Semi-truck drivers operate a vehicle that has 18 tires, is 13-and-a-half-feet high (4.1 m.), 8.5 feet wide (2.5 m.), 72 feet long (21.9 m.), and weighs up to 80,000 pounds (36, 287.3 kg.). The men and women behind the wheel of gigantic semi-trucks log millions of miles driving loads around the world of food, clothing, gas, cars, ...