To give detail, I’m surprised how grey and dull they get as they age, anyway, pictures tell it all,
Gave them a good clean then used Bilt-Hambers Hydrate 80 (rust killer barrier system) to rust convert and Ruskins heat resistant Matt black top coat.
By way of process I removed 2 opposing nuts from each wheel so cleaned, dipped and painted over about 24 hours, replaced, removed another pair, then finally the locking nuts. So did them all over about a week.