The yolk will be about 1 1/2 tbsp and the whites will be about 2 tbsp. An extra large egg will have about 4 tbsp of liquid inside, while a medium egg will have only 3 tbsp.
Test the meat after 30 minutes with a meat thermometer. Remove it from the grill when it is 135 degrees (medium rare) or 150 degrees Fahrenheit (medium). The tri-tip cut will start to get tough if you cook to a higher temperature than this.
The real answer is it depends, but a total time of 25 - 30 minutes for a smaller tri-tip is usually a good starting guess. Each tri-tip roast and grill is different though, so you really need to use a meat thermometer to make sure the roast is cooked to perfection.