Thanks. I remember trying to put a standard tire on the rear wheel and oops! The chain grip I put on is marked 26 x 1-3/8 but it states it is for Schwinn. It was common for that size to be on a tire for a Schwinn. My first 3-speed was a used Schwinn and I learned about tire size in mid-tour. In the early 70's I ran a bike shop that did over 100 repairs a week. I think everybody was caught by that at least once! I am going to solve the tire issue with new rims. I just hope the cracked tires last the rest of the season.