When I went to my LBS the salesman wanted to sell me 1.25 tires because they did not have 1.5's. I have a Park Tool Big Blue Book Of Bicycle repair that says the tire should be no thinner than 1.5 times the rim width. That would be aprx a 1.372 tire for my rims. I thought the Bike shop was trying to sell me tires that were too thin. The book says that a tire that is too thin for the rim will flatten the profile of the tire. Since I joined this site I can see that a 1.25 tire is a common thing to do. In fact most of the LBS carry 1.25 and not 1.5. It took me a while to find a LBS that had 1.5 80psi in stock. I think the 1.25 would be a better faster tire but because of my weight I got the 1.5. Tire sizes and rim size is new to me. I'm a rookie when it comes to working on modern bicycles.