Bike Incident

Gavin wanted to ride his bike yesterday, so we put some air in his tires. While pushing Riles in the stroller I noticed that one of his tires didn't look right on the rim.
We made it to the park by our house and Gavin said that it was getting hard to ride. I looked at the tire and it was getting bigger, so I told him to walk his bike. After a little ways he could no longer push the bike, so we put the bike in the stroller and headed home.
About two minutes later we heard a loud bang and the inner tube was destroyed. Gavin was devastated!