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Nitrogen filled tires question


rstripe's Avatar
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01-03-18, 07:39 PM   #1  
Nitrogen filled tires question

My business partner bought a new car a couple of years ago that came with nitrogen filled tires, and has complained on many occasions that when it gets cold outside, his instrument display tells him his tires are too low. While, in theory, I understand that the leakage would be slower over time due to the absence of the smaller oxygen molecules, I thought the pure nitrogen was less affected by extreme temperature changes, as well, but he thinks not, he says the nitrogen is more affected by temp. swings. He's had a tire company purge the tires of nitrogen so he can go back to regular air.

What's the deal here?

 
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01-03-18, 07:48 PM   #2  
I believe you are right, they say nitrogen filled tires are less affected by temperature swings. That's why they use it in racecars.

But let's think about this for a moment. The air we breathe is 78% nitrogen, 21% oxygen. That's what we normally pump into tires. So they say nitrogen filled tires stay pressurized better, since oxygen slowly leaks out. Well if it's the 21% that is leaking out... and you refill it with more of the same 78% / 21% mix, and that oxygen leaks out... and you refill it again...

Get my drift? Wouldn't we eventually end up with a greater percentage of nitrogen just by refilling our tires when they get low? If the oxygen is what is leaking out you would seem to naturally end up with a greater concentration of nitrogen each time you lose oxygen and refill. Why would I ever pay extra for "nitrogen inflation"? Sounds like a scam to me for people who have been watching too much Nascar.

Hmmm.

 
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01-03-18, 08:01 PM   #3  
I guess there's a good and bad to everything. My friend bought four tires from Costco for his SUV. They put in nitrogen. He hasn't added anything in the several years he's had them.


~ Pete ~

 
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01-03-18, 08:05 PM   #4  
The business partner paid a tire company to let stuff out of his tires? Seriously? I suppose he wanted to pay for every trace of nitrogen to be purged from those tires before he also paid someone (?) to fill them back up with plain air containing 78% nitrogen, huh. Hahahah man I'm in the wrong line of work.

 
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01-03-18, 08:23 PM   #5  
If this forum had a "like" button I would +1 that. LOL!

 
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01-03-18, 09:03 PM   #6  
I suspect he's only more aware of the pressure changes because the dash indicators and idiot lights are more prevalent nowadays...kinda like my mother used to say how there was so much more crime in the world now, not realizing it's the increased news coverage plus more time when you're retired, to watch news on TV all day....

Now that he's got "pure air" in the tires, the experiment will be to see if he's notified of low tires at the same rate as before. Expounding on Xsleeper's comment, "regular" air is already 78% nitrogen, so the difference in characteristics must be very minimal, and I suspect "human factors" influences his prejudice against nitrogen, more than anything.

 
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01-03-18, 11:18 PM   #7  
I believe that there is validity behind the rationale to run nitrogen in tires, but this has been debated by both professionals and laypersons since its' inception, on this site and many places elsewhere, so I'm not going to reopen that part. But I do think that you probably hit the nail on the head when you mentioned the dash indicators and idiot lights that have become standard equipment on every new vehicle sold. Again, I'm not going to reopen the nitrogen debate, but, regardless of that or plain old air, temperature does affect pressure, just a little more or less depending on the gas. I am not an expert, but have driven 3/4 ton pickups as my primary vehicle for around 40 years, and with those tires being larger than a majority of passenger car tires, and relying on load carrying ability, am accustomed to checking tire pressure regularly, particularly as average temperatures change. Every day? No, although I generally do at least look at them every day just because, but I do check them about every other week during seasonal changes. Whenever it was, sometime a couple of weeks ago, when the temperature took a nosedive and the forecast was to stay cold, all of the tires on my truck were down about 12-15 lbs., and the tires on my wife's car were down about 5-7 lbs. Perfectly normal. But I think that a lot of people list tire pressure as one of those things to check before going on vacation or whatever their routine is. And of course a lot more people pay to have their vehicles serviced today, right down to and including oil changes, so many times their tire pressure is adjusted almost unbeknownst to them. But now they have gadgets, and what do we do with gadgets? We watch and play with them as much as we can. So you have people driving to grandma's house and carrying on about the fact that their tire pressure went up two pounds on the way there. It's amazing! No, it's perfectly normal, but now they can see it with their own eyes. And I do agree with thinking a "like" button would be good for times like this.

 
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01-04-18, 12:45 AM   #8  
It's the condition of the tire to the wheel seal during cold weather, has nothing to do with the air or nitrogen in the tire!


He's had a tire company purge the tires of nitrogen so he can go back to regular air.

What was that statement that PT Barnum maid?

 
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01-04-18, 04:00 AM   #9  
Me thinks Marq1 statement is truer. Look at the most simple thing first. Besides the pressure sensors all have a percentage of error. That may be different from unit to unit.

 
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01-04-18, 04:06 AM   #10  
I just run regular air in my tires. I've had my jeep with it's low tire sensor for 8 yrs. Every year when it gets cold the low tire light comes on. With my jeep the light comes on if any tire's pressure drops to 33 psi.

I have a hard time wrapping my head around anyone paying to remove the nitrogen to replace with air!


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01-04-18, 04:36 AM   #11  
While there may be some benefits, mostly snake oil IMHO.


Measure it with a micrometer; cut it with an ax.

 
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01-04-18, 06:34 AM   #12  
I see about 1 PSI change per 10 degrees change in temperature. The monitoring systems on my vehicles have made me more aware of the changes. I add plain air when needed during cold weather.

Nitrogen is advertised to make the tires last longer. I think it is all a scam to charge more for something that is not needed. Just my 2 cents.

 
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01-04-18, 07:41 AM   #13  
I despise tire pressure monitors because they were never meant to be good enough for people to WANT to purchase them. They come standard, are sealed forever so when the battery dies in ~8 years you have to replace the entire sensor. They're NOT particularly cheap and the labor required to replace them probably costs more than the true cost of the sensors. And they're not accurate. When the temps took a dive last week my sensors all read about 25psi and the warning on the dash display could not be dismissed. So I carefully filled each tire to the specified 34psi. Later I took a drive & noticed the sensors all read about 41psi. No warning for over-pressure so they remain over-filled.

 
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01-04-18, 07:47 AM   #14  
I'm also not fond of those tire pressure monitors. The one in my jeep just lets you know if one [or more] tire is at 33 psi or less. The one in my wife's nissan is presumably better. It gives a tire pressure reading for each of the 4 tires. I don't know how accurate it is as I rarely drive her car. Between my butt on the seat and hands on the wheel I've always been able to sense a tire that is more than a couple pounds low without any high priced gadget.


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01-04-18, 07:50 AM   #15  
Gasses expand with heat and contract with cold, so cold tires usually need more gas added, be it N or O. We add air to our tires up here in the fall as it cools and then let air out in the spring when temps rise again.

It's the same reason you're supposed to check air pressure before the tires have been rolling a while.

 
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01-04-18, 07:58 AM   #16  
I don't know that I've ever let air back out in the spring but have had to add more at the start of fall/winter more times than not. BUT our cold normally isn't as severe as it is for those further north. I normally only need to add a few lbs per tire.


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01-04-18, 09:05 AM   #17  
A lesson learned.

Dont buy used TPS, sellers on eBay give you a great price but they install a new stem and cap and the damn thing looks brand new BUT the battery can be years old.

Been there, done it!!

 
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01-04-18, 12:05 PM   #18  
About 10 years ago Consumer Reports did a study supporting the contention that tires leak down more slowly when filled with nitrogen instead of air, but the difference was only 1.3% over the span of a year, which works out to a 32-psi tire leaking down to 31.6.

The reason nitrogen is used almost exclusively in tires used in racing applications is that it's more temperature stable because bottled nitrogen in anhydrous. Air is not, and the water vapor that invariably stows away in air makes it substantially more temperature-sensitive. Exactly the same reason nitrogen is the chief gas used in charging high-end shock absorbers. Especially on vehicles like dirt bikes and dune buggies, shocks can get crazy hot.

A lot of airplanes require their tires be filled with nitrrogen because their tires are comparatively high pressure (some in excess of 200 psi) and nitrogen doesn't support wheel corrosion, plus it's somewhat kinder to the rubber in the tires as well. Some mechanics have been injured becauses a tire or wheel exploded while they were servicing it.

There also have been tire explosions on touch-down that were linked to tires being filled with air. Airplane tires can be required to go from a dead stop to accelerating to 150(-ish) mph in a fraction of a second, which causes them to get really hot really fast. The FAA determined that this rapid heating was causing the tire liner to emit a combustible gas which became explosive in the presence of ccompressed air. Not to mention an airplane could leave a 90 Miami and land five hours later in 20 Buffalo, and that's a big ask of a tire that's subjected to such tremendous stresses every time it lands.

 
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01-04-18, 03:52 PM   #19  
Space shuttle used Nitrogen saw that advertised once!

 
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01-04-18, 06:06 PM   #20  
I had my last set of tires nitrogen filled only because I got a better price on the tires by letting him add that. I in fact noticed a slower leakage rate over previous air filling with the same tires. The molecules are larger and the pressure doesn't vary much with temperature (think expanding, then contracting). I doubt it's anything to do with the nitrogen fill if he anything close to pure nitrogen in them. Having installed about 1000 tires myself, I've seen plenty of hard plastic stickers installed on tire beads that caused slow leaks. I always removed them as a personal preference but know most guys didn't.

 
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01-05-18, 05:06 PM   #21  
Space shuttle used Nitrogen saw that advertised once!

5 orbiters, and "only" 2 of them blew up. Hull loss rate of 40%. Yeah I don't think I'd use that in an advertising campaign.

 
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01-06-18, 04:55 AM   #22  
In answer to your question:

Nitrogen is less affected by temperature changes and is why it is used in specialty applications.
The auto industry has spun specialty uses of nitrogen into a value added product that consumers believe will benefit them.

Some trucking firms use nitrogen in transport truck tires to decrease tire wear from increased pressures due to rolling down a hot highway surface.
Some trucks are able to get a half milion miles out of a set of drive wheels and the use of nitrogen could assure that they get that.
I am not sure how an average car truck owner can spin the nitrogen idea to be an advantage for themselves.
Could be they just don't know how to say no to a pushy salesperson.


GregH.........HVAC/R Tech

 
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01-06-18, 05:05 AM   #23  
Could be they just don't know how to say no to a pushy salesperson.
I think it's more of a good sales pitch to an uninformed customer. A lot of times someone can be convinced they need something when presented with the right sales presentation. Facts are often presented in a misleading manner


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01-13-18, 09:55 PM   #24  
well, after opening up this can of worms, I think the general consensus is that Nitrogen is LESS affected by temperature, not MORE, as my partner thinks, although the difference in effect is apparently quite minimal.

 
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