Some states have official tolerances codified into law, usually 5-10 mph, depending on the posted speed, road, how the speed was measured, etc. http://www.mit.

Some states have official tolerances codified into law, usually 5-10 mph, depending on the posted speed, road, how the speed was measured, etc. http://www.mit.edu/~jfc/laws.html http://www.mit.edu/~jfc/laws.html