The reason for this configuration is to help drivers see their outer wheel while traversing the road.

This means it has large outer wheels, but small inner wheels to make grinding easy.

The diwheel design has the two large outer wheels completely encompassing an inner frame.

In addition, the outer wheels (up to 9 of them, some double) need to be removed to access the inner ones.

The outer wheel on the 1980s version featured only one Double space (three during the pilot episodes).

When a vehicle turns the outer wheel has to travel further than the inner wheel.

From here it is necessary to pull the bridge in until the outer two wheels arrive at the trays.

It raised oddly on its outer wheels, and turned upon its side.

If the outer wheels fail to maintain or reach the required speed, the train may derail.

The truck lifted to its outer wheels before it reached The Shadow.