A standard 18 wheeler has 12 gears. These 12 gears are traditionally made up of 10 forward-drive gears and two reverse-drive gears, though the number varies depending on the manufacturer of the semitruck.
While most 18 wheelers have 12 gear shifts, some semitrucks can have up to 18 gears. The number of gears an 18 wheeler has is not only dependent on the manufacturer of the truck, but the type of materials that the truck is designed to carry. Standard semitrucks can haul a variety of goods, but heavy-duty equipment needs to be transported in vehicles that can handle the extra weight.