Weeds,
if you look at the front axles, from the front, you will notice that the kingpins slant outward from top to bottom. In theory, the line through the kingpins is supposed to intersect the ground in the middle of the tire tread. I don't think that small changes here are a big deal, myself. Even using tires of a different diameter will change this relationship and this is a pretty common situation.
True bumpsteer can be caused by a draglink that is not horizontal, but on an angle. This can happen if the ride height is changed. What happens is when the wheel goes up or down, the arc of the drag link causes movement in the horizontal forward/aft direction causing the steering arm to turn.
