The truth behind nitrogen

[Indysteve]

Hey guys,

I found this article while doing some tire research and I thought it might be of use here.

Link to the original article:
"http://blog.gasbuddy.com/posts/Tire-inflation-the-truth-behind-nitrogen/1715-432662-482.aspx"

"Have you bought new tires lately? Have you seen a poster or been asked if you'd like to fill your tires with nitrogen instead of compressed air? Some service shops charge $40 or more to fill your tires with nitrogen- so let's find out if it's worth it, with some help from a Consumer Reports study.

I've been asked dozens of times in my current position and from my previous experience in the auto industry- is it worth it to pay to use nitrogen inflation? The short answer- and my opinion- is no. While nitrogen inflation has benefits over compressed air, it would not be worth additional cost.

You see- nitrogen inflation is more of a marketing gimmick- nitrogen inflation inflates your tires with 95% or so nitrogen. Compressed air is typically already 80% nitrogen, so you're seeing just a small benefit.

So what's the big deal with nitrogen? Companies try to sell you that you never need to check your tire pressure OR that your tires will not lose pressure- another stretch of the truth. According to a Consumer Reports year long study, nitrogen tires still lost air pressure (over a year)- but less than tires filled with compressed air. To read more on that study, click here. The bottom line? You'll always need to check your tire pressure. You simply can't fill with nitrogen and forget about your tire pressure. To do so would be a big mistake.

Even tire manufacturers have stated that they design cars around compressed air, and that nitrogen isn't necessary. Although they state that you can benefit from nitrogen inflation, you should be skeptical of claims from nitrogen machine manufacturers and tire shops that say you'll extend the life of a tire. Regular monitoring of a tire and rotating it would likely do more to extend the life than simply filling it with nitrogen and forgetting about it.

There are also claims of increased gasoline mileage or better fuel economy. There is no scientific evidence of this. Had nitrogen had solid claims of improvements in fuel economy, don't you think vehicle manufacturers would be using it to increase their vehicles efficiency and as a selling point? Let me remind you- if it sounds too good to be true, it probably is.

Nitrogen inflation is recommended if there is no additional cost, such as at Costco, where it is included. Paying upwards of $40 or even more is simply flushing money down the toilet. With gas prices approaching an average of $3.10/gallon today, you have better things to spend your money on."


YMMV

 

[chuckycheese]

Gas

Gas

You're paying $3.10 for a gallon of gas? (I paid $3.98 yesterday and got the best deal in town.)

 

[mike_of_bbg]

The article was written in January. We've just dropped down to 3.59/gal. But then I'm not in the great green state of Cal-ih-for-nigh-eh.

 

[mike_of_bbg]

Think we could get a government grant to develop a mechanism to "sequester" carbon dioxide in peoples' tires?

 

[chuckycheese]

Gas

Gas

The article was written in January. We've just dropped down to 3.59/gal. But then I'm not in the great green state of Cal-ih-for-nigh-eh.

It should have occurred to me that it wasn't timely. And, yes, California is 'unique' to say the very least.

My Florida property 'closed' yesterday....and it's all mine!:dancing:

 

[David_510]

I wish i had your guy's gas prices. Im paying $4.35 here in the bay area.

 

[Hovmod]

I wish i had your guy's gas prices. Im paying $4.35 here in the bay area.

Hahaha - I'm paying $2.6 for a litre of the stuff, that's $9,85 per gallon if my math fu is strong today...

 

[Guest]

The aviation industry uses nitrogen to inflate aircraft tires.

But for another reason entirely. At altitude it is very cold and moisture in the tires will condensate pool at the lowest point of the tires then freeze. On landing you have unbalanced tires. Another reason is if the aircraft does a rejected takeoff. The wheels will get Very warm, having nitrogen in the tires will reduce the chance of the tires catching fire too soon. A definite possibility at maximum reject speeds.

http://www.youtube.com/watch?v=wXpjBxD0Rhg

DP

For aviation, nitrogen seems to be useful for two reasons.
1) It is dry (little or no water vapor)
2) Little or no oxygen to aid oxidation of the rubber.

CO2 could be used for this instead of N2, as long as it is dry.

I find it hard to believe that airplane tires get hot enough to burst into flame. The autoignition point must be quite high. Maximum heat stress on an airplane tire comes during taxiing before take-off. The plane travels a long distance, and the load is much higher that at landing, because the fuel load at take-off can be a third of the total weight. Still, maximum temperatures come in the upper sidewall, in the middle, not on the surface. I would be surprised if rubber that was hot enough to ignite, would not be so soft that the tire would fall apart. If you have other information, I would greatly appreciate some citations and sources.

 

[JEEPRUSTY]

The aviation industry uses nitrogen to inflate aircraft tires.

But for another reason entirely. At altitude it is very cold and moisture in the tires will condensate pool at the lowest point of the tires then freeze. On landing you have unbalanced tires. Another reason is if the aircraft does a rejected takeoff. The wheels will get Very warm, having nitrogen in the tires will reduce the chance of the tires catching fire too soon. A definite possibility at maximum reject speeds.

http://www.youtube.com/watch?v=wXpjBxD0Rhg

DP

Is the amount of moisture present in a tire that signifigant?
How come a large vehicles tires do not show an imbalance at high speeds?

I know the aircraft have larger diameter tires and all. But what is the the range of ise that can be produced and how much impact does it have?

I am sure some engineers have done tests on this.

 

[Guest]

Hi.

The tire will not autoignite.

If you look at films of rejected takeoffs you will see the brakes glowing red even flames come out of them. The heat transfer from the brakes is what will heat up the the tire even more. The pressure increase in the tire due to that heat. The wheels have "Blow plugs" in the rims. These plugs will release the pressure and prevent injuries to firemen or ramp personnel.

I have found an FAA text that describe testing, plugs, autoigniton, etc...

I hope that will answer your request. I am by no mean an expert.

http://rgl.faa.gov/Regulatory_and_G...e18b9cadcf1a66da86256a3100713354!OpenDocument
...

Thanks for the URL. I quickly read through the document. It says that gases can be released from hot innerliner that can autoignite when the concentration of oxygen inflating the tire exceeds 5%. This happens at temperatures upwards of 530F. I had no idea that innerliner could release a significiant amount of inflammable gas. The regulation talks about hot brakes.

autoignition and explosion of a mixture of explosive vapors released from the innerliner of a severely overheated or abused tire, and any oxygen that may be present inside the tire​

(Innerliner is the thin layer(s) of rubber on the inner surface of the "doughnut". It is made from a type of rubber that has very low permeability to gases.)

Tires can get very hot without any braking. (I worked with people who measured tire temperatures in service.) As rubber flexes, it gets hot from internal friction. The thicker the rubber, and the more it flexes, the hotter it gets. An earthmover tire can reach 300F at the shoulder in only ten minutes, under some conditions. Speed limits are imposed on the trucks to keep the tires from failing due to overheating. I don't recall data for airplane tires. I do know that they are very thick, so they should heat up quickly.

I'm guessing that the reason brake temperature matters so much, is that it keeps the outside of the tire hot, so heat from the interior has no place to go.

Anyway, thanks for finding the regulation. You taught me something.

 

[1_v8_merc]

Don't know anything bout aviation tires to argue, I just use to fuel 'em and tow em.
Man what a fun job.