Today I noticed my front tire was soft, nearly flat when leaving the liquor store to ride back home. Upon examination, I had picked up a tiny thorn along the way. Lacking a really sharp implement, I struggled to work it out of the tire before installing my spare tube. Which acted a little funny as I went to pump it up -- with only a little air in the tube it still bunched up when I tucked it into the tire, and seemed to want to stay "skinny" as I put in air. While I was able to get in enough air to ride home, it was clear from outside the tire that the tube had inflated unevenly. When I got home, I took the spare tube out again, and found it was marked 26" x 1-3/8" - 1-1/4" (the tires on this bike are 26"x1.75"). My only wonder at that point was how that oddball tube had gotten into my collection! I tried it on a spare 700C rim and found that was a much better fit, so I marked it "700C" and put it in a different tub to avoid making this mistake again.