What kind of vehicle falls under each group for a CDL license?

The commercial motor vehicle groups (also known as “classes”) are as follows:

• Combination vehicle (Group A) — Any combination of vehicles with a gross combination weight rating (GCWR) or gross combination weight (GCW) of 26,001 pounds or more, whichever is greater, provided the gross vehicle weight rating (GVWR) or gross vehicle weight (GVW) (whichever is greater) of the vehicle(s) being towed is in excess of 10,000 pounds.
• Heavy Straight Vehicle (Group B) — Any single vehicle with a GVWR or GVW of 26,001 pounds or more, whichever is greater, or any such vehicle towing a vehicle not in excess of 10,000 pounds (GVWR or GVW, whichever is greater).
• Small Vehicle (Group C) — Any single vehicle or combination of vehicles that meets neither the definition of Group A nor that of Group B but that either is designed to transport 16 or more passengers including the driver or is used in the transportation of materials found to be hazardous for the purposes of the Hazardous Materials Transportation Act and which require the motor vehicle to be placarded under the Hazardous Materials Regulations (49 CFR Part 172, subpart F).