Originally Posted by
miamijim
Something to consider is the axle diameter. If its smaller than the dropout width there's a possibilty the wheels rocking to one side.
This is a good point. Using a large crescent wrench to gently bend the dropouts so as to tilt the wheel properly in the vertical direction could shift the axle's position high of one side and low on the other side (if there's slop in the dropout slots, or if you file to get some slop). If you tilt the axle in the dropouts, you need to tilt the dropouts or the wheel will just clamp down in the wrong place.