Figure 3 a set of completed wheels for a Sunbeam car
But there are snags, mostly to do with the nature of timber. It has a habit of exchanging water with the atmosphere, and this makes it shrink, swell, or sometimes crack. Like most engineered structures, if it starts to ‘work’ loose, the wheel can rapidly deteriorate and become dangerous, though to be fair, they usually give visual and audible warning before collapsing. So they must be kept tight, not too dry not too wet, a bit of a conflict when the rest of the vehicle would rather be very dry so corrosion is minimised. The mode of making them too has to take account of the nature of the tyre, likely to be a channel made to accept the beaded edge tyre…a ‘cover’, and that has to be a given size. Your old-fashioned wheelwright made his wheel and then cut the tyre [the iron tyre of the Celt] to fit, where would that leave the makers of pneumatics, which I believe Swedes call ‘gummibonds’? The new sort of wheel has to be exactly the right size, and it must also have the channel tyre fitted in a manner which doesn’t distort the steel, either of these points being omitted will lead to problems in fitting the rubber tyre. But the channel must also be the means by which the wheel is compressed into a firm strong structure. So the man who makes your wheels needs to think in a manner more modern than the Celt, less rustic than the country wheelwright of yore, and the tolerances he works with need to be about 50%...or perhaps that means 100%, I’ve heard so many economists lately that a strange confusion sets in….finer.
the OED doesn’t help in supporting my supposition that the origin of the word ‘tyre’ in this
use is that it ‘ties’ the wheel together, the Americans spell it tyer, the French use ‘bondage’ [no, you need to pronounce that ‘borndarge’ or it leads to misunderstandings]. It is used for the rim of a wheel at odd moments before the physical application of a continuous band apparently came back into use. But it still looks a good theory to me, though I claim absolutely no expertise as a philologist.