i found if you go racing the day after you fitted your slick, you would see a few inches of movement. if you fitted your slick a couple of weeks before you go racing you'll see very little movement if any. i put this down to the soapy lube they apply to help your slick fit over the rim & slip onto the bead is still wet so it allows movement. i used to screw just the back of my rim as to hide the screws, but in the last 2 seasons we've gotten a bit lazy & haven't bothered to screw at all. i'm not seeing any movement & we still mark the rim to check at each meeting. i'm doing 9.4's at 139 mph with 1.34 60's in a 2950lb car with me in the chair.