For what it's worth, we have 13 bikes in the family, tire sizes from 700x23 to 700x41 on the roadies and 26x1.4 to 26x2.3 on the mountain bikes. The only tube sizes I've bought in at least 10 years are 700x25 and 26x1.5. It simplifies inventory, and i've never had a problem. They're rubber; they stretch.