XSp.

I think this is already kinda old news, but since I don’t pay much attention to car news, missed it.
From Discovery Channel:

A new technology for tires that doesn’t require air and has a design with several advantages, called Michelin Tweel.

It’s not only interesting because it doesn’t require air… though not having to calibrate the wheels is already good enough for me. 😛
German Demonstration

There’s also the risk of getting your tires blown or pierced. You just won’t get flat tires anymore. And on the heavy security side, you can even continue driving if the tires get blown by explosives.
Live Presentation

Finally, seems it’s a greener technology.
The only downsides I can see in this is: Since the technology is relatively new, the tire price will probably be skyhigh at first.
That and auto repairers will have to find a second job or something… 😛

Para leitores brasileiros (for brazilian readers)

Source: TechEBlog