To keep the corn from getting tough on the grill, first brine the corn. Use 1/2 cup of salt and 1/2 cup of sugar per gallon of water for the brine. Brine at least 30 minutes, but no more that 6 to 8 hours.
Clean and preheat grill
Place ears of corn on the grill and cover. Rotate corn every 2 minutes such that it cooks evenly all the way around.