Aftermarket wheels...how safe are they??

I was at an AUTOx when an OEM aluminum (350z) wheel broke off the hub like that at 45-50mph as the car loaded up into a sweeper. On inspection it had a crack for a very long time before it went. Another kid with bargain basement cheap aftermarket wheel had cracks in 3 of 8 spokes. Cracked as cast, hit a pot hole, who knows. Heat cycles are a *****.

Inspecting your wheels at tire rotations is just good practice.