Since the deposits are on the rims SS ring, you should be able to use any good metal cleaner/polish to remove them without much difficulty. Blue Magic is the product I prefer, but there are several to choose from. (On a side note: The Blue Magic Carpet Stain & Spot Lifter is the best product for car or home that I've ever used.)

You can also use Eagle One's Never Dull swadding polish. This might be the best choice to remove the oxide forming on any metal surface, SS or others. Just tear off a piece & rub the SS rim surface. The oxide will disappear, a polish residue will remain that you remove with either a cheesecloth or microfiber polishing cloth. Rim should look like new. This product also works good on the iron oxide that can form on chrome rims. I use it on my F150 chrome rims every year (spring & fall).

Later,