OnStar Diagnostics Report- TIRES.

[Dack]

Green valve stem caps don't mean nitrogen do they? My Onstar said it was a bit low so I checked the vehicle and it said it was down to 30 psi. I tried filling them up but it looked like a valve stem filled with something and it didn't seem to accept air. Any ideas or am I completely retarded?

[Russell James]

Originally Posted by Dack

Green valve stem caps don't mean nitrogen do they? My Onstar said it was a bit low so I checked the vehicle and it said it was down to 30 psi. I tried filling them up but it looked like a valve stem filled with something and it didn't seem to accept air. Any ideas or am I completely retarded?

Your dealership probably put nitrogen in there. Which is meaningless as is evident by you are low already. It won't affect how you add more air. It is just a green cap instead of black.

Give it another shot. Stick your tongue out and push harder this time.

[RickRay]

Originally Posted by incustody

Ok I am glad that I am in smarter company. I was going to post a question why I am getting so low tire pressure reading all of a sudden. At 2k miles the nitrogen should be ok but it is staying around 31-33. So I will check with a real pressure guage. Another question though, if you have nitrogen in the tires and you are starting to get low how do you get them filled? Will the dealership still charge you $70 for a 4 tire filling if all you need is 2 psi in each tire? I don't think you want to mix normal air with the nitrogen filled tires.

Mine just charges me $4 to refill all.

Also if you buy your tires next time at WalMart they put nitro in for free and even the refills..

[RickRay]

Originally Posted by Russell James

Your dealership probably put nitrogen in there. Which is meaningless as is evident by you are low already. It won't affect how you add more air. It is just a green cap instead of black.

Give it another shot. Stick your tongue out and push harder this time.

Green is for Nitro....

[nemosgt]

Lot of info here, some mostly accurate.

1) Buy a tire-pressure gauge and use it once a week.

2) Set your required tire pressures when tires are cold, period. They will rise as the tires heat up driving. Just ignore the new pressures.

3) In the winter tire pressures will be lower. Don't ignore the fact that you still have to set the recommended pressures by adding air to compensate for the colder temps. Some of you assume it's okay to drive on the lower pressures because the tires heat up to the required pressures as you drive. Wrong.

4) In warmer weather, you may have to take pressure out of the tires to get the recommended settings. Do this, as always, with the tires cold.

5) Don't rely on On Star. See point number one. My wife's CTS gives inaccurate readings too.

6) Nitrogen may have application for racing cars but is of little use otherwise in normal driving except to generate income for the dealer/seller.

Cheers all.

[Russell James]

Originally Posted by RickRay

Green is for Nitro....

I know, and a complete waste of time and money. Look at how people are now confused at how to top off their tire pressure when they see green caps. What do I do, will it cost me money, where can I get them filled.....

Myth. I have nitrogen in my tires, I'll get better mileage and never have to check my tires again for thousand of miles.

Reality. Your tires are probably low right now. Top them off with good old air from any compressor in the world, and throw those stupid green caps in the trash.

I laugh my ass off every time I see a low tire with a green cap. What, how could that be. The nitrogen molecules were not supposed to leak out of the pores in the tire. I'm sorry, some people are just so gullable, an industry has sprung up to sell them air.

[mtcwby]

Originally Posted by strobi

I put 32 lbs in mine cold...when they are warm they are 36-37. I found that if I put 36 in cold...they ride rough and are 40 or more when warm... SENSORS...What useless, expensive pieces of CRAP!

You should always have your tires at 36 psi COLD. Meaning after it has sat all night, check the pressures before driving the car and before the sun has shined on any of the tires, warming them up and giving a false reading.
Your tires will lose 1 psi for every 10 degrees the temperature drops. They will also gain 1 psi for every 10 degrees the temp rises.
Always use a good calibrated guage. The TPMS are not very accurate, just a point of reference. My TPMS on my car are all 4 degrees low.(when my tires are 36 psi the tpms reads 32 psi on the DIC) But since I know this, I compensate and still know if I have a low tire.

Originally Posted by Russell James

I know, and a complete waste of time and money. Look at how people are now confused at how to top off their tire pressure when they see green caps. What do I do, will it cost me money, where can I get them filled.....

Myth. I have nitrogen in my tires, I'll get better mileage and never have to check my tires again for thousand of miles.

Reality. Your tires are probably low right now. Top them off with good old air from any compressor in the world, and throw those stupid green caps in the trash.

I laugh my ass off every time I see a low tire with a green cap. What, how could that be. The nitrogen molecules were not supposed to leak out of the pores in the tire. I'm sorry, some people are just so gullable, an industry has sprung up to sell them air.

Nitrogen has alot of proven benefits, just ask the tire manufacturers, most of which now recommend Nitrogen in their tires. A low tire with N in it is because the outside temp dropped below what it was when they were filled. They still drop from temperature, not from leaking. Just because you don't understand something, doesn't mean it is BS. Just means you are ignorant.

My Tires are Low! Now What?
Low tire pressure is generally due to one of the following three conditions:

1. A leak. Most tire leaks are the result of a hole or puncture, faulty valve, or a porous or corroded wheel.
2. Permeation. Permeation is the normal process by which the air in a tire bleeds through the tire’s body or carcass. It is typical for an "air" filled tire to lose 1-2 psi of pressure every month through normal permeation whereas it can take several months for a NitroFilled tire to lose a single pound of pressure.
3. Temperature Change. All gases expand and contract with temperature. If you live in an area that experiences dramatic temperature changes, you will have to adjust your tire pressure accordingly. Typically you will only have to adjust your tire pressure "up", adding pressure as ambient temperatures decrease. Count on losing about 2% of your total tire pressure for every 10 degrees in temperature reduction.

[Jarhead]

All tire adjustments should be made when cold. Adding air when hot is OK in times of need, (leaks, and the like) BUT PER ALL TIRE MANUFACTURES GUIDELINES, Only adjust tire pressures when COLD. All recommended tire pressures are based upon COLD settings. Read the manual it will also tell you the same thing.

TPMS Tire Pressure Monitoring System can be re-set. remember these were adjusted initially at the factory, many factors will play into the readings. Altitude, air density, temp, barometric pressure, humidity, etc. All of these are different than where the car was initially set up. (unless you live next to the factory) thus have the dealer perform a TPMS calibration, or even go to Walmart, they can do it for around 20 bucks or so.

Originally Posted by jrhaus76

It does.



You can. Its in the DIC, it says reset. The horn will beep a few times when you hit it. Very strange.


Mine does it all the time. Don't worry about it and don't over inflate them. if it is cold out and the car has not been driven, the air compresses and the pressure is low. As you drive, the tires heat up, the air expands and the warning goes away. if you get the warning and fill them up in the cold, the tires will warm up, the air will expand and you will be over inflated. Best advise... on a decent day in the 60s, drive the car around a while doing osme turning to heat the fronts up too and go fill them where you want them using a pressure guage and then ignore onstar. If the warning comes on in the DIC, take a quick check to make sure you are only a few pounds off and go on your way. It is a good idea to check incase you actually do have a leak. If it reads 20psi.. you have a problem. Expansion/contraction only changes them a few pounds and if you run low 30s you will get the warning alot.

Second way to eliminate it is go and have them filled with nitrogen. Expansion/contraction is much less.

[2010 SSRS]

my report always shows my tires are low to, I thought 36 pounds sounded like a lot anyways, I always ran around 30-32 pounds in my other Camaro's, but I guess it is because of the 20 inch wheels.

[The_Blur]

Cold weather will cause the air molecules to retract. It may have been 36 psi going into the tire, but the contracted air may lose pressure over time, hence your reading of 30 psi.

[warmongoose66]

I have tha same problem I only have 197 miles on my Bumblebee and my tires came with nitrogen air according to the bleu caps and a window sticker above the driver side window. All reports that I pull from onstar are not the same as the computer, it has a 2-5 PSI difference.

[RickyTheStorm]

It's just another computer/electronic thing that can't be perfectly accurate and has discrepencies and can go bad.


Get an analog good quality tire gauge and run off of what it says.