I was on my way home from work today and had an unusual event. Sometimes my tire will pick up a little tar from the road on a hot day. It sticks to the tire and picks up a little bit of small rocks, so I stop and pull it off and go on. I thought that was what was going on today. But when I stopped I had a big bubble forming on my tire. I thought well great, not quite half way home. I decided to ride it until it popped and call "Budget and Finance" to pick me up. It finally popped a half mile later. To my surprise the tire was still inflated and did not feel even low. I finished the additional 6 miles, and rode another 10 tonight with no problems. I guess an outer layer of the tire formed a bubble and popped. I have never seen or heard of anything like this happening. I haven't inspected closely but I really can't see where it was.
Has anyone had this happen or know what caused it?