[Spartan01]

A critical factor in determining speed limits is the relatively safe speed at which tractor trailers can operate and corner. These are cumbersome, multi-axle, 40 ton behemoths.
As a student of physics, I have often noticed that while going through a turn/curve, a decent sports car with a skilled driver can easily (theoretically, I would never actually do anything illegal) negotiate the curve/turn at roughly twice the posted limit. Thsi si of course dependent on outside factors, such as surface composition, temperatur, superelevation, suspension, entering speed, front or rear whell drive, and front/rear/mid engine.

So, yes, to answer the question, we do in fact need speed limits, but they should only apply to dumb people, people with the reflexes of a tree sloth, and tractor trailers.