Why are wheels circular in shape?

Question

why are wheels circular in shape?does it make sense if the wheels of a car are triangular or rectangular in shape?

Answer 1

Trianglular or rectangular would give a really uncomfortable ride. There was an old silent movie (Ben Turpin I think) which had a car with elliptical wheels which was quite entertaining.  

Answer 2

They are circular so they can go round!

Answer 3

common sense dude . It is wheel which gave us the circle not the other way.  Cicle provides least friction during tangential motion. tats why skates are flet tat provides least resistance in linear motion.

Answer 4

Triangular or square will not roll.

Elliptical will give a bumpy ride.