how long is tri tip good in the fridge
You shouldn't marinate a tri-tip. It is already a good and tender piece of beef, and marinating it is just going to ruin it. Specially for 7 days. Beef can actually benefit from an extra day or 2 in the fridge, as it developes the flavor. But like I said 7 days in a marinade, your beef may be ruined but not yet rotten.