agree with @LonzinomakerCS... apply your rub while the smoker is coming up to temp
i typically do the same thing as Lonzino during the last hour or 2 but wrap in butcher paper as opposed to a pan with foil. i feel this retains the moisture but lets things breathe as not to boil the ribs. gives me tenderness but still a bit of tug required to gnaw the meat off the bone.
do a few racks at once do each of them a little different. experiment and see what you like best.