tires with Nitrogen

[bighammer]

Personally, I don't believe in Nitrogen inflation for anything other than racing or aircraft use. An interesting article.

Instead, I've decided to run a specialty mixture of gasses in my tires, at specific pressures to optimize their performance. Here's my "special" formulation:

Front:
78. 1% Nitrogen at 43 psig
20. 95% Oxygen at 11. 5 psig
0. 038% CO2 at 0. 021 psig
0. 0018% Neon at 0. 001 psig
0. 0005% Helium at 0. 000275 psig
0. 0001% Krypton at 0. 000055 psig
0. 00005% Hydrogen at 0. 0000275 psig

Rear:
78. 1% Nitrogen at 39. 1 psig
20. 95% Oxygen at 10. 5 psig
0. 038% CO2 at 0. 019 psig
0. 0018% Neon at 0. 0009 psig
0. 0005% Helium at 0. 00025 psig
0. 0001% Krypton at 0. 00005 psig
0. 00005% Hydrogen at 0. 000025 psig

Those are approximate numbers, of course. Takes be about 2 hours to get the mixture just the way I like it, but I've found it optimizes tire life and my tires typically lose <1 psig over 6000 miles.

[You gotta have a lot of time on your hands to come up with stuff like this]

-Ryan

So Ryan, for your special mix are you offereing a TDR discount of $7. 50/ tire (instead of the normal $10)

 

[MCummings]

Wierd. That's the same ratio, but at varying pressures for my twin turbo setup. Odd.



Coincedence?



Merrick

 

[klenger]

What's the high altitude recepie?

 

[CarlsonR]

the reason all commercial aircraft are required to use nitro is for fire saftey only. In case of on board fire you won't have a tire exploding adding 130psi of O2 saturated air in your wheel well

 

[WYoung]

When I was a kid we were preparing to move our mobile home, but the tires were pretty much flat. My Dad knew a guy who was an air conditioning tech, and he came over and inflated the tires with freon Not too much, didn't want it to expand beyond safe limits before the truck driver could get to a service station. :-laf The other funny part is the truck driver said they had used propane before in a pinch.



Wayne

 

[blacksheep4x4]

What happens if you need to fill up the tire or raise the pressure? I don't know if nitrogen is available all over the country, where you go. What happens if you mix in regular atmospheric air?

Nothing it just doesn't stay as cool. We use Nitrogen in the tires of our F-16s (I am in the Montana Air Gaurd). The nitrogen keeps the tires cooler on landings. It is always best to use nitrogen in your tires if possible. The tire pressures don't fluctuate like they do using air when they are in constant use.

Air can build up alot more heat, this is the same reason they use nitrogen in shocks instead of air. Liquid nitrogen is around -275* in temprature.

 

[blacksheep4x4]

We put regualr air in the tires on our jets (Air Force)

How long are your tires lasting. If I remember right the T. O. states that you are to use Nitrogen!

 

[Nate]

I'd have to talk to the guys in the wheel and tire shop. I work Ammo, my post was based on watching the guys work on the jets while I was out on the line delivering stuff. I can't think of a time where I've seen a nit cart out there. I've used them sometimes to fill the air tanks on our 20mm trailers, just because it's fast.

 

[george]

in vegas

Anybody know where I could get Nitrogen for my tires in Vegas?

 

[scootergmc]

I don't know of any longevity benefits, but Nitrogen is used in the roadracing world, and most of my experience dealing with that is from the motorcycle side. The primary benefit, and only one I can remember right now, is temperature resistance, i. e. , the pressure you set is the pressure you will have once the tire is up to temp, which can be a big issue w/ the handling of a motorcycle. That's the only benefit I can see. But if people are willing to pay $5 per tire for nitrogen for their tires, more power to 'em. I'm opening a nitrogen station.



I really see no benefit on the street.

 

[george]

Well, when I'm towing my 12k trailer on the highway and its 115 degrees outside the faster you go the hotter the tires get, anything that will help cool them down is a plus and $5 a tire is cheap enough compared to a possible blowout on either the truck or trailer.

 

[moparmarty]

The Costco here in Eugene, OR puts nitrogen in all the tires they mount at no additional charge. They say the nitrogen molecules are larger and don't leak out as fast. They put green valve caps on to indicate nitrogen.

 

[rbattelle]

Now I am honestly not trying to be a smartty pants here or make anyone look stupid but here is an image from a thermodynamics table. As someone else pointed out above air is predominantly nitrogen and as a result their thermodynamic properties are very similar. In the range of temperatures and pressure we are talking about here both Nitrogen and Air follow the "ideal" gas law quite closely with less than 1% deviation (Pv=RT), P is pressure, v is specific volume (inverse of density), T is temperature, R is the gas constant. Thus the conclusion that the "expansion coefficient" for nitrogen is much different from air is not correct, i. e. they have very similar values for R (actually only 3. 4 % different). Also note that the specific heats are very similar, which means that the temperature increase of the air (or nitrogen)due to absorbing thermal energy from the tire rubber will be just about the same (within about 3. 5%) and will thus result in about only a 3. 5 % difference in temperatue everything else being the same. Now I am not saying that Nitrogen doesn't have some other benefit (e. g. moisture free, no oxidation of the rubber or something else going on to reduce wear) but I don't think it is likely related to the thermodynamics of the nitrogen if there is any real impact at all. I would have to read more about the tire wear studies to convince myself.

Those who believe nitrogen tires run significantly cooler than air-filled tires would do well to review this excellent post by JOblenes. Let's look at some numbers.



Taking the ideal gas law, P=rho*R*T, for a tire filled with air and with pure diatomic nitrogen to the exact same pressure, we get the following equation:



T_N2 = [(rho_air*R_air)/(rho_N2*R_N2)]T_air



Plug in specific gravity with respect to air for N2 is 0. 9737, gas constant for N2 is 53. 2, gas constant for air is 53. 35 (ft*lbf/lbm R), and you get:



T_N2 = 1. 03*T_air



So at the same pressure, N2 is 3% HOTTER than dry air. Someone check my math...



I'm not clear on why people say nitrogen holds pressure "better than air". I have yet to hear any scientific argument as to why that would be true. Perhaps it's true, but I haven't seen any data that shows why or how.



In my opinion, nitrogen is used as an inflation medium because it's inert, and can improve tire compound life for tires used over VERY long periods of time.



-Ryan

 

[CDyksman]

I think Formula One race car tires are filled with nitrogen. I run nitrogen in my shifter kart tires. The pressure increase is much more predictable, so the kart handles more consistently.

 

[DieselFiend]

No, they're servicing aircraft tires and struts with a liquid nitrogen cart or a self-generating nitrogen cart. Nitrogen doesn't react to temp changes like regular air does. Tires stay at pretty much the same pressure not matter how hot or cold outside. Also, nitrogen is stable (doesn't expand or contract while the airplane is at high altitude).

I could be wrong... I work Ammo, so I don't deal with the jets so much.



I remember working on the flightline last year and I usually saw the crew chiefs filling tires with a low pack or hi pac (with the pressure turned down) I don't remember ever seeing a nitrogen cart on the line.



Either way, it's not worth $5 a tire!



Alot of guys have Co2 tanks in their off road rigs. Not because it's better for tires, etc... Just that it's cheap, a tank lasts a while, and it's ok for the tires.

 

[rbattelle]

Nitrogen doesn't react to temp changes like regular air does.

People keep saying this, yet we've seen that the gas constant for nitrogen is almost the same as air. How do you reconcile this?



The ideal gas law clearly shows, as JOblenes points out, that for a given change in temperature nitrogen will change pressure only about 3% less than ordinary air. 3% is hardly justification for going to the trouble of using compressed nitrogen.



-Ryan

 

[Nate]

Isn't air like 78% Nitrogen?? No way in hell I'd pay even $1 a tire to put nitrogen in my tires.

 

[george]

Called Costco yesterday and discovered they will fill tires with Nitrogen for free so all it will cost is the fuel to drive over there Oo.

 

[Slingblade]

ViperQA1 is correct. That is exactly why the Navy uses it too.



Deployed USS Abraham Lincoln (CVN-72)

No, they're servicing aircraft tires and struts with a liquid nitrogen cart or a self-generating nitrogen cart. Nitrogen doesn't react to temp changes like regular air does. Tires stay at pretty much the same pressure not matter how hot or cold outside. Also, nitrogen is stable (doesn't expand or contract while the airplane is at high altitude).

 

[cosborne]

I would pay $1 for somebody to PROVE that there is a benefit... . it can't be done. You could spend many hours reading and reading but there is NO scientific proof that there is a NOTICABLE benefit in running it in our trucks.



FWIW :-{}