At the very bottom of the page » FITTING MODERN TYRES TO VINTAGE BICYCLES The Online Bicycle Museum reads a text

Any idea what tire they might be referring to?

"the original type of tubeless tyre is no longer made. The only options are to use a replacement solid tyre currently sold in USA (costing around US $250 each + carriage) or remove the wooden wheels and replace them with metal wheels. In America, most vintage enthusiasts who want to ride their pre-1932 wooden wheeled bicycles replace their old wooden wheels with modern 36-hole wooden rims made in Italy."