First of all, I am not a LEO or attorney but I stayed at a Holiday Inn express......I did have a Class "d" chauffeur's license since I was 18.
Like many here, when I started in this hobby and looking to buy my M923; I had preconceived notions for the requirements of cdl, air brake endorsements, gvwr, state and federal laws, commercial use etc. I also looked on the ss forums and there was so much information and it all seemed to contradict each other that I did my own research, asked local Leo, and State Troopers and finally motor carrier safety officers.
I would like to offer the following suggestions to all:
1.) Download and read your state dmv laws straight from your state website. Do not use a 3rd party website but go direct to the source. Pay careful attention to air brake endorsements and gvwr weight standards. Be aware of the penalties for not having a cdl when required. (In Louisiana they are usually much worse than the standard moving violation)
2.) Download and read your state cdl manual/test guidebook directly from your state. Again, do not use a 3rd party website. Pay careful attention to air brake endorsements and gvwr weight standards.
3) Do NOT ask for guidance from the following folks:
A. State dmv office. As ArYankee stated already. They are tax and license fee collectors who are NOT the law enforcement Post certified. They generally are not versed on all aspects of their laws and most are low level hourly clerical workers. Their jobs are to issue plates and licensees and not interpret the law.
B. Local LEO, no disrespect intended ! These folks are usually not well versed on IFTA, hours of service, License requirements, overweight, permits etc. When they look at a big truck on the road they are looking for obvious safety equipment violations- bald Tires, no brake lights etc and moving violations- speeding, tailgating etc. Most local LEO are not going to be enforcing "truck" regs.
4.) Do ask your State troopers who are specifically motor vehicle safety officers. They are normally a separate unit or division of their state agency. For example in Louisiana, they are a separate entity of the Dept of Public Safety but still under the umbrella of the State Police. These are the folks who will be doing inspections at weigh stations and the ones you see doing roadside stops and inspections. All they do is enforce CDL, permits, overweight, IFTA, hours of service log books , vehicle safety standards etc. They will be called to the scene of truck, trailer, bus etc accidents.
When you look at all this information, Most will understand what is required and that air brakes and weight will override the definition of "commercial". Yes, I understand there are exceptions to Farm vehicles, historical etc but they "should" be clearly spelled out in #1 & #2. if not use #4
Remember that if you are involved in an accident that is not your fault such as someone runs into you, you will be looked at also to make sure you are complaint in the eyes of the law. Normally anything that happens on a state or US Hwy & interstate will be the jurisdiction of your State Police. If local LEO has a question and needs assistance, they will contact #4
Please take #1 & #2 seriously and you will gain the knowledge you seek.