Cooking Tri Tip in the oven at 425 F degrees takes between 40 minutes to 60 minutes depending on how well done you want the Tri Tip to be.
If you want the Tri Tip to be medium rare then 40 minutes would cook the Tri Tip enough for it to be medium rare.
If you want the Tri Tip to be fully cooked all the way through then it will take 60 minutes which is an hour and if you want the Tri Tip done even more then 1 hour and 15 minutes to 1 hour and 30 minutes should be enough.
While preparing the Tri Tip preheat the oven to the 425 F degrees and then place the Tri Tip in a roasting pan and set the time for 1 hour and check it to see if it's done after 40 minutes and if not continue cooking it for another 10 minutes or so.
If you have a meat thermometer you can tell when Tri Tip is done by sticking the thermometer into the thickest part of the meat.
When the meat thermometer reads 145 F then the Tri Tip is done.