to do with it. Now I have a reason to have someone code my car. So useful to have that feature. Stupid BMW.

What you can code is temp to show, not the entire thing....
You might need extra hardware for the thing to show up on a non-tech pkg car... but maybe not....

what stems do you have ? are they rubber or metal?

[2msport]

Originally Posted by pikcachu

What you can code is temp to show, not the entire thing....
You might need extra hardware for the thing to show up on a non-tech pkg car... but maybe not....

what stems do you have ? are they rubber or metal?

Metal. No extra hardware needed. Otherwise how would my car be able to know when my tires are low and give the color coded readout on the systems page. The system knows what the exact pressure is. It's coded so that it doesn't display it

[pikcachu]

Well cause there are 2 kind of systems... FTM (flat tire monitor) that just measures how fast the tire rotates and if one rotates much slower than the other assumes you have a flat tire and the TPM (tire pressure monitor) that actually measures the pressure of the tire and send it to the car wirelessly

http://www.e90post.com/forums/showthread.php?t=36772

[pikcachu]

I doubt BMW would include the TPM sensors... if you can't use them, but only way to know is to code it and see if you see it or not

[2msport]

TPM Menu. Tire Pressure Monitor. I agree with you, it would be stupid for BMW to include the equipment and then code it to not display the information. But you know what, thats the world we live in.

[pikcachu]

ya but doesn't look like the readings would fit in the smaller screen.... you might have to add the tech package to your FA to be able to get it to work

[2msport]

I agree I probably had to get the tech package. But to say they won't fit....

[pikcachu]

well what I'm saying is that UI screen from the non-tech and tech packages might be different so the readings on the non-tech UI might not even exist...
You might not need the tech package, just add the option to the FA and VO code HU-NBT

You can see what type of system you have by checking the value of:

HU_NBT REIFENUEBERWACHUNG_RDC_RPA
if it's RDC you have the reading if you have RPA you don't

[2msport]

Originally Posted by pikcachu

well what I'm saying is that UI screen from the non-tech and tech packages might be different so the readings on the non-tech UI might not even exist...
You might not need the tech package, just add the option to the FA and VO code HU-NBT

You can see what type of system you have by checking the value of:

HU_NBT REIFENUEBERWACHUNG_RDC_RPA
if it's RDC you have the reading if you have RPA you don't

Fair enough. I still think there has to be a pressure sensor in there. Otherwise how would the car know if it's underinflated. That FTM tech sounds like old tech to me. It's in the older 3 series cars

Oh I don't know what FA is. Nor how to code. Is it easy? I'm pretty good with computers and cables.

[lichenlt]

I bought a digital pressure gauge off Amazon and there's about one psi difference (cold tires) between what the gauge says and what the TPMS says. The readings are lower by TPMS if you think driving the car for a few minutes would have increased the pressure.

should I trust the digital gauge or the TPMS?

[Delnari]

Only check tire pressue when cold. Tires don't heat up to the same temperatures all the way around. Trust you guage over the TPMS first. If there is only 1 pound difference then add one more pound so the TPMS reads the correct cold tire pressure number listed in your driver's door jam.

The picture was from car after I just finish coding the TPMS for pressure/temp. Was then I notice the dealer had over inflated my tires