Pat the chicken thighs dry with paper towels.
Trim away excess fat and loose skin.
Lightly coat the chicken with olive oil.
Combine the brown sugar, smoked paprika, garlic powder, onion powder, salt, black pepper, chilli powder, and cayenne.
Coat both sides of the chicken generously with the dry rub.
Preheat the Traeger to 225°F.
Place the chicken thighs skin side up on the grill grates.
Smoke until the chicken has developed a good smoky exterior and is approaching the final cooking stage, usually around 60 to 90 minutes depending on size.
Increase the Traeger temperature to 375°F.
Continue cooking until the thickest part of the chicken reaches at least 165°F.
For especially tender dark meat, continue cooking to 175–185°F while monitoring the chicken closely.
Remove the chicken from the grill and rest for 5–10 minutes.
Serve hot with your favourite BBQ sides.