two main things that can kill tires, though not the only ones:
1. Bad alignment. First thing I would have checked. You should get a ton more miles out of those tires.
2. How much air are you putting in? Most here run around 30 psi or less.
3. Rotate the tires at every oil change. They will last longer. Include the spare, that way when it is time, you aren't stuck with a brand new tire if you want to change size or brand.
4. driving habits. On sports cars it is peeling out and stopping too fast. Off-roaders can go through tires fast depending on the trails taken. Big sharp rocks are bad for rubber.