I built a new wheel. On the first pass the spokes were too short; I couldn't figure why. So I switched to building it 3-cross instead of 4-cross. After I finished I tried to mount a 700c tire: the tire was too small: they had given me a 27-inch rim instead of a700c. They cheerfully exchanged rims (700c was on the invoice) but didn't refund the 10 hours I spent building the wheel.
A tourist traveling long distances on back roads will have an easier time finding a replacement 27-inch tire - at least that was the state of affairs 20-30 years ago. Wal-Mart has one 700c tire now, a 38, which is bigger than I like, but better than walking. Oddly they sell bicycles with 700cx25 tires.