I looked at my wife and saw a bit of hesitation. She was buying it. Literally, if I dindn’t stop her. “Ahem,” I got her attention and she snapped out of it. “Isn’t air already 78% nitrogen?” I asked the finance manager. “Uhh… well I’m not a scientist,” he replied with a sheepish grin. My wife, fully back to her senses smiled broadly, pointed at me and said, “but he is!” I’m not, but having stayed at my share of Holiday Inn Expresses, and having paid some attention in my Chemistry classes, I knew $5.00/tire every time they got low wasn’t an expense I wanted. And, if we filled a tire with air somewhere else, it would be $60 to service the tire and fill it back up with nitrogen. The tire that already had 78% nitrogen.
- Nitrogen-filled tires maintain proper pressure longer
- The rubber of nitrogen-filled tires last longer
- Nitrogen is less volatile than oxygen and thus safer in a fiery crash
- Cars with Nitrogen-filled tires get better gas mileage
- Cars with Nitrogen-filled tires are better for the environment
1. Do nitrogen-filled tires maintain proper pressure longer? The premise for this claim is that nitrogen is a larger molecule than oxygen. It is. Only slightly. But let’s not omit the fact that we’re talking about molecules here and not just the element. Oxygen and nitrogen are both diatomic molecules. Nitrogen actually has less mass than oxygen, so Graham’s Law dictates that it diffuses a bit faster than oxygen. However, since the actual size of the oxygen molecule (O2) is a bit larger than that of a nitrogen molecule (N2), this only applies if the opening from which the molecules are effusing from is large enough to permit the largest of the two. In such cases, N2 will diffuse faster.
The question, then, becomes, are the pores in rubber (assuming there are such pores) smaller than the N2 molecule but larger than the O2 molecule? I don’t know the answer to this. Nor could I find any literature in the few minutes I searched, but if anyone has a citation to an independent (i.e. non Nitrogen Tire industry) study or bit of research, I’m interested. Without digging out my old chemistry textbook, I’m willing to tentatively accept Wiki Answers on the sizes of N2 and O2 molecules: N2 is roughly 300 picometers while O2 is slightly smaller at 292 picometers. I’m open to revising these figures if someone cites a more reliable source, but I can’t imagine that there’d be any reason for the link to be more than slightly wrong.
2. Does rubber oxidize faster when exposed to oxygen rather than pure nitrogen? I’d expect so. The real questions are: a) how to you keep oxygen on the outside of your tires from causing oxidation?, and b) does it really matter to me since every single tire I’ve ever replaced was because of worn tread and not oxidation?
3. Why do I give a shit whether or not the oxygen in my tires will fuel the fire of my fiery crash? If the explosion is powerful enough to consume the oxygen in the surrounding air leaving only my tires as reserve fuel, I suspect I’m going to be a crispy critter anyway.
As for 4. and 5., I’m not that arsed for time that I can’t continue my routine of checking my tire pressure every 3,000 miles when I change my oil. In fact, nearly every time I’ve ever checked my tires at 3k, they’ve either been dead on for the proper psi or just a pound or two off. Whenever I’ve had to fill more than that, it’s been either because of a faulty valve or a nail in the tire itself. I suspect that the resulting points of egress in a faulty valve or pucture would create holes large enough for either O2 or N2 to escape through effusion. So, in that case, Graham’s Law would be in effect and N2 would escape faster than O2.
The bottom line: if nitrogen becomes a free option, easily obtainable (i.e. cheaper and easier than the $5.00 Walmart compressor that I plug into my cigarette lighter), I’ll use it since there’s a very slight chance I won’t need to top off my tire pressure as often. But, as long as I have to pay for it or even just drive to the dealer for it, I call bullshit!
Nitrofill is a scam. Nitrogen-filled tires for general consumers is a scam.
Filed under: Archaeology |
Hot Cup of Joe 
Cfeagans
Hello. You may recall that I posted the below entry on your blog, Hot Cup of Joe, countering some of your arguments against nitrogen tire inflation. I was just curious to know why you decided not to publish it? I was always under the impression that the beauty of blogs was that you could often see differing points of view and readers could make their own determination.
Best regards,
John Lucidi
jlucidi@parker.com
First, in an effort to be as forthcoming as possible, I should inform you that I am involved with nitrogen tire inflation. I am a firm believer in nitrogen tire inflation, not only because of the benefits to the consumer, but the environment as well. I run a blog dedicated to nitrogen tire inflation located here:
http://tirenitrogen.typepad.com/tirenitrogen/
Today I came across your blog post about nitrogen tire inflation, and wanted to address a few of your points.
1.) I have no intention of arguing molecular chemistry with you, but will tell you that oxygen permeates through the rubber sidewall of a tire 4-6x faster than nitrogen. If you are looking for non-nitrogen tire market proof, I can direct you to the following reprint from Bridgestone, a major tire manufacturer.
Click to access BridgestoneReprint.pdf
This is a reprint from their corporate publication Real Questions, Real Answers. I have seen supporting documentation from Ford as well that back up these numbers.
Here are bulletins from Goodyear and Michelin that reference the better pressure retention characteristics of nitrogen inflated tires.
Click to access goodyear_n2_inflation.pdf
Click to access goodyear_n2_inflation.pdf
It is a well proven fact within the tire industry that nitrogen inflated tires maintain their pressure better than air filled tires.
2.) You bring up a good point of oxidation of the outside of the casing. As John Baldwin from Ford points out in his paper entitled “Effects of Nitrogen Inflation on Tire Aging and Performance”, chemical aging of the rubber is nearly halted when tires are filled with nitrogen.
Click to access FordBaldwinResearchRaper.pdf
The reason, no oxygen is permeating through the tire, causing belts to wear and rubber to break down and oxidize internally. By minimizing this internal wear, a nitrogen inflated tire is structurally stronger after 2 years than an air filled tire after 10 weeks (Figure 4).
You will also see, from page 3 of his report, that the Ford Explorer rollovers were partly caused by this issue: “defective in part because the physical properties of rubber in the steel belt area had deteriorated due to oxidative aging.”
3.) Point taken
4 & 5.) NHTSA has stated that 85% of the population does not check their tire pressures regularly and that 30% of cars and light trucks have at least one significantly (25% or more) underinflated tire. These underinflated tires cause the USA to waste 2.8B gallons of gas/year (1.6B cars & light trucks, 1.2B heavy duty trucks). Over $11B in wasted money in the US alone due to underinflation.
By maintaining proper inflation pressure longer, nitrogen inflated tires get better gas mileage and have a longer tread life. Goodyear recognizes that underinflation is a major contributor to poor gas mileage and tire life, and are running a summertime air inflation program to combat these issues. More information is available here:
http://tirenitrogen.typepad.com/tirenitrogen/2008/05/goodyear-summer.html
While I doubt that this is proof enough for you that nitrogen tire inflation makes sense for the common consumer, I would hope you could at least understand the proposed benefits a bit better.
I will begin by stating that I have twenty years experience in the tire and automotive industry and cannot understand how people can fall for this bill of goods. The argument for nitrogen inflation is an industry driven phenomenon. The reason the people run around on under-inflated tires is a lack of maintenance. And anybody that has a tire that is more than 25% under-inflated is because they refuse to have the slow leak fixed. Having nitrogen in your tire will not plug the hole. I live in northern Canada where the temperatures vary widely and the pressure in my tires rarely are off by a pound or two even in the cold. Again we are being told that if we just do this or buy that we can avoid the responsibility of looking after whatever it may be. TPMS systems in new vehicles are a perfect example of this. They are supposed to prevent people from driving when a tire goes low yet in owners manuals the first thing car manufacturers tell you is the TPMS is not a substitute for proper tire maintenance. Once again the snake-oil salesmen are back with a new improved method to take your money. If you believe in nitrogen inflation I have some PVI (platinum vapour injection) systems for sale. For the average consumer nitrogen is a waste of money for the supposed gains.
I’ve been in the Air Force for 10 years and all aircraft tires have been required to be serviced with nitrogen rather than air since I’ve been in. Only under temporary circumstances can plane tires be serviced with air. I’m not sure exactly the science behind it as I am a mechanic not an engineer, but if it’s required I’m sure there is a good reason for it.
Perhaps it has to do with altitude and fast changing temperatures? Air pressure and temperatures change drastically with altitude and nitrogen molecules are probably more stable than oxygen through this.
Hey Ryan (Air Force guy) — do your research; it should be pretty easy considering your claim to have been in for 10 years, to just ask someone why they must do that. Nitrogen in the wheels of aircraft is a requirement to avoid a heat-induced explosion as the jet accelerates and decelerates. This has nothing to do with air-pressure or any other point other than the one least likely event possible in a vehicle (a fiery explosion that somehow doesn’t kill you before it gets to the tires), it only pertains to the fact that compressed O2 in a rapidly-heating tire is a ticking time-bomb, while N2 poses no threat of internal combustion.
N2 has a molecular weight of 28…the standard atmosphere is 29. The difference in mass is negligible. The case of the air outside the tire is good but the whole idea that tire tread will last long enough for the tire to oxidize would be a factor if you were speaking about the typical Gradma that drive 20 miles a week, and her car has original equipment tires on the 1975 Cadillac. 🙂
Joking aside…if you maintenance your tires properly it would not matter if you used N2 or the standard air provided at the tire store or gas station. Absolutely no one fills their tires with pure O2 so the comparison with this is not valid for either side. The argument that the standard atmosphere already contains 78 percent N2 is the most valid defense for not using this product, not to mention the added expense.
Then there is the fire response…really…come on, your driving a car that likely has a substantial amount of fossil fuel in the tank and the worry is that the tires will burn?
The lesson here is to not be lazy and do not forget to take care of your tires!
[…] but since it ended up being so lengthy, I decided to make a separate post. The original comment is here and was caught by the Akismet as spam. I’ve since approved it to be […]
I’ve responded to the comment above as a separate post found at: https://ahotcupofjoe.wordpress.com/2008/07/16/nitrogen-tire-scam-part-3/
Utter SCAM!
Claims about expansive behavior of water vapour are all based on 14 year old school kid physics. A tyre filled from 1bar atmosphere with wet 100RH air at 15°C holds 10.7g water / Kg air. 195/60R15 tyre that’s about 1.4g of water. At 32psi the boiling the point of water isn’t 100°C, it’s 136°C so no boiling and no expansive steam in a 80°C tyre or even 100°C F1 tyre. The actual increase in pressure at 80°C due to vapour pressure of water is about 0.7psi.
All compressors at tyre shops and service stations should have a dryer fitted. Just compressing air to 100psi reduces the amount of water air can hold at 15°C to 1.34g water / Kg air. Let it stand and the excess condenses in the tank to be released though the drain tap. Tyre filled to 32psi with air at 15°C and 1.34g water / Kg air will show a 0.03psi overpressure at 80°C. If you don’t let it stand and cool you will have under pressure problems as the air pressure reduces as it cools to ambient in the tyre. Get a tyre fitted at a busy shop with a hot compressor and you will always have low pressure the next day.
Click to access graham.pdf
Statement: Diffusion rate for N2 is 3, O2 it’s 10. (3rd para from end)
Air contains 78% N2, assume rest is O2
Total diffusion rate of air = N2 0.78 x 3 + O2 0.22 x 10
= N2 2.34 + O2 2.2 = 4.54.
The N2 is exiting the tyre 6% faster than the O2!
93% N2 diffusion rate = N2 0.93 x 3 + O2 0.07 x 10
N2 2.79 + O2 0.7 = 3.49.
Ratio = 4.54/3.49 ~ 1.3
Assuming all loss is diffusion. A tyre with N2 will have same pressure after 6 months as an air filled tyre has after 4.6 months. All it can possibly do is allow you increase the pressure check intervals by 1.3. Every 9 days instead of every week.
Yet the N2 industry makes claims that it’s 3x better (or in the case of Bridgestone 6x). Seems yet again they can’t do a proper analysis but have relied on school kids.
People that fill with N2 are even less likely to check the pressures as they don’t have the N2 to fill them with (though bridgestone do say top up with air). After all it’s sold on the claim that tyres become virtually maintenance free (I can see some law suits real soon). If it takes a special trip to somewhere with a N2 machine then it’s an environmental disaster due to the fuel used making that trip.
Then there is issue of what the temperature is when you check the tyres pressure. Start with 32psi, the temperature you set the pressure at gives several psi variation in running pressure as does the running temp.
temp °C at 60°C at 80°
0 42.26 45.7
5 41.23 44.6
10 40.25 43.5
15 39.29 42.5
20 38.37 41.5
Doesn’t matter if it’s dry air or dry N2 both obey the Ideal gas law. P x V / T = const.
Then there is there is the “they use it on aircraft” crap. They use O2 reduced air, requirement is 5% or less O2. A plane took off with a brake on. This overheated the brake and tyre a lot. It didn’t blow out straight off but it was slowly cooked by the overheated brake. CAP 747, appendix 1, GR No. 16 Tyre Bursts In Flight – Inflation Media. 2.5Mb pdf doc source on this page, link “open doc in new window”.
http://www.caa.co.uk/application.aspx?categoryid=33&pagetype=65&applicationid=11&mode=detail&id=1331
Only applies to aircraft with RETRACTABLE undercarriage and over 5700Kg. I’ve yet to see a car or truck driven on retractable wheels.
Peter,
Sorry it took more than 10 days for me to approve your comment. I’ve been more or less away recently and Akismet caught it as spam since it had several links in it.
Anyway, great stuff! Thank you!
Carl
I also wrote a post ( http://energy-eng.blogspot.com/2008/03/nitrogen-filled-tires-myths-and-reality.html )
on why the nitrogen molecule is larger than oxygen molecule, even though N (atomic # 7) is less heavier than oxygen (atomic # 8).
The difference lies in “kinetic diameters”. More is here
Click to access graham.pdf
Ultimately, my back-of-the-envelope calculations indicate that a N2 filled tire will hold its pressure for ~40% more time , compared to the air inflated tire.
The real question is whether we are actually checking our tire pressures, rather than what we are filling it with.
Nitrogen doesn’t expand under heat like regular air does (or very minimally, relatively). It’s this singular property that makes it optimal for race cars / motorcycles that need predictable tire pressure. It’s unnecessary for everything else. Just check your tire pressure when you get your oil changed like you should.
You get the same MPG benefits by filling your tires to their max pressure with any air gas.
PS: The only thing you can accuse the salesperson of is selling refrigerators to eskimos.
I do not know the entire chemistry bit, however I do know that its a way we can become more lazy and not have to check our tires as frequently as we should. N2 has benefits, but when your oil hasn’t been changed for 5-8K miles or your putting E85 octane in your car to save money it won’t matter what goes in your tires if your car is not running @ 100% its capabilities. You can’t “Rob Peter to Pay Paul” ! You have to take care of your entire car and then you’ll know what mpg $$ you are saving, otherwise its just another expense putting N2 in your tires ! Good Luck !
Here is a scientific paper that does a good job of explaining why O2 permeates most rubbers more easily than N2. Basically, while O2 and N2 have roughly the same diffusion values in rubber, O2 is much more soluble in rubber. It is the combination of solubility and diffusivity that determines total permeability.
Click to access D116%20Haibing%20Zhang%20et%20al.pdf
However, for many of the same reasons already stated in the original post, I agree that for the most part nitrogen-filling has a very, very limited benefits.
Nitrogen expands under heat, just like every other gaseous molecule. PV=NRT for oxygen as well as nitrogen. (If you forget your high school physics, this means that temperature and volume are directly related, for any “ideal” gas. Oxygen and nitrogen both reasonably approximate ideal gases for this purpose.
All I know is I bought my 2008 Toyota Camry with 5K miles on it. No one told me I had Nitrogen in my tires! After 4K miles I put on, I was on a trip and my “light” lit on the dashboard saying my tire pressure was low. I went for an oil change and asked the guy to fill my tires. He told me he couldnt due to the Nitrogen. I now have to go to the Toyota dealer on my vacation to have this checked out. I am not a fan of Nitrogen!! He said it was good that I didnt try to put air in the tire myself. So after 9K miles, I’m having problems!!
You were misinformed. There’s absolutely no reason you can’t put air in nitrogen filled tires. All that will happen is your nitrogen will be a little less pure. No big deal. Air is already mostly nitrogen so the worst that will happen is you’ll have a tire serviced similar to normal air. The tires themselves are just regular tires. There’s nothing special about them.
[…] Nitro in Tires – Today, 03:49 PM found a good link: Nitrogen Filled Tires: a Scam? Hot Cup of Joe …dead on with what I would agree to. […]
[…] Originally Posted by nymyth Whats the purpose of this?? Im curious Peace Supposedly, Nitrogen doesn’t seep out of your tires are quickly since the molecules are larger than compressed air mixture. However, Compressed Air is already 80% Nitrogen. just googled and found this link: Nitrogen Filled Tires: a Scam? Hot Cup of Joe […]
[…] (except those by the folks selling N2) saying it does a darned thing for street-driven vehicles. Nitrogen Filled Tires: a Scam? Hot Cup of Joe __________________ ’97 F250 XL, 5.8L, ’05 Escape Hybrid, ’06 Escape Hybrid […]
Maryann,
I don’t understand why you can’t add regular air to your nitrogen filled tires? You would just be reducing the percent nitrogen. I could see how it might be a problem if you later decided to refill the tires with pure nitrogen, but it seems you’re not too fond of the NitroFill anyways.
Ok first off, I run my families Tire Store. We have just acquired a Nitrogen inflation machine. While trying to “bone up” on the positives of Nitrogen, I found this website. Interesting to say the least!
As I read the posts I feel there isn’t a right or wrong answer to the question of putting Nitrogen in tires. There were some amazingly cool demonstrations of chemical breakdowns and more arguments of plan nonsense.
Another stated that since we have a majority of non-metal wheels now, there would be no rust. This is not true. Being our shop is near the beach in Southern California, we have continual problems with chrome peeling and wheels flat out rusting causing leaks to occur. Whether Nitrogen wlll solve this problem remains to be seen. But, if there is a chance that spending $5.00 per tire could spare a $300.00 tire from going flat, due to rust between the wheel and tire, then the math speaks for itself!
Another person claimed they could not put regular air mixed with Nitrogen. Unless I didn’t understand the earlier chem lesson, by mixing the two only the purity of the Nitrogen is compromised. So when I read of a shop saying they can’t work on tires that have Nitrogen, I’m baffled!
Lastly, we get requests upon requests for Nitrogen. By understanding as many benefits of Nitrogen as we can, we can give the proper prospective to the customer. Will we push it as a major way to save money and gas mileage, no.
Is it a scam….No…It is simply an alternative!
Steve, I completely agree. And, good wishes to you and yours in business and health! JDW
could the corrosion or rusting on the rims be the result of the salty air in your area, rather than the air in the tires?
[…] article I found if you guys are interested in reading: Nitrogen Filled Tires: a Scam? Hot Cup of Joe Now I’m not saying filling your tires with Nitrogen is a scam, but this article makes some good […]
I would like you to know we have nitrogen in our tires and it is a big problem. Because the caps are stainless steel and the stems are a different alloy,
They have corrodite. We are trying to get the dealer to
take care of the problem, which they have been awear
of. In order to fill the tire which got low the stem had to to be cut off and replaced to a tune of $85 dollars and we have three other tires which need to be addressed.
Forget the nitrogen tires, they have a problem.
“…our caps are stainless steel…”
So, how is it there’s an incompatability with stainless?
Valva stems are made of steel, or brass. I’ve never before heard of corrosion between the two. Are you being told NITROGEN is the real culprit? Air is comprised of 78% N2, so, how’s that possible?
[…] article I found via Google, read it and others you’ll find and either laugh or fall for the hype.. Nitrogen Filled Tires: a Scam? Hot Cup of Joe __________________ "Fill your hands you son of a bitch" Rooster […]
Geez, I get 70,000 miles from my air-filled tires with no visible deteriorization. Eventually, the treads wear and I need new tires. So, what will nitrogen do for the most destrutive issues with my air-filled tires-TREADWEAR? I just hate people who scam the public like these guys are trying to do. They must work for the Bush administration!… did the Moon rover have N fills?
Yes, it did.
Actually the moon rover had titanium tires. Think about, no atmosphere on the moon means the ambient pressure is near zero, so a tire couldn’t contain the pressure, it would explode instantly. Check out wikipedia, some good pics there.
i would say yes the moon rover did have n2 in it since the space shuttle uses n2 in its tires.
The Lunar Rover tires were non-pneumatic (meaning no gas inside). They were constructed of a metal mesh ribbed with titanium chevrons for tread and, inside, was a bump-stop frame to protect the hub. The tires only needed to support about 65 pounds or so.
The Space Shuttle used N2 in its tires because it lands on Earth (not the Moon) and is undertaking significant pressure changes from zero pressure (vacuum) to 1 ATM at sea level in just a few very short minutes. With this kind of pressure change, temperatures also change and the small bits of moisture in a regular air mix can form ice. In addition, temperature affects metals and rubber on a molecular level and the larger, diatomic N2 molecules are less likely to escape into the vacuum of space than the much smaller, but also diatomic, O2 molecules through pores in tires that are facing temperature extremes no Earthbound consumer automobile will ever know.
I was at a tire shop today and saw this scam as well. I just started laughing at the diagrams. Here’s what Nitrogen looks like in a tire, versus here’s what Oxygen looks like. I don’t know a single person that inflates their tires with Oxygen…um…we use regular old mixed up air.
I haven’t had chemistry in 20 years, so I was thinking air was 74% Nitrogen (maybe that’s the percent of the earth that’s water?) but regardless, I have NEVER had tires lose air pressure for anything other than having a nail in them (once in my life) or just seasonal temperature changes…fill up in the fall. Air is free at gas stations and has never been the cause of my tires’ need of replacement.
Maybe if you let your car sit around in a showroom for years the air would do damage to the rubber before the treads wore out, but if you actually drive your car, I doubt that will ever be a problem.
well if you fill your cars tires at a gas station in the summer your getting all the condesation from the compressor in your tire. the change in pressure due to seasonal temps is happening because the water in your tire in condensing then expanding. n2 is a dry gas and it eliminates the water.
Except the water, which exists in an extremely small quantity, isn’t a problem. Nothing adverse happens to the tire. The claim is that the water accelerates oxidation and deterioration of the rubber and metal, but this isn’t shown to be the case. Long before any appreciable deterioration occurs from the water to the rubber on the interior, the normal road wear on the exterior of the tire has necessitated new rubber.
If N2 were free, there’d be a cost benefit. But since it is rather expensive, it is a money-making scam when one considers the benefit in return.
Good assessment and I wholeheartedly agree. Airplanes and the Space Shuttle use Nitrogen in their tires because it expands less with thermal variation than air does.
I bought new tires at Costco, including the nitrogen thing. Nothing I read here tells me it’s a flaming wonderful idea, altho it might provide modest benefits.
The mechanic who services my car says he can’t check the tire pressures, let alone add air to the tires. So the pressure doesn’t get checked as often as if I had air!
I just called Costco and was told that their “free” service would likely take 1.5 hrs. just to get to the front of the line, and another who-knows-what to rotate the tires and check pressure. I don’t have that kind of time and I certainly don’t want to hang out at Costco in my “spare” time.
I am getting elderly – I still have a compressor and a pressure gage, but due to ill health I haven’t worked on cars for a couple of years. I used to restore old cars.
So… my question. What is the danger in adding air to nitrogen-filled tires to restore pressure? Can it be done (like, are the valve-stems incompatible with my gauge and compressor chuck). Because of my health it’s a lot easier to write this question on the computer than it is to actually check this myself – sorry I sound lazy.
Thanks
Richard
Hi Richard,
filling up with regular air will only reduce the “purity” of nitorgen in your tires. i.e from 95% to worst case 78% Nitrogen. There is no danger to it and can be done with your regular equipment that you use to fill tires.
Richard, you’re gonna be OK. There is NO danger to adding ‘regular ol’ air’ to your “special” tires. No differences in stems, etc. You’re gonna be just fine.
However, you will lose a couple hundreths seconds off of your Laguna Seca lap times! Sorry dude!
OK so if oxygen diffuses thru the tire wall faster than Nitrogen, then assuming I fill with air initially and don’t have a flat tire, and just keep the pressure where it should be with air, (78% N2) , the tire will slowly become filled with pure nitrogen. If this takes a long time to happen, then all we are saying is that the oxygen doesn’t leak out very quickly. I fail to see any reason to put pure nitrogen in my tires, let alone pay for it.
I’m fairly sure that a lot of water vapor in tires is undesirable so there should be some benefit to using nitrogen or dry air to keep the water vapor low. As for the nitrogen itself, I think the gas in tires should naturally increase in nitrogen level over the life of the tire. Assuming the statements about nitrogen and oxygen diffusion are true, the oxygen part of the gas should leak out first leaving a higher than 78% portion of nitrogen. Every time the tire is brought up to pressure with air, the percentage of oxygen will be less than the previous filling. Eventually the tire should have a very high percentage of nitrogen. I think I have actually seen this happen as new tires seem to lose pressure more rapidly until they have been refilled several times.
I don’t know if anybody has already stated this.. because I didn’t want to read through every single comment, but I would like to say, there should be almost no difference at all..
This is because air, which is what we put into tires regularly is around 78% nitrogen.
Meaning putting nitrogen in your tires would only be increasing the percentage by what, 20%? It will not make a difference, and it is a scam. Some new way to make money, or else it would have been out years ago, and not just now as a fad.
well it has been out for years just not in the consumer market. the military and nasa have been using it for quite some time so i guess gps and cell phones are just a fad too because the military and nasa is where those fads started as well.
You’re creating logical fallacies to support an illogical conclusion.
There are reasons that the military and NASA use N2. They use equipment that is prone to sudden and drastic changes in altitude which affect temperature and pressure. Consumer automobiles do not experience these drastic or sudden changes (see previous comments).
So, to characterize an argument against N2 as a fad because the military and NASA use and pioneered GPS and cell phones that these aren’t simply “fads” is to either reveal ignorance or a lack of understanding how logical arguments work. What you’ve done is create a straw man argument since the argument against N2 isn’t that it is a “fad,” rather that it is too expensive to be taken seriously. If it were free or very close to it, then, and only then, would the cost/benefit ratio make enough sense to replace normal air from a compressor with pure N2.
Consumer automobiles simply don’t need this anymore than we need rocket fuel -both of which the military and NASA use in great quantity and, also, are not “fads.”
We have been in the tire business for 50 years and anybody thats dumb enough to pay to have nitrogen put in their tires deserves to lose the money they paid. I just want all their names so I can sell them air in a jug to breath. When your racing for millions you may want to try nitrogen for daily driving your just a fool!
Do you have a mouse in your pocket? I or we (my family) have been in the tire business since old henry put those affordable cars on the road, as I’m sure other american families. I wouldn’t listen to the num-nut idiots on this page. Make your own decision with facts and research from credible sources, fallacy of print, I use to put pure oxygen in the wagon’s going west until jesse james held up my station.
[…] but since it ended up being so lengthy, I decided to make a separate post. The original comment is here and was caught by the Akismet as spam. I’ve since approved it to be […]
Here is the third letter I’ve written Modern Tire Dealer magazine about this issue. Some of the editors supposedly wanted to publish the first one I wrote, but were over-ruled by the publisher. Too many advertiser make nitrogen generators. Two editors, one a managing editor, and the editor called me and I had lengthy conversations with both. In the end, the advertising big bucks won the day.
This was in response to their August ’09 issue in which they “re-visited” the nitrogen issue to see if their past claims “needed adjustment”. Needless to say, it was just a re-write of earlier articles praising the “benefits” of nitrogen. It was entitled “Analyzing the Benefits of Nitrogen Inflation”. Not the issue, but the “benefits”.
They no longer respond to my emails.
Here is my letter (text taken from MTD are in quotation marks):
MTD: “CLAIM: Tires hold their psi longer with nitrogen than air. This is true…”
But is the difference enough to be significant? The University of Bologna puts the loss at 1.6 vs. 3 % per month. In a tire that was originally inflated to 32 psi, this is .512 vs. .96 psi. Less than ½ lb.. Most air gauges won’t even read this. Consumer Reports says the loss is much less, .18 lbs. vs. .29 lbs. per month, from a starting point of 30 psi, if memory serves. .11 pounds. That’s “point eleven”. Eleven one-hundredths of one pound. (Getnitrogen obviously was not pleased, and tried to discredit CR’s findings by saying the tires were on a “test stand” and would therefore lose less air than tires being used. To MTD’s credit, they dismissed this theory. It has been my experience that tires being used, or run, lose less air than those that are not).
The claim is that nitrogen molecules are “larger” than oxygen molecules. In fact, they are-a mere 3% larger. According to what I’ve found, nitrogen molecules are approximately 300 picometers compared to oxygen molecules, which are 292 picometers. Thus, proponents of nitrogen would have you believe that the “pores” in tires are somehow magically kept below 300 pm, which would prevent the escape of nitrogen, but larger than 292 pm, which would allow for the escape of oxygen.
But, most damning of all, if what Getnitrogen and the rest of the proponents of nitrogen tell us is true, once a tire has lost approximately 22% of it’s original pressure and this pressure has been restored, this tire then has approximately 95% nitrogen, which is more than the 93% advocated. This holds true whether the tire is a passenger tire with 32 psi or a truck tire with 100 psi.
Even if some of the nitrogen does leak out with the oxygen, (which sort of defeats the purpose, doesn’t it?) after a couple of these loss-refill cycles, you would still end up with, well, what others are paying big bucks for, for free.
MTD: They wrote that the performance results at 96% were not substantially different than at 99.9%.
“This is important for the average consumer because the need to purge existing tires completely of air before filling with nitrogen may not be necessary,” they concluded.
(“Effects of Nitrogen Inflation on Tire Aging and Performance,” authors John Baldwin, David Bauer and Kevin Ellwood )
Translation: The machines that are supposed to produce 93% nitrogen may well produce somewhat less, and the technicians that are in a hurry to get to the break room are not going to purge your tires the required number of times. After all, who’s going to check for purity? And you’re going to wind up with something above 78% IF you’re lucky.
If the results at 96% were not substantially different than at 99.9%., would they be substantially different at 92% than at 96%? 89% than at 92%? What about at 78%?
MTD: CLAIM: “Properties of nitrogen minimize deterioration of rubber and tire cords.” If the purity of nitrogen in the tire is high enough, yes. In the Ford study, the authors concluded that “the oxidation of the steel-belt rubber is truly driven from the contained air pressure inside a normal passenger or light truck tire.”
Tires do not deteriorate from the inside. Just last month we pulled one off that was 15 years old, according to the DOT number. The outside had the worst weather cracking I’d ever seen. You could literally put a nickel in the cracks. The inside looked like new-shiny, black, supple. I’ve never seen a tire that has been mounted and maintained with any visible deterioration inside. If “the oxidation of the steel-belt rubber driven from the contained air pressure”, why is the inner liner so unaffected?
MTD: CLAIM: “For customers who drive a lot, nitrogen makes a big difference in their pocketbooks,” said McCune, who uses ready-made tools like fuel savings calculators on various Web sites, including http://www.getnitrogen.org). We checked out three such calculators, one from a supplier, one from a dealer and one from http://www.getnitrogen.org. We put in these numbers:
What in the world does this prove? You used three calculators from three sources, all three of which have a vested interest in the promotion of nitrogen.
The average fuel savings by using nitrogen, all things being equal, is about 3.3%, according to the Get Nitrogen Institute, http://www.fueleconomy.gov and a Canadian study of trucking fleets conducted by a nitrogen tire inflation equipment supplier.
MTD: “…according to the Get Nitrogen Institute.” “…conducted by a nitrogen tire inflation equipment supplier.”
Once again, MTD has relied on obviously biased sources to reach their conclusions.
I would also like to add that the air we breath is 78% nitrogen so the air inside the tires is pretty much 80/20 mix.
With all this talk about nitrgon in tires.
What would the problems be if I used Argon gas to inflate my tires.
Then I could use my Keg and fill my tires at the same time for very little extra cost, except a longer air line.
Another scam that you that you mentioned in this blog is the 3000 mile oil change. Most all service staions try to get you to change your oil at 3000 miles. However the owners manual usually always tells you to change your oil at 7500 miles. The service staions are selling you oil at a rate of 2-1/2 times more than is required.
[…] to try and talk my boss out of spending $10,000 on a Nitrogen filling system for our truck fleet. Nitrogen Filled Tires: a Scam? Posted on July 5, 2008 by cfeagans While this is primarily an anthropology and archaeology blog, […]
I just subscribed to your RSS feed, not sure if I did it accordingly though? Nice article by the way.
[…] but since it ended up being so lengthy, I decided to make a separate post. The original comment is here and was caught by the Akismet as spam. I’ve since approved it to be […]
[…] is an excellent link someone else had posted about this subject. Nitrogen Filled Tires: a Scam? Hot Cup of Joe __________________ Black pearl 2009 […]
Filled airliner tires with nitrogen for 35+ years but aircraft tires are recapped many times after the carcass is x rayed. The dust in the tires & the heat generated by takeoffs & landings plus the oxygen in the tire if filled by air makes for an explosive mix. Thus the use of nitrogen in aircraft tires. It also keeps the rubber interior form deteriorating so they can be recapped numerous times Auto tires don’t need nitrogen. No explosive mix the tread will wear out before the interior rubber deteriorates.
I’ve worked as an airline mechanic for 60 years. Most airline aircraft use nitrogen in their tires for several reasons. Less expansion when tire heated, especially during taxiing; less chance of an explosive blowout on a new tire (new tires out gas volatiles – the new tire smell- very explosive in the right environment such as a hot tire) because no oxygen present; no corrosion on the mag wheels due to the dry nitrogen; longer tire life due to no exposure to oxygen on the inner walls and less heating as mentioned earlier; tires need less frequent servicing. Race cars and military aircraft use nitrogen for many of the above reasons. I recommend every tire be filled with nitrogen.
Military aircraft should use nitrogen. But my 2009 Escape isn’t going to suddenly climb to 30,000 feet then back to sea level any time soon. I’ll save the money, regularly check my tires, and be happy. Should nitrogen become a free service at some point, I’ll gladly switch. But I’ve yet to notice any corrosion inside my tires. Even when I was in the military, I never noticed corrosion in the tires we used on small or large wheeled vehicles. And I used to change the rubber myself. And we used good, old-fashioned, air.
[…] discussion, in depth, on nitrogen filled tires. Draw your own conclusions, then decide. https://ahotcupofjoe.wordpress.com/20…-tires-a-scam/ My dealer automatically fills every car with Nitrogen, then charges a $39 fee upon delivery as a […]
I found this website through a search of nitrogen filled tires due to an ad in a local newspaper and I thought it was a scam plain and simple. Okay, maybe not a scam but the general public is being led to believe that nitrofill is a miracle product and the public is not being properly informed. The facts are that air is comprised of around 80 percent Nitrogen with the remaining 20 percent being oxygen and other miscellaneous items. Someone needs to convince me that driving to my local service station to top off my tires is more economical than using my air compressor at home.
I read one ad that stated loss of a $300 tire due to rusted rim is worth the $5 per fill – REALLY? I would like to know how many people have the problem with rusted rims. I would be willing to bet that very few (if any) people have problems with rusted rims being the cause of tire replacement. Normally tire replacement is due to tread or a hole in the tire. In some cases – primarily tractor trailers you have tires that develop weak spots and/or overheat and explode but that is not due to the 80% or 100% nitrogen or the 20% oxygen in the tire.
The problem comes in that if you are intelligent enough you can gather the appropriate facts/studies to state your case and you will be right. There will be people that will believe nitrofill is the way to go and in general once people make up their mind it is difficult to change their views.
There have been so many products (especially in the automotive industry) that have come and gone due to similar situations – the manufacturer pushes that it is the latest and greatest thing and people buy it. The manufacturer makes millions to billions and then the product is found to be another scam. In this case the tire manufacturers, dealers, service stations, etc will push it and in 5-10 years people will become informed and find out the costs far outweigh the benefits.
I loved your article. I recently found out that the county I live in pays to have nitrogen filled tires. I was researching the idea because it sounded like hooey to me. I appreciate that you took the time to write about it and was wondering if I could get permission to share a link to your article with a letter I am planning on posting to my local newspaper.
Thank you,
Jennifer
Sounds like a hoax to me. Even if it’s not, they’re more expensive and you can’t just go fill up your tire with air if it gets low. Costs outweigh the benefits.
I can fill your ass with hot air “no charge”.
I can fill your ass with hot nitrogen “$5.00”.
Thanks.
I filled tyre with Nitrogen and within a month its pressure came down. I got it refilled with Air to maintain correct tyre pressure.
Its expensive and useless. You keep on thinking that tyre pressure is getting maintained but actually it is not.
It is not readily available also.
I guess demeaning comments as supposed to pass as intelligent conversation. Thanks, I’ve had it with this uneducated group. As for all that think filling tires with nitrogen is a scam, I’ll keep my comments to myself. bye bye
What an interesting debate! I have questioned this N2 filling business for car tyres a few times and the usual answer was better tyre life and cooler running which didn’t make sense to me as N2 and O2 have the same Cp/Cv ratio, ie 1.4, so when the gas is being “worked” the temperature rise should be the same for both gases . As said, about four fifths of the gas in an air filled tyre is N2, the rest is O2 and traces of some other gases and water vapour. I really cannot believe that a tiny bit of water and about 20% O2 is really going to affect truck and car tyre life. The state of road surfaces, correct wheel alignment and tyre pressure certainly do.
N2 is usually a by- product of air separation (oxygen and argon production) and because an awfull lot of it is released back to the atmosphere, this is basically “wasting” about 80% of the air compressor power consumed pushing the atmospheric air into the air separation column. So if someone can be persuaded to fill tyres with N2 for a few bucks, the gas companies can recover some of their “losses” . I do accept the points made regarding aircraft and shuttle tyres but for car tyres??!
Now what a tyre mechanic said to me today made much more sense. He told me that N2 filled tyres are fitted with a valve cap which has a green marker band and the cap has a seal in it to assist the tyre valve keep the gas in the tyre. Air filled tyres are usually fitted with plastic non sealing caps which are there to simply keep out dirt. This I am sure is the principle reason the N2 filled tyres appear to hold their gas better than air filled tyres. I have just fitted 5 new wheels and tyres to my car and all the wheels do have metal caps with seals in them, so if I can keep my new tyres nail free, it will be very interesting to see for how long they hold their air charge.
I was always told that tyres get hot when incorrectly inflated for the load and so on long journeys especially, I often walk round the car to the tyres to see if they are “hot to the touch”. If they are warm, I am happy because when running at high speed, around 120km/h on hot roads, it tells me all is ok. When travelling at speed, the windage over the wheel/tyre is quickly removing any heat build-up providing there are no abnormalities .
A scam? I think it maybe!
I have used nitrogen our family tires since 2006. Our tires usually exceed the posted life by 10,000 miles or more. I rotate and keep an eye on inflation even using nitrogen which usually requires very little top off over tire life. I have a classic Ford 1956 f100 show truck that put new 3″ whitewall tires on in 9/08. The truck sits most of the time (like the consumer reports test did instead of using daily driven tires for a more accurate comparison) and finally in 7/2010 I decided to top off. The lowest psi was 3# loss and others 2# or less and spare still at 32# after almost 2 years. The whitewall tires are still white with no discolor. I have read that as air permeates through sidewall has some affect of turning whitewalls yellow.
I have a part time business that I do mostly during summer months is Nitrogen Tire Inflation at car cruises. I bought my own nitrogen tire inflation system and have about 2k invested..Yeah I drank the cool aid but it has paid for itself already and many times do the service for free for safety and feedback. The tire system will purge all 4 tires simultaneously twice then top off to recommended psi automatically in about 10 minutes. Most of the classic cars and motorcycles I have done and followed up on after a year still have same psi. The feedback from customers on how the handling improved is encouraging. I charge 20.00 for 4 tires and 10.00 on a motorcycle and give free top off for life of tire or they can have done at Costco or any other of the 50 plus dealers in the Portland area. The Harley dealer in town who promotes nitrogen charges $23.00, most car dealers charge $40.00 some do for free. Bikers have given almost 100% positive feedbacks on handling improvement. Another person who tracks his daily mileage drives 150 miles a day had an increase of 1.5 mpg. The tires were only about 2 weeks old and match same psi of air to nitrogen used.
Not all people have seen mile increases but some have exceeded tire life by 10k or more as well. There are some Nitrogen dealers charging as much as 50.00 per vehicle and think is ludicrous. Eventually nitrogen will be a free and a standard in tire inflation. Lance Armstrong and tour d France bikers use in their bikes so must have some merit. Some people spend 4$ or more on a bottle of water of cup of coffee each day which seems excessive too but choice is your own.
There are many truck fleets online that have done testing and have seen the advantage of nitrogen inflation. One company said a tire failure cost them about $500.00 since using nitrogen failures have ceased and tire life has increased 30%. Wal-Mart has tested and is converting their fleet because of tire life increase and tire failure decrease.
In conclusion these people are doing real live studies without all the science, windsocks and plumb bobs people use to down play the benefits of nitrogen tire inflation on paper. Proper tire inflation is paramount whether you use air or nitrogen. I will be starting a blog soon of people who have used with feedback positive or not.
The majority of the classic cars and motorcycles I check are usually underinflated by 10 pounds or more. Motorcycle riders had rode 300 miles on tires with less than 15#psi they should have around 38-40# psi kind of scary.
Millions of barrels of fuel are wasted each day due to underinflated tires or tyres in Europe.
Ok now check your tire psi especially the spare that will be usually severally underinflated.
[…] up yourself. Air is 78% nitrogen anyway. (Atmosphere of Earth – Wikipedia, the free encyclopedia) Nitrogen Filled Tires: a Scam? Hot Cup of Joe FYI. Any difference at all is completely and utterly negligible. Nobody at the track uses nitrogen […]
v ery interestng.i have one quesion,how many liters of oxygen or nitrogen will take the passenger tyre?
i need an answer.
thanks
very interesting issue
Well, maybe not a “scam” in the worst sense of the word, but it might be more accurate to say:
“the minimal, real-world benefits of having a nitrogen-rich mixture of gas in your tires on an average passenger car do not come close to outweighing the costs.”
I also go so far as to say that the claims made by those selling nitrogen to motorists are either terribly misinformed, or blatantly deceptive in their statements about the physical properties of nitro-filled tires (thermal expansion rates of nitrogen, pressure leak-down in tires over time, etc.) It just doesn’t stand up to basic scientific scrutiny. How’s that for intelligent discussion?
I made a video about this that helps lay out the facts visually too. You can find it here: http://TheGearHeadSkeptic.wordpress.com/2010/07/24/nitrogen-filled-tires/
For me, it comes down to this:
1) Nitrogen gas (even 100% pure N2) absolutely DOES expand and contract with heat changes, causing pressure changes in a sealed tire, just like any known diatomic gas. The PV=nRT gas law applies to Nitrogen gas just like any other gas, and its thermal expansion properties don’t differ from Oxygen gas in any real way outside a closely controlled lab. Any high school physics text will confirm this (look up Van der Waal’s Equation for details).
2) It’s the water vapour contamination in compressed air that contributes more to thermally driven pressure changes than the physical properties of the gas(es), but this is seldom talked about. Nitrogen in a tank is an engineered product and is free of water vapour, but this will only be of benefit to you if you had high water vapour in your tires to begin with! If you live in an area with high humidity, ensure the air compressor that fills you tires has an in-line dryer, and this is a non-issue.
3) Nitrogen “filled” tires do not contain pure nitrogen; they are at best 95% N2. Atmospheric air is 78% N2. Does this not defeat the “no oxygen inside the tire to attack the rubber and rims” fallacy right out of the gate?
4) O2 does in fact migrate through a tire wall faster than N2, but that leaves a higher concentration of N2 inside the tire – exactly what they want you to pay for! Top up your tires with air a few times, and you will have a nitrogen rich gas mix inside for free.
5) Aerospace and racing applications use Nitrogen. This is true, but we must ask WHY they do. Racing wheels are often made of magnesium for ultra light weight but magnesium is highly reactive to oxygen under the right conditions. Reducing the oxygen in the tires would help guard against and explosive reaction. No passenger car has magnesium wheels. None (and if you call your aftermarket wheels “mags” and think they are actually made of magnesium, you are mistaken). Aerospace applications may also use magnesium wheels for weight, I don’t know, but both would find the low water vapour content of N2 gas a benefit due to the extreme temperature changes their tires undergo. No passenger tire would go through that range of temperature changes. None. The “NASA and NASCAR use it, so it must be good” argument falls apart.
If you would like to present a facts-based rebuttal (that does not begin with “I’ve been a [insert random technical profession] for [insert random number] years and I think…”) and addresses those points, I’m all ears and would be happy to learn something new and change my mind if your argument is compelling and factual.
Good on ya for exposing the reality of this newest scam.
The benefits of Nitrogen filled tires are so minimal over the life of a normal tire, that the expense and inconvenience are no where near the payoff if indeed there actually is a payoff from Nitrogen in tires.
What a scam
Thanks for addressing it
My personal experience with nitrogen has been positive. I currently have a set of Uniroyal Liberators on my Sport Trac. The tires are rated for 50000 miles and I currently have 55000 on them with half the tread life left. I’m saving a lot of money by not having to replace these tires. Scam….I think not….good for the environment and good for my pocket book….that’s a WIN-WIN to my thinking.
I get similar results with the tires on my Saturn. And I only use the air from my $5.00 compressor from Walmart. And, since I’m not reliant on the energy required to separate nitrogen from normal atmosphere, I’m actually greener than Billy O, saving more $$$ in the process. I’m not buying it. Nitrogen for consumer automobile tires is a flat out scam.
Personal experiences are not testable data. There are any number of reasons why your tires may have lasted so long, mostly to do with your driving style and maintenance routines, not what gas is inside them.
The plural of “anecdote” is not “data”.
Wow….a completely waste of time this blog entry….The motor
sport racing industry has been spedning billions each year on
N2 filled tyres and believe me, they do their research before
spending that kind of money. N2 is better than plain old air for
tyres.
No arguement. It’s science.
Filling tires with nitrogen is such a scam. Next they are going to sell us helium filled tires so our cars are lighter and will therefore get better gas mileage…
They were trying to take the same route as bottled water: Why not find a way to charge for something that people could easily get for free?
if my nitrogen tire has to be replace,can it be replaced with any tire?Why did my son in law have to replace with a matching tire worth $600 on his Ford product?
I just purchased a new Nissan with N2 in the tires. Total cost for this “Lifetime” service was $145. Since it was a dealer add-on I just subtracted it from the price I was willing to pay for the car. In all, I don’t think there is a major benefit and would not go out and refill my other car tires with N2, but I don’t have a problem going to the dealership if the new car gets low. I don’t own an air compressor, so it’s cheaper than paying $.75 for air at the gas station.
I was looking at new Hyundai cars and the local dealership has added a few items to inflate his profits. One of the items was a $200.00 charge for filling the tires with Nitrogen. I was under the impression that most tire dealers will do it for $5 to $10 a tire. Does it actually cost the dealership anything to change the tires from air to nitrogen? Plus, the car dealership will charge a nominal fee to maintain the proper inflation pressure. As far as nitrogen prolonging the life of a tire, I think the treadwear will remain about the same regardless of what you fill the tire with. I have yet to have a tire destroyed by oxygen before the tread is worn out. So what’s the point of paying to put nitrogen in your tires? They are still going to wear out in the same amount of time. Do you actually believe the tire industry is going to do anything to make tires last longer than they already do? They’re in business to sell tires, not make them last forever.
I have the ability to monitor my tire presure while riding my Gold Wing motorcycle. When checking air in your tires you have to do it when the tire is cold. Once riding a motorcycle it doesn’t take long for the air pressure to climb 10-12 psi above the cold tire temperature. The pressure does not rise as dramatically while using nitrogen. Another reason to support the use of nitrogen is that there is no moisture in nitrogen while non of the commercial compressors are moisture free. If you fill air at a gas station check the air coming out of the compressor before placing it on your valve stem and you will see water vapor. Moisture inside your tires undergoing wide range of temperatures affects the life of the tire. The tire may look fine on the outside but is breaking down on the inside. For motorcycles, NASCAR and military applications the moisture free nitrogen is the way to go. If you are on a trip and you need to top off your tire pressue go ahead and use air. A few lbs of air will not add enough moisture to be of concern.
If oxidation is a problem, The oxygen will soon be over inside the tyre after oxidation of a thin layer. We have to calculate and find out how much tyre is oxidized. OK!, then what is left inside is just some water vapor and nitrogen!!!!.
if you cant dazzle them with brilliance baffle them with nitrogen,the chance of you getting a high percentage in your tire is slim to none,on race tires we would purge them 4 times,but on race cars it has a purpose,in street cars its down rite dangerous,when you load your vehicle and get on the highway air pressure builds this increases load capacity and high speed stability.exactly what you need,i would not allow a family member or friend to use nitrogen i would educate them on the safety of proper tire maintenance
But now we have a new problem. Why are you wasting your money and polluting the environment by changing your oil every 3,000 miles???? http://www.edmunds.com/car-care/stop-changing-your-oil.html
I think its true that oil change services are designed to make money -which is why I change my own, usually about every 4,000-5,000 miles. But I don’t worry about the environment. My oil gets recycled.