These roasts, cut from the rear end of a steer are leaner and a little tougher than loin cuts. A rump roast is cut from the bottom round. If the bone remains, it is a standing rump roast. The top round is a little more tender than the bottom round, but also very lean.
Two ways to improve these cuts are injecting and larding (inserting strips of fat into slits into the roast). Injecting produces a more even distribution of flavor and moisture. Oils or melted butter can be added to the injecting liquid.
I like to inject them and cook indirect using roasting temps around 325° to 375° measured at the grate, then pull them off at 135° or so. They will rise about 5 degrees during the rest.
Slicing thin, against the grain helps keep the meat tender.
Cooking Time Chart:
2-3/4 pound roast - 325° pit temp - 1.5 hours to reach 135°