What's a future car without a future tire? Well, Michelin's got us covered with a combination wheel and tire that doesn't use air, making it impossible to go flat. The "Tweel" uses flexible polyurethane spokes and promises to last two to three times longer than traditional radial tires, and when it does wear out it can simply be retreaded. The first commercial use for the tires will be on Dean Kamen's iBot wheelchair, with military applications likely to follow before you'll be able to stick 'em on your car. There is one potential drawback, however; it's not clear whether they'll be able to be chrome-plated or not.