I agree with tropictour...good tires go on the front and back. On my old Tempo in the winter I got stuck in a couple iced up driveways (And once in a snow bank...being a kid with an e-brake on unplowed roads) until my front tires were nearly bald, so I put them on the back and switched the good ones to the front. She went up hills well, but one time doing 20 MPH on snowy unplowed roads, her back tires slid out and she did a 360 until she was backend into a ditch on the other side of the road...moral is, don't be cheap, if you think any tires are bad, replace them immediately.
