Chapter 4 of 518% of exam
Speed & Conditions
Oregon relies heavily on the basic speed rule. Posted limits are maximums for ideal conditions, and you must slow down when the road or weather calls for it.
The basic rule
You must not drive faster than is reasonable and prudent for traffic, weather, and road conditions, even when that speed is below the posted maximum.
Posted maximums
Oregon posts up to 70 mph on some rural interstate sections, with 65 mph common elsewhere and lower limits in towns and school zones. Always obey the posted signs.
Adjust to conditions
Slow down and increase following distance on wet or icy roads and in fog, since stopping distances grow. Obey reduced school-zone limits during posted hours.