Nitrogen vs. regular air in tires

[GunniPWguy]

Other than it costs more and you get green valve stem caps, Is there really any difference? I have heard different things such as better pressure regulation, tires last longer, less rolling resistance. Seems like a "snake oil" kind of thing to me. Anyone else have any opinions one way or another?

[GunniPWguy]

Here's the "snake oil". The homogenous mixture known as air is only about 78% nitrogen, 16% Oxygen, and the rest mostly methane, helium, hydrogen, and carbon dioxide. It has a greater coefficient of expansion than pure nitrogen due to the intermolecular forces of the various gases that are not inert (most everything but nitrogen). Nitrogen is fairly inert and has no dipole, and is therefore an better approximate of "perfect gas". Basically, pure N2 expands/contracts less in response to temperature changes, so you get more consistent tire pressures, which decrease rolling resistance because you can properly fill them (no change upon heating/cooling). It makes the biggest difference for people who drive a lot at high speeds, and has been practiced in the racing, law enforcement, and highway transportation industries for several years.

[coder]

For a street vehicle I think there is a small value, I air my tire down when off roading then pump them back up with air, so there's no value for me.

[2wagons1driveway]

It's snake oil. The value over a year would probably still drop 5-10lbs in a bigger tire probably the same as just air


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[Ducky's Dad]

Nitrogen is inert, so no internal oxidation. Nitrogen has no oxygen or hydrogen, so no moisture in the tires (H2O). Nitrogen molecules are bigger than most of the molecules in ambient air, so less leakage through the sidewalls. Nitrogen does not expand as much as air so less pressure change as the tires heat and cool. Nitrogen is a great deal, if your tire shop does it for free or if you never air down. If you are paying out-of-pocket for the nitrogen, it's not worth it. It's not snake oil but it's also not going to pay for itself if you are not getting it free.

[Cactus Red]

I used a scuba tank sized bottle of nitrogen as an OBA system on the rock crawler. It would refill roughly 12 tires from 8 to 25 PSI at a cost of $18.00 per tank. I was trying it as a replacement for CO2 to avoid the frozen regulator and hose. That didn't last long due to the cost, and I put the old 20 lb CO2 tank back on.

Anyway, it's no better than air IMO....

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[2wagons1driveway]

Nitrogen is inert, so no internal oxidation. Nitrogen has no oxygen or hydrogen, so no moisture in the tires (H2O). Nitrogen molecules are bigger than most of the molecules in ambient air, so less leakage through the sidewalls. Nitrogen does not expand as much as air so less pressure change as the tires heat and cool. Nitrogen is a great deal, if your tire shop does it for free or if you never air down. If you are paying out-of-pocket for the nitrogen, it's not worth it. It's not snake oil but it's also not going to pay for itself if you are not getting it free.

I think if it's free. It's not 100% nitro. If it comes from a sealed tank and not a filter style machine it may be worth it like you said if you never air down. Etc. given the huge popularity of it at dealers for economical self maintaining nitro the use of "nitrogen purifier or air purifier" that converts regular shop air to nitro is snake oil. I'm guessing if it did work the filter would need to be changed regularily and I'm guessing most shops don't do that. I know from a nitro machine at our work had a Schrader test port on the side of it. and some schmuck in a "nitro 2000" shirt would come and "test it" monthly and one day I hit the Schrader that he always used and there was no pressure from it not nitro not air......lol just no pressure. Now that's snake oil. But if your buying a bottle like a welder would require that's the real deal. I believe the science behind it.


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[Ducky's Dad]

I think all Costco tire centers now have nitrogen generators, with a very large gray tank, green label as I recall. I didn't read the tank last time I went by there, but the tank is probably 300 gallons or more. They fill a lot of tires every day, and I think they have to generate their own gas. As for me, I have perfected generating my own gas, but that's another story. The best tire store chain in our area is America's Tire (known as Discount Tire in other states) and they don't use it. Some of the boutique garages that cater to the carriage trade use nitrogen, but most shops don't bother. Nitrogen is good for the average non-car-guy driver who lets the shop fill his tires and doesn't worry about pressure between service visits, because it maintains pressure over time better than air does. I would not be surprised if the CA or federal government isn't working on plans to make nitrogen mandatory for tire stores. After all, these are the same clowns who forced TPMS on us.

[2wagons1driveway]

Tpms-sucks. BMW has the best system they use in Canada and Europe. It's called ftm. It's flat tire monitor. Measures tie circumference. Not pressure. The driver an choose to reset it. At any pressure. If a lose of approx 30 percent is seen. Generally that's what 8lbs on a 35psi tire. The lamp illuminates. Want to reset it at 15lbs. Done. It will go off when your tire is very flat. Lol


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[nts007]

I had a 70cube tank of nitrogen mounted in my pw. I would do it again in a heartbeat. It never seemed to run out of air. In over a year I never refilled it. And I ran an air nailer on it for 2 days and aird my tires up twice a weekend. There is a lot of nitrogen in those tanks. very high pressure though. 3000psi or more I can't remember right now. It's on my wish list to do again. Yes it was securely bolted down with zero movement. Was $80 to fill and I paid $5 a month to have it. When empty just roll it off at welders supply and get a new one. I did notice the air on the nailer was dry with no moisture. And the recovery rate on the nailer is instant. As far as if it makes a difference in the tires I could care less

[Bill2014]

Okay - there are some VERY insignificant benefits from using nitrogen vs air.

Let's get real:

Most of the water is eliminated with nitrogen - so rust or corrosion from the moisture on the inside of the wheel is eliminated. When is the last time you had to throw out a wheel because of rust or corrosion on the inside? Answer: never

Nitrogen will leak "through" the typical tire about 33% slower than air. I have found that my air filled tires (without any bead leaks) lose about 1 psi per month. So my tires with 65 psi air, drop down to 62 psi three months later. If I had them filled with nitrogen, they would only have dropped down to 63 psi. Who really cares if the pressure is 63 psi or 62 psi after three months. Most of our tire gauges aren't even accurate enough to measure that difference.

For the most part the Nitrogen is a gimmick. Come buy your tires from us - we use Nitrogen and Nitrogen is better.

As for TPMS, I check my TPMS readings neary every time I take the truck out. I wouldn't have bought the truck if it didn't have TPMS sensors. I check my TPMS readings in my car the same way. Last week I noticed that one of my car tires was down 5 pounds when I got home from work. I got out and looked at the tire and it appeared to be normal. I felt around and found a screw in the tread of the tire. I drove down the street to the garage and had them put a plug in the tire. The TPMS saved me from waking up with a flat tire that I would have had to change.

It's not the TPMS that people dislike, it's the fixed pressure alarms that people can't adjust - that's the problem!

[2wagons1driveway]

Has to be a fix in the sensor for that. Just a different resistor in there to simulate the frequency of 60lbs lol. With a car I can see the Benifits ftm or tpms. With a 37" tire if it has a significant leak. You'll knowthat being said even a slow leak your still going to be able to drive on that big ass sidewall with 15lbs in it on the highway and make it home to patch it.


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[RustyPW]

My take on nitrogen. If you have a race car and looking for the Nth degree of performance. Then it's worth it. For Daily, not so much. Because most people who use nitrogen in their tire don't get all of the air out. So they have a mixture in there. It's not pure nitrogen. To get pure nitrogen in the tire. The tire shop will have to use nitrogen powered tire changers. From the first blast of pressure into to tire to the final airing up at the shop. Has to be with nitrogen. Mounting the tire to the rim should be done in a nitrogen fill chamber. That's the only way to get pure nitrogen into the tire. If some time down the road. You have a low tire and stop someplace to fill it up. The only thing you can get is air to use. You just lost all of the benifits of nitrogen.

[Ducky's Dad]

From what I have read, the commercial size nitrogen generators can produce between 95% and 99point-something% pure nitrogen, and are adjustable within that range. The "standard" acceptable fill is 95% or better actual nitrogen in the tire. Don't remember who sets the standard, but if the target is 95%, then the air in the casing before filling with pressurized nitrogen seems to be a non-issue. If I find it for free, I'll use it, otherwise can't be bothered on my street vehicles.

And I still don't like TPMS.

[adeluca73]

It's mostly hokum. The enemy to air in tires is water vapor entrained in the tires by using unfiltered compressors w/o an in-line dryer. It's the water vapor which plays havoc with your pressure as temperature changes. Water vapor has an atomic weight of 18, while Oxygen & Nitrogen have weights of 32 & 28 respectively, hence since its lighter, it will displace air molecules, decreasing its density, & using the ideal gas law, it's pressure as well. The elemental oxygen & hydrogen DONT form water in your tire. In air, their composition is diatomic. & therefore atomically unable to form water. Nitrogen is an element, with a diatomic weight of 28g/mil, while air is a molecule, w/ an atomic weight of about 29g/mol, of which, 22g/mol of it is diatonic Nitrogen, & 6g/mol is diatomic oxygen.

Most of the temp/pressure discussion & the positive attributes of running pure Nitrogen are actually incorrectly attributed to the near inert properties N2 possess. The variations in temp/pressure are more directly related to water vapor in the tire, not running pure N2. The same benefits ascribed to running pure N2 will be realized by filling with filtered & dry air. Realizing the inert benefits of N2 is only possible if the tires are completely evacuated & dried, & all metal surfaces are similarly treated, & then filled in a humidity controlled environment, & can only be check in humid free environment, & can only ever have pure N2 added if ever low.
Again, there is some technical merit, but it's mostly gimmick. Your best, cheapest, & most practical path is to find someone with a well regulated air supply.

[GunniPWguy]

Wow! Didn't realize there were so many scientists here! Good info. Thanks for the replies. No free nitro here so I think I will just ask for the green valve stem caps instead! lol