While you always have to drive at a safe speed for road conditions, Alaska does help you determine these safe speeds by posting limits for clear, perfect weather. The highest limit you’ll see is 65 miles per hour on highways. In school zones, the speed limit is 20 miles per hour, and in all other zones, the speed limits range from 35 to 55 miles per hour. Remember, you’ll also hit lower limits (and higher fines) in construction zones and safe corridors. If you are pulling a motor home, speeds are set lower, even on highways.