[Doc]

they're not thickies, they're right

Imagine if you turned the plane upside down - spinning the wheels wouldn't cause it to move would it?

The purpose of the wheels on a car is to provide traction - that is generate friction between the wheels and the ground, so that when you spin the wheels (using the engine) the car moves forward because of the friction.
The purpose of the wheels on the airplane is the opposite - reduce the friction, bacause they're not driven. They're like casters on a piece of furniture