A carton suitable for packaging a coil of wire with a payout tube has a cover for selectably closing the open side of a five-sided clamshell. The carton can be loaded by placing the coil and payout tube on the cover and then closing the clamshell over the coil. The clamshell has a payout tube aperture and an entryway that permits the clamshell to fit down over the payout tube with the tube extending through the clamshell. Doors open to permit initial access of the tube to the aperture during closure of the clamshell. The doors then close to prevent the tube from becoming dislodged from the aperture. Guide flaps constrain the coil during closure of the clamshell. The final panel of the carton to be closed is secured on all of its free edges to prevent inadvertent opening of the carton. Fold lines are reinforced with reinforcing tape. The carton blank is laid out to have a waste percentage of less than 20%.