Nitrogen tires

[CapriRacer]

Mr. Monkey,

Unfortunately you neglected to mention the Law of Partial Pressure of Gases (also known as Dalton's Law) that states that you can treat a mixture of gases (like air) as though they were individual gases. So at sea level, where the atmospheric pressure is 14.7 psi and oxygen is 21% of the mixture, 02 has a partial pressure of 3.1 psi.

What happens is that oxygen will flow through the tire, into the air chamber as though there is 3.1 psi pure oxygen on the outside, instead of an air mixture - in spite of the nitrogen flowing out.. Yes, this has been verified.

So, No, the rubber inside the tire gets to see oxygen, but at a lower pressure than if the air chamber is filled with pressurized air. And, of course, when the oxygen combines with whatever it combines with in the rubber, the partial pressure insures that more oxygen is moved into the interior of the tire.

[oil pan 4]

Originally Posted by Howlermonkey

It is largely something used to generate revenue but there are a couple of minuscule advantages already mentioned on this thread and one that is not.

Oxidation........in that oxidation requires the presence of oxygen or ozone to occur.

Rubber is aged by oxygen and ozone to the point that areas with high ozone levels experience rubber products such as tires, belts, and hoses experience significantly shorter lifespans.

Tires are porus and the pressurized gas inside them will seek to pass through them to reach a lower energy state (lower pressure).

If the gas passing through the tires contains no oxygen or ozone, the tires will likely last longer before suffering what people label as "dry rot".

Also, this constant outflow ensures that all but the exterior surface are never exposed to any "air" containing oxygen or ozone in addition to the previously mentioned lack of moisture.

Thats all well and good if you want to keep tires on your vehicle for 10 or 12 years.
If you want tires that old on your vehicle you are a suicidal idiot.

Only advantage I see from oxygen depleted inflation media is on trailer or RV tires that will dry rot off befor they wear down.
With on road vehicles the tread mysteriously rots off due to contact with the road for me.

You would be better off covering the tires, keeping the sun off them than filling them with snake oil.

[Frank Lee]

Ha- I didn't know I was a suicidal idiot until just now!

[oil pan 4]

I have done it before too, my conclusion was its a bad idea.
On a truck hard working truck tire I have found that right around 10 to 12 years the tread package and steel belt have a tendency to stop liking each other. When they do that they want to seperate, most of the time they like to seperate while you are driving down the highway.

On cars its more like 12 years, the side walls just crack so much you wash you car one day and see soap bubbles forming on the side wall. And then you just found that slow leak you have had for a while.

capri racer has the stats for numbers of accidents and fatalities caused by tire failure, most failures are due to neglect and old age. The number was a lot more than I thought it would be.

[Frank Lee]

I run 'em to failure and extract the last possible mile. Sometimes that means blowouts and flats. Sometimes I deem the tire a good candidate for getting a tube if the tread is still deep. Never has it caused anything worse than a minor inconvenience.

I'll have to look for a date code on the wide whites the '59 wears in the spring when I get it out- they have to be 20 years old and their gonna stay on there until they physically can't.

[Howlermonkey]

Originally Posted by CapriRacer

Mr. Monkey,

Unfortunately you neglected to mention the Law of Partial Pressure of Gases (also known as Dalton's Law) that states that you can treat a mixture of gases (like air) as though they were individual gases. So at sea level, where the atmospheric pressure is 14.7 psi and oxygen is 21% of the mixture, 02 has a partial pressure of 3.1 psi.

What happens is that oxygen will flow through the tire, into the air chamber as though there is 3.1 psi pure oxygen on the outside, instead of an air mixture - in spite of the nitrogen flowing out.. Yes, this has been verified.

So, No, the rubber inside the tire gets to see oxygen, but at a lower pressure than if the air chamber is filled with pressurized air. And, of course, when the oxygen combines with whatever it combines with in the rubber, the partial pressure insures that more oxygen is moved into the interior of the tire.

Incorrect.

"Tire pressure" is the pressure differential between atmospheric and the pressure inside the tire.

The flow of the pure nitrogen from the higher energy state (inside the tire) through the porus tire to the lower energy state (outside the tire) ensures very little, if any oxygen contacts anything but the outside surface of the tire.

[t vago]

Originally Posted by Howlermonkey

Incorrect.

"Tire pressure" is the pressure differential between atmospheric and the pressure inside the tire.

The flow of the pure nitrogen from the higher energy state (inside the tire) through the porus tire to the lower energy state (outside the tire) ensures very little, if any oxygen contacts anything but the outside surface of the tire.

So, if N2 can flow through a porous barrier, from one side that is at 14.7 psia, to another side that is at 11.8 psia (roughly the partial pressure of atmospheric N2), then...

Why can't O2 flow across that same porous barrier, from one side that is at about 2.8 psia (roughly the partial pressure of atmospheric O2) to the other side that is at 0 psia?

[niky]

Originally Posted by Howlermonkey

Incorrect.

"Tire pressure" is the pressure differential between atmospheric and the pressure inside the tire.

The flow of the pure nitrogen from the higher energy state (inside the tire) through the porus tire to the lower energy state (outside the tire) ensures very little, if any oxygen contacts anything but the outside surface of the tire.

You're talking to one of the tire-gods of the internet.

But if you don't believe him, maybe you'll believe the NHTSA:

http://www.nhtsa.gov/DOT/NHTSA/NRD/M...009/811094.pdf

Tires inflated with nitrogen of greater than about 97 percent purity actually gained oxygen during the 90-day test. This strongly indicates that the change in oxygen in the tire cavity is primarily a result of diffusion and not reactive consumption of the oxygen.

Whereas tires inflated with regular air went from 20% oxygen to 15%...

The only way to keep new oxygen out of the tire is to have a certain percentage of oxygen such that the partial pressure of oxygen inside the tire is the same as the partial pressure of oxygen outside it.

The kicker:

The results for 23 tires subjected to hundreds of hours of laboratory roadwheel aging with air,50/50 N2/O2, or nitrogen inflation were inconclusive. Results did not indicate a correlation be*tween the inflation gas used and the time to failure in this particular roadwheel durability test

They did successfully get a few tires to fail, but only by oven-aging them while inflated with oxygen-enriched (not normal) air.

[CapriRacer]

Originally Posted by niky

You're talking to one of the tire-gods of the internet.
.......

Nope, more like Pope - you may kiss my ring.

Originally Posted by niky

.....They did successfully get a few tires to fail, but only by oven-aging them while inflated with oxygen-enriched (not normal) air.

What was interesting about the failures is that only the Cooper's, Sumitomo's, and Hankook's failed - and BOTH of the tires tested failed - suggesting that there is something different about those brands.

[oil pan 4]

A reason to use nitrogen or some less reactive gas in tires:

http://m.youtube.com/watch?v=jBUVzgCHHuA