Whats the advantage of filling the tires with nitrogen?
01-08-2005, 05:47 AM
#5
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Seems like a mostly dubious claim. Nitrogen is almost 90% of "air" and...
Gasses expand/contract as a function of temperature. PV=nRT is the general equation descibing this behavior. R may vary from one gas to another, but until the pressure rises or the temperature drops to the point where the phase changes to liquid, the pressure will vary some.
01-08-2005, 05:50 AM
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"normal" air contains a higher percentage of moisture. Under extreme conditions...
ie. track, heat causes a wider degree of tire pressure variation. Nitrogen in a street application is a waste IMO.
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01-08-2005, 06:04 AM
#8
What planet are you from? On Earth, the atmosphere is 21% O2, 79% N2 (approx)
There is a small amount of the other gases like CO2 and the inert gasses so the real figures are 20% and change for O2 and 78% and change for N2 to account for the other gasses.
01-08-2005, 06:15 AM
#10
Main benefit is that N2 is a larger molecule so it doesn't diffuse through the tire's butyl rubber
inner liner as quickly as the O2. The other side benefit is that the N2 is generated on site and is dried so the moisture in removed - this is a significant problem with the typical gas station air compressor. Water vapor can condense during the fall/winter and expand a lot when tires are hot, causing wide fluctuations in tire pressures.
It does have a slightly lower thermal expansion coefficent so pure N2 does not expand as much as normal air mix when tires get hot, but the difference is pretty small. Some F1 teams use dried air and not pure N2 for their tires, so it isn't the be all and end all. I would and have put it in my tires, but only because it was free. I wouldn't pay extra for it unless you rarely check your tire pressure. I would say 50% real benefit and 50% gimmick; but if all else is the same I would go to the tire dealer that offers it over one that did not.
Cheapest best bet is to fill you tires with normal compressed air on dry days; avoid summer nights and rainy days. Test the line with your finger on the valve (release some pressure) and see it any liquid water comes out - if it does avoid using that air and if you can't then bleed the pressure off later on and refill with dry air.
It does have a slightly lower thermal expansion coefficent so pure N2 does not expand as much as normal air mix when tires get hot, but the difference is pretty small. Some F1 teams use dried air and not pure N2 for their tires, so it isn't the be all and end all. I would and have put it in my tires, but only because it was free. I wouldn't pay extra for it unless you rarely check your tire pressure. I would say 50% real benefit and 50% gimmick; but if all else is the same I would go to the tire dealer that offers it over one that did not.
Cheapest best bet is to fill you tires with normal compressed air on dry days; avoid summer nights and rainy days. Test the line with your finger on the valve (release some pressure) and see it any liquid water comes out - if it does avoid using that air and if you can't then bleed the pressure off later on and refill with dry air.