Whisk all ingredients together in a medium bowl. Season with salt and pepper, to taste.
Stir spices together in a medium bowl.
About 1/2 hour before cooking time, soak hickory chips in enough water to cover. Drain chips. In a covered grill, place slow burning charcoal in both sides of a drip pan. Sprinkle coals with wood chips.
Rub top side of each rack of ribs with about 3 tablespoons of the rub. Place ribs, bone side down, on grill. Close cover or place cover on the smoker. Grill about 1 1/2 hours, adding chips every 20 minutes. During the last 10 minutes of grilling, brush liberally with the Maple-Horseradish Glaze.