Why does a bicycle tire get heavier when you pump air into it?

A bicycle tire does not get heavier when you pump air into it. The mass of the tire remains the same regardless of the air pressure inside it.

When you pump air into a tire, you increase the pressure inside the tire. This pressure pushes the tire outward, causing it to expand. The increased volume of the tire displaces more air, which makes the tire feel heavier. However, the actual mass of the tire has not changed.