Cleaning Recommendations Needed

I'm cleaning out these mag wheels and the hub is a nightmare. I'm sure soaking in mineral spirits or acetone would probably do it but

A) I'd need a lot to be able to submerge it enough in either orientation
B) I don't want to destroy the wheels themselves… even though they need deep cleaning as well

Any suggestions on what to use and/or how to do it would be greatly appreciated. Thanks in advance!