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

The easy answer, even though the tires are sealed and made of rubber, the material in the tire isn’t truly leak proof. The gas inside the tire, while being contained well, is still able to get through the rubber. The rubber is just a fraction bit porous. Slowly, over time, the heating and cooling of the tire leads to the loss of the gas inside the tire. It just happens really slowly because the rubber isn’t as porous as a sponge.