Pat the chicken thighs thoroughly dry with paper towels to ensure optimal skin crisping.
In a small bowl, combine the salt, pepper, paprika, and garlic powder; apply the dry rub evenly over all surfaces of the chicken.
Preheat the grill for two-zone cooking, establishing a high-heat direct zone (400°F/204°C) and a cooler indirect zone.
Clean and lightly oil the grill grates using a lint-free cloth or paper towel.
Place chicken skin-side down on the direct heat zone and sear for 5 to 7 minutes until the fat renders and the skin is golden brown.
Flip the chicken and move it to the indirect heat zone.
Close the grill lid and roast for 25 to 30 minutes, or until the internal temperature reaches 155°F (68°C) as measured by an instant-read thermometer.
Whisk the BBQ sauce and apple cider vinegar together in a small bowl; brush a generous layer of the mixture onto the chicken thighs.
Continue cooking over indirect heat for 5 to 10 minutes until the glaze is tacky and the internal temperature reaches a safe 165°F (74°C).
Remove the chicken from the grill and let it rest for 5 minutes to allow juices to redistribute before serving.