This topic rears it's ugly head every once in a while. Many states differ, and what makes it even more confusing is the fact that the very officials of the states (State Troopers/DOT Employees) who are charged with enforcing these very laws either have little knowledge of them or are completely wrong in their enforcement of them. In the STATE OF PENNSYLVANIA for example: One does NOT need a CDL to operate a privately owned antique vehicle that is not operating within commerce- no matter what the combination is; whether it be a straight truck weighing less or more than 26,001 lbs. It can be a Tractor and Trailer weighing 35,000 GVWR- as long as it is a privately owned and registered as such and is not operating within the laws of commerce- no CDL is needed, however you do need to possess the appropriate non-CDL operators license. My 1958 FWD Firetruck has a GVWR of 31,000lbs however only weighs 18,500- were it a commercial vehicle operating in the laws of commerce, yes I would need to have a class B CDL. It does not have air brakes so the air brake endorsement would not be needed. But again, it is a privately owned vehicle and registered as an antque/historic vehicle and is operated for private purposes and not for commercial gain, I do not have to have a CDL. When I first bought it, I was curious as to the proper operating requirements. I wont bore you with the long story but the short version involves several hours of telephone calls to one of my elected representatives office staffers, and another hour or two with people at PENNDOT in Harrisburg- which probably resulted in several bottles of MAALOX and TYLENOL being consumed on their part as I could not get the same answer from any two people. So I made a stink and in the end, I received a letter from the Commissioner of PENNDOT himself, stating the requirements. I have never been pulled over, I do not intend to get pulled over, but that letter remains to this day- in the glove box. All that being said, do yourself a favor, and obtain a CDL- it's in everyones best interests.