The stopping distance of a car traveling at 55 mph is 193 feet under normal driving conditions.

 A National Safety Council study of reaction time and braking distance found that at speeds of 55 miles per hour, a passenger car requires 193 feet to stop safely and a loaded truck needs 430 feet – longer than a football field. On slippery roads, the stopping distance is even greater. Your low-beam headlights illuminate the lane ahead of you for less than 200 feet, which is why you should use high beams whenever you're neither following nor meeting other vehicles.