Nitro Tires

Cowcatcher · **Posted:** Thu Sep 14, 2006 5:14 pm

This got kinda sorta touched on in another topic so I thought I would start a new, specific thread. It was cold last night and my 38 lbs per tire dropped to 33. It got me to thinking!

In the other topic someone offered that for the average motorist the nitrogen in the tires was of questionable added value. Is it? It seems to me that if nitrogen keeps your tires at a more even pressure it pays in multiple ways including tire life and fuel economy.

DarbyWalters · **Posted:** Thu Sep 14, 2006 7:11 pm

Yep...it expands and contracts at much slower rates. Plus you can run air tools off the bottle in your barn :wink:

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

Air and nitorgen expand and contract at near the same rate.

Just take the ideal gas law for example. PV=nRT
Pressure decrease proportional to temperature.

Yes, that is the ideal gas law. However, both air and nitrogen are near ideal gases any where near those pressures. Also, air is 78% nitrogen so you pretty much have all nitrogen anyways.

The compressibility factor (Z) for N2 is 0.9997 and the same for a dry air.
The compressibility factor measures how much the gas deviates from the ideal gas law. A value of 1 means no deviation. Therefore you can see both N2 and air are almost identical in thermal expansion and follow the ideal gas law very well. No notical difference in thermal expansion between air or nitrogen.

Wet air will be a slight bit different, but I am willing to bet it doesnt deviate more than 10% from the ideal gas law. If I had my handbook with me I could give you numbers on Z for damp air.

Hence, you might be able to tell a 1 psi diffence between a N2 inflated tire and a tire inflated with very humidy air if you where lucky.

And all that is from a chemical engineering, but don't take my word on it just search around on the web and you will come to the same conclusion.
http://www.cartalk.com/content/columns/ ... er/05.html

vtdog · **Joined:** Fri Sep 30, 2005 11:27 am **Posts:** 640

Even Avogadro understood: nitrogen filling of tires is just alot of hot air designed for those who have not spent enough on secret oil enhancers and mpg increasing potions

DarbyWalters · **Posted:** Thu Sep 14, 2006 9:45 pm

I will say just a couple things about the "air" vs "nitrogen" when it comes to tires and air pressure. Both sets of tires being equal, including leak rate, the pure nitrogen filled tires will show a couple of things over air filled tires. Nitrogen is a bigger molecule and will tend to "leak down" slower. Nitrogen will also have no moisture as the "air" filled tires. Water will expand at a higher rate than pure oxygen or nitrogen. This expansion rate of the "water" inside a tire is what causes the change. So there is a difference but it is probably negligent when it comes to a passenger tire unless you pay "close" attention to air pressures.

When it comes to "racing" the reason is more pertinent. With tire temperatures above 180 or more, small differences make a bigger difference in handling. When I raced with Mazda and Karting, tires temps would dictate pressure changes in increments as small as 1/10 of a pound sometimes to get dialed in. The reason we used "nitrogen" was to limit variances...and...run power tools.

oldnavy · **Posted:** Thu Sep 14, 2006 11:47 pm

I used it to see if the leak down was less and keep moisture out of my tires. So far after 6 months the tires are still holding same pressure on my digital tire pressure gage. I have only spent $10 for the N fill and top ups are free.

Desert_Busa · **Posted:** Fri Sep 15, 2006 12:35 am

I'll stick to the N78 brand of tire filler. N100 may sound like a good idea, but when you really get down to it the sidewall states N78 pressure limits and not N100 pressure limits. If the dealer finds out that N100 is in the tires, our warranties will be voided and possible rejection of an egr replacement. While testing in some of the hottest desert testing grounds, there have not been any problems on the Jeep using N78 or seepage of the O21 contained within.

DarbyWalters · **Posted:** Fri Sep 15, 2006 7:25 am

Desert_Busa wrote:

I'll stick to the N78 brand of tire filler. N100 may sound like a good idea, but when you really get down to it the sidewall states N78 pressure limits and not N100 pressure limits. If the dealer finds out that N100 is in the tires, our warranties will be voided and possible rejection of an egr replacement. While testing in some of the hottest desert testing grounds, there have not been any problems on the Jeep using N78 or seepage of the O21 contained within.

True but they might also void all warranties if the X22 that is not covered by the N78 is not of the same concentration and properties as the N78/X22 that was supplied at the factory. I have heard that you can order thru a 5 Star Dealer the correct mixture...but it is on back order due to Ball Joint shortage. :wink:

vtdog · **Joined:** Fri Sep 30, 2005 11:27 am **Posts:** 640

The N78 air is also approved for respiration by Dr. Z

Cowcatcher · **Posted:** Fri Sep 15, 2006 11:24 am

vtdog wrote:

The N78 air is also approved for respiration by Dr. Z

NO! Dr. Z only apporves N2O for respiration.

DarbyWalters · **Posted:** Fri Sep 15, 2006 1:42 pm

SO...TO COVER EVERY BASE...We should put laughing gas in our tyres...that way when you have a leak, it just makes you giggle like a little girl

Nitro Tires

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