What is the size of the wheels, I need a spare from the junk yard and I need to know what size to ask for. Thanks

Go to your vehicle with a pad and a pencil, look carefully at the sidewall of your tires and you will see what the tire sizes are for your truck, they will look like this...example only....P225 75 X 15.
The 225 represents the tire height, the 75 is the width across the tire, the 15 is the size of the rim you have on the vehicle.
My example size may be the size you have, but double check it to be sure.