I can NOT believe I am having to do this. FROM THE SC WEBSITE! Code K - Intrastate Only If you're 18 to 20, you must have this restriction on your commercial driver’s license or commercial learner’s permit which means you cannot operate any commercial motor vehicle outside of South Carolina. This restriction only allows intrastate transportation of shipments/loads that start and end in this state. The load cannot start or finish outside the state of SC (interstate shipment). For the SCDMV to remove this restriction, you must visit an SCDMV office once you turn 21 years old to upgrade your license.
I stand corrected, thanks. For some reason I thought K was for air brakes, must've had an "old" moment....