...there is a reason the tires were pulled off with so much thread, generally there was a good reason.
You risk having tires with uneven tread wear etc...considering they probably came off a different car, due to different wear patern you are at the very least compromising ride quality, and possibly handling & overall safety (someone wanna chime in on the handling/safety? ...as its just my opinion, and those are like A**hol*s...everyones got one