It's sort of disappointing when a tire suffers a cut when it's relatively new and it does feel wasteful to toss it when it could conceivably be repaired and run for several hundred more miles. However, think about how you would feel if the tire failed after a makeshift repair and you suffered an injury because of it. A replacement is far less than a trip to the ER. I try to repair objects instead of junking them whenever I can, but I don't mess with tires--just not worth it to me--I'd rather not be worrying about the integrity of my tire repair going 35 mph down a 8% grade while being followed by an Escalade.