Flour tortillas will keep longer than corn tortillas (ever had a stale nacho chip?), and I've noticed that the big 'brand name' flour tortillas keep longer than the smaller ones produced by Mexican companies (if you have access to a Latino market, you can get them there).
A little story about stale corn tortillas; one very cold, snowy winter in New Jersey, we noticed that the deer were trying to forage in the 3 feet of snow in our yard, and not having much luck. So we scrounged around the house for stale bread, none was to be had. Then found a huge package of old corn tortillas in the back of the pantry, that I had forgotten about. Well, we stood on the deck, and threw out the tortillas like frisbees - and the deer loved them! Wish we would'a had a video camera for that - and don't know what was funnier - the deer eating the tortills, or us playing frisbee with them!