Traditional Prime Rib

1 (8 to 10 pounds) boneless beef ribeye roast, fat cover trimmed to 1/8-inch thick 1/4 cup black pepper 2 tablespoons white pepper 2 tablespoons salt 1 1/2 teaspoons ground thyme 1 1/2 teaspoons garlic powder 1 teaspoon onion powderPreheat oven to 350°F.In a small bowl, combine all spices. Rub evenly over surfaces of roast.Place rack in shallow roasting pan. Insert meat thermometer so bulb is centered in thickest part, not resting in fat. Do not add water or cover.Roast in 350°F oven approximately 18 to 22 minutes per pound for medium-rare to medium doneness. Remove roast when meat thermometer registers 140°F for medium-rare or 155°F for medium. (Temperature will continue to rise to 145°F for medium-rare and 160°F for medium.)When thermometer indicates that roast has reached desired doneness, remove the roast from the oven, tent with foil and allow to rest for 15 minutes before carving.Makes 16 servings.