We hear the term “re-inventing the wheel” all of the time. It's a term used so loosely, and the phrase has all but lost its impact.
Until you consider, that Goodyear has actually gone and done it.
They have created a spherical wheel: the Goodyear Eagle-360. It looks like a big rubber ball and here’s a picture to prove it.
Of course, it's just a concept. The maglev drive they need to make the wheels rotate doesn’t actually exist yet, but it probably will soon, given the amount of money that is being thrown at it.