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Why would 100% Nitrogen display a significantly different pressure increase due to heating than the ~80% Nitrogen and ~20% Oxygen of the atmosphere?
Moisture content. Typical nitrogen supplies are considered "dry" with a low dew point. Ever drain water out of your air compressor's tank?
 

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Discussion Starter #42
I have had at least two heated discussions with some guys from local (national-wide) tire shop.
One was about TPMS another about lug nuts.
In both cases I heard very similar statement - I am stupid and know nothing, while this guy spent over 25 years working in tire industry and he knows all of it.
Only to prove him wrong in the very next moment.

What I hate with those folks the most is sticking to their story even if all evidence proves them wrong.
I was polite and just wanted to get my TPMS installed. Nope, I was being forced to buy their stuff (80 a piece), while my OEM ones I got at 15 a piece.
Another story was with lug nuts, but very similar problem. Aftermarket wheels (but only 5-hole style - specifically spoke with manufacturer to make sure OEM lug nuts will fit). I measured the seats and all was good.
Nope. I was told to get aftermarket nuts (almost 100 for a set).

Once I showed him the lug nut fits no problem and the socket wrench sides inside as well, he started off going that the seat is different (it is not tape, but ball style - although the specs was clearly saying it is taper...).
TPMS - no way they would program. Well, they did...



So the moral is - many times it boils down to the quality of service. Your TPMS issues could be nothing more but poor skills. Or lack of them.
I believe the proper term for these guys is "A$$ hole"
 

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Nitrogen filled tires is... a scam.
Not only atmospheric air contains 80% of nitrogen while the "nitrogen fill" is not pure 100%, but it also works just like any other gas.
As for expansion and moisture.

Air you get in your tire is quite dry already.
The compressor keeps pressure of about 100 psi (some might be higher - 100 psi kicks in, 125 psi - stops).
Because of this pressure, all moisture will condense and collect in the drain.
Then, you decompress this air to say 40 psi making this air much drier than the ambient.
It is not a huge improvement, but always something.

Theoretically, if you assume 125 psi and air moisture saturation (100% relative humidity (RH)), when you drop the pressure to about 40 psi, you will end up with air of about 35-40% RH.


If you were in very dry areas, say 25% RH, by using tire compressor, you are going to make the air inside about 50% or more anyway... so big compressor with tank and drain is still better.
 

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@Fivedoor reported the sealant was dried up at the end of life of his Bolt's tires. Made me wonder if putting air in the tires might degrade the sealant. Some sealants cure with moisture. Maybe a real reason to actually use dry nitrogen in the Bolt's tires.
Weird, but it sounds very unreasonable to have the sealant "floating" in the tire and be moisture sensitive.
It mush be sandwiched between rubber layers. Otherwise you'd have flat spots or imbalanced tires each time you are parked for a while.

Finally, if that was the case - dry air or nitrogen feel would be a requirement on the door jamb sticker.

Yes, polyurethanes cure faster if exposed to elevated temperature and moisture.
 

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Weird, but it sounds very unreasonable to have the sealant "floating" in the tire and be moisture sensitive.
They have it encapsulated inside the tire so it's not floating around. But how robust is the encapsulation to moisture intrusion being exposed 24/7 365 days of the year for several years? I'm extrapolating from one data point. I don't know what type of sealant they used and what method of curing is required. Maybe it's light activated. So then nothing bothers it inside the tire until it starts extruding through a hole. Just that Fivedoor observed that it was dried up at the end of life of his tires.
 

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I could not find any details on the Michelin selfseal technology.
Hard to say why it dried out and how it cures. I think it is just a thick gel that may harden with exposure to air.

You know, there is a chance he already had some punctures earlier that activated the gel and it already hardened or stiffened enough.

I cannot really think of air or moisture activation. Or even light.
The first two - both sides of the tire would be sensitive during puncture.
As for light - what about night driving? :)

I had KIA Forte5 (two separate models) for over 40k miles total, that is roughly 5 years. I bought spare wheel for it. Never had to use it...
 

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Do the TPMS sensors throw a warning when the air pressure is low? I got an OnStar email showing my tires being low by 4psi but I get no warning. I need to go remind myself how to show the readings on the dash, but I expected some kind of light to go off with being that low.
Thanks-
 

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I don't remember seeing a warning displayed, but after I got a couple of those OnStar messages, I check the tire pressure frequently. Access it by scrolling through the "trip odometer" fields using the up/down arrows on the front of the steering wheel. When you select the correct page, TPS is displayed on the dash in the same location as the trip odometer and miles/kWH
 

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I just leave the center circle to show the tire pressure. Seems the most useful screen as I can get efficiency on the main infotainment screen.
 

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Do the TPMS sensors throw a warning when the air pressure is low? I got an OnStar email showing my tires being low by 4psi but I get no warning. I need to go remind myself how to show the readings on the dash, but I expected some kind of light to go off with being that low.
Thanks-
You won't get a warning message from a small pressure loss. The warning threshold is around 26 PSI.
Go to vehicle info on the far left screen using the arrow keys on the right steering wheel pod.
After you get into vehicle info, scroll until your TPMS data comes up. See where the inflation PSI
is and adjust accordingly.
 

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Yeah, I think mine was complaining when cold pressure was at 28 psi. My car was delivered from Florida in January to Michigan. Poor tires must have felt cold.
Since some paperwork was not finished, I did not drive it everyday, so I did not care, but TPMS was complaining a few times, but only initially. After several miles it was OK when pressure increased to 30 -32 psi.
 
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