Rub rib roast with salt, pepper, and garlic; cover and chill at least 8 hours.
Soak wood chunks in water 1 hour.
Prepare charcoal fire in smoker; let burn 15 to 20 minutes.
Drain chunks, and place on coals. Place water pan in smoker; add water to depth of fill line.
Place rib roast on the lower food rack, and cover with smoker lid.
Cook 5 hours or until a meat thermometer inserted into thickest portion registers 145° (medium). Let roast stand 10 minutes before slicing.