What type of roast was it; shoulder, loin, or sirloin?
If it was a loin or sirloin roast, you only need to take it to 145°F, with at least three minute rest; which is the USDA recommended temperature. I take mine to 140°F. At these temperatures it should remain moist.
If it is from the shoulder, you will need to take it to a temperature that the collagen will break down into gelatin. At the temperatures you used, taking it to an internal temperature of 175°F, it will be good for slicing. At 195°F - 205°F, it will be good for pulling. And of course your cooking time will be much longer.
If you rub it down the night before, and the rub has salt, wrap the meat tightly in plastic wrap.