I've mostly stretched sew-ups on rims, not wheels. But, a couple of years ago, I got careless and mounted some tires on wheels without glue, just to stretch them. Preparing for a ride last year, I saw that my front tire was flat, so on leaving the house I "grabbed" a front wheel that had a good tire on it. Ten miles into the ride, the front tire rolled and so did I. The tire had zero glue on it. Lesson Learned: Never stretch your tires on a wheel unless you are disciplined enough to properly mark them to preclude use. Lou Deeter, Orlando FL