Nitrogen Tires

[David Ragan]

What the deal with Nitrogen tires on wifes new Honda Pilot?

Less oxidation to the innerds of the tire?

How do you air up if needed?

Necessary for on-board pressure detection?

[Kent A Bathurst]

supposed to not expand/contract as much with temp changes, hence less overall issues with refilling/topping off.

tires stores have the nitro.

[Gordon Eyre]

I have been using it for years and rarely have to top off. Most tire store like Big O, etc. will have nitrogen. You usually have green valve caps on and tire stores recognize this as being pressured with nitrogen.

[Mike Lassiter]

another reason is nitrogen molecule is suppose to be slightly bigger than "air" molecule and cannot seep out as easily. I'm not sure I can agree with that (based on opinion only) in a class over the years someone stated that tires are porous. There is space between the rubber molecules that air can seep through. It's sounds feasible (I guess) but I have never researched it to see it that is accurate and factual or someone's opinion. With "air" also containing nitrogen but not 100% not sure myself what I believe.
I know if nitrogen is put in tires they are suppose to have a green colored valve stem cap to indicate it. I have had to add to low tires in the cold weather using a 12 volt pump, and just don't get concerned about it. I don't think it is anything to get anal about causing a problem. Running too low pressure in the tire is more cause for concern to me than if I put air in with the nitrogen.

[Dave Richards]

For years I've been using a mixture of gasses with nitrogen making up about 78% of the mixture. It seems to work fine in my tires. :D

FWIW, there's no such thing as an "air molecule." Normal clean air is comprised mostly of nitrogen molecules, oxygen molecules and trace amounts of some other gasses.

[Ken Fitzgerald]

For years I've been using a mixture of gasses with nitrogen making up about 78% of the mixture. It seems to work fine in my tires. :D

FWIW, there's no such thing as an "air molecule." Normal clean air is comprised mostly of nitrogen molecules, oxygen molecules and trace amounts of some other gasses.

Those biomedical engineers are brutal!:rolleyes::D

[Dave Richards]

Those biomedical engineers are brutal!:rolleyes::D

Especially when gas is the main focus. :D :D

[David Ragan]

For years I've been using a mixture or gasses with nitrogen making up about 78% of the mixture. It seems to work fine in my tires. :D

FWIW, there's no such thing as an "air molecule." Normal clean air is comprised mostly of nitrogen molecules, oxygen molecules and trace amounts of some other gasses.


I thought it was more like 80%

I thought that it was to protect the rubber from oxidation. Not true?


Those biomedical engineers are brutal!:rolleyes::D

Yep. It is all about the Science, though, aint it?

[Jerome Stanek]

It's a gimick to get you to pay more for air. If the oxygen escapes and you top it off you will keep putting in more nitrogen. When they first air a tire there is oxygen in it.

[Phil Thien]

Didn't we just have a similar thread in the last year?

I think the consensus was that repeated topping-off with atmosphere would result in oxygen leaking out and nitrogen staying in, so using a regular air compressor is the equiv. of using nitrogen, over time.

[John Stankus]

another reason is nitrogen molecule is suppose to be slightly bigger than "air" molecule and cannot seep out as easily. I'm not sure I can agree with that (based on opinion only) in a class over the years someone stated that tires are porous. There is space between the rubber molecules that air can seep through. It's sounds feasible (I guess) but I have never researched it to see it that is accurate and factual or someone's opinion..

There are a lot of misunderstandings when it comes to tires and inflation.

From a physical chemist's viewpoint (my day job is chemistry professor)

Dry Air is made up of 78% nitrogen 21%oxygen 1% Argon and other stuff

The real issue for pressure change is if there is a lot of moisture in the tire, enough that some can be liquid at lower temperatures. This will cause pressure changes as the liquid vaporizes as the temperature increases. But this pressure rise should be proportional to the vapor pressure of water, which means that it could be at about 4 psi for a tire temperature of 150 F.

There is a pressure change due to temperature difference from 70F to 150F should be a 15% increase in pressure.

The property of a gas passing through something like a tire wall is called effusion. The rate of effusion is proportional to the inverse of square root of the molecular weight of the gas. Nitrogen molecules and oxygen molecules are about the same size but oxygen is a heavier molecule(32 grams/mole vs 28 grams/mole for nitrogen) Nitrogen should effuse about 7% faster than oxygen, but I would venture to argue the rates are so low that this difference is not a practical concern. There are questions of the nitrogen and oxygen solubility in the tire rubber, but again I think the rate is so low to be of little consequence. My guess would be the loss of pressure in tires is more likely from seepage around the bead on the rim and the valve than effusion through the sidewall of the tire.

One of the last times the nitrogen in tires thing came up, I did a calculation as to how much oxygen was available to react and it was pretty small amount. Real rough back of the envelope indicated that if all the oxygen reacted with the rubber it would be about 90 milligrams of rubber that would be reacted, or about 0.0008% of the tire mass. Again I would think this is negligible.

I would say dry air should be just fine. From my autocross racing days the pressure growth due to liquid in the tire was a concern for some, but they were running slicks that may have been running at the 20 psi range.

Personally, I think the nitrogen in tires is for two reasons 1) marketing and 2) to provide more profit for the tire stores.

In high speed aircraft tires, nitrogen is specified not for leakage concerns but to reduce chance of fire during catastrophic tire failure.

John


p.s. As a related aside, most people don't realize that humid air is LESS dense than dry air. This is due to the water molecule having a much lower mass than oxygen or nitrogen molecules.

[Chris Padilla]

316645

There ya go. :)

[Chris Padilla]

p.s. As a related aside, most people don't realize that humid air is LESS dense than dry air. This is due to the water molecule having a much lower mass than oxygen or nitrogen molecules.

Just to be a bit more rigorous, nitrogen and oxygen are usually bound together with another nitrogen and oxygen hence why we often see N2 and O2 written. The bond is quite strong as I understand it. So if the amount of water vapor increases, water being H2O of course, I can see that: O2 and N2 are heavier than H2O.

[Steve Peterson]

For years I've been using a mixture or gasses with nitrogen making up about 78% of the mixture. It seems to work fine in my tires. :D


That's what I use to top off also. All the stations around here fill up with nitrogen. It is perfectly OK to top off with a 78% nitrogen, 21% oxygen, 1% argon mixture.

Half of the reasons listed on their flyer are completely against the laws of physics. A properly inflated nitrogen tire will have exactly the same gas mileage and performance as a properly inflated "air" tire. All gasses experience the same amount of pressure change relative to temperature. The only true statement is that nitrogen filled tires loose pressure slower than an air filled tire, but the effects are very minor.

Steve

[Art Mann]

supposed to not expand/contract as much with temp changes, hence less overall issues with refilling/topping off.

tires stores have the nitro.

That claim is utterly false. Anyone who has completed a high school chemistry class and remembers anything about it will know that. Nitrogen, oxygen, carbon dioxide, water vapor and the trace gasses that make up what we call air all obey closely the predictions of the ideal gas law. The formula is PV=nRT, where P is pressure, V is volume, T is temperature and n and R are both constant numbers. What it says is that as temperature rises, either pressure, volume or both increase. Since the volume of a tire is pretty much fixed, the pressure goes up with the temperature, no matter what gas you are talking about. It doesn't matter whether the gasses are pure or mixed. The only time when this formula starts to fail is when the gas in question is so compressed that it becomes a liquid. The only reason why anyone who really understands what is going on would prefer pure N2 is that it is normally sold anhydrous.

[Lee Schierer]

From a physical chemist's viewpoint (my day job is chemistry professor)

Knowing that most tire shops don't pull a vacuum on the tires after they are mounted on the rims. The tire is filled with air at atmospheric pressure. If they then fill the tire with 100% nitrogen to 35 psig, what percent of Oxygen is then present in the tire.

[Malcolm Schweizer]

The rate of increase in nitrogen in your tires is directly proportional to the rate of decrease in the money in your wallet.

[Erik Loza]

Knowing that most tire shops don't pull a vacuum on the tires after they are mounted on the rims. The tire is filled with air at atmospheric pressure. If they then fill the tire with 100% nitrogen to 35 psig, what percent of Oxygen is then present in the tire.

This is exactly my question ^^^^.

"Filling with nitrogen" would seem to imply that 100% of the internal voume would then be nitrogen but that's impossible unless you create vacuum before filling it. It might indeed be that nitrogen has all these benefits but how much "nitrogen" are you actually getting?

Erik

[Kent A Bathurst]

That claim is utterly false. Anyone who has completed a high school chemistry class and stayed awake, and then completed honors chem classes in college engine school and stayed awake, and then gave enough to remember it all 40 years later....

Art - corrected it for you. ;)

I scored on #1 and #2, but failed on #3.

But, thanks for the lecture.........which is promptly consigned to #3 as well. But - I know I can get back to you, as the need arises.

You realize I was simply passing along the marketing pitch, don't you?

[Jerome Stanek]

not only the tire but also the hose

[Chris Padilla]

I fill my tires with xenon. It is heavier than air and therefore keeps my vehicle well-grounded. :D

[Wade Lippman]

This is exactly my question ^^^^.

"Filling with nitrogen" would seem to imply that 100% of the internal voume would then be nitrogen but that's impossible unless you create vacuum before filling it. It might indeed be that nitrogen has all these benefits but how much "nitrogen" are you actually getting?

Erik

Presumably they flush the air out with nitrogen; leaving very little oxygen.

All I know is that my wife's run flat tires smell like dead fish when I put air in; two different brands. Why is that?

[Erik Loza]

For years, I worked in the pet trade. More specifically, the live aquarium fish trade. The common practice of "bagging fish up" for the customer to take home involves placing some aquarium water in a little polyethylene bag, netting up the fish, dropping it in that water, inflating the bag somewhat, and securing the top into a sort of knot, with a tiny rubber band. Like a small balloon with water and live fish. This is how everyone does it. For years, I kept hearing, "Don't blow from your mouth into the bag because the CO2 in your breath will kill the fish". Some fish stores even touted using compressed air or even O2 to fill their fish bags with for the ride home.

I have probably bagged thirty or forty-thousand fish, blew in every bag from my mouth, and guess how many fish died on the ride home? Zero.

There's probably some science in everything but potentially a lot more hocus pocus. Just my 2-cents as always.

Erik

[Erik Loza]

Presumably they flush the air out with nitrogen; leaving very little oxygen.

All I know is that my wife's run flat tires smell like dead fish when I put air in; two different brands. Why is that?

No idea on the smell but where would they flush the regular air to? It would have to go somewhere. Where? Not arguing, just saying. I'm curious to the hear the (alleged) science of it all, myself.

Erik

[Ken Fitzgerald]

I fill my tires with xenon. It is heavier than air and therefore keeps my vehicle well-grounded. :D

An electrical engineer should know you can't ground an insulator.:eek::rolleyes::D

[Larry Edgerton]

We were using nitrogen twenty five years ago in our off road race truck. With 900hp spinning the tires constantly temps would go way up with O2, so you use nitrogen to control it. We still had to start a bit lower than we ultimately wanted, but not as bad as O2.

Tires only lasted 15 minutes, so wear/aging was not our concern. Besides, I have never seen a tire rot from the inside.

[Art Mann]

Art - corrected it for you. ;)

I scored on #1 and #2, but failed on #3.

But, thanks for the lecture.........which is promptly consigned to #3 as well. But - I know I can get back to you, as the need arises.

You realize I was simply passing along the marketing pitch, don't you?

Yes. Actually I thought you were joking but I didn't want anyone to get the idea that you were serious. You have been known to joke around from time to time.

[Mike Cutler]

What the deal with Nitrogen tires on wifes new Honda Pilot?

Less oxidation to the innerds of the tire?

How do you air up if needed?

Necessary for on-board pressure detection?

David

I don't think you got your last question answered.So;

It won't effect your TPMS system should you choose to just use standard air from your shop compressor.

[Kent A Bathurst]

Yes. Actually I thought you were joking but I didn't want anyone to get the idea that you were serious. You have been known to not joke around from time to time but rarely.


fixt once more.........:p

all about context............

[Tom Stenzel]

Sounds like a lot of hot air to me. I'll fill my tires with nitrogen when the NFL begins to fill footballs with nitrogen.

"See, it wuz that leaky O2 that done it, it wuz!" -Tom Brady quote*


-Tom

*That I just made up

[Larry Edgerton]

Sounds like a lot of hot air to me. I'll fill my tires with nitrogen when the NFL begins to fill footballs with nitrogen.

"See, it wuz that leaky O2 that done it, it wuz!" -Tom Brady quote*


-Tom

*That I just made up

Maybe not. Todays cars are going for optimal mileage, and the tires are part of that equation.

On the race truck we would pick up 7-8 psi once heated up with compressor air, and with nitrogen we would pick up 2-3 psi. Street tires get pretty hot as well on a hot day, especially when loaded. Handling on all cars is impacted by tire pressure so in the interest of consistency it is not a bad idea, especially on a performance oriented vehicle. When I ran autocross I had tire warmers to get my tires up to temp, partly because the tire compound I was running needed to be warm, and to keep the pressure where I wanted it.

I don't worry about it on my drivers, but hey, if its free when you get tires there is no downside.

[Jason Roehl]

I don't worry about it on my drivers, but hey, if its free when you get tires there is no downside.

Shame on you, Larry!

You're a businessman--you should know it's NOT "free". I bet the shops pay more money to have a nitrogen-fill system (in addition to compressors to run their air tools), so they have to raise their prices somewhat to pay for that nitrogen. They may not charge a line-item for it, but it's definitely wrapped into their overhead as part of the price of their other services.

[Curt Harms]

In high speed aircraft tires, nitrogen is specified not for leakage concerns but to reduce chance of fire during catastrophic tire failure.

John
p.s. As a related aside, most people don't realize that humid air is LESS dense than dry air. This is due to the water molecule having a much lower mass than oxygen or nitrogen molecules.

I'm certainly not qualified to comment on most of your post but what I was told about air in aircraft tires is that it has to do with moisture. Bottled nitrogen is dry, compressed air may not be. What I was told by aircraft maintenance personnel is that tires filled with air may also have a fair bit of water vapor in it. Air temperatures above 35,000 ft. can get pretty chilly - like -40F to -60F chilly which would cause the moisture to condense. It could puddle then freeze. If the aircraft were landing at a cold destination that ice puddle probably won't melt before landing. You now have an unbalanced tire that's going from 0 to 100 m.p.h.+ in the blink of an eye. I was also told that if my choice was to run a tire low until I could find a nitrogen bottle or inflate with compressed air, to use the compressed air.

[John Stankus]

I'm certainly not qualified to comment on most of your post but what I was told about air in aircraft tires is that it has to do with moisture. Bottled nitrogen is dry, compressed air may not be. What I was told by aircraft maintenance personnel is that tires filled with air may also have a fair bit of water vapor in it. Air temperatures above 35,000 ft. can get pretty chilly - like -40F to -60F chilly which would cause the moisture to condense. It could puddle then freeze. If the aircraft were landing at a cold destination that ice puddle probably won't melt before landing. You now have an unbalanced tire that's going from 0 to 100 m.p.h.+ in the blink of an eye. I was also told that if my choice was to run a tire low until I could find a nitrogen bottle or inflate with compressed air, to use the compressed air.
FAA airworthiness directive 87-08-09. Specifies nitrogen for flammability issues
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/55850E6389EFBA3C8625695B006723A3?OpenDocument
It does specify dry nitrogen but the focus is flammability

John

[Lee Schierer]

On the race truck we would pick up 7-8 psi once heated up with compressor air, and with nitrogen we would pick up 2-3 psi.

Boyle's gas law says that your psi difference was probably water vapor going to steam and not the lack of oxygen since air is 78% nitrogen. Your nitrogen was like moisture free and unless you purged your tires, you still had a percentage of oxygen present from the air that was present before you pressurized the tire.

[Curt Harms]

FAA airworthiness directive 87-08-09. Specifies nitrogen for flammability issues
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/55850E6389EFBA3C8625695B006723A3?OpenDocument
It does specify dry nitrogen but the focus is flammability

John

I wonder if transports which is what this AD addresses are more prone to brake fires than G.A. aircraft. It would ultimately be down to what the aircraft publications as amended specify . One Citation II unofficial document called for either dry nitrogen or dry air. I did find this which is the first authoritative source I'm aware of that says nitrogen may reduce tire degradation.

http://www.goodyearaviation.com/resources/pdf/aircraftmanual.pdf

Page 11


3. USE DRY NITROGEN GAS (WHEN REQUIRED)

Nitrogen will not sustain combustion and will reduce degradation of the liner material, casing plies and wheel due to oxidation.

[Larry Edgerton]

Boyle's gas law says that your psi difference was probably water vapor going to steam and not the lack of oxygen since air is 78% nitrogen. Your nitrogen was like moisture free and unless you purged your tires, you still had a percentage of oxygen present from the air that was present before you pressurized the tire.

I have no doubt that you are correct Lee, I just know that is what works. The tires would be so hot that you could not touch them for about fifteen minutes after the race. Measured the temps, but its been a few years and can't remember. Too hard a tire gets no traction, and too soft will come off the rim on hard hits.

[Mike Circo]

After three pages of science on the subject, I thought I'd interject a bit of human engineering.

Does anyone with nitrogen filled tires... done by a shop... KNOW, without a doubt, that they have 100% nitrogen in them?
What a great way to make money. Offer, for an additional cost, nitrogen fill. Then you can put anything you like in there because 99.9% of the population has no way to test if there is nitrogen in the tire or just air. Just another placebo effect I'm certain. You believe you have nitrogen in your tires, thus begin to experience the alleged benefits.

[Mike Lassiter]

After three pages of science on the subject, I thought I'd interject a bit of human engineering.

Does anyone with nitrogen filled tires... done by a shop... KNOW, without a doubt, that they have 100% nitrogen in them?
What a great way to make money. Offer, for an additional cost, nitrogen fill. Then you can put anything you like in there because 99.9% of the population has no way to test if there is nitrogen in the tire or just air. Just another placebo effect I'm certain. You believe you have nitrogen in your tires, thus begin to experience the alleged benefits.

Where I got our tires at has a nitrogen filling station that has a high pressure nitrogen tank sitting in it with a regulator and the hose with the air chuck attached to it. Other places I have gotten tires and/or a flat patched from the inside of the tire - I cannot say.

[David Ragan]

I wonder if transports which is what this AD addresses are more prone to brake fires than G.A. aircraft. It would ultimately be down to what the aircraft publications as amended specify . One Citation II unofficial document called for either dry nitrogen or dry air. I did find this which is the first authoritative source I'm aware of that says nitrogen may reduce tire degradation.

http://www.goodyearaviation.com/resources/pdf/aircraftmanual.pdf

Page 11


3. USE DRY NITROGEN GAS (WHEN REQUIRED)

Nitrogen will not sustain combustion and will reduce degradation of the liner material, casing plies and wheel due to oxidation.



Well, it looks like the Nitrogen is all fluff in the civilian population, but it is nice to have my own theory validated, however insignificant it may be in the real world.

[Charles Wiggins]

http://www.popularmechanics.com/cars/how-to/a3894/4302788/

[Jerome Stanek]

since when have aircraft tires changed to need nitrogen.