Who knows beef roast?

Weights please

Your brother must be a magician because if I tried that time/temp on a sirloin tip roast, I'd have a beef flavored hockey puck!

When I smoke roasts I bring them up to 200 then wrap them in foil and let it rest with a broth for an hour or more. Similar to brisket. I have had sirloin tips that fell apart and chucks that needed to be cooked longer. I try and rely on the tender probe. Temps do not seem as important anymore. The probe knows!

It would seem to me that your chuck roast for sure is probably undercooked, it takes a long cook to get all that tissue to break down to the "fall apart" tender you are looking for. As for the sirloin tip, I've never done one.

My guess is you just pulled it to early. Sometimes my briskets are tender at 195 other times it is 210 before they probe tender.

Sirloin is best served rare to med not enough connective tissue and marbling ( to lean) IMO

I know its not the same thing…. at my restaurant I use a top round for our roast beef, with the fat cap trimmed off. We cook ours in a cook-hold oven. I use 17 minutes per pound for a cook time, at 200 deg. After that, hold in the oven at 140 deg. for at least 4 hours. The oven is programmable so I in put these times and temps. When the roast is finished after the appropriate cook and hold times, it is around 135 deg. It is not fall apart tender… but this may help with your times and temps in the smoker.
For catering events I do at times slice our cold roast beef in to a full size restaurant pan shingle style, then partially cover with beef stock, cover the pan with film wrap and foil and reheat. This is almost fall apart tender at this point.
Good luck
Chris

If you gave me weights I'd be able to give you times since most of my cooking is at 400-450f.
No, you cook at sirloin at that temp that long bro, and tender will not be the adjective you will be using.

Actually, you can cook both sirloin and eye of round to falling apart tender and cook it that long. They do not need to be cooked only to rare. The same rules that apply to brisket or chuck, apply to any beef. Cook it long enough, the protein will break down and the meat will fall apart. I might argue that it is not the best way to cook sirloin, but, it can be done.

The key is that you do need to have some moisture in the pan, as this is what prevents it from completely drying out. And you must have a covered cooking vessel. The traditional roast done this way is also roasted with fruit, often prunes or stone fruit. I prefer red wine, butter and water to Liptons, but, to each their own. Smoke for 30 minutes, then place the roast in a covered casserole or braising pan, add aromatics, fruit and liquid, maybe 2 cups, then roast for three hours, at 425F. Then turn oven off, do not open door. Allow to cook for another 2 hours. It should be fork tender. Of course, meat varies, but, this works.