I am planning on replacing my tire, but I'm curious as to how dire it is. Should I put the spare on right away, or is it safe to drive on until I make an appointment with the dealer? The damaged occurred because of hitting a curb. It tore the rubber about less then a quarter inch thick and about 3 inches long.
I can't really advise that you try and make it to the tyre shop as I have no idea how far away it is, nor how fast the roads are to get there.. However to be 100% certain and for your safety.. I would advise that you change the wheel for the spare.
You may have only taken maybe 1mm or so of rubber from the sidewall surface, but it's like a cut were the rim has pinched the tyre initially, so you can't really tell what damage has been done to the tyre structurally. Better to be safe than sorry.