Does CO2 leak out faster than air?

Question

A mechanic told me that if you use a carbon dioxide inflator that unless you drain it and re inflate you will lose pressure more rapidly.  Knowing that CO2 molecules are larger than nitrogen and oxygen I find that hard to believe.  Is it true?

PeteR · Accepted Answer

I believe that the CO2 passes through the wall of the tire by osmosis - it does not leak through the valve.

CO2 is more soluble in the rubber for some reason.

I · Answer

It's true. I found that out when I used a CO2 inflator on my road bike mid-ride -- now I just use a mini-pump. (This was on a brand-new tube, no patches or holes or anything.)

Try it yourself if you want to see. Use a standard 16g (oz?) CO2 inflator on a 700c tire of your choice. It'll be a lot softer after a given period of time than the same tire filled with air.

My grasp of AP chemistry (my teacher explained this then) is fairly rusty, so I won't pretend to remember why this happens.

Anonymous · Answer

Yes..if you use CO2 you will ahve to fill the tire up every few days if...I recomend you buy a mini pump for if incase you get a flat tire..that way to you can keep on riding for hours without having to worry about it..even though it is more work

nodopenomore · Answer

I don't know but seems like you will not get 110 PSI out of a cartridge. People tell me they only get 80 PSI, just enough to finish a ride.

suzonka · Answer

would suggest using a regular bike pump from wall mart ,even a mini pump is better than a CO2 cartridge . once you have it yo never have to purchase more cartridges .

? · Answer

Don't see why it would or why you have to worry about it.  You need to check your tire pressures every few days anyway.

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Does CO2 leak out faster than air?

6 Answers