Nitrogen vs Air: your thoughts

[Steve A]

I just put on 4 Nitto Terra Grapplers and had the opportunity to have either nitrogen or air in the tires to inflate them. I went with air because I did not know if there were any advantages to having nitrogen in the tires.

I have since done some research and have found that nitrogen is a viable replacement for the air in the tires. I can take it back to the shop in town to have them replace the air with nitrogen at 10 bucks a tire. (they will only do it for new tires)

Has anyone else run nitrogen in their tires and if so what were your thoughts?

Steve

 

[Bartonmd]

Well, I guess we probably haven't settled this (or driven it into the ground) on this new site yet, so might as well...

nitrogen molicules are quite a bit larger than oxygen and CO2, so instead of 1PSI/month, they maybe drop 1PSI/2 months...

Nitrogen doesn't contain moisture (because it's from a bottle, not an air compressor), and is very pressure stable over temperature ranges. This is actually kind of a big deal if you're racing, but no big deal, otherwise.

Since the nitrogen leaks out slower than O2 and CO2, and air is ~70% nitrogen, you'll end up with a much higher percentage of nitrogen in the tire, anyway, over time...

In short, it's a good thing if they do it for free when you get your tires, but unless you're racing a car on a track or something, it's in no way worth paying anything for.

Mike

 

[SBUBandit]

The theory is Nitrogen is heavier and won't leak out quite as tiny a hole as normal air. Not sure how proven it is, but you can always see cars with new tires that have the green valve stem caps, those are nitrogen. personally, I go with air, for one pretty simple reason. i don't have my own nitrogen pump, but i do have an air compressor. If I have a low tire, I'd like to be able to pump it up without running to town.

 

[4wVoy]

I agree, unless you are going to be going through heat cycles consistently with your tires then just leave air in there. I have put nitrogen in my motorcycle tires for track riding. If anything, you would be deflating your tires of pressure for off road and would be wasteful IMO. Just stick with air.

 

[Me007gold]

The theory is Nitrogen is heavier and won't leak out quite as tiny a hole as normal air. Not sure how proven it is, but you can always see cars with new tires that have the green valve stem caps, those are nitrogen. personally, I go with air, for one pretty simple reason. i don't have my own nitrogen pump, but i do have an air compressor. If I have a low tire, I'd like to be able to pump it up without running to town.

You can add Air to a tire that has Nitrogen, its not going to effect anything.

 

[SBUBandit]

You can add Air to a tire that has Nitrogen, its not going to effect anything.

Except that now you have air in your tires instead of the nitrogen. In that case, just skip a few steps and start with air to begin with

The whole Nitrogen thing is a bit of a snake oil thing anyways for most street vehicles.

 

[The_Roadie]

The whole Nitrogen thing is a bit of a snake oil thing anyways ....

I concluded that after doing the math on the physics of the claimed benefits. Then I was totally convinced when I read some ads and an article in a tire store management magazine that they left lying around when I was getting some tires balanced. Basically it was: Here's a GREAT NEW PROFIT CENTER we've just invented for you to rip the customers off with. Just buy our magic machine and charge them whatever you can get away with. If your customers balk at $10 a tire, try $8, or $6. It doesn't matter WHAT you charge them, it's ALL PROFIT!!!!! WHEEEE!!!!!!!

 

[Steve A]

I concluded that after doing the math on the physics of the claimed benefits. Then I was totally convinced when I read some ads and an article in a tire store management magazine that they left lying around when I was getting some tires balanced. Basically it was: Here's a GREAT NEW PROFIT CENTER we've just invented for you to rip the customers off with. Just buy our magic machine and charge them whatever you can get away with. If your customers balk at $10 a tire, try $8, or $6. It doesn't matter WHAT you charge them, it's ALL PROFIT!!!!! WHEEEE!!!!!!!

Bill,

You always have a way of shining the light on a topic to make it so much easier to see! LOL

Steve

 

[Wyle]

I concluded that after doing the math on the physics of the claimed benefits. Then I was totally convinced when I read some ads and an article in a tire store management magazine that they left lying around when I was getting some tires balanced. Basically it was: Here's a GREAT NEW PROFIT CENTER we've just invented for you to rip the customers off with. Just buy our magic machine and charge them whatever you can get away with. If your customers balk at $10 a tire, try $8, or $6. It doesn't matter WHAT you charge them, it's ALL PROFIT!!!!! WHEEEE!!!!!!!

Since the nitrogen leaks out slower than O2 and CO2, and air is ~70% nitrogen, ...

No, I'm sorry. We must charge $10 a tire for pure nitrogen. We do however, offer a 70% nitrogen mixture for $7 a tire.

Now THATS marketing.

 

[djthumper]

So to add to it, don't waste you money on that nitrogen compressor either.

 

[Mark20]

It probably only pays to use nitrogen if you can borrow a system from work. We have plenty of shop air where I work but no nitrogen source. Guess I'll stock with good 'ol air.

 

[gmcman]

unless you are going to be going through heat cycles consistently with your tires then just leave air in there. I have put nitrogen in my motorcycle tires for track riding. Just stick with air.

Yeah, that's really the main reason, nitrogen reacts less as far as pressure changes when the temps change. Nitrogen is mainly used in aircraft tires due to the drastic temp changes at altitude.

 

[Mark20]

Yeah, that's really the main reason, nitrogen reacts less as far as pressure changes when the temps change. Nitrogen is mainly used in aircraft tires due to the drastic temp changes at altitude.

And from ambient. Somewhere I read they'll hit 150F from the takeoff run.

 

[gmcman]

And from ambient. Somewhere I read they'll hit 150F from the takeoff run.

Wow....did not know that.

 

[MacMan]

We use nitrogen in our race tires SOMETIMES. Yes, the nitrogen molecules are bigger, and won't seep out as fast, and yes, it doesn't change in pressure as much as tire temps go up (that's the ONLY reason we use it).

But as has been mentioned above, pure air is already about 70% nitrogen, so it's use/benefits in passenger car or light trucks is, at best, non-existant, and at worst, is just another money making scheme by dealers/tire shops/garages.

 

[Chickenhawk]

Actually, air is 78% nitrogen.

Nitrogen-filled tires are 100% bullshit; 0% science. This is one of the biggest jokes played on unsuspecting consumers in recent memory.

They have applications in race tires and aircraft tires but it is nothing to do with less "leak-ability." Seriously, do any of these dealers who maintain that the "bigger nitrogen molecules are less likely to leak" even KNOW how big a molecule really is?

I may have slept through most of high school physics but even I know that, saying a larger molecule is less likely to leak through a rim leak or tire hole than a smaller molecule is like saying a 10 big guys are more likely to fill up the Grand Canyon than 10 skinny guys.

An oxygen molecule is only 3% smaller than a nitrogen molecule, and air is only 21% oxygen by volume. Plus, the "nitrogen" they use to fill tires is about 95% nitrogen, so consider the actual difference in molecular size to be infinitesimally small.

Now consider an area the size of the period at the end of this sentence can contain between one million and ten million molecules.

If someone wants extra molecules to help slow leaks, here are some for them ...

Here's some more ...

(Let me know if they run out and I'll give them some more.)

My periods in those sentences above are just as likely to resist slow leaks as the air they sell as "nitrogen" by dealers trying for every profit they can from unknowledgeable consumers.

(Seriously, if nitrogen was less likely to leak through tires, wouldn't one simply have to add air, wait for a few months for all the "smaller" oxygen molecules to leak out, and be at that same 95% nitrogen figure ... for FREE?)

There are NEVER been a single, documented, scientific, double-blind, independent test that has ever proved that nitrogen has the slightest benefit in automotive street tires.

Even Consumer Reports found no statistical difference between 31 pairs of test tires; 1 of each pair filled with air and 1 filled with nitrogen, after ONE YEAR. The leakage difference was so slight that it would have been below the readable accuracy of most consumer tire gauges.

 

[Chickenhawk]

And, just to add to the debate, based on further research, I see the players who sell nitrogen equipment to dealers are even faking their studies:
Nitrogen in Tires : Information about Nitrogen Tire Inflation News, Benefits, Generator Dealers, Location Finder & More
If you click on the supposed double-blind scientific government test on fleet tires by "Transport Canada," you will note that Transport Canada did NO SUCH TEST. The link takes you to a test performed by the Drexan Corporation of B.C. who SELL compressed gas equipment to truck fleets ... and if you read the test, you will note that it was in no way a double-blind test and didn't factor in most of the fleet running air in winter and had switched to nitrogen by the time summer rolled around.

This highly unethical and faked "tests" are simply an indication of the sliminess of these snake oil sales people.

 

[The_Roadie]

Somewhere I read they'll hit 150F from the takeoff run.

I was on a very heavy DC10 once leaving Honolulu for DFW, and the wind shifted. Instead of taxiing out to the reef runway's west and end taking off to the east, we had to taxi about three miles to get to the east end of the runway and take off to the west. The pilot advised us that because of the extended at-weight taxi, that sidewall FLEX was going to heat up the tires to the max allowed temp at the start of the takeoff roll, and that they got hotter still during the run. So he was going to delay gear retraction a portion of a minute to allow airflow after takeoff to cool them before getting them up in the wells. I talked to him after landing (as a private pilot I love to talk to them) and he said the heated tires expand quite a bit when the weight is off, and he doesn't like the risk of retracting them while they're at max size.

(Seriously, if nitrogen was less likely to leak through tires, wouldn't one simply have to add air, wait for a few months for all the "smaller" oxygen molecules to leak out, and be at that same 95% nitrogen figure ... for FREE?)

A point I was about to make. I like the way you think, comrade!

I think the only POSSIBLE rationalization that has any physics behind it is that shop air isn't dried, and that water vapor (assuming that tire store nitrogen is dried) adds more pressure per degree Kelvin as temperature goes up than gasses do. Gay-Lussac's law and the universal PV=nRT demand certain behaviors out of gasses. Nitrogen, Oxygen, CO2, etc - are not "ideal" gasses as mentioned in the various Gas Laws, but they're pretty damned close, and none of them exerts MORE pressure than the others as temperature goes up. And who CARES if a tire's pressure goes up as its temperature does? Tires have been doing this since there have been tires, and their performance is pretty well understood.

 

[Chickenhawk]

Exactly!

If the local garage isn't keeping moisture out of their air compressors and changing the filters regularly, what would make us think they are suddenly going to do that with their nitrogen generators?

There is zero documented benefit of nitrogen over good, filtered and dried shop air.

Aircraft tires use nitrogen because of the extra stability at the extremes of temps that those tires run at, as you point out, but unless your tires are going to change 200 degrees in a few seconds like an aircraft (or race car) tire, the benefits are minimal to non-existent.

Aircraft also use nitrogen because it can be manufactured as an inert gas. This means that if there was an onboard fire and a tire were to explode, compressed air would feed nearby flames and increase combustion. Nitrogen-filled tires that burst would tend to decrease or extinguish nearby combustion. I may not remember everything from flight school, but I do remember that fire + aircraft = bad.

(I am sure Roadie will remember being told another important lesson that I remember from flight school: the three most useless things in the world are runway behind you, altitude above you and fuel still in the fuel truck.)

 

[Mark20]

The dealer filled my wife's new Hyundai Accent with Nitrogen. Since it was cold and raining they did the new vehicle demo in the shop and right by the car were two gas cylinder carts with nitrogen. The cylinders were the standard 200 lb gas tanks with a somewhat fancy fill system (did not get a chance to examine it too closely ). I'll assume the nitrogen in those is reasonably dry from the fill company. They also put green caps on the tires (as was on my camper when I got it - hmmmm they never talked about nitrogen). I like the green caps since you can find them when you put them down.

The shop air spigots at work have dryers in them. Does that give what would be considered dry air?

I did a lot of aviation studies while in high school but never got my pilots license. Got to know a lot for a private pilots license and that amount of knowledge only goes up as the aircraft get bigger.

 

[The_Roadie]

(I am sure Roadie will remember being told another important lesson that I remember from flight school: the three most useless things in the world are runway behind you, altitude above you and fuel still in the fuel truck.)

Yep, and "Better to be on the ground WISHING you were in the air than the other way around."

 

[Chickenhawk]

I was taking a brand-new Cessna 172 for a quick flight test one afternoon. As I pulled to a stop at the taxiway that intersected the runway at the halfway point, here is the conversation:

Tower: "Cessna Golf Uniform Kilo Yankee, you can backtrack the runway from that intersection or you can take off from there. For your information sir, you have 4200 feet of runway from the intersection."

Chickenhawk: "Thank you sir. I will backtrack."

Tower: "Copy that. Kilo Yankee, you are cleared to backtrack at your discretion."

Two minutes later, with an 8000 feet of runway in front of me and a takeoff roll of about 800 feet ahead of me and not the slightest hint of sarcasm from the tower controllers.

Tower: "Kilo Yankee, cleared for takeoff."

Chickenhawk: "Cleared for takeoff, Kilo Yankee."

Less than twenty seconds later, after reaching an altitude of about 100 feet: KaBOOOOMMMM!!!

Chickenhawk: "Kilo Yankee landing!"

Tower: "Copy your are landing Kilo Yankee. What is the nature of your emergency?"

Chickenhawk: "Ah ... it appears the windshield just failed ... (unintelligible)"

Tower: "Land at your discretion sir." (Easy to say with two thousand feet of long glorious pavement STILL in front of me.)

Chickenhawk: "Uh, I will need clearance back to the shop and a change of shorts."

Tower: "Copy that Kilo Yankee. Changing your shorts."

New windscreen = $1500 (under warranty)
New shorts = $9.99 on sale at Sears
A personal policy to NEVER accept an intersection takeoff = priceless

 

[harmless]

Just to fan the flames of idiocity a little more...

I wanna start selling HELIUM filled tires. Those stem caps will be purple.

The marketing theory behind it is this:

The helium, in all four tires will make the vehicle lighter, therefore increasing fuel mileage and lowering road/wind resistance.

If you srping a leak or have an emergency, all you gotta do is mug the nearest kid with a balloon.

Anyone want to put some capital forward for this venture? :wootwoot:

 

[gmcman]

I don't know at what point helium becomes equal or more dense than air but I'm guessing it's much less than 35 psi

 

[SBUBandit]

Might as well go all out and go straight for Hydrogen. Can you say HindenBlazer?

 

[MichEnvoyGuy]

Might as well go all out and go straight for Hydrogen. Can you say HindenBlazer?

BWAHHAHAHHAHAHA!!!

 

[The_Roadie]

I don't know at what point helium becomes equal or more dense than air but I'm guessing it's much less than 35 psi

Interesting point. The math is relatively easy, if I'm remembering correctly with a bit of Google assistance. Helium is around 7 times less dense than air. So you would have to compress it to about 7 ATM (atmospheres) of pressure to get the density to equal normal air at sea level, uncompressed. Sea level 1 ATM = around 15 PSI, so the density crossover point is around 100 PSI. 35 PSI Helium would be still less dense than air, and would give a bit of buoyancy. How many ounces of buoyancy depends on the size/volume of the tire and is left as an exercise for the student. Hint: Volume of a torus is = 2pi^2Rr^2 Torus - Wikipedia, the free encyclopedia

 

[Steve A]

How many ounces of buoyancy depends on the size/volume of the tire and is left as an exercise for the student. Hint: Volume of a torus is = 2pi^2Rr^2 Torus - Wikipedia, the free encyclopedia

Good thing I failed english back in high school, cause I have no idea what those words mean... Let alone the math, which I unfortunatly didnt do too well in either...

Steve

 

[Jkust]

...or just look down at your TPMS and refill as needed. If in a bind, the onboard compressor will do the trick.

 

[harmless]

Don't forget to put Helium in the spare! That'll change the dynamics too!!!


HindenBlazer!

 

[RayVoy]

Might as well go all out and go straight for Hydrogen. Can you say HindenBlazer?

To get the hydrogen, we could fill the tires with water, after a few months, the oxygen would leak out, leaving nothing but hydrogen, hmmm, I think it will work.

 

[blazinlow89]

Don't forget to put Helium in the spare! That'll change the dynamics too!!!


HindenBlazer!

Hydrogen

But it's is still funny.

I like the HindenPeter better.

Nitrogen is the only thing approved for A/C, you be amazed at how much we can through. Not sure about what kind of contraption they use for air transfer, we have what basically amounts to a fancy inflator that screws on with a large pressure gauge. Then again we put about 150-200 PSI in your average tire, and some other things can require over 3000 PSI.

 

[kardain]

Or......

Just wait for this.

 

[blazinlow89]

The tweel.

 

[harmless]

I have FOUND the solution.

Goodyear's RSA Runflats.

 

[blazinlow89]

Kicking it OG

 

[The_Roadie]

To get the hydrogen, we could fill the tires with water, after a few months, the oxygen would leak out, leaving nothing but hydrogen, hmmm, I think it will work.

Capture the oxygen, tap into the hydrogen, feed it to your intake and run the engine on TIRE HHO! I think we're onto something in the GMTN Phractured Physics Phorum!

 

[harmless]

Capture the oxygen, tap into the hydrogen, feed it to your intake and run the engine on TIRE HHO! I think we're onto something in the GMTN Phractured Physics Phorum!

Wouldn't popcorn and pixie farts be more attainable as a fuel source?

 

[The_Roadie]

Wouldn't popcorn and pixie farts be more attainable as a fuel source?

Pixie farts are not CARB-approved for use in California, even though we are the largest exporter of them. Damn CARB (California Air Resources Board) won't let us have any of the fun stuff. All you can buy at the local Costco is compressed rooster poot, and that only contains 17% of the energy by volume. Sigh...

 

[harmless]

Pixie farts are not CARB-approved for use in California, even though we are the largest exporter of them. Damn CARB (California Air Resources Board) won't let us have any of the fun stuff. All you can buy at the local Costco is compressed rooster poot, and that only contains 17% of the energy by volume. Sigh...

I am the Governator.

I approve of that message. Mainly because I probably blindly signed off on it at some point in time.