Funky wheel
 

The sidewall-less tire thread made me think of this:

<IMG SRC="http://www.amenmotorcycles.com/reform/aments/bikes/hub.jpg">

I have no idea how it works. But it's damn cool.

<IMG SRC="http://www.amenmotorcycles.com/reform/gallary/hublessfronta.jpg">

<IMG SRC="http://www.amenmotorcycles.com/reform/gallary/hublessbacka.jpg">

Amen makes some crazy shit.

It seems to have rollers on the front. How it works on the back my be similar to the front except the roller is powered in the back to force the wheel to spin. That is fucking amazing though.... I would love to see it on the road.

Here's a link for the hubless wheel. Pretty neat and wacky stuff.

http://www.osmoswheel.com

So how do they get to power to the wheels again?

Umm, not to reliable in appearance, but then again, it does make an impression.

http://www.osmoswheel.com/images/gal...ection_149.jpg
chains & sprockets around the rim (at least on bikes)

I've always found that pretty interesting but I've never seen it implemented in an ultra high performance application. I imagine it could dramatically improve handling since the weight is pivoting so low on each wheel ...sort of like holding those long poles on a high wire to move your center of gravity below the wire, so you almost can't fall off.