Tri-tip takes a fraction of the time that brisket does. When smoking a brisket the goal is get the internal temperature somewhere in the neighborhood of 195-200º. That means that all the connective tissues have released and the meat becomes melt in your mouth tender.  Unlike traditional brisket or other smoked cuts of meat, you want to pull the smoked tri-tip off around 140 degrees. If you let it go too long the meat becomes dried out and tough.