Nitrogen
12-11-2008 | 08:21 AM
#21
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Obviously a lot of people didn't do Chemistry and/or Physics at school (too busy planning how to become filthy capitalists who could run BMWs I guess! 
). I'm stretching my memory here but I seem to remember the following:
ALL gases expand when heated (Charles's Law).
Water is no less likely to be present in a given volume of Nitrogen than it is in a sample of any other gas; it depends on how you store the gases and the care with which you replace the gas in a tyre. The process of compressing air tends to boil off a fair amount of any water vapour that is present.
Nitrogen atoms are in fact slightly smaller than Oxygen (Nitrogen is just before Oxygen on the periodic table), but its molecules (they are diatomic, i.e. they come in linked pairs) are slightly larger. It is reckoned that O2 molecules permeate (pass through) tyre walls 3 to 4 times more quickly than N2 molecules, both however being comparatively slow if a tyre is well maintained. However, NOBODY has O2 in their tyres so the comparison is not valid. As others have pointed out, the majority of the compressed air you have in your tyres is Nitrogen anyway. In addition although the often quoted statistic suggests that 20 percent (or thereabouts) of air is Oxygen, a lot of the molecules in air are actually ones in which some of the Nitrogen and some of the Oxygen have combined with each other. In these cases the Nitrogen will require multiple Oxygen atoms to bond with or vice versa, producing molecules quite a bit bigger than either of them alone, which makes them less prone to permeation. (There is another type of escape (called effusion) that might be able to be applied if the holes between the polymer chains in the rubber of the tyre were sufficiently large to allow the molecules to pass almost unobstructed ( Graham's Law). They aren't and it doesn't apply.)
Air does have one clear drawback in that the Oxygen in it reacts pretty readily with metals such as Magnesium and Aluminium, so if it is present it could cause oxidation damage to the wheels that Nitrogen wouldn't cause. However if anyone is worried about that think about the oxygen in the air on the outside of your alloy wheels.
If anyone wants to put Nitrogen in their tyres I won't stop them. It's certainly getting cheap enough. But I won't be going out of my way. Colour me sceptical.
). I'm stretching my memory here but I seem to remember the following:ALL gases expand when heated (Charles's Law).
Water is no less likely to be present in a given volume of Nitrogen than it is in a sample of any other gas; it depends on how you store the gases and the care with which you replace the gas in a tyre. The process of compressing air tends to boil off a fair amount of any water vapour that is present.
Nitrogen atoms are in fact slightly smaller than Oxygen (Nitrogen is just before Oxygen on the periodic table), but its molecules (they are diatomic, i.e. they come in linked pairs) are slightly larger. It is reckoned that O2 molecules permeate (pass through) tyre walls 3 to 4 times more quickly than N2 molecules, both however being comparatively slow if a tyre is well maintained. However, NOBODY has O2 in their tyres so the comparison is not valid. As others have pointed out, the majority of the compressed air you have in your tyres is Nitrogen anyway. In addition although the often quoted statistic suggests that 20 percent (or thereabouts) of air is Oxygen, a lot of the molecules in air are actually ones in which some of the Nitrogen and some of the Oxygen have combined with each other. In these cases the Nitrogen will require multiple Oxygen atoms to bond with or vice versa, producing molecules quite a bit bigger than either of them alone, which makes them less prone to permeation. (There is another type of escape (called effusion) that might be able to be applied if the holes between the polymer chains in the rubber of the tyre were sufficiently large to allow the molecules to pass almost unobstructed ( Graham's Law). They aren't and it doesn't apply.)
Air does have one clear drawback in that the Oxygen in it reacts pretty readily with metals such as Magnesium and Aluminium, so if it is present it could cause oxidation damage to the wheels that Nitrogen wouldn't cause. However if anyone is worried about that think about the oxygen in the air on the outside of your alloy wheels.
If anyone wants to put Nitrogen in their tyres I won't stop them. It's certainly getting cheap enough. But I won't be going out of my way. Colour me sceptical.
12-11-2008 | 06:06 PM
#22
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From: Pikes Peak- Colorado
My Ride: BMW 535xi
Model Year: 2008
Originally Posted by JMC' post='743066' date='Dec 11 2008, 12:21 PM
Obviously a lot of people didn't do Chemistry and/or Physics at school (too busy planning how to become filthy capitalists who could run BMWs I guess! ). I'm stretching my memory here but I seem to remember the following:
ALL gases expand when heated (Charles's Law).
Water is no less likely to be present in a given volume of Nitrogen than it is in a sample of any other gas; it depends on how you store the gases and the care with which you replace the gas in a tyre. The process of compressing air tends to boil off a fair amount of any water vapour that is present.
Nitrogen atoms are in fact slightly smaller than Oxygen (Nitrogen is just before Oxygen on the periodic table), but its molecules (they are diatomic, i.e. they come in linked pairs) are slightly larger. It is reckoned that O2 molecules permeate (pass through) tyre walls 3 to 4 times more quickly than N2 molecules, both however being comparatively slow if a tyre is well maintained. However, NOBODY has O2 in their tyres so the comparison is not valid. As others have pointed out, the majority of the compressed air you have in your tyres is Nitrogen anyway. In addition although the often quoted statistic suggests that 20 percent (or thereabouts) of air is Oxygen, a lot of the molecules in air are actually ones in which some of the Nitrogen and some of the Oxygen have combined with each other. In these cases the Nitrogen will require multiple Oxygen atoms to bond with or vice versa, producing molecules quite a bit bigger than either of them alone, which makes them less prone to permeation. (There is another type of escape (called effusion) that might be able to be applied if the holes between the polymer chains in the rubber of the tyre were sufficiently large to allow the molecules to pass almost unobstructed ( Graham's Law). They aren't and it doesn't apply.)
Air does have one clear drawback in that the Oxygen in it reacts pretty readily with metals such as Magnesium and Aluminium, so if it is present it could cause oxidation damage to the wheels that Nitrogen wouldn't cause. However if anyone is worried about that think about the oxygen in the air on the outside of your alloy wheels.
If anyone wants to put Nitrogen in their tyres I won't stop them. It's certainly getting cheap enough. But I won't be going out of my way. Colour me sceptical.
). I'm stretching my memory here but I seem to remember the following:ALL gases expand when heated (Charles's Law).
Water is no less likely to be present in a given volume of Nitrogen than it is in a sample of any other gas; it depends on how you store the gases and the care with which you replace the gas in a tyre. The process of compressing air tends to boil off a fair amount of any water vapour that is present.
Nitrogen atoms are in fact slightly smaller than Oxygen (Nitrogen is just before Oxygen on the periodic table), but its molecules (they are diatomic, i.e. they come in linked pairs) are slightly larger. It is reckoned that O2 molecules permeate (pass through) tyre walls 3 to 4 times more quickly than N2 molecules, both however being comparatively slow if a tyre is well maintained. However, NOBODY has O2 in their tyres so the comparison is not valid. As others have pointed out, the majority of the compressed air you have in your tyres is Nitrogen anyway. In addition although the often quoted statistic suggests that 20 percent (or thereabouts) of air is Oxygen, a lot of the molecules in air are actually ones in which some of the Nitrogen and some of the Oxygen have combined with each other. In these cases the Nitrogen will require multiple Oxygen atoms to bond with or vice versa, producing molecules quite a bit bigger than either of them alone, which makes them less prone to permeation. (There is another type of escape (called effusion) that might be able to be applied if the holes between the polymer chains in the rubber of the tyre were sufficiently large to allow the molecules to pass almost unobstructed ( Graham's Law). They aren't and it doesn't apply.)
Air does have one clear drawback in that the Oxygen in it reacts pretty readily with metals such as Magnesium and Aluminium, so if it is present it could cause oxidation damage to the wheels that Nitrogen wouldn't cause. However if anyone is worried about that think about the oxygen in the air on the outside of your alloy wheels.
If anyone wants to put Nitrogen in their tyres I won't stop them. It's certainly getting cheap enough. But I won't be going out of my way. Colour me sceptical.
Here is what the BMW dealer states:
Nitrogen in tires is becoming a very popular replacement for air for many reasons. It may improve your fuel economy by up to 10% and increase your tire life by 30% or more, while increasing the safety of your vehicle.
According to NitroFill sources, ?high purity nitrogen has been used for decades in NASCAR, Formula One, the Tour de France, and the U.S. military. Only the high cost and complexities of generating and properly administering nitrogen have kept it out of reach of the general public. Recent advances in nitrogen production technology have now made nitrogen inflation economically viable for the automotive service industry.?
Why nitrogen? Oxygen leaks out of tires faster, whereas nitrogen maintains tire pressure longer. This is due to oxygen molecules in compressed air being smaller, leaking out three to four times faster than nitrogen molecules. Nitrogen is an inert, noncombustible, nonflammable , non-corrosive gas, reasons why nitrogen is used to fill the tires that push performance limits under extreme conditions. Oxygen in the air inflated into tires, on the other hand, deteriorates rubber, causing a loss of elasticity and strength.
12-11-2008 | 06:43 PM
#23
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My Ride: carbonized MB coupe
Originally Posted by JMC' post='743066' date='Dec 12 2008, 01:21 AM
Obviously a lot of people didn't do Chemistry and/or Physics at school (too busy planning how to become filthy capitalists who could run BMWs I guess! ). I'm stretching my memory here but I seem to remember the following:
ALL gases expand when heated (Charles's Law).
Water is no less likely to be present in a given volume of Nitrogen than it is in a sample of any other gas; it depends on how you store the gases and the care with which you replace the gas in a tyre. The process of compressing air tends to boil off a fair amount of any water vapour that is present.
Nitrogen atoms are in fact slightly smaller than Oxygen (Nitrogen is just before Oxygen on the periodic table), but its molecules (they are diatomic, i.e. they come in linked pairs) are slightly larger. It is reckoned that O2 molecules permeate (pass through) tyre walls 3 to 4 times more quickly than N2 molecules, both however being comparatively slow if a tyre is well maintained. However, NOBODY has O2 in their tyres so the comparison is not valid. As others have pointed out, the majority of the compressed air you have in your tyres is Nitrogen anyway. In addition although the often quoted statistic suggests that 20 percent (or thereabouts) of air is Oxygen, a lot of the molecules in air are actually ones in which some of the Nitrogen and some of the Oxygen have combined with each other. In these cases the Nitrogen will require multiple Oxygen atoms to bond with or vice versa, producing molecules quite a bit bigger than either of them alone, which makes them less prone to permeation. (There is another type of escape (called effusion) that might be able to be applied if the holes between the polymer chains in the rubber of the tyre were sufficiently large to allow the molecules to pass almost unobstructed ( Graham's Law). They aren't and it doesn't apply.)
Air does have one clear drawback in that the Oxygen in it reacts pretty readily with metals such as Magnesium and Aluminium, so if it is present it could cause oxidation damage to the wheels that Nitrogen wouldn't cause. However if anyone is worried about that think about the oxygen in the air on the outside of your alloy wheels.
If anyone wants to put Nitrogen in their tyres I won't stop them. It's certainly getting cheap enough. But I won't be going out of my way. Colour me sceptical.
). I'm stretching my memory here but I seem to remember the following:ALL gases expand when heated (Charles's Law).
Water is no less likely to be present in a given volume of Nitrogen than it is in a sample of any other gas; it depends on how you store the gases and the care with which you replace the gas in a tyre. The process of compressing air tends to boil off a fair amount of any water vapour that is present.
Nitrogen atoms are in fact slightly smaller than Oxygen (Nitrogen is just before Oxygen on the periodic table), but its molecules (they are diatomic, i.e. they come in linked pairs) are slightly larger. It is reckoned that O2 molecules permeate (pass through) tyre walls 3 to 4 times more quickly than N2 molecules, both however being comparatively slow if a tyre is well maintained. However, NOBODY has O2 in their tyres so the comparison is not valid. As others have pointed out, the majority of the compressed air you have in your tyres is Nitrogen anyway. In addition although the often quoted statistic suggests that 20 percent (or thereabouts) of air is Oxygen, a lot of the molecules in air are actually ones in which some of the Nitrogen and some of the Oxygen have combined with each other. In these cases the Nitrogen will require multiple Oxygen atoms to bond with or vice versa, producing molecules quite a bit bigger than either of them alone, which makes them less prone to permeation. (There is another type of escape (called effusion) that might be able to be applied if the holes between the polymer chains in the rubber of the tyre were sufficiently large to allow the molecules to pass almost unobstructed ( Graham's Law). They aren't and it doesn't apply.)
Air does have one clear drawback in that the Oxygen in it reacts pretty readily with metals such as Magnesium and Aluminium, so if it is present it could cause oxidation damage to the wheels that Nitrogen wouldn't cause. However if anyone is worried about that think about the oxygen in the air on the outside of your alloy wheels.
If anyone wants to put Nitrogen in their tyres I won't stop them. It's certainly getting cheap enough. But I won't be going out of my way. Colour me sceptical.
in the real world i am happy not having to queue to get my tyre pressures checked everytime i am at the gas station,
because after all these discussions i don't have tyre pressure changes which could affect my performance or economy.
i can understand F1 guys being overzealous, but if aviation guys use Nitrogen then it must be something else as well.
22% makes a lot of difference, and if you are using replica wheels then you will luv Nitrogen, when i had replica ACiv's
they leaked air out at abt 30% after 2 weeks, i got fed up with that.
of course where you live and the climate there may affect that change in your tyres.
in fact if you don't believe don't get nitrogen
12-12-2008 | 05:37 AM
#26
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Originally Posted by swallx46' post='742578' date='Dec 10 2008, 07:55 PM
i always use nitrogen, the only thing is nitrogen doesnt expand like air does when it gets to a certain temperature so its more accurate when checked with a tire gauge. It just makes it so that your tires are always right on the dot with air pressure
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