I had my bike loaded up this morning, took it out and noticed the rear tire was flat, so I ended up driving. It didn't tear me up too much because I had of the stock, 16-year-old Kenda hybrid tires in 700x38C size with two and a half years worth of heavy commuting wear on them (the bike was NOS when I got it). I was very pleased with the Kendas, but being 16 years old, they were wearing out quickly. This was the third flat in two and a half years, so I really can't complain. This flat was found at home; one of the others was quickly fixed on the road; the other happened a mile from home and I decided to walk the rest of the way instead of fixing it. I was already planning for this and had some money set aside. I bought a pair of Schwalbe Marathon Plus HS 348 tires in 700x25C. A quick ride around the neighborhood is as expected: Much less rolling resistance! Maybe I can shave a few minutes off my commute time. I have a double header softball game after work tomorrow (and I'm bringing the beer ), so my first chance to commute with the new tires should be Thursday.