Rumors abound about new regulations, and law enforcement preferences. One guy tells me you need CDL to drive air brakes, another says you can't get a CDL unless you are employed as a truck driver, Another says all tires must be identical. Most are old wives tales. I went through the licensing process not so long ago. Equipment typically must be DOT approved. There certainly are cops more interested in writing law, than enforcing it. I'm not aware they are required.
Willie