Ahh, the things we learn through experience:
I've always taken the flat tire and placed it under the rocker panel or frame rail. That way, if the car falls the tire and rim will keep the car from hitting the ground and you could still get the jack under the car and start all over again.
i would never put the flat tire back in the truck UNTILL the spare is installed! id hate to see the car fall off the jack from a tire being thrown in the trunk
I've had a car drop to the ground. I think I had to use 2 jacks to get the car back up. Fit the jack as far under the car as you can, then get the other jack a littke farther and so on...