My PS2's probably wont see 11k. I really did nothing to shorten their life, mines a Ltd and I don't spin the tires. My car had 300 miles on it when I got it and all I can figure is they were 300 hard miles. I'd like to think the person selling the car had your best interests and safety at heart and that is why he/she is putting new tires on it. There are limits on just how long a tire will last, there was a piece on 20/20 or one of those type shows about tires that were blowing because they were old and dry rotted.
As for how many miles is on the car? Some good suggestions have been given. I didn't see anyone mention the CarFax report but if they did ...sorry. get the CarFax report. Order it from CarFax and don't let the person selling you the car give it to you. You can only be too careful. Good luck.