Nitrogen for tires?

[lsnetman]

Nitrogen in tires

Has anyone considered using nitrogen to fill their tires? I used to do this when I lived in the mountains. As it's denser than oxygen there are less pressure changes with temperature, and reportedly better tire wear, perhaps due to better maintenance of correct pressures. IIRC, it cost $5 per tire for the fill.

 

[FlasherZ]

Nitrogen for tires?

I prefer the 78%/21% Nitrogen/Oxygen variety, myself.

 

[ecarfan]

There is really a significant difference in tire wear with 100% nitrogen compared to 78% nitrogen? I find that hard to believe. But I'm sure the company that wants to sell you 100% nitrogen is completely sincere...

See http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191&affiliate=HM5&s_kwcid=AL!3756!3!62690668813!b!!g!!_cat:tires&ef_id=U9gJfQAABDwIaCSA:20150217200853:s

That Tire Rack article says that for street driving there is no advantage to using pure N2 unless you don't drive the car very often, in which case the pure N2 results in less interior rubber oxidation and your tires might last longer. I'm skeptical, because the outside of the tire is of course exposed to lots of O2 and it will oxidize and crack. Tires should be replaced about every 8 years regardless of how much tread remains. I doubt using pure N2 to inflate them will extend that timeframe. But if someone can find evidence that it does, please post it.

This topic has been discussed extensively on many classic car forums.

 

[dhanson865]

Too bad it cannot use methane. My wife says I could provide a constant supply. (I wonder what she could have been talking about????)

I'd say she just doesn't realize how much hydrogen and carbon dioxide are in your flatulence or that the smell is from the less than 1% of volatile sulfur compounds.

Hydrogen, carbon dioxide and methane are all produced in the gut and contribute 74% of the volume of flatus in normal subjects. Not all humans produce flatus that contains methane. For example, in one study of the faeces of nine adults, only five of the samples contained archaea capable of producing methane. More recent evidence proves that the major contribution to the smell of flatus comes from a combination of volatile sulfur compounds.

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This is one the big downsides to using nitrogen in tires. You cannot easily just top off at home, so you are less likely to keep them at optimal inflation.

I get the free nitrogen fill at the tire shop, they never want to inflate them as much as I want, then I go home and fill up the rest with air. So maybe I'm running 85% nitrogen instead of 78% or 100% but it varies by tire. I had a loose valve stem and I refilled that one with regular air. Tire shop was too stupid to drain and refill after I told them what I did and I didn't want to argue about the 15% or so extra nitrogen I would have gotten if they did.

 

[Todd Burch]

Meh. As has been pointed out, air is mostly nitrogen anyway. Not a huge difference and definitely not worth $5 a fill.

 

[dhanson865]

Meh. As has been pointed out, air is mostly nitrogen anyway. Not a huge difference and definitely not worth $5 a fill.

Who charges for it? It was included free at my tire shop, I wouldn't pay extra for it.

 

[jerry33]

There is really a significant difference in tire wear with 100% nitrogen compared to 78% nitrogen?

The times when it makes a difference:

1. You are a professional racer and you're trying to tune the suspension for that last 1/100 of a second. Nitrogen is dry, so there is no water vapour expansion which can cause uneven lap times.

2. You are working underground (mine, subway, etc.) or flying a high altitude plane and you don't want the extra oxygen in case of a fire (makes no difference above ground/low altitude flights as there is already plenty of oxygen).

3. You're an amateur racer and the track you race on has no electrical connection. A nitrogen bottle is as cheap and safe as anything.

Otherwise, inflating tires with nitrogen is kind of silly. The best you can say is that it does no harm to the tires.

 

[ecarfan]

Thanks @jerry33. My skepticism about the value of 100% N2 in tires remains undiminished.

 

[lsnetman]

The times when it makes a difference:

1. You are a professional racer and you're trying to tune the suspension for that last 1/100 of a second. Nitrogen is dry, so there is no water vapour expansion which can cause uneven lap times.

2. You are working underground (mine, subway, etc.) or flying a high altitude plane and you don't want the extra oxygen in case of a fire (makes no difference above ground/low altitude flights as there is already plenty of oxygen).

3. You're an amateur racer and the track you race on has no electrical connection. A nitrogen bottle is as cheap and safe as anything.

Otherwise, inflating tires with nitrogen is kind of silly. The best you can say is that it does no harm to the tires.

in my admittedly limited experience, using nitrogen did result in significantly less variation in pressures with changes in temperature. Knowing the finickiness that some of our tires express regarding excess wear, is there no role for nitrogen to limit that variation?

 

[Cottonwood]

in my admittedly limited experience, using nitrogen did result in significantly less variation in pressures with changes in temperature. Knowing the finickiness that some of our tires express regarding excess wear, is there no role for nitrogen to limit that variation?

I'm sorry, but this just does not make sense.

The Ideal Gas Law (Gas laws - Wikipedia) states:

PV = nRT, where:

• P is the Pressure of the Gas
• V is the Volume of the gas
• n is the Number of gas molecules
• R is the universal gas constant
• T is the absolute Temperature

The number of molecules has nothing to do with what kind of molecules they are, and as long as the volume stays the same, pressure changes with absolute temperature, period.

 

[roblab]

I'm sorry, but this just does not make sense.

The Ideal Gas Law (Gas laws - Wikipedia) states:

PV = nRT, where:

• P is the Pressure of the Gas
• V is the Volume of the gas
• n is the Number of gas molecules
• R is the universal gas constant
• T is the absolute Temperature

The number of molecules has nothing to do with what kind of molecules they are, and as long as the volume stays the same, pressure changes with absolute temperature, period.

Thank you for sense in all the nonsense. (I tried to make something out of N2, but I couldn't do it) +46psi.

Also good to note that it uses ABSOLUTE temp, 273 degrees K, so the scale is considerably larger and temp change considerably smaller, than when using degrees C or F.

 

[Electroman]

The last time I bought a new car there was a line item for $100 for Nitrogen filled tires.

 

[woof]

The number of molecules has nothing to do with what kind of molecules they are, and as long as the volume stays the same, pressure changes with absolute temperature, period.

Thanks, I was gonna respond in kind, but then started thinking about phase change from gas to liquid, as water vapor introduced on a hot day might condense on a cool one, and then it's no longer a gas and PV=nRT no longer applies. Does anyone know if this is the case?

 

[jerry33]

Thanks, I was gonna respond in kind, but then started thinking about phase change from gas to liquid, as water vapor introduced on a hot day might condense on a cool one, and then it's no longer a gas and PV=nRT no longer applies. Does anyone know if this is the case?

Well, yes. I saw some tires that had six inches of water in the bottom after mounting at the vehicle factory. The water froze and the drivers complained about vibrations. Best practice is to have a line dryer between the compressor and the tires when filling. This will dry the air and prevent that. Even draining the compressor daily will help a great deal. Checking the pressure in your tires regularly will do more than anything else you can do to keep them in good shape.

 

[roblab]

Thanks, I was gonna respond in kind, but then started thinking about phase change from gas to liquid, as water vapor introduced on a hot day might condense on a cool one, and then it's no longer a gas and PV=nRT no longer applies. Does anyone know if this is the case?

And Nitrogen doesn't take care of water in the tank, either.

 

[doctorwho]

Lot of talk about inflating tires with nitrogen. Is it worth it or should i just get a decent inflator for home and keep tires properly inflated?

I've used it in my tyres for about 15 years. The tyres don't leak, I've given up regular tyre pressure checks as the readings were always spot on. Of course it doesn't prevent a puncture but its inexpensive and well worth it for me.
The only negative I can think of is that I've become complacent about checking pressures but its never become a problem

 

[SteveS0353]

I've used it in my tyres for about 15 years. The tyres don't leak, I've given up regular tyre pressure checks as the readings were always spot on. Of course it doesn't prevent a puncture but its inexpensive and well worth it for me.
The only negative I can think of is that I've become complacent about checking pressures but its never become a problem

I run nitrogen in my tires and they definitely maintain proper inflation longer than when I use compressed air. Here is a scholarly paper on the subject... http://www.getnitrogen.org/pdf/graham.pdf explaining the scientific principles. The conclusion reads...

"O2 permeates faster through rubber than does N2 and a major aspect of why it is a good idea to significantly reduce the amount of O2 used to fill tires by replacing most of the O2 in air with enriched N2. Since N2 permeates through the tire rubber more slowly than would O2, using enriched nitrogen instead of air for tire filling contributes to better maintenance of the proper inflation pressure for the tire."​

 

[FlasherZ]

I run nitrogen in my tires and they definitely maintain proper inflation longer than when I use compressed air. Here is a scholarly paper on the subject... http://www.getnitrogen.org/pdf/graham.pdf explaining the scientific principles. The conclusion reads...

"O2 permeates faster through rubber than does N2 and a major aspect of why it is a good idea to significantly reduce the amount of O2 used to fill tires by replacing most of the O2 in air with enriched N2. Since N2 permeates through the tire rubber more slowly than would O2, using enriched nitrogen instead of air for tire filling contributes to better maintenance of the proper inflation pressure for the tire."​

Remember to follow the money:

Dr. Keith Murphy
Air Products and Chemicals, Inc.
Prism Membranes
St. Louis, MO

 

[Barry]

"O2 permeates faster through rubber than does N2 and a major aspect of why it is a good idea to significantly reduce the amount of O2 used to fill tires by replacing most of the O2 in air with enriched N2. Since N2 permeates through the tire rubber more slowly than would O2, using enriched nitrogen instead of air for tire filling contributes to better maintenance of the proper inflation pressure for the tire."

If that is correct, your tires would approach 100% Nitrogen over time.
If you start with 80% Nitrogen and20% Oxygen, and you are losing Oxygen preferentially, your Nitrogen concentration increases. Even after adding with 80% N2 and 20% O2, your N2 concentration is higher than air. Or am I missing something?

 

[liuping]

If that is correct, your tires would approach 100% Nitrogen over time.
If you start with 80% Nitrogen and20% Oxygen, and you are losing Oxygen preferentially, your Nitrogen concentration increases. Even after adding with 80% N2 and 20% O2, your N2 concentration is higher than air. Or am I missing something?

That is correct. With each fill you will have a higher and higher nitrogen content. Just one more reason to be suspicious of all the "benefits" promised by Nitrogen fill proponents.