Prepare grill for high, indirect heat and fit with grill pan (for a charcoal grill, bank coals on 1 side of grill and put drip pan on empty side. For a gas grill, leave 1 burner turned off and place drip pan over unlit burner). Add water to pan to a depth of 1/2 inch.
Season chicken generously with spice rub. You want to make sure the entire chicken is coated in the spic rub. I like to rub some spice rub under the skin for extra flavor. Place cavity of chicken, legs pointing down, onto open beer can. Position the chicken so that the can fully supports the chicken in an upright position. Place can, with chicken, on grill over indirect heat (and above drip pan).
Grill chicken, covered, until cooked through and an instant-read thermometer inserted into the thickest part of thigh registers 165°, about 45–60 minutes. (If using charcoal, you may need to add more to maintain heat.)
Let chicken rest 10 minutes before carving. Serve with pan drippings.