Yes, flat tires can be frustrating. The last one, I ran the inside of the tire with my hand to see what might have caused it, but couldn't find anything. I put in a patched tube and it got me home, before it went flat. I pulled the tire off and with a magnifying glass and the tire inside out, I found something I could not identify, almost wood like. I pulled it out with tweezers and it's been good ever since. Between glass and pieces of metal on the sides of roads, its a wonder I don't get a flat every day.