This isn't correct.
You can tow a trailer up to 10k GVWR with a class B. (over 10k if the combined GVWR is under 26k.)
A class A is not reqired until the combined GVWR exceeds 26k. Even then it is only required IF the GVWR of the trailer is over 10k.
There is also no such thing as an air brake endorsement. That is why a CDL is not required solely because a truck has air brakes.
Ok guys, here is how the CDL breaks down:
Class B: Vehicle over 26,000 lbs GVW, No combination (Means no trailers behind it)
Class A: Vehicle over 26,000 lbs GVW, Combination Weight (meaning truck and trailer) over 26,000lbs, or any trailer over 10,000lbs GVW. That's right, a tandem axle bumper-pull flatbed with 2 5000lb axles that's plated for 10,000lbs GVW is illegal to tow (even behind your pickup) if you don't have a Class A.
Air Brake: an endorsement for various license classes (A, B, S, etc) for driving a vehicle with air brakes..... Some states (such as Michigan) allow anybody with a drivers license to drive an air brake equipped vehicle if it is for private use and doesn't require a CDL otherwise to operate.... (i.e, for weight purposes, etc.)
