That's a pretty cool way of making the hubs. What sort of wood to you use for the tire portion of the wheels? I often get issues with fluff and uncut fibers from much of the wood that is readily available to me (usually some sort of Eucalypt, as I'm in Australia). Also, have you tried ebonizing the tire wood using iron acetate (steel wool dissolved in vinegar)? I did this on a mine truck I made for my son when he was 2 and it turned out very nicely, the mystery wood I used must have been very high in tannins as they went almost totally black.
