Apply the hand brake while rolling down the road to see if it pulls then. If it doesn't you know the problem is probably in the front - unless the proportioning valve is screwed up.
Run out is the disc wobble from side to side. There has to be a little built in to push the piston in a wee bit when you release the brakes. Too much will make the front end vibrate or you will feel like you are riding on the head of a pigeon!
