Nitrogen vs compressed air in tyres tested

The Van der Waals radius, the effective size of a molecule, for N2 is 1.55 Å (Angstrom) and 1.52 Å for O2. Heat capacity, how much energy does it take to heat up, N2 1.04 J/g.K and O2 0.92 J/g.K. So the nitrogen molecule is slightly larger than oxygen, so cannot tunnel through rubber or other molecules that easily, and it also take more energy to heat up. Hence, even though the differences are small, and in normal air you have only about 21% oxygen, it should theoretically do the things that the "fill with nitrogen" people market. In racing, where milliseconds matter, it probably makes a difference.

Air being dried or nitrogen being dried is same difference - the one is not naturally "drier" that the other, as neither of them is water. One could make a slight argument that O2 is more polar than N2, hence would attach more to the (also polar) water, but that is not significant on the non-molecular level where we want water removed to fill tyres. However, some of the devices that remove the oxygen from air to provide the nitrogen used to fill tyres, might also extract the water with the oxygen, if present in the incoming air stream, while not all compressors used to fill tyres with air have the necessary water traps and/or chemical dryers in the line.

The one thing that is not well known, nor shown, is that any degradation of rubber and plastic (synthetic rubber used for tyres), as well as metal and just about anything on earth, is normally from reaction with oxygen; chemists call it oxidation, and the one we deal with every day, is called rust, which is oxidation of metal. Nitrogen is fairly inert, i.e. it does not react easily with other chemicals, so does not cause the same degradation. Also, the gas inside a tyre is at higher than ambient pressure normally, so the partial pressures of all the gases inside are increased, so any influence, chemically speaking, from gas inside a tyre is enhanced, more so than the gas outside the tyre at lower pressure. So, if you keep your tyres on your car for say, a decade (or a few decades), the nitrogen filled ones should last longer as the rubber will degrade slower :)
 
How many of you bother to supervise the filling of tyres? How many of you bother to check that the "air" or Nitrogen coming out of that hose is at least "dry" to the touch before allowing it to be used to fill the tyres?

How does anyone ensure the total replacement of the gases in the tyres with Nitrogen? At best, the "stuff" you get at filling stations increases the proportion of Nitrogen from about 78% to >78%. Hence any subjective test done as per OPs article is full of holes. The outcome, therefore, means very little in practical terms.
 
R13... said:
We evolved to work that way, if the air turned 100% O2 we wouldn't survive. Would probably burn to death before suffocation, which may be the same thing in the end.
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Yeah but think how everyone always thinks we need oxygen, when in fact we predominately breath nitrogen.
 
Neuk_ said:
Meh, I use shitty Jhb air in my car tyres and I very rarely have to top them up, the most I do is adjusting pressures for when we are fully loaded and on a long trip.
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The potholes don't discriminate so no real benefit with nitrogen.
 
Hennie_Mouton said:
The Van der Waals radius, the effective size of a molecule, for N2 is 1.55 Å (Angstrom) and 1.52 Å for O2. Heat capacity, how much energy does it take to heat up, N2 1.04 J/g.K and O2 0.92 J/g.K. So the nitrogen molecule is slightly larger than oxygen, so cannot tunnel through rubber or other molecules that easily, and it also take more energy to heat up. Hence, even though the differences are small, and in normal air you have only about 21% oxygen, it should theoretically do the things that the "fill with nitrogen" people market. In racing, where milliseconds matter, it probably makes a difference.

Air being dried or nitrogen being dried is same difference - the one is not naturally "drier" that the other, as neither of them is water. One could make a slight argument that O2 is more polar than N2, hence would attach more to the (also polar) water, but that is not significant on the non-molecular level where we want water removed to fill tyres. However, some of the devices that remove the oxygen from air to provide the nitrogen used to fill tyres, might also extract the water with the oxygen, if present in the incoming air stream, while not all compressors used to fill tyres with air have the necessary water traps and/or chemical dryers in the line.

The one thing that is not well known, nor shown, is that any degradation of rubber and plastic (synthetic rubber used for tyres), as well as metal and just about anything on earth, is normally from reaction with oxygen; chemists call it oxidation, and the one we deal with every day, is called rust, which is oxidation of metal. Nitrogen is fairly inert, i.e. it does not react easily with other chemicals, so does not cause the same degradation. Also, the gas inside a tyre is at higher than ambient pressure normally, so the partial pressures of all the gases inside are increased, so any influence, chemically speaking, from gas inside a tyre is enhanced, more so than the gas outside the tyre at lower pressure. So, if you keep your tyres on your car for say, a decade (or a few decades), the nitrogen filled ones should last longer as the rubber will degrade slower :)
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The best response yet to this thread!
 
Geoff.D said:
How many of you bother to supervise the filling of tyres? How many of you bother to check that the "air" or Nitrogen coming out of that hose is at least "dry" to the touch before allowing it to be used to fill the tyres?

How does anyone ensure the total replacement of the gases in the tyres with Nitrogen? At best, the "stuff" you get at filling stations increases the proportion of Nitrogen from about 78% to >78%. Hence any subjective test done as per OPs article is full of holes. The outcome, therefore, means very little in practical terms.
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If you are going to supervise the petrol attendant you might as well just do it yourself.

I just do it myself.
 
TheJman said:
You're like my friends haha! I often see their tyres look 'pap' and they say they always forget to check. Not sure how you forget when the guys always say "oil, water, tyres?"
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Since working from home, I only fill up once a year :p
 
PhireSide said:
Nah, we should use hydrogen. Being the lightest element, this puts less weight on the axles, thus making for a lighter car and better fuel economy.

Trust me, I'm a scientist
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Or just put all people on legally enforced diets.

No point in in wanting to save a few grams in the tires when the person driving the car is 30kgs overweight.
 
rietrot said:
Or just put all people on legally enforced diets.

No point in in wanting to save a few grams in the tires when the person driving the car is 30kgs overweight.
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That's a good plan. I could do with some kilo shedding.

Five years ago was a different story, though. If I lost five kilos back then I'd probably have fallen through my own arsehole
 
PhireSide said:
Nah, we should use hydrogen. Being the lightest element, this puts less weight on the axles, thus making for a lighter car and better fuel economy.

Trust me, I'm a scientist
Click to expand...
also hydrogen and heat go so well together, you might even end up being a real hotwheel.
 
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