Nitrogen in tires, again!

[B47]

Originally Posted by wincrasher

This is another subject that keeps coming up and we all prattle on about. It's been a scam since the 50's. I was surprised to see Costco doing it recently - thought they were above that kind of thing, but I guess not.

You see this repeatedly in scams - a morsel of science used to con people out of their money.

This thread needs to be retitled from "Nitorgen in tires,again" to "Nitrogen in tires, again and again and again ..."

And I am the one who started it

[TheGoodwin4]

I've been using CO2 in my Jeep tires for years to air up after four wheeling any of you thought of this? You wouldn't believe how far a small refillable tank will go.

http://www.powertank.com/truth.or.hype/

[TheGoodwin4]

I should also add that I can also run my impact wrench off it. It's really nice to rip the lug nuts off really quickly on a flat when its over 100 degrees outside!

[BigTJohn]

CO2 in tires leaks out rather quickly. Nice to be able to use it on air tools. But how often does one really change a flat? CO2 molecules are much smaller than air or N2. They will escape a tire rapidly. Using CO2 to inflate a bicycle tire works very well and it is fast. However, the next day that tire is very low on pressure. It goes from 110 psi to less than 60psi overnight. So I would have to say CO2 in vehicle tires would get very expensive very quickly.

[TheGoodwin4]

BigTJohn - I've never used enough to verify that but after some research this morning it looks like many bicyclists are stating the same thing. Interesting though that the reason seems to be:

(Disclaimer - Stolen from someone who seems to know what they are talking about)

Molecular Size N2 smallest, O2 next CO2 biggest.

The loss of CO2 through the rubber is called permeation. CO2 permeates the rubber faster since it is more soluble in the rubber than the N2 and O2.

This effect is well known and used to separate CO2 from many gases. High CO2 permeability is common to alot of polymers.


I personally mainly use my CO2 tank for air tools and topping off my tires but now after this research I'll be sure to deflate and re-inflate if I end up using a lot of it when on the road.

Thanks for bringing up your experience with CO2