What is a class A drivers license?

Commercial vehicles with a Gross Combination Weight Rating of more than 26,000 lbs., in which the vehicle in tow - such as a trailer - itself has a Gross Vehicle Weight Rating of more than 10,000 lbs. Tractor-trailers are one example.

Some states also have a non-CDL Class A licence for vehicles which fall into the same category, but are exempt from the FMCSR (commercial vehicle regulations), such as recreational vehicles, registered farm vehicles, firefighting and first response apparatus, etc.