I had a meat smoking and charcuterie business for 15 years. For St Louis cut ribs, dry rub them and let them sit in the fridge overnight. This gives the salt time to do its osmotic magic and helps prevent the meat from drying out. In my experience, 250F is a bit too hot for pellet grills. I found 225F to be a good balance of time, temp, crust, and moistness.

The ribs will stall around 160F for a while when the collagen starts breaking down into gelatin (endothermic reaction). When the temp in between the bones reads about 165F to 167F, start checking for a “break test.” Twist the rack of ribs; if the meat cracks easily, they’re done.

Edit to add: Even at 250F, that 4-hour number seems a bit fast. I’d expect closer to six hours for St Louis cut.

I did completely untrimmed ribs on Saturday because I got a deal at the store, but didn’t have time to do much of anything (we were doing a crawfish boil for the first time). I used pepper and slap yo mama cajun seasoning. I placed a small metal pan of water to increase the humidity. Literally left them alone for 4 hours at 250, didn’t check at all. Wrapped in foil with some Stubb’s in a cooler for 1.5hr . The meat was tender, maybe a little dry, and I cut them into individuals because of the membrane. I used 2 tbsp of sauce per rack, since I wasn’t feeling like sweet meat.

I will definitely do untrimmed again, at least for casual weekend stuff. I liked the flavor I got from pepper+Cajun+Stubb’s. Maybe should have spritzed.