If you drive a truck with air brakes for a company do you need a cdl?

Not necessarily. If the vehicle is under 26,000 lbs., and is not carrying sufficient quantities of hazardous material to require the display of placards, and is not designed to transport more than 15 persons (driver included), it's not considered a commercial vehicle, whether or not it has air brakes, and the only times you would need a CDL for such a vehicle is if it were carrying hazmat or if it were a bus designed to transport more than 15 persons.