Okay, so because I have access to another car (my sister keeps one at my place for when she's in town, which is rare), I didn't get around to shopping tires until yesterday. Found out I have a weird size, so unless I can find exactly what I want elsewhere, I'll go back and order from Costco. While I was there, I asked him if he could bring up when I got my tires. "2006." "How many miles?" "37,000. If you have any more than 50,000 miles on your car, then yes, you should probably get new tires." "I have over 115,000 miles on my car." "Well, you definitely got your money's worth out of them." "I would say so." I looked when I got back in my car, I was off a little bit: I have 126,000 miles on my car. I put 89,000 miles on 20,000 mile tires (I think -- worst case, I put 89,000 miles on 80,000 mile tires, but I don't remember them being that high, but I would allow 40,000 -- I remember the higher mileage ones being more expensive, and remember not buying the most expensive ones). And I still have thread left on the other 3, so I probably just needed an alignment.
So of all the things that can be said about my driving, being hard on tires is not one of them.