My daughter has one of those. The original tires were 24x1 1/4, but the local Schwinn shop only had 24x1 1/4 / 1 3/8. She wanted flat bars anyway, so it looked more like a hybrid. I did have a problem mounting the tires, though. They were a little loose on the rim and the first one didn't get exactly centered. About five minutes after I inflated it, it blew off the rim. I was more careful after that to center the beads and I didn't have any further problems. She rode the bike for three summers until she out grew it.