Originally Posted by Duracell

You likely bent the rotor when the wheel was off for the tire change. You can pump up the brakes and they will hold tight until the bent rotor turns and pushes the pads apart slightly. Press the pedal and you can close the pads again but the rotation of the bent rotor will push them back out as you ride.You might be surprised how little it takes to cause this problem.

Originally Posted by shaggieshapiro