Reduce heat to 250 degrees and continue roasting an additional 1½–2½ hours or until the internal temperature reaches the desired level of doneness on a
meat thermometer. This may happen a little faster depending on the shape and size of the roast so begin checking the temperature after 1¼ hours. As a general guide, remove the roast at 120 degrees for rare, 130 degrees for medium-rare, 140 degrees for medium and 150 degrees for well-done.