Soaking wheels in water is a very temporary and damaging way to tighten wheels. I have rebuilt many original wagons and cannon wheels. I have driven a wagon from Omaha to Salt Lake City, and have had no issues with reset tires coming loose, even after 1200 miles of use, To tighten the tire, you need to cut it, remove it, cut a small piece out, and either pull the tire back together with clamps, reweld it or weld and heat to slip over the felloes. Soaking in water will cause swelling and then even more trouble with the wheel in the long run. I have built a small trough that lets at least one fellie to be submerged in linseed oil, which is then heated up, and painted on the 2 spokes and hub. I rotate after the wood has stopped bubbling (about 20 mins) and rotate the next section into the hot oil. A dry wheel will take a gallon of oil sometimes. Then I paint the wheel and it is good for several years, I have a full scale light 6pdr that I treated this way in 1996 , and she is still tight as a drum!
J Colonel