That's where it got confusing. My tire is stamped 54-559 and 26x2.1. My wife's Raleigh road bike is stamped 700x38C. For some reason and reading that 26" and 29" are common, her old bike (which pre-dated 29") must then, be 26". Thinking that 26" goes into 26" exactly, her tires must fit my rim. So, I took her tire and tube off. I then tried to fit her tire to my rim. The rim went straight through her tire without touching side. Duh? I then checked up and saw that 700x38C is roughly 28". No bloody wonder. I put my original tire back on and I was fortunate to have kept an inner tube from a few years ago. It's rated as 26x1.9 to 26x2.1 so I can ride with a tube for a few weeks until I can perhaps find a faster-rolling tire.
And, can I find the original puncture I had in the tubeless tire? Nope! Not a mark, not a blemish, nothing. Typical. I can see why people are suspicious of tubeless tires. I can't even change wheels as Cannondale (in their infinite asinine stupidity) opted (then) to use a 20mm thru-axle on the front wheel. 20mm axles were so successful that everyone is using them (roll eyes). I can't change the front suss because it only accepts these wonderful 20mm axles so my only option is to replace the forks (not an option) or get someone to build a new wheel for me using the original hub. Who actually said (apart from themselves) that Cannondale is an innovative company?