Nitrogen tires

[ssnsvibe09]

Absolutely, I am talking perfect world mathamatics, but from the reading that I have gone through.... Apparently for every 3 N2 molecules that are lost through permation, 10 O2 modecules are gone. Imagine over the course of several years filling 1 or 2 PSI of atmosophere, the concentration would approach purity and it was free.

The avid maintainer usually top up 1 or 2 PSI a month, where the folks that have nitrogen filled tire, many only check once a year with limited risk. That is the only real advantage in my opinion. I do have personel experience with respect to the N2 option.

I have both variations here, my truck has N2 filled by the manufacturer. my car had it for a while when I got my P4's installed but is was a hassle to get topped up even just every 6 months. I had to practically make an appointment to get topped up... About 1/2 hour of my time each visit. as I stood around and waited for the bay to open up.

I currently top up with normal atmosheric air in both vehicles. it is free and only takes 2 minutes one a month.

Maybe we need to get somebody with set of old tires that are still be used and maintained with normal air and get a gas sample test done.

My bet is 23 dollars (the cost of N2 in Nova Scotia per set of tires), on the fact that the concentration of N2 in those tires are very high, well beyond 79% and I would support a bet at 95% and up.

The real question in my mind is how many topups it would take to equate the concentration?

How has a gas detector, and some time on there hands?

[ecomodded]

I think my tires threw osmosis have about 90-95% nitrogen in them now !

I own my own own small tank air pump , I think i should start selling nitrogen fills , $1 a tire for 79% at first 90-95% over time I will offer them the Math as proof , as we suspect oxygen leaks out faster at the same pressure.. Money to made that's for sure !
Remember Air has only 20% oxygen meaning there can only be a possible 20% difference in air loss time , but should be more like 5-10% when compared to to the small percent of difference in oxygen amount mathematically.

from link
The Reality

In 2007 Consumer Reports published a comparison of air-inflated tires and nitrogen-inflated tires to see how fast each type lost pressure (article here). It was a pretty thorough test, involving 31 different models of automotive tire inflated to an inital pressure of 30 psi, with the loss of pressure measured over a period of one year. Detailed results are shown in a spreadsheet, but what it all boils down to is that on average the air filled tires lost 3.5 psi, and the nitrogen-filled tires lost 2.2 psi. 3.5 divided by 2.2 equals a leakage rate for air that is 1.59 times as great as nitrogen. That's remarkably close to what the theory predicts.

If you check out that spreadsheet (see link, previous paragraph), you'll notice there's a wide variation in pressure loss from tire model to tire model. Some tires lost a fraction of a psi, while the BF Goodrich tire lost around 7 psi. So if your buddy notices his new nitrogen-filled tires are hardly losing pressure at all, ask him if they're the same brand as his old tires. There may also be a difference in leakage rates between brand new tires and tires that have racked up thousands of miles. Nitrogen for Tires: Question #4

[GTR]

Probably also a difference between tires and wheels that are sitting with weight on them and tires and wheels that are just sitting there ummounted on a car.

In my nitrogen filled GTR tires which have lost little to no N2 over the last 5 years, it sat during this winter for 3 months without moving. Came out to start it up, 3 tires lost no N2, and 1 tire was down from 28lbs (cold) to 12lbs. Filled it up with air and drove it around....and it hasn't lost any more air in the ensuing 2 months.

Aside from the strange massive loss during those 3 winter months, it's pretty cool to never have to fill your tires up for 5 years.

[RedDevil]

About the theory that the oxygen inside a tire will get out faster than the nitrogen:
That is very easy to test.

All you need to do is release some of the air from one of your tires that you've pumped ages ago and collect it in a large plastic bag.
Now light a lighter inside the bag, releasing as little as possible.
If indeed the oxygen has escaped the lighter shoud not burn at all. Not if there is less than 15% oxygen.

It will ultimately run out of oxygen if the bag contains pure air too, of course, but not immediately. I predict it will do just that with any air from an air filled tire, and even with some so-called nitrogen fills. Unless every nitrogen pump holder is honest and not interested in a quick win.

I'm gonna do this test on my tires tomorrow if weather permits. My summer tires hardly leak at all, most of what is in there has been there for over 2 years now.

EDIT be pretty damn sure there are no combustibles in the tire before you do something like this! Ever used a tire repair kit on a tire, then keep away fire.
Test in the bag, not at the valve. An explosion in a thin plastic bag is just a bang. An explosion confined in a tire may cause serious damage when that rips.

[ecomodded]

That's a good idea RedDevil , That test sounds pretty sound.

I found in wiki that Nitrogen gas is about 3% lighter than Oxygen, then I found its atomic make up, it looks like oxygen has a larger "footprint" or mass so it should not leak faster then nitrogen, if I read the information correctly this myth is Busted !
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



- Oxygen -
Atomic Mass: 15.9994 amu
Melting Point: -218.4 °C (54.750008 K, -361.12 °F)
Boiling Point: -183.0 °C (90.15 K, -297.4 °F)
Density: 0.001429 grams per cubic centimeter

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




- Nitrogen -
Atomic Number: 7

Atomic Weight: 14.0067

Melting Point: 63.15 K (-210.00°C or -346.00°F)

Boiling Point: 77.36 K (-195.79°C or -320.44°F)

Density: 0.0012506 grams per cubic centimeter

~~~~~~

[niky]

Originally Posted by Old Tele man

IF that were "true" then eventually all of the O2 would 'seep' away and leave only the 78% N2 and 1% "other" gases behind! Which ain't what happens.

I think the article by the NHTSA (or some similar group) was linked here a dozen pages back.

What happens is that the partial pressure of oxygen equalizes between the inside and outside of the tire.

If your tire is pumped to twice atmospheric pressure (around 28 psi), your 20% oxygen will, over time, become around 10%.

Same thing with Nitrogen. Over time, the oxygen seeps in until you have nearly 10% oxygen (at 28 psi)... or around 8% or less if you have 35 psi or more.

But, from what I recall the paper said, this takes a very long time.

[ssnsvibe09]

Your elemental numbers for Oxygen and Nitrogen atoms are bang on, but those two elements are bonded in pairs in normal chemical state of the gases. (apparently I am better at chemistry at 44 than I was at 16...LOL)

It seems that the bond between the two Oxygen atoms is just slightly more compact than the bond between the Nitrogen atoms.

Think of the rubber in the tire as a filter media... We are talking about portions of a billionth of Meter, Dioxygen molecules have a smaller crosssection compared to Dinitrogen therefore they slip through the rubber more readily.

The link below is what has helped me. Now it is from a supporter of nitrogen but I would think the physics and chemistry of basic elements could not be construed.

http://www.getnitrogen.org/pdf/graham.pdf

[niky]

Since oxygen permeates much faster, the simple way to get 92% Nitrogen is to fill to 50 psi and let the oxygen permeate out:

http://www.nhtsa.gov/DOT/NHTSA/NRD/M...094.pdf‎

if a normally maintained in-service tire is not punc*tured or deflated, the faster diffusion/consumption of oxygen relative to the nitrogen content ofthe inflation gas results in an increase in the percentage of nitrogen gas from the original 78 per*cent to as high as the 91 percent observed, thus lowering the effective rate of inflation pressureloss.

They didn't use such high inflation pressures, but it's an interesting idea... considering many hypermilers use significantly higher than the 29 psi used in the field aging test.

Want 95% nitro? Keep filling with 60 psi, and eventually, you'll get there.

[markweatherill]

I definitely want my tyres filled with 'Nitrogen Enriched' air.

[RedDevil]

Like I promised I tested the air in my tires.

When I bought one and a half year ago I raised the pressure to about 42 PSI. Kept checking and occasionally adding a bit to compensate for lost pressure.

Today I took a small plastic bag, a long nozzled gas lighter, a tiny stick and a rubber band and went testing.

First test, filled the bag with air from inside the house. Put the lighter in, ignited it, burnt fine for 7 seconds. Cut the flame when the bag began to wrinkle.

Second test, filled the bag with air from the tire (tripped the valve with the stick inside the bag). The lighter would not light. I coud see it spark, but it refused to flame even once. There was not enough oxygen to cause any kind of reaction.
Smelled the air from the bag as I let it out, smelled like rubber and unburnt lighter gas as expected, nothing else.

Third test, lighter in open air. Fired up fine, as expected.

Fourth test, held my breath for some time and then blew up the bag. Put the lighter in. Fired up just like in the other pure air tests, even though there must have been less oxygen in the bag.

So, I have only put air into the tires, quite some over time.
I am not the first owner though, they may have been filled with nitrogen initially, but I doubt it. The first year the tire pressure did drop off gradually in all four tires; this effect diminished over time to almost none now.

What is certain is that there is not enough oxygen in the tires to make a flame burn, while that flame does burn quite normally in slightly oxygen deprived (exhaled) air.
So the air in the tires has lost a substantial amount of oxygen.

The fact that the rate of pressure decline went down noticeably over time also confirms that nitrogen does in fact seep out less easily.
I did not expect that.
Myth confirmed, I guess.

So, apparently there is a benefit from filling tires with "nitrogen enriched" (oxygen depleted) air. They will keep their pressure better than tires filled with plain air, as those will lose most of their oxygen.
Having said that, you will need to keep an eye on the tire pressure regularly regardless of what they are filled up with, and in the end you will end up with almost pure nitrogen anyway.
You will just need slightly more air than if you use pure nitrogen.

As for better ride quality etc; obviously even if it does make a difference it is hardly an issue as the oxygen will get lost anyway.