When smoking ribs something that is often overlooked is resting. While it's not as important with ribs, it can be somewhat important (more on that below).
Resting allows the gelatinized collagen and connective tissues to redistribute and reabsorb juices. It also allows the ribs to come down to a safe eating temperature - ie. the bones can be held without burning your fingers.
In my opinion, for pork ribs a 10-15 minute rest is more than enough time for the meat to come down to an appropriate slicing temperature (140 - 160F) and it allows the bones to be held safely.
To Preface this article:
In the barbecue world, there are lots of differing opinions on resting ribs; The above is my personal preference based on my own experiences.
However, other People will typically believe one of two things:
The latter idea more-so lines up with my ideas, only because these folks are "resting" but aren't calling it that.
Truth be told, it takes 10-15 minutes for the bones to cool off which is ends up being more than enough time to rest ribs.
Pork ribs are primarily made up of collagen and connective tissue. Depending on the type of pork rib you're smoking - whether loin backs or spares - they'll take about 4-6 hours to become probe tender.
You can learn more about the types of pork ribs here.
After which, it's recommended to rest the ribs down to a slicing temperature. Slicing temperatures are often overlooked in barbecue.
From a food safety standpoint there is the Food Danger Zone which occurs between 40-140F. Meaning, the lowest internal temperature you should rest down to is 140F.
Conversely, if you were to slice as soon as you take the ribs off the smoker, you may end up shredding the meat from the bone.
Resting for 10-15 minutes allows the meat to set back up, and makes handling the bones easier.
After a 10-15 minute rest, the internal temperature should be at around 140-160F.
During this rest, you can also sauce the ribs.
Some people might be keen to "re-wrap" their ribs with aluminum foil to rest.
Don't do this.
The reason you wrap ribs with foil is to speed-up the cook time.
For much the same reason, re-wrapping your ribs with foil while resting will cause them to continue cooking and potentially overcook; It may also ruin the bark and cause it to turn soft or soggy due to the build up of moisture.
Rather, when resting ribs, simply leave them on a serving tray or "tent" them with the foil. Tenting allows for heat and steam to escape while also protecting the surface of the food from the environment.
Most of this article has been about pork ribs - if you're smoking beef ribs. My suggestions in terms of temperature still stand.
Wait until around 150-165F to slice.
With beef beef short ribs, this can be longer simply due to the size of the meat and the fact that the large bones conduct heat to the interior.
You can learn more about beef ribs here.
Nevertheless, it will typically take an hour rest to come down to 150F.
For beef back ribs - which are much smaller - the rest time is about the same as pork ribs. Usually 10-15 minutes is more than enough time.