Chapter 4 of 518% of exam
Speed & Conditions
Safe speed depends on conditions, not just the posted number. Weather and visibility change how far you need to see and stop.
Speed limits
Many rural interstates in Illinois are posted at 70 mph, with lower limits on urban interstates and other roads. Always obey the posted limit and reduce speed in work zones and school zones when in effect.
Basic speed law and headlights
You must never drive faster than is reasonable and proper for conditions. Turn on your headlights from sunset to sunrise and whenever rain, snow or fog reduces visibility or requires continuous wiper use.
Following distance and skids
Increase your following distance in rain, snow or fog because stopping distances grow. If you skid, ease off the gas, avoid slamming the brakes, and steer gently toward where you want the front of the car to go.