Aluminum Wheels

I cannot tell you about visual inspection other than to look for cracks and pits, but usually the manufacturer will check them with a dial indicator to see if they are round!

Non ferric parts can be checked for cracks or pin holes with dye penetrants. Some of the spray penetrant/powder developer types are messy and expensive when checking production volumes. One type, Zyglo, can be wiped, sprayed or dipped, rinsed off with water and checked with an ultraviolet light. By far the least messy. I don't know the cost.

Here is a link to an Alcoa Wheel service manual with a section on inspecting wheels.

http://www.todaystrucking.com/images/AlcoaSVM_Manual.pdf