Michelin has been working on their Tweel for some time now which is a tire and wheel ("tweel", get it?) technology that needs no air. They also have an airless tire that mounts on a separate wheel but uses plastic bands for the sides in place of the normal sidewall. You get the flex characteristics of a normal sidewall tire without any air required. Although I had heard of developments for motorcycles, I had not seen any photos. Motoblog.it has been at the Milan show and shot these photos of the Michelin airless motorcycle tire. It doesn't look quite as radically different as the Tweel except for the fact you're exposing the inner bands, pretty radical in its own right.
Interesting, too, is the tread and plastic sidewalls can be made in various colors as the blue version shows. No word, as far as I can tell, about how close these are to commercial application. It would be interesting to ride an airless tire to see how it responds under various riding conditions. Since a broken band doesn't require a tire change and there is no air to lose, these would seem to be a natural for extreme offroad use though they would be great for normal riding, too. Cool technology.