Preheat smoker to 350°F
In a bowl, combine salt, garlic, pepper and brown sugar. Completely coat roast evenly with seasoning.
Line a tray with aluminum foil and cover tray with a row of carrots. Place roast on top of carrots
Smoke at 350°F for 1 hour. Reduce temperature to 275°F and cook for 2 hours or until desired internal temperature (120°F for Rare or 130°F for Medium).
Once you have removed the prime rib, cover it with aluminum foil and let rest for 15 to 20 minutes before cutting. This will help keep the prime rib warm and juicy.
Serve and enjoy!