Ford rims that just cracked

My husband has a diesel 2005 F350 Harley-Davidson edition pickup. He has had to replace all the rims with a dealer- suggested less expensive type after replacing one of them to the tune of $1,400.00, and then another one cracked. Ford could not explain why the factory rims just seemed to disentegrate. There was no accident, no pothole, no impact of any kind. Any thoughts?

Ford must have gotten some wheels from a bad casting batch.

Where, exactly, did they crack?

As a commercial truck driver, I was trained to look for cracks in wheel rims, but what I usually see are cracks in the paint on a wheel rim, and rust coming through the crack.

Could it be that the rims are really just bent?