We ran out of our handy-dandy air cartridges a few flat tires ago.

Luckily, for the last few flat tires, there was a gas station nearby, so we could use their air machines. (And a phone in the end, so we could call a taxi to drive us and our bikes home!)

By the way...
It took two separate trips to the bike shop to eventually find out what was causing all of these flat tires. The first guy suggested the tube kept getting pinched by the wheel. Thankfully, we got a 2nd opinion... The guy at the 2nd bike shop spent a good deal of time examining that tire inside and out, before he discovered a small shard of glass that was wedged deep within the lining of his tire. It had nothing to do with the bike tubes, or the amount of air in them.

Regardless, Jim hasn't really been interested in cycling much since this day.