These GM large sized wheels have a tendency to get some surface corrosion on the bead surface. I've had a number of wheels leak air and the fix that finally ended my leak miseries was to pull the tires and lightly wire wheel the mating area the bead sets on. The chrome is not bonded well in that space and it literally flaked off with ease. From what I been told condensation caused by climates with large temperature swings is where they see the wheels do this the most.