A good metal prep for alluminium is either Alumiprep 33 or Metal Prep 79.
If you're painting the wheels, you can also then use Alodine 1201 as a passivating/etching treatment.
No point in using the Alodine if you want a natural finish, or are polishing, as it leaves the alloy with a gold-ish surface finish.
The above are what we used to use for preparing an aircraft for repainting. The Alumiprep (or Metal Prep) removes oxidation (it can be diluted for light oxidation, or used full strength), then we use Alodine 1201 for the surface treatment prior to paint. Note - you must follow the application directions on time you leave Alodine applied before rinsing.
Swab or brush the material on....if you spray it, use a respirator.
You can buy this stuff on line or at aircraft parts supply companies.