TPMS might be bad?

[G701LE]

I can't just put regular air in it can I?

[Talladega]

Yes you can put air in a tire filled with nitrogen. It will not hurt anything. If you take your car to a tire place to have the air topped off 9 times out of 10 they will put compressed air into it even with green caps.

[Edzo]

Originally Posted by Rock-It Man

Dear fellow car guy:

All gasses lose pressure at the same rate, about 1 psi per 10 deg F.

It's called the ideal gas law, as per your general science class in the 7th grade.

Also, the green cap means you have nitrogen in your tires. Hydrogen is highly flammable. Nitrogen in your tires means either you or previous owner fell for a scam aimed at people who don't know the ideal gas law.

And by the way, chances are, if one of your tires is down, you have a nail in it.

The only good thing about the nitrogen fill is that the bottled nitrogen has very little moisture in it. This does affect tire pressure if you are a racer and the air in your tires reaches 212 F. That's not gonna happen in every day driving.

PS: your cold tire pressure should be around 36 lbs. It's at 29 'cause you didn't put more air in when the weather got cold.

Ideal Gas Law? I know I've heard that somewhere else before!

[Dizzy82]

Check your tire pressure with a normal tire pressure gauge. If the sensors are off, there is your problem. FYI, my tire sensors are about 3 pounds under reading.

[Norm Peterson]

Originally Posted by G701LE

I can't just put regular air in it can I?

Absolutely you can.

All you'll be doing is reducing the nitrogen concentration down from about 95% - 98% that's about as good as a N2 fill can get down toward the 78% N2 that is the atmospheric content. IOW, the presence of nitrogen is not an all-or-nothing thing but varies between 'mostly' and 'almost entirely'.

Most likely, a little moisture will be introduced because most 'regular air' stations and consumer-level compressors do not feature air dryers. This will affect the amount of pressure gain with tire operating temperature slightly. In and of itself, moisture isn't going to be harmful over however many years/miles/number of cold to hot to cold cycles that you are able to get out of the same tires.


On the matter of erratic TPMS-measured readings, for now I'd just use a manual pressure gauge on the tire having the erratic readings, and maybe the opposite-side tire as a check.


Norm

[MrChrisLS3]

Originally Posted by Dizzy82

Check your tire pressure with a normal tire pressure gauge. If the sensors are off, there is your problem. FYI, my tire sensors are about 3 pounds under reading.

Agree

I think there's more to that relearn feature. believe there is a certain tool that needs to be used in conjunction with it.

My TPMS went out after using that one time. All four tires read "--". Being one that doesn't really trust the reading, I just ignored it as I check the pressure the old fashioned way. When I went to have a leaking tire changed, (valve stem), I asked the dealer to check the system. It works now and I know they didn't change them out, I wasn't there long enough for that.

And yes, change of season has a huge effect on tire pressures.

[chuckie669]

Discount tire has a relearn tool they just hold next to each valve stem to reset. I imagine dealer uses something similar

[Norm Peterson]

Originally Posted by MrChrisLS3

And yes, change of season has a huge effect on tire pressures.

Figure 1 psi for every 10 degrees F of temperature change away from the temperature you last checked them at (meaning cold pressures). Close enough for pressures anywhere between 30 and 40 psig.


Norm

[CamaroFred]

Originally Posted by chuckie669

Discount tire has a relearn tool they just hold next to each valve stem to reset. I imagine dealer uses something similar

2010-11 doesn't need that. There is a relearn procedure outlined in your owner's manual.

The reason they changed to the tool is because when the vehicles are packed in like sardines one sensor could become connected to the wrong vehicle. That caused all kinds of havoc.

The new sensors are now encrypted.

[chuckie669]

Originally Posted by CamaroFred

2010-11 doesn't need that. There is a relearn procedure outlined in your owner's manual.

The reason they changed to the tool is because when the vehicles are packed in like sardines one sensor could become connected to the wrong vehicle. That caused all kinds of havoc.

The new sensors are now encrypted.

Understand is not needed, but boy is it convenient.

[G701LE]

Ok. I bought another tire pressure gauge. The front passenger was so low that it didn't even register. So I took all the caps off and filled them to 39 PSI. All were low, but not like the front one as stated. I have been running around 30 PSI this whole time and wondered why I was getting horrible mileage. The DIC read 32 all around when I bought it through Certified Chevy dealership. So, I ASSumed that was what it was suppose to be. Anyway. hopefully I don't have a nail in the tire or leak. Can't afford tires this time of year......

[Norm Peterson]

Small punctures can be repaired at little cost. Almost $0 per repair if you're OK with doing your own plug repair.


Norm

[Rock-It Man]

Originally Posted by G701LE

Ok. I bought another tire pressure gauge. The front passenger was so low that it didn't even register. So I took all the caps off and filled them to 39 PSI. All were low, but not like the front one as stated. I have been running around 30 PSI this whole time and wondered why I was getting horrible mileage. The DIC read 32 all around when I bought it through Certified Chevy dealership. So, I ASSumed that was what it was suppose to be. Anyway. hopefully I don't have a nail in the tire or leak. Can't afford tires this time of year......

Dude, there's only one reason that one tire is that low. It has a puncture.

The correct tire pressure is 36. There's a sticker on the door jamb OF EVERY CAR ON THE PLANET telling you what the pressure is supposed to be.

[samgray20]

Originally Posted by Rock-It Man

Dude, there's only one reason that one tire is that low. It has a puncture.

The correct tire pressure is 36. There's a sticker on the door jamb OF EVERY CAR ON THE PLANET telling you what the pressure is supposed to be.

+1

There's also a pretty good chance the sidewall of that tire is now ruined if you drove it very far with that little pressure in it. You may very well end up replacing at least one tire if they were run that low.

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