Preheat the pellet smoker to 250°F.
Clean the spare ribs and remove the membrane from the back of the ribs.
In a small bowl, make the BBQ rub by combining the brown sugar, chili powder, cumin, salt, mustard, garlic powder, onion powder, white pepper, and cayenne pepper with a fork.
Pat the ribs dry with paper towels then rub the BBQ rub all over the ribs, making sure they are fully coated.
Place the ribs in the smoker and smoke for 4 hours.
After 4 hours of smoking, start checking the internal temperature periodically until they reach 205°F.
Let the ribs rest for 10 minutes before slicing and serving.
Remove the ribs from the smoker, and let them rest uncovered for 10 minutes before serving
Serve with Texas-Style Barbecue Sauce and lots of napkins!