Nitrogen vs. Air in your tires

[RVhauler]

Believe that the auto racing industry basically uses nitrogen to prevent tire pressure changes which would affect the chassis set up

[Barrier2]

Just curious how would one compensate for weight variations when corner weighing a coach? Does anyone who uses Nitrogen carry spare cylinders of Nitrogen?
It seems to me that the benefits which are claimed reminds me of the "Magnetic fuel mileage extenders or mothballs in fuel tanks.
In all fairness I do understand that the difference in molecular size reduces any leakage with temperature change with hot and cold cycling of the tires.
Robert

[TandW]

I'm thinking the oxygen gets taken up anyway. Steel wheels rust. Aluminum corrodes.

[TandW]

Racing tires aren't on the rims long enough for oxidation to be a factor, therefore the immediate need for a nitro-fill.

[Flagelpater]

My question is, With Air the tire chart anticipates a PSI rise as the tire heats up, but the Nitrogen Serviced Tire will Not have that PSI rise, so, should we increase the PSI and amount equal to the anticipated Air Serviced tire when filling with nitrogen? My Air Serviced coach tires rise 12 PSI above 95 PSI Cold.

[TandW]

Flagelplater, does this chart you are referencing account for snow or ice on the road?Does it account for asphalt or concrete or even dirt. Does it account for your style of acceleration/deceleration and /or cornering habits. Why does it seem you insist on overinflating your tires. I'm certainly no tire engineer, but then I just can't make sense of your insistance on overinflation for static pressures.

[RVDude]

Some folks really like those green valve stem caps. It's all good. In our car/RV applications, the practicality is that N2 is more of a fashion statement, than it is a measurable performance benefit.

Make no mistake, most of the N2 claims are true, within extreme or laboratory conditions. Cars/RV are not extreme or laboratory conditions. So yes, N2 has benefits, and yes the benefits really aren't measurable/cost effective for regular car/RV use. So "yes", everyone in this ongoing religious debate is "right" to a point. And "yes" there is no harm in using N2 (except to the wallet) and "yes" there is no right/wrong answer to which gas to use. It is merely a question of choice.

Nitrogen is commonly used in auto shops now for 2 practical reasons 1) it is quicker to fill a tire and 2) it is drier than poorly filtered shop air. Both are important things. What's the real reason? The shops score a price premium and/or a service level distinction for selling it to you and putting on those green caps. So it is all about greed from the shop's perspective. That's it - no other meaningful or discernible performance reason on cars/RV. Race cars and aviation (both extreme uses) enjoy the added benefit of N2 thermal properties and other aspects mentioned which are slightly better than air and in these extreme applications is actually measurable.

Air and N2 both change with temperature - has to by physics. So YES seasonality temps will affect pressure in either. To be realistic, we just can't measure it effectively with the imprecise equipment we all have and under the infinitely variable conditions we measure in. We can do the temp expansion calculation if you really insist. It's the ideal gas law, PV=nRT from which we can derive P1/P2 = T1/T2. Which says the change in pressure is proportional to the change in temperature where volume is constant. Applies to all gasses to differing degrees. So while we can mathematically prove the subtle thermal benefits of N2 over air, our home equipment and car/RV performance characteristics will not be able measure it. But, "feeling" better about it is just as important so those those that use N2 "feel" better and that's good.

If any of us common folk has a gauge precise enough to register the thermal expansion difference between an air filled tire and an N2 filled tire then you have a laboratory instrument under laboratory conditions. Not sitting in our driveway with a Wal-Mart gauge conditions. Air is 78% N2, do you really think you have the experimental conditions and laboratory equipment to measure the thermal difference between 78% air and 95% N2 in your tires?

In our car/RV applications - hardly extreme conditions - N2 will not run discernibly cooler than air. Just think about that. It's the flexing of the sidewall that heats whatever is inside, not the other way around. Again, in our car/RV applications, there is no way you'll be able to tell the thermal difference between either gas.

Air oxidizing the inside of the rims and changing performance by wheel corrosion is really pushing physics and chemistry. BTW, aluminum "corrodes" (oxidizes) far far far faster than steel. In fact, Al oxidizes so rapidly it makes an extremely powerful explosive.

The sun through UV destroys from the outside in, so whatever is inside the tire makes no difference to UV decomposition. Carbon Black is the substance in the tire to deter UV, regardless of either air or N inside.

Yes, N2 inside will not oxidize the rubber as fast as air from the inside out, but really, do you think you can actually isolate the difference and measure it?

Green caps are the new cool. The one up on the Jones' thing. YES, technically there is a difference. Is it a meaningful and measurable difference to warrant the cost and effort to maintain N2? That is a personal choice.

Either choice is right - as long as it means we inflate our tires correctly (based on weight and ambient temperature) and monitor that inflation!

Here's an interesting perspective:
Consumer Reports Cars Blog: Tires - Nitrogen air loss study

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[Flagelpater]

TandW We are not sync. The OP questioned the accuracy of the advertisement. My response indicated that only by operators Not taking proper care of their tire pressure could the advantage stated be possible. Then, I posed, that the Tire Charts for proper inflation are for Air, Not Nitrogen. It is my understanding that the Tire Chart prescribes a Cold Tire Pressure to obtain a proper sidewall profile. If Nitrogen were used, I would think a Nitrogen Tire Chart should be used. And, I have never seen one for a car or RV. I do not intend to overinflate my tires, but, I am concerned that those that do use nitrogen May Be underinflating their tires. Am I still missing something? Where did you find the proper tire pressure for your rig?

[TandW]

Dude, you might know that I for one am just too damned old and tired to be worried about Charles' Law or Boyle's Law. Hell, why am I worrying at all?

[Route 66]

Another solution to a non existent problem, IMHO.

[RVDude]

Originally Posted by TandW

Dude, you might know that I for one am just too damned old and tired to be worried about Charles' Law or Boyle's Law. Hell, why am I worrying at all?

Originally Posted by Route 66

Another solution to a non existent problem, IMHO.

TandW and double 6 have said it best!

Right on and more power to Klaatu!

Now where did I leave my cocktail?????

PS Sidewall tire pressure is most likely significantly OVER inflated on most applications (unless your application is at the maximum rated weight for the tire).

[TandW]

Flagelplater, for all of my days so far my tires have been inflated on every vehicle I have ever owned to what is stated on the tire sidewall to be the maximum cold inflation pressure. Sometimes during the winter I have deflated tires on 2 wheel drive vehicles to gain emergency traction.

[Flagelpater]

TandW I think your comment to Dude summed up your position best. Why do they waste money embossing the word Maximum in the label Maximum Cold Inflation Pressure? Why don't they just state Cold Inflation Pressure? Sidewall flexing does generate the heat and higher PSI will result in less flexing. However, the tires are part of the suspension system and proper inflation is part of the overall equation for shock absorption, not just for ride comfort, but also for chassis reliability as well. Flagelpater

[Flagelpater]

Isn't life great when we can sit here and talk about tire pressure! Flagelpater