If I had never wanted to be corrected, I would have stayed in the womb.

Mike

Air is already 78% nitrogen, so I see little benefit, other than eliminating the water vapor (which is minuscule compared to N2 and O2 even in high humidity).

There is a measureable difference in inflation loss but it takes months of neglect ( not checking and adjusting as you have been instructed) for you to see a meaningful difference in inflation.

It is the O2 that leaks out faster and this is based on lab measurement of an increase in the % N2 in the tire over a period of several months. In fact I understand you could consider tires an O2 separator with the %N2 ever increasing over the life of the tire.

All tha claims of improvements in mileage if you inflate your tires with N2 seem to be based on the data that shows that most drivers seldom if ever check their tires.

I do not think it would be possible for a person to measure a fuel economy difference in normal driving between tires inflated and adjusted per recomendations with air vs N2.

With the claimed decrease in inflation build-up it is even concevable that you will get lower mileage with N2.

There are some long term (years) benefit by decreasing the O2 permiation into the tire structure but again if you check and adjust your tires per instructions I doubt that you will see any difference in the durability before your tires wear out in 3 - 4 years.

Tire design Engineer w/ 37 years experience.

The only way that this would be possible is if the main mechanism for air loss is permeation through the rubber. However, I do not believe that this is the case. If permation is the main mechanism, O2's higher leak rate would probably not be because the O2 molecule is smaller. It most likely would be because the O2 would have a higher solubility in the tire rubber than N2.

Another thing to point out, 0% O2 inside of a tire would not last. (still assuming permeation is the main mechanism for tire loss.) If it is possible to pump in pure N2, the partial pressure of O2 outside would be higher than the partial pressure of O2 inside and O2 would essentially permeate into the tire until the partial pressure of O2 is the same inside as it is outside.

I would love to see the study that shows O2 leaks out faster than N2. Do you have a link for this. It would be even better if it is an independent study.

Thanks.

Not sure who would satisy your def of "independant". While some individual dealers are offering N2 inflation I am not aware of any rubber company doing this on a broad basis.
Permiation is thaa mecagnism as there are studies involving thin sheets of rubber as one side of a container. If it were just soluability, the volume of rurrer would be insufficient to hold the O2. Think of helium filled balloon. We have all seen them go "flat" overnight.
RE partial pressure. Would need someone to do tha calcs as I am not sure if this works either as the higher pressure internal to the tire would have a significant effect on results.

No matter what the mechanism the facts remain
1. Tire rubber is permiable to normal gasses
2. Lab measurements show %N2 increases over time in the air chamber
3. If you maintain your tire inflation per instruction i.e. monthly, you will probably never be able to measure a fuel savings by inflating with N2
4. There is a theoretical long term ( multiple years in hot climate) benefit to tire durability with N2 inflation but again you will probably never be able to measure this as a consumer.

You could provide links to any studies. I would just like to look them over. To clarify, permeation is a function of solubility and diffusion. A gas dissolves in the rubber, diffuses through the rubber, and escapes from the other side. What I was saying is that O2 and N2 are very different chemically and I would think it would have more of an effect on their solubility than their diffusion.

Also, keep in mind that if the partial pressure of the gas is the same on each side, there will be no net change. Also, if there is 0% O2 or H2O inside the tire, the concentration of these gases will be greater outside the tire. The net effect will be that these gases permeate into the tire.

As for helium, it is much smaller than O2 and N2 and will diffuse much faster. The foil balloons provide a much better barrier for He balloons and they will last much longer.

I can believe all of this, but I would still like some links to studies if you have any. I would not have thought that permeation was the main mechanism for air loss in a tire, but I do not really have anything concrete to base this on. Also, do you know the chemical name of the rubber used in tires? If so, I could probably find some of these studies myself.

Thanks.

Here is an interesting presentation on tire aging.
http://www-nrd.nhtsa.dot.gov/vrtc/ca...inglessons.pdf
To summarize how I feel about the topic of inflating tires with Nitrogen, I can believe that it can have a small positive benefit. However, if I go to a pro-nitrogen website, I see mostly lies and a very poor understanding of what is actually going on. I would not go out of my way or pay extra money for nitrogen inflation.

Why should a tire design engineer with 37 years of experience have to cite an independent study?

Is this a problem? This does not mean that Tireman9 is wrong. I just want more detailed information so I can judge for myself. If you choose to easily believe what somebody tells you, that is fine. As for me, I want to see some studies. I even said he could provide a link to any study although I would prefer an independent study. If this topic was a real issue, I'm sure there would be independent studies.

I think it's a touch rude. If he really does have 37 years of experience in tire design, he's an expert in his field. Anything he says carries as much weight as any independent study. I'll gladly yield to his expertise.

If he's not a tire engineer with 37 years of experience, he's bats**t insane. That's a really weird thing to lie about.