For our purposes here, most drivers will be interested in driving your every day, average tractor-trailers requiring a CDL Class A license.
There are, however, various types of circumstances and vehicles that will require either a lower class of CDL, or not require a CDL at all.
Those in the farming industry, military, or emergency response fields may not be required to have a CDL.
You will be required to have a CDL in order to operate any of the following types of vehicles. Keep in mind that each individual state may have different rules and definitions:
The FMCSA defines 3 different classes of CDL, depending on what definition the CMV meets:
Any combination vehicle with a Gross Vehicle Weight Rating (GVWR) of 26,001 lbs or more, with the vehicle being towed weighing more than 10,000 lbs.
Any single vehicle with a GVWR of more than 26,001 lbs., or combination vehicle as such towing less than 10,000 lbs.
Any single or combination vehicle that is not classified under either Class A or B, but is designed to carry either placarded hazardous materials or 16 or more passengers, including the driver.
Drivers operating emergency response vehicles or snow and ice removal vehicles are generally exempt from needing a CDL. Most military drivers are also exempt from the requirements, with the exception of the U.S. Reserve.
Operators of farm vehicles that meet certain criteria do not need a CDL. They must be driving a vehicle specifically used for farming, not be driving for a carrier, and stay within 150 miles of their farm.