you might be able to get 4mm out of them depending on the current forward pressure setting. To set it, turn the arms of the heelpiece (the things that hold the release to the turntable), you'll probably need some pliers or something to do this. I can't remember off the top of my head, but I believe turning left makes them go out, it's hard to judge, so you'll have to keep trying to pop the boots in place every now and then until the fit properly.