Could somebody give me an idea of how many miles might be expected of stock BFG g-force KDW's on a '00 Contour with "standard" use?

Recently got a nasty close-to-sidewall puncture in one w/ 15k miles onit & wondering if I should just buy a single cheap tire/used & get a new set when they're used up or go for 2 new ones now.

I'm inclined to go for the cheap & dirty fix now, since I figure these tires are soft enough that they'll probably only go 25k or so...
Thanks.