A Tweel is Michelin's future answer to the run-flat tire. The tire and wheel are built together with a replaceable rubber thread band that is bonded to an aluminum wheel hub via polyurethane spokes that radiate outwards. This tire needs no air and is a different alternative to the all polyurethane tire we spoke about a couple of weeks ago. This tire has a way to go before street application, but it's good their thinking. It's obvious people are striving for something other than the standard tire. Just think of all that space and weight we'll save when we don't have to lug around spares. This link sends you to the middle of the story where they start talking about the Tweel, the rest of the article is about other run-flat technology.