I have a set of GM XG code rally wheels and the smaller 67 style center caps. All parts, including the center caps, are real GM parts that I bought back in the 80's. The center caps pop in place with the palm of my hand and seat firmly.
However, I have noticed that the gap between the center cap and the wheel is not even all the way around. The gap is a little smaller at the valve stem location and opposite the valve stem. This is where the 'nubs' are located on the wheel (2 nubs are centered on the valve stem and one is located opposite the valve stem). So, it appears that the center cap base is being slightly bowed out after installation. If I jack up a front wheel and spin it, you can notice the slight runout of the center cap. All the center caps have the same runout. And all of the center caps are flat & true when removed & put on a flat surface.
Is this normal for original factory rally wheels? Any way someone could check and original wheel/center cap set up fro me? I'm just wondering if this is simply the unavoidable result of installing the center caps.