Nature's wheel

Last spring I was driving to East Germany and talking with my brother. We saw the wheels of a truck next to us. The first thing that came up whas the inefficiency of a wheel. Only about 5% of the wheel is touching the road and bearing the truck, the other 95% is busy traveling around until it can touch the road again.

So, if we need only 5% of the wheel, why not get rid of the other 95%?

May be we need another 5% to be used immediately after the first 5% is used. When the first 5% is used up for rolling and bearing the truck it cannot be ready again immediately, so we need a second 5% to be used alternately with the first 5%.

If we would let the first 5% go around after it was used it needs to travel a long way (90%), so we may better just move it back, the distance is then only 10%.
But how should we move it back without causing resistance by touching the road? Two possibilities: 1. lowering the resistance by adding small wheels or liquid or something and 2. lifting it up a bit so it won't touch the road.

Let's consider the second possibility. If we lift it up by means of a hinge somewhere we have made a knee. Hey, that's interesting, where have we seen this before?

Oh, and if we don't need to move the 5% around the axis we have place to move up the axis which doubles the radius and therefore halves the rolling resistance! Oh, and with such a knee we can adjust for bumpy roads like rocky paths.

The round wheel has been evolved away a long, long time ago.