Mithrandir

So I've read in multiple places that when you fill a tire with CO2, you should fully deflate it when you get home, and reinflate it with air. I recall the reasoning was that CO2 escapes quicker from tubes than normal air. *

So, I've got large tires. 26x2.0. Lot of volume. I use 2 cartridges to fill them up, and when I get home, I deflate them. But every time I deflate them, I wonder to myself "is there enough volume of CO2 in there that it could cause me to not breathe in enough oxygen and hurt myself?". So I usually just deflate them in small bursts. I'm not a physics or biology major, but something tells me I'm probably worried over nothing; there's probably not enough volume in the tire, even if it's deflating near my face, to cause a notable lack of oxygen for a long enough period to make any of a difference whatsoever. But I'd just like to know if anyone knows this for sure?


* - I'm not even sure how much sense this makes, since it seems to me that CO2 molecules are larger than nitrogen molecules, which make up the majority of air... so is it even true that CO2 escapes quicker than normal air?