Little Suzy has a tricycle (you know, with three wheels). She wants to travel 1 mile with the tricycle, but she wants to spare her tyres (you know the price on tricycle tyres just keep going up). She is taking 2 spare tyres.

Assume she knows when to exchange wheels so that each of them travels an equal distance. How far does each wheel travel at the end of one mile? How did she exchange the wheels?