(a) on an interstate highway outside an urbanized area of 50,000 population or more is 80 miles an hour at all times and the speed limit for vehicles traveling on interstate highways within an urbanized area of 50,000 population or more is 65 miles an hour at all times;
(b) on any other public highway of this state is 70 miles an hour during the daytime and 65 miles an hour during the nighttime;
(c) in an urban district is 25 miles an hour.
(2) A vehicle subject to the speed limits imposed in subsection (1) may exceed the speed limits imposed in subsection (1) by 10 miles an hour in order to overtake and pass a vehicle and return safely to the right-hand lane under the following circumstances:
(a) while traveling on a two-lane road; and
(b) in a designated passing zone.
(3) Subject to the maximum speed limits set forth in subsection (1), a person shall operate a vehicle in a careful and prudent manner and at a reduced rate of speed no greater than is reasonable and prudent under the conditions existing at the point of operation, taking into account the amount and character of traffic, visibility, weather, and roadway conditions.
(4) Except when a special hazard exists that requires lower speed for compliance with subsection (3), the limits specified in this section are the maximum lawful speeds allowed.
(5) "Daytime" means from one-half hour before sunrise to one-half hour after sunset. "Nighttime" means at any other hour.