A couple of years ago I had a Hertz car that I had rented in Southern CA and driven up to Northern CA. I got a flat and pulled over and called. They offered to send a truck out but I said that I didn't want to wait and asked if I could put the spare on myself. They said that would be fine and advised that after I had swapped spares that I could go to any Hertz location and pick up a new car. I did so with zero hassle and I never heard another thing about it.