Nitrogen Tire Fill

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Originally Posted By: George Bynum
Originally Posted By: CapriRacer
NOT the real deal:

http://www.geocities.com/barrystiretech/n2cavitytemp.jpg



I'd like to reduce my ignorance ... that looks like they say higher temperature with lower pressure ... what are we looking at here, temperature after operation if the pressure is lower? Or asked another way, what is cavity temperature?

Aside from standard physics such as PV = nRT (pressure x volume = molecules of gas x gas constant x temperature)....

Maybe they're making the claim that nitrogen is less likely to leak and create a lower pressure situation. We all know that in operation (and within reason) tires filled with lower air pressure will heat up more from higher rolling resistance. Think the Firestone Wilderness fiasco with Ford making a 26 PSI recommendation when Bridgestone/Firestone thought it should be 30 PSI.
 
Originally Posted By: y_p_w
Originally Posted By: George Bynum
Originally Posted By: CapriRacer
NOT the real deal:

http://www.geocities.com/barrystiretech/n2cavitytemp.jpg



I'd like to reduce my ignorance ... that looks like they say higher temperature with lower pressure ... what are we looking at here, temperature after operation if the pressure is lower? Or asked another way, what is cavity temperature?

Aside from standard physics such as PV = nRT (pressure x volume = molecules of gas x gas constant x temperature)....

Maybe they're making the claim that nitrogen is less likely to leak and create a lower pressure situation. We all know that in operation (and within reason) tires filled with lower air pressure will heat up more from higher rolling resistance. Think the Firestone Wilderness fiasco with Ford making a 26 PSI recommendation when Bridgestone/Firestone thought it should be 30 PSI.

Sorry - didn't look at the picture before posting. Looks like they're countering some sort of claim that nitrogen results in lower final cavity pressure during normal operation. The details seem to be missing, but I would guess that this is for a certain load and speed being measured. Of course the graph seems to support most assumptions that a high inflation pressure results in a cooler tire in normal operation.
 
Dumb question: If you get your tires nitrogen filled, and then later you find that they are a little low, can you adjust them with regular air? Or must you use nitrogen?
 
Originally Posted By: VeeDubb
Dumb question: If you get your tires nitrogen filled, and then later you find that they are a little low, can you adjust them with regular air? Or must you use nitrogen?

You can do it, but the nitrogen generator suppliers claim it detracts from the "performance benefits" of the nitrogen fill. If you find yourself in a situation where your pressure is low and only atmospheric air inflation is available, do you have any other choice? There's no incompatibility. Atmospheric air is about 79% nitrogen anyways. I understand most of the generators create about 95% nitrogen.

Again - one of the claimed benefits is that nitrogen from the generators is that it's relatively dry because water vapor is severely reduced in the process. I've also heard of ways of removing water vapor from atmospheric air (dry air). In any case, tires are typically wet lubed (I've heard even dish soap mixtures can be used) when mounted so there's going to be water vapor in a freshly mounted tire unless it's later bled of all air and reinflated, after the water in the lube has a chance to evaporate.

My folks Camry got filled with nitrogen once when they had their tires rotated at Costco. They completely bled the air out and refilled with nitrogen. Then they placed on green valve caps to identify it as containing generated nitrogen. I supposes it's supposed to be a warning to only top off with generated nitrogen.
 
Generated Nitrogen?? Ours comes out of bottles, just drop in any time for a check or adjustment for free. I wandeer in every 2-3 months for a pressure check, usually nothing needs adding maybe a lb here or there.
 
Originally Posted By: VeeDubb
Dumb question: If you get your tires nitrogen filled, and then later you find that they are a little low, can you adjust them with regular air? Or must you use nitrogen?



I have had to use regular air recently in my nitrogen filled tires. It was an emergency as I had a nail in the tire. Those 50 cent machines located at most service stations can add a significant amount of moisture to the mix. Later, I drove to Tire Kingdom, had the tire fixed and reinflated with nitrogen. There is no charge associated with the nitrogen tire fill as long as you own the tires (after of course the initial cost)
 
Originally Posted By: sprintman
Generated Nitrogen?? Ours comes out of bottles, just drop in any time for a check or adjustment for free. I wandeer in every 2-3 months for a pressure check, usually nothing needs adding maybe a lb here or there.


Seriously? Why don't you just buy a tire pressure gauge? I check my tires regularly and add a lb every few months too, but I don't have to leave my garage to do it.
 
Originally Posted By: sprintman
Generated Nitrogen?? Ours comes out of bottles, just drop in any time for a check or adjustment for free. I wandeer in every 2-3 months for a pressure check, usually nothing needs adding maybe a lb here or there.

At least Costco locations use large membrane nitrogen generators on premises to separate nitrogen from atmospheric air. The membrane separates the nitrogen from the rest of the input gas, sort of like a reverse osmosis water filtration unit. It's supposed to be cheaper than having liquid nitrogen delivered. The large gas storage tanks themselves store compressed nitrogen that isn't liquified. Here are a few examples:

http://n2cel.com/default.html
http://www.visnitro.com/NitrogenFAQ.asp
http://www.parkertiresaver.com/
 
crinkles,

In racing (I think of F1) where pressure changes of 0.1 psi are critical, the nitrogen is more "stable". In "normal" applications, people will never know b/c most pressure gauges are not accurate enough to detect the difference anyway much less the driver/car.
 
How is the nitrogen "more stable" ?

If you are referring to moisture content, then get better air driers for the same effect...it's not the nitrogen doing it.
 
That's what I run in my Tacoma. It's just so easy to air up/down when ya have #20 CO2 in yer bed.
 
Nitrogen is claimed not to leak through the tire walls. They say Nitrogen has bigger molecule and so does not leak through. And yes, air is 78% Nitrogen. Also it is claimed that the pressure will not drop in winter,which I find hard to believe as all gases behave the same. Pressure drops by 1 PSI per 10 F drop in temperature. So Canadians will have to increase pressure in two stages. For me in Tennessee I only pump up the tires in Sep, and then remove some air in March.
 
Tire Kingdom down here in South Florida maintains the nitrogen pressure free of charge whenever I stop by. The tires usually don't take much or any N2. It looks to me that nitrogen pressure stays where it's supposed to be compared with the atmospheric air mix. I used to lose 2 or more pounds a month with regular air but not with N2.
 
Originally Posted By: harry j
Tire Kingdom down here in South Florida maintains the nitrogen pressure free of charge whenever I stop by. The tires usually don't take much or any N2. It looks to me that nitrogen pressure stays where it's supposed to be compared with the atmospheric air mix. I used to lose 2 or more pounds a month with regular air but not with N2.


Harry,

If you are losing 2 psi a month, you have a leak - and nitrogen is not the fix for this. The size of the molecules are different, but not enough different to account for a 2 psi drop vs none!

And just for reference, when I add 2 psi to my tires, it takes about this long: 1 Mississippi, 2 Mississippi. Also not much!!
 
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