Nitrogen Tyre Inflation

[snrub]

Hi, I have recently just started flying an aircraft with Nitrogen inflated tyres. Can anyone shed any light on the reason for using Nitrogen instead of compressed air for inflation?

[Krystal n chips]

The use of nitrogen is primarily to reduce the risk of fire in an overheated tyre as it's an inert gas. Air contains oxygen and will therefore burn if the conditions for combustion occur.

[Mr @ Spotty M]

A far better gas than compressed air, Costco over here in the UK use it for car tyres, my car has run on them for a few years now.

[AutoAbort]

It is like Krystal says, Primarily to decrease risk of fire because it is an inert gas. Maybe slightly better from a corrosion point of view. But I think that filling your average car with Nitrogen is a bit over the top. Another way to squeeze out a buck or two from the customer:}

[Bullethead]

Two main reasons 'dry nitrogen' is used instead of straight compressed air, firstly it doesn't conduct heat as well as air and secondly it has no water vapour in it.

Both an advantage when the brakes get really hot and the heat starts to conduct into the wheel/tyre assembly.

The heat soak takes longer and the lack of water vapour ensures that steam is not generated in the hot wheel causing a much increased pressure.

Peak brake temps in a an airliner after a high speed rejected take off can exceed 900degC.

Concerning filling your car tyres with nitrogen, pretty much a waste of money IMO, what's already in there is 78.8% nitrogen anyway and very few car drivers will ever have peak brake temps much over a couple of hundred degrees if that.

Last time I had the tryes replaced on my car the tyre tech asked,
'Dya want nitrogen in 'em mate?"

I said,
"No thanks, I already run an 80% nitrogen mix"

"Oh" says he and wanders off. :8

Regards,
BH.

[cribble]

This is from an article I read a while ago (source unknown). It agrees with what I was taught as a boy, but I can claim no better authority than that.

"Nitrogen is used for a few reasons, first it is a inert gas. This means that it is a stable gas and non oxidizing. These things that are important for safety. As a non oxidizing gas, it is a fire retardant, and prevents corrizion of the rims. Second it that is has no water vapor. Water vapor can freeze at high altitudes making ice in the tire, or even worse, when landing, and the heat buildup, can cause steam which will result in a tire blow out. (Water when turned into steam, will expand over 1000x its original volume).
Third, is the ease of storage and cost. Nitrogen gas is relatively cheap compared to other inert gases, and can be stored in a metal tank for long periods of time with out any negative effects. This is the main reason N is used, even though there are many other types of inert gases.
Another reason, is that N maintains a more constant pressure 3 to 4 x longer because of the lack of oxygen and water vapor found in "shop air". ."

[sinkingship]

I think the main purpose is to remove moisture, the AMM sates:

If nitrogen is not available, Source of Clean Dry Air, maximum moisture content that isequivalent to an atmospheric dew point of -208 F (-298 C).

but being an inert gas is valid in my point of view.

[Spitoon]

I recall being told many years ago when I learned to fly that it was also because nitrogen expanded less at altitude. Never really thought about it 'til now...and can't remember my physics from school. Was I being fed a line by an engineer with a sense of humour?

[Exmek]

One other reason for Nitrogen.
We were taught in the early 1960's (by the Royal Air Force) that during inflation pressure release of the tyre (tire) prior to disassembly of the wheel (Split or detachable rim) even if the schrader valve core had been removed, the rapid reduction in pressure could cause any moisture in the air within the tyre to freeze in the aperture of the valve causing a blockage that could lead to the false impression that the tyre was fully deflated with obvious danger of accident if the rim securing devices were released while pressure still was trapped.

From memory tyre pressures on the Handley Page 'Victor' main gear were in the region of 250 psi (around 16 bar?)

and the English Electric 'Lightning' mains 400-450 psi (30 bar?)

Always inflated for the first time in the workshop in a safety cage.

Exmek

[Graybeard]

and probably in Part 25 ops.

It was about 1987 that a Mexicana 727-200 arrived at Mexico City airport with squawk of dragging brake. Departing Capt took the plane without delay, had his wife aboard and kid on his lap to depart for KLAX and Disneyland. It was a full 178 SOB, at gross.

Brake was still dragging, so he powered back to help tug move the plane. MEX is 7400' elevation, with warm to hot temps. Normal initial climbout in 727-2 there is 500'/min until cleaned up, after rotating upon reaching the red lights at the last 1,000' of 13,000.

Pilot had retracted gear right after takeoff, of course. There was a catastrophic explosion before they reached cruise.

Cause was initially thought to be a bomb. Reportedly this was the Capt wife first flight since surviving a bomb in a 727 as FA some years prior.

NTSB determined that oxygen in the tire combined with volatile gases released from the very hot rubber made an explosive mixture, and only needed a spark.
--------

A similar fate befell a DC-8 on hajj in that same year.

-------

Yes, 100% nitrogen is better than air in even your car tires. Its larger molecules won't leak out as easily, so I'm told.

[engineer07]

There are several reasons why nitrogen is used, most of which have already been mentioned in other posts
- It is 'dry' therefore expands less with changes in temperature - so as tyre heats up during taxi or during an RTO the change in tyre pressure is lower. This can also be important if operating to/from airfield with very different ambients temps.
- It's inert, so if after an RTO the fuse plugs in the wheels melt to release the pressure before the wheel explodes you are not releasing any oxygen onto already red hot brakes
- The nitrogen molecule is bigger than oxygen and hence the tyre will hold it's pressure better/longer thus reducing maintenance
- Nitrogen also does not attack/degrade the membrane on the inside of the rubber tyre - the rubber is porous and the membrane makes it airtight.

Using nitrogen in car tyres is a good thing - it means you can increase cold inflation pressures and still get the same optimum hot inflation pressures. It means that the car will use less fuel on short journeys when tyres are cold as the higher inflation pressure reduces rolling resistance and for those with sports cars it means the car will handle better until the tyres warm up. The smae can be acheived with 'dry' air if you can get it.

[airfoilmod]

Used in race cars for years, in tyres and intakes.

Nitrogen is NOT an inert (Noble) gas.

It isn't used for its own qualities as much as it displaces O2 and Water
as above.

[Flash2001]

A couple of minor points...

Nitrogen molecules should be smaller than oxygen, MW=28 vs 32.

There ain't no such a thing as -298 C.

How do they get it so dry? It probably comes from air and unmixing the water vapour should be an expensive process.

After an excellent landing you can use the airplane again.

[airfoilmod]

Just run air through big bottles of Stainless Steel BB's first.

AF

[Flash2001]

What is the desiccating mechanism here?

After an excellent landing you can use the airplane again!

[airfoilmod]

Condensation.

[Flash2001]

In fact I see a whole bunch of methods on the www. I wonder which is cheapest?

After an excellent landing etc...

[Graybeard]

I'm pretty sure I read it in Aviation Week & Space Technology, IGh. Mexicana started using nitrogen in the tires after that.

Did you find anything on the Hajj DC-8? It was possibly a Canadian carrier, and IIRC, they had either low tire or dragging brake, and no nitrogen available at the airport, so used air.

GB

[Graybeard]

Flight 940 was operating its scheduled flight route Mexico City (http://en.wikipedia.org/wiki/Mexico_City)-Puerto Vallarta (http://en.wikipedia.org/wiki/Puerto_Vallarta)-Mazatlán (http://en.wikipedia.org/wiki/Mazatl%C3%A1n)-Los Angeles (http://en.wikipedia.org/wiki/Los_Angeles) operated by Mexicana Airlines (http://en.wikipedia.org/wiki/Mexicana_Airlines) (Compañia Mexicana de Aviación).

On March 31 (http://en.wikipedia.org/wiki/March_31), 1986 (http://en.wikipedia.org/wiki/1986), the flight departed from Mexico City utilizing a Boeing 727 (http://en.wikipedia.org/wiki/Boeing_727)-264 registered as XA-MEM.

Shortly into the morning flight an over-heated tire, a part of the main landing gear unit, exploded within the gear bay. It exploded because it was filled with compressed air (http://en.wikipedia.org/wiki/Compressed_air), rather than inert (http://en.wikipedia.org/wiki/Inert) nitrogen (http://en.wikipedia.org/wiki/Nitrogen). The explosion damaged the aircraft's hydraulic and electrical systems and caused a fire. Although the crew reported the problem and declared an emergency, the aircraft crashed near Maravatio (http://en.wikipedia.org/wiki/Santiago_Maravat%C3%ADo), northwest of Mexico City.

The crash killed all 167 passengers and crew and remains the deadliest airline disaster in Mexican history and is the world's worst air disaster involving the Boeing 727.

GB

[happybiker]

The CAA (GR16) also require with effect from 1 April 1988, all braked wheels of retractable landing gear units on aeroplanes above 5700 kgs will be required to have tyres inflated with Nitrogen, or other suitable inert gas, and maintained such as to limit the Oxygen content of the compressed gases to not greater than 5% by volume.
http://www.caa.co.uk/docs/33/CAP747.PDF

[con-pilot]

There was another case of a main tire exploding the wheel well from overheating. It was in 1973 involving a Braniff 727. The aircraft was badly damaged and landed safely at Dulles Airport in Washington DC.

I have seen photos of the aircraft, but I cannot find any thing on line now about the incident.

Perhaps someone else will have better luck.

We did have ground distance charts in the 727 with waiting times, with the parking brake not set, that you had to follow if you had a long taxi, landing distance and estimated takeoff distances were including in the calculations. I can only remember a couple of times we were ever affected by the chart in the ten years I flew 727s, so it was not much of a limiting factor. If I remember correctly if you were parked for more than an hour there was no problem.

[18-Wheeler]

Using nitrogen in car tyres is a good thing

In racing car, yes maybe, but a complete waste of time and money in road cars. You never get road tyres anywhere near hot enough to get any benefit whatsoever from it.

[snrub]

Thanks for all your replies to the thread, I have found the information provided very helpful and informative.
snrub :ok:

[Old Smokey]

Please satisfy my curiosity. Is it true that Nitrogen inflation of tyres (tires) was an initiative of Ansett ANA, long long ago, or is it yet one more myth?

I suspect that John_Tullamarine may know the answer:confused:

Regards,

Old Smokey

[Flare-Idle]

The "best" inflation gas for aircraft tires from a performance point of view is sulfuric hexafluoride, SF6, a gas which is normally used in gas-insulated switchgear for high voltage applications (>100 kV) world wide. SF6 has excellent dielectric properties and its extinguishing capabilities are outstanding and outperforming every "competitor". Combine this with a really big molecule, Nitrogen can dust off....
Well, on the downside, SF6 is a "climate killer", so no good and therefore no large scale use in aircraft tires.
I stand to be corrected that the space shuttle still uses this gas in its tires ?

[RNAV.CAP]

hi!

but doesnt it vary with the amount of pressure relative to the proportion of manufacturer's allowable "time of compression" as allotted by the ISO standards?

rnv

[john_tullamarine]

Please satisfy my curiosity. Is it true that Nitrogen inflation of tyres (tires) was an initiative of Ansett ANA, long long ago, or is it yet one more myth?

I suspect that John_Tullamarine may know the answer

.. at a loss here. However, next historical do at Essendon I will track down one of the old chaps and see if he can throw any light on the question.

[Ex Cargo Clown]

Nitrogen molecules should be smaller than oxygen, MW=28 vs 32.

Not quite as simple as that !!!!

If it was, my life would be much easier !!!

[omniplasm]

Thanks for asking this question, had always meant to do so. Having always doubted the O2 bigger story in my mind dubious due to the MW being greater, have found and been corrected by (presuming it's true - sounds authentic):

www.getnitrogen.org/pdf/graham.pdf

I wouldn't think one expands more than another - physics hazy these days but I think the only time the ideal gas laws don't approximate reality is close to the liquid or sublimation points - certainly not relevant to O2 or N2 in these conditions

[Graybeard]

I asked around at Old Bold Pilots' breakfast this morning, and one ex-electrical mechanic remembers well his airline using nitrogen by the late 1960s, as he used the supply for his car tires.

Another OBP said the use of nitrogen in tires at the Bonneville Salt Flats goes back much further. How about Sir Malcolm Campbell?

GB

[Flash2001]

Even at my advanced age I learn something every day.

After an excellent landing you can use the airplane again!

[airfoilmod]

The Bluebird and Mickey Thompson's quad Pontiac. LSR. Em were the Days. Sorry, off thread.

[Ozgrade3]

This thread has got me thinking, as Im just about to get some new tyres for my car.

How much heat is generated at highway speeds in 60 serries tyres, if its true that with nitrogen you could increase the PSI by say 2 PSi without having them over inflate on the highway, there might be some merit for short trips in fuel economy, by having a slightly higher inflation with nitrogen.

Any idea on how much to go up by?

[onetrack]

Not precisely aircraft related... and some thread drift... but here's an interesting video that shows the results of welding... even for only a very short time... on an inflated light truck/pickup tyre.
This video was produced by a rim manufacturing company that became concerned about the practice of repairing steel rim cracks, in situ, on earthmovers.
At least one welder has been known to have been fatally injured by a tyre explosion caused by welding a cracked rim whilst the tyre was still inflated.
What I find interesting is how rapidly the internal fire in the tyre propagates, once started.
You can well imagine the damage caused by a tyre explosion/fire in a wheel well.

YouTube - Tire Explosion (http://www.youtube.com/watch?v=HiLeji8bLOk)

[IFixPlanes]

The reason according the (still valid) AD 87-08-09 (http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/0/55850E6389EFBA3C8625695B006723A3?OpenDocument):
To eliminate the possibility of a chemical reaction between atmospheric oxygen and volatile gases from the tire inner liner producing a tire explosion

[stilton]

'We did have ground distance charts in the 727 with waiting times, with the parking brake not set, that you had to follow if you had a long taxi, landing distance and estimated takeoff distances were including in the calculations. I can only remember a couple of times we were ever affected by the chart in the ten years I flew 727s, so it was not much of a limiting factor. If I remember correctly if you were parked for more than an hour there was no problem'




We avoided that problem by not having those charts !

[18-Wheeler]

How much heat is generated at highway speeds in 60 serries tyres, if its true that with nitrogen you could increase the PSI by say 2 PSi without having them over inflate on the highway, there might be some merit for short trips in fuel economy, by having a slightly higher inflation with nitrogen.

A complete waste of time, just stick with regular air.
Most of your tyre heat is generated by the brakes as well, not by the myth of the tyre sidewalls flexing and thus causing all the heat in the tyre.

[SNS3Guppy]

A complete waste of time, just stick with regular air.
Most of your tyre heat is generated by the brakes as well, not by the myth of the tyre sidewalls flexing and thus causing all the heat in the tyre.

This is untrue. While obviously brake use heats a brake and wheel assembly, sidewall flex accounts for significant heat rise. In large heavy aircraft, this can have a significant impact on brake energy determinations, just from taxiing the aircraft.

The fact is that in an automobile, the underinflation is the primary cause of blow-outs, largely due to heat rise. The reason for the heat rise is sidewall flex.

In large aircraft, sidewall flex, sans brake application, causes substantial heat rise during a long taxi. At maximum weights, one can heat brakes substantially without hardly any use, due to the tires getting hot during taxi and subsequent heat transfer.

[18-Wheeler]

All true, however I wasn't talking about aeroplanes I made it clear I was talking about car tyres. I also did not mention underinflation but again you have to be pretty low on pressure in a car tyre to get that and also going a fair rate of speed.
Thanks for the input, Mr Mitty.

[con-pilot]

Thanks for the input, Mr Mitty.

Don't even start it, Okay! :ok:

[aterpster]

SNS3Guppy:
The fact is that in an automobile, the underinflation is the primary cause of blow-outs, largely due to heat rise. The reason for the heat rise is sidewall flex.

Like everything else, improper maintenance of safety equipment is just asking for trouble. Everything I've read states to check the pressure (when cold) of a passenger automobile at least once a month and with a high quality gauge. (Sadly, done by far too few people.)

With proper inflation and at least minimum safe tread remaining, plain old air is as good as nitrogen. But, if the automobile tire is seriously underinflated, sidewall flexing (as you stated) will eventually ruin the day, pure nitrogen in the tire notwithstanding.

[goldfish85]

Engineer 07: The nitrogen molecule is bigger than oxygen and hence the tyre will hold it's pressure better/longer thus reducing maintenance

I think you'll find that oxygen molecules are slightly larger.

[aterpster]

goldfish85:

The nitrogen molecule is bigger than oxygen and hence the tyre will hold it's pressure better/longer thus reducing maintenance.

And, the practical difference for an automobile tire is?

[barit1]

The water vapor story puzzles me. If when filling the tire, water vapor enters the tire and NOT LIQUID WATER, then there is no expansion of the gas. Steam IS water vapor.

Only if liquid water is introduced during filling can the 1000:1 expansion take place.

[SNS3Guppy]

The physics behind sidewall flex in an aircraft tire and sidewall flex in a car tire are the same.

The primary reason for blow-outs in car tires is underinflation, and it doesn't take much to cause significant heat rise and eventual tire failure. It also doesn't take a significant value of underinflation to cause excess shoulder wear, contributing to rapid tire wear and degeneration, which also assists a car tire in failing.

On a short trip with a of braking, of course the majority of the heat received by the wheel assembly will be through braking. However, underinflation will cause temperature rise in the wheel regardless of braking. A long road trip with no brake application on the highway can still cause a tire failure due to the weakening of the tire, and the temperature rise from sidewall flex, alone.

For normal applications, nitrogen isn't available for car tires and a rule, and isn't absolutely necessary. It's still preferred, where available.

Pressurized atmospheric air in a tie sustains combustion, whereas nitrogen does not. Blowouts in tires with a much more flammable mix, using air (and worse, using propellants from inflation cans, and products from inflation cans) can contribute to catastrophic failures and explosions, as can hydrocarbon products from the tire itself. Nitrogen discourages combustion. It can mean the difference between a tire that fails explosively, and one that simply goes flat. One is more likely to see this difference manifest in Phoenix in the summer, vs. Minnesota in the winter, but it's also another reason that performance vehicles do use nitrogen in the tires.

So yes, sidewall flex is a consideration, and is not a myth.

[Ex Cargo Clown]

A discussion with a colleague today about N2 reactions reminded of this thread.

N2 will undergo reactions, there is no doubt about that. So we came to the conclusion why not use something else that is cheap,nice and bulky so no pressure loss, plentiful, and so unreactive that if we found a reaction it would undertake over 50 Kelvin we would get a Nobel Prize for!

Argon

[SinglePilotCaptain]

I am pondering if anyone in here has actually topped off a plane tire with nitrogen, or r/r a plane tire, or seen the inside of a car/plane wheel..

[aterpster]

SNS3Guppy:

For normal applications, nitrogen isn't available for car tires and a rule, and isn't absolutely necessary. It's still preferred, where available.

My Honda dealer disagrees. They have the word all the way from the engineers in Japan.

[SNS3Guppy]

I am pondering if anyone in here has actually topped off a plane tire with nitrogen, or r/r a plane tire, or seen the inside of a car/plane wheel..

Yes, I surely have. Extensively. I don't put anything but nitrogen in aircraft tires. When home, I put compressed air in my car tires, either from my own compressor, or one found at a gas station. I don't keep nitrogen at home.

Aircraft are a different matter. Aside from a general recommendation and sometimes requirement for nitrogen in aircraft tires, it's also good practice.

AC 41-131B, the FAA's publication on standard maintenance practices (and a sort of bible for any aviation maintenance technician and mechanic), states in chapter 9, section 1:

NOTE: The use of nitrogen to inflate tires is recommended. Do not use oxygen to inflate tires. Deflate tires prior to removing them from the aircraft or when built-up tire assemblies are being shipped.

It's also a certification standard ("dry nitrogen or other gases shown to be inert") and requirement for large aircraft, as found in 14 CFR (code of federal regulations--the "FAR's) 25.733(e):

(e) For an airplane with a maximum certificated takeoff weight of more than 75,000 pounds, tires mounted on braked wheels must be inflated with dry nitrogen or other gases shown to be inert so that the gas mixture in the tire does not contain oxygen in excess of 5 percent by volume, unless it can be shown that the tire liner material will not produce a volatile gas when heated or that means are provided to prevent tire temperatures from reaching unsafe levels.

Advisory Circular AC 20-97B, Aircraft Tire Maintenance and Operational Practices, establishes the following, regarding nitrogen in aircraft tires:

(3) Initial Inflation for Tubeless Tires. Inflate the tire assembly in a safety cage using dry nitrogen to ensure, that the tire does not contain more than 5 percent oxygen by volume (Those aircraft required to comply with AD 87-08-09 shall inflate the tire wheel assembly in accordance with the procedure specified in that AD). The nitrogen source regulator should be pre-set to a value that is no more than the maximum load capacity of the tire. The tire growth will produce a drop in inflation pressure after initial inflation. Pressure stabilization normally occurs within 12 hours. After an initial 12-hour minimum stabilization period at the rated inflation pressure, the tire should maintain the inflation pressure within 5 percent of the initial pressure for a period of 24 hours. The leak source should be discovered and corrected if pressure losses exceed 5 percent. Operators should use this procedure when applicable or comply with the aircraft manufacture’s maintenance manuals, or CMM, as applicable to the aircraft and the assembly. Although AD 87-08-09 applies to a specific aircraft, the procedures set forth in the AD are acceptable procedures that should be used for similar tire assemblies.

(3) Service Pressure. Service pressure is the inflation pressure needed to support the maximum operating load for a wheel position. Service pressure is measured with the assembly under load. When pressure testing a loaded assembly, inflate and maintain mounted tires with nitrogen. The gauge pressure should indicate a range between 100 percent and 105 percent of the specified service pressure, provided that the rated pressure of the tire and the wheel’s TSO qualification pressure is not exceeded.

Advisory Circular AC 25-22, Certification of Transport Airplane Mechanical Systems, under Section 25.733, provides the reason that the regulation 25.733 requires nitrogen or other inert gas:

b. Intent of Rule. This rule specifies type certification requirements for both design and performance of tires used on transport category airplanes. The tire must be of proper fit and have approved speed and load ratings for a particular airplane application. The maximum static ground reaction for the condition specified must not exceed the maximum static load rating of each tire. Retractable gear system tires must have adequate clearance from surrounding structure and systems. The tire inflation medium is to be an inert gas to avoid explosions. Tires installed on landing gear axles with multi-wheels (main wheel tires only), must have a 7% load margin included in their rating. Tire performance standards are contained in Technical Standard Order (TSO) TSO-C62. A TSO approval is not approval to install tires on the airplane. The airframe manufacturer/user must conduct the applicable airplane certification tests and receive FAA approval for installation.

The same advisory circular goes on to explain:

(6) Amendment 25-78 (March 29, 1993) added paragraph § 25.733(e) to require that for airplanes with a maximum certified takeoff weight of more than 75,000 pounds, the tires mounted on braked wheels be inflated with dry nitrogen or other inert gases so that the tire does not contain oxygen in excess of 5 percent by volume to prevent tire explosions. The 75,000 pounds weight limit was based on a review of the service difficulty reports indicating that tire explosions, as opposed to tire bursts, tend to occur on the larger, heavier airplanes. The 5 percent by volume limit for oxygen content was based on a series of laboratory tests indicating that an abrupt auto-ignition could occur for oxygen concentrations of 10 percent or more.

(a) There had been several cases where tire explosions had occurred in transport category operations. A tire explosion differs from a tire burst, which can occur when an overheated or over inflated tire fails and releases the high pressure air contained therein. Protection against tire burst is required under § 25.729(f). A tire explosion is the result of a chemical reaction occurring when gases released from overheated tire material mix with oxygen in the inflation air and ignite. In 1987, the FAA issued an airworthiness directive (AD 87-08-09) requiring use of nitrogen for tire inflation to ensure that the tires on braked wheels of airplanes do not contain more than 5 percent oxygen. Amendment 25-78 was intended to accomplish the same purpose for new airplanes.

Finally, the 800 lb. gorilla: Airworthiness Directive AD 87-08-09, called out above in the advisory circular. It applies specifically to certain Airbus, Boeing, McDonnell Doublas, and Lockheed products, but is also applied or referenced by other manufacturers and other applications, for the language contained therein, and specifically the intent. That is, the AD can't be applied to aircraft not called-out in the AD, as an AD, but it's an oft-referenced directive, and the basis of further certification and operating ammendments that affected regulations, and aircraft beyond the scope of the AD. I'm citing the AD itself here, as it was specifically referenced in the portion of the advisory circular quoted above. Suffice it to say that the application is substantially more far-reaching than the direct application of the AD itself:

87-08-09 AIRBUS INDUSTRIE, BOEING, BRITISH AEROSPACE, LOCKHEED, AND MCDONNELL DOUGLAS: Amendment 39-5613. Applies to Airbus Industries Models A300 and A310; Boeing Models 707, 720, 727, 737, 747, 757, and 767; British Aerospace Models BAe 146 and BAC 1-11; Lockheed Model L-1011; and McDonnell Douglas Models DC-8, DC-9 (includes MD-80 series), and DC-10; certificated in any category.
To eliminate the possibility of a chemical reaction between atmospheric oxygen and volatile gases from the tire inner liner producing a tire explosion, accomplish the following, unless already accomplished:
A. Within 180 days after the effective date of this AD, to ensure that all aircraft tires mounted on braked wheels do not contain more than 5 percent oxygen by volume, accomplish paragraph 1. or 2., below. Either of these procedures is acceptable, or they may be used together:
1. Install a placard, either in each wheel well or on or near each landing gear strut incorporating braked wheels, and in a location so as to be easily seen and readable by a person performing routine tire servicing. This placard shall state "INFLATE TIRES WITH NITROGEN ONLY." The words "SERVICE" or "FILL" may be substituted for the word "INFLATE".
2. Incorporate into the FAA-approved maintenance program procedures that include the following items:
a. On braked wheels, install only tires that have been inflated with dry nitrogen or other gases shown to be inert such that the gas mixture does not exceed 5 percent oxygen by volume.
b. Tires on braked wheels may be serviced with air at remote locations where dry nitrogen is not available, provided that:
i. the oxygen content does not exceed 5 percent by volume; or
ii. within the next 15 hours time-in-service, the tire must be purged of air and inflated with dry nitrogen so that the oxygen does not exceed 5 percent by volume.
B. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region (Airbus Industrie, Boeing, and British Aerospace models); or the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region (Lockheed and McDonnell Douglas models).
C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of the modification required by this AD.
This Amendment becomes effective June 1, 1987.

In addition to these requirements, many manufacturers will issue service instructions and documentation calling out nitrogen as a specific requirement for tire inflation and maintenance.

As an aside, for those who think underinflation isn't a significant factor, the AC 20-97B states:

NOTE:
Accurately maintaining the correct inflation pressure is the single- most effective task in the preventive maintenance regimen for safe tire operations!

So...to get back to the original point of the thread, which asked "Can anyone shed any light on the reason for using Nitrogen instead of compressed air for inflation?," the answer is yes. Aircraft tires use nitrogen for inerting purposes, because it's a more stable gas, because it doesn't support oxidation of aircraft wheel assemblies or contain as much moisture (use of dry nitrogen is required, remember), and doesn't support tire combustion at elevated temperatures during gassing of tire structure materials under heat and pressure.

My Honda dealer disagrees. They have the word all the way from the engineers in Japan.

Do you mean to say that the Honda dealer (and their engineers in Japan) recommend against the use of nitrogen?

I've taken tire courses from several tire manufacturers, who all recommended the use of nitrogen where it's available. Generally the use of nitrogen in car tires isn't common (except high performance tires and certain industrial applications), largely because of availability and cost.

The use of nitrogen is especially a good idea for those using alloy wheel assemblies, but also steel assemblies, to help prevent corrosion in the presence of moisture.

[sb_sfo]

is providing N2 inflation with new tires purchased as of a couple months ago. I'm running on it now.

[HAWK21M]

If its an Inert gas...Its always preferred.

[Mechta]

Corrosion is a real problem on painted alloy car wheels. Once the corrosion gets under the paint, a leak path results which is the cause of many tyres not maintaining pressure. Bead sealants don't help unless the undermined paint and corrosion are removed first (usually with a wire brush). For this reason I can see why Costco might encourage the use of nitrogen, as it might also inhibit further corrosion of the rim.

I would like to know how the oxygen content of the nitrogen in an aircraft tyre was supposed to be monitored. For practical purposes the only way is to refer to the purity of the nitrogen in the bottle and make an allowance for the air in the tyre before inflation (unless of course it was somehow purged first).

[tristar 500]

When you get a new nitrogen bottle from BOC it comes with a label saying "oxygen free" gas.

tristar 500

[JABBARA]

I guess this high speed camera view is a good explanation what happens if tire pressure is low.

http://i1222.photobucket.com/albums/dd499/Jabbara1/PagesfromTIRESGOODYEAR-1.jpg?t=1293660362