Why do tires slowly lose air? From what it seems, they are sealed and shouldn’t really be letting anything in or out, but they still need to be refilled every now and then.

Question

I understand pressure changes as heat changes, but even in the same season you will still lose a slight amount of pressure.

In: 141

Answer 1

Air molecules are really really really smaller, oxygen and nitrogen molecules are made up of just two atoms.

So from our “giant’s” perspective, yea, the rubber looks like a totally perfect solid seal that nothing can get through, but on a molecular level there are still gaps between all the tangle of rubber molecules that the tiny little air molecules can slowly but surely get through.