davidc1

Nitrogen is now available at Costco. Actually, it's been available for a long time, but they wouldn't fill outside tires with it. Now, they'll fill anybody. It's only $11 for all four, or $23 and they'll balance your tires as well. Sounds like a good deal to me.

They do a fill, purge, and refill. And I bet if their cool about it, you could have them fill up one of those small 40lb air tanks as well. When I try it, I'll just have them overfill, and bleed down at the track, cause I don't have one of those tanks.

bruthaboost

I apologize for being captain pedantic, but we're talking about changing only approx 21% of the composition of air in the tires. Our atmosphere is already nearly 80% nitrogen. Additionally, oxygen and nitrogen similar physical properties. For example, only 8 degrees C separate their boiling points.

summitrider2012

I do it in my tires. Free for me though.

robinson

When I care, I use a desiccant to dry the air in my tires.

will010100

For the longest time, I was in your camp in this point, then someone point out another component of air I had grossly overlooked, water vapor. Water vapor has a much higher expansion rate than dry air, and is the biggest contributor to pressure increase relative to temp.

The purpose of using nitrogen has less to do with nitrogen and more to do with it being a pure gas - no vapor. Nitrogen makes up 79% of air, so it is cheap compared to other gases and safe to use.

I suppose if you have access to a desiccant compressed air dryer, that may work - depending on how dry you get the air (filling tires has low resistance, so be careful not to exceed the rated flow rate). These have other pitfalls - high cost among them. Centrifugal coalescers sold at the hardware store are not dryers despite misleading labeling. They can only remove water that is liquid a few degrees lower than the current dew point. Since compressed air is relatively hot, it's probably not even reaching the ambient dew point. (I sold Wilkerson and designed air treatment systems for 4 years.)

I don't use nitrogen or dried air, but I certainly understand and appreciate why some do. It definitely stabilizes tire pressure.

Note, if you plan to use any form of dry air, consider that tires have about three atmospheres of air in the (1 ambient + 2 pressure). That ambient atmosphere gets in when the tire is mounted, so it is critical to purge it out. Otherwise, you'll still have 1/3 the water vapor in your tire.

davidc1

It's not about how much N or O2 is in the air. There are two considerations which make pure N desirable.

For the average Joe, N won't leak out of a tire as quickly as O2, therefore it's easier to keep tire pressures up since most average people don't check it often.

For racers, N doesn't expand as much with heat, mostly because it doesn't absorb water as much as O2, and therefore your tire pressures won't rise as much on the track.

This is a good quick read:

http://blog.tirerack.com/blog/make-d...s-and-myths-v1

http://www.tirerack.com/tires/tirete...sp?techid=191&