chrome is a multi-step dipping process including nickel, acid dips, and pure water. It corodes just as any other metal or metal-plating, but it is much more resistant to it, and it corrodes clear.
Black chrome goes through roughly the same process as Nickel-Chrome (aposed to matte and satin chrome) but the final product has a tinted color. It is less durable than decorative chrome and has a much stronger solar absorbance, thus it is most commonly used in solar pannels.
ive had my centerline chromes on my car 24/7/365 since senior year of high school. I use soft cloths on it, simply because thats all I own. Chrome is a very durrable substance, hense the fact that 18 wheeler trucks use it so much. Do you think a truck that sees 275,000 miles a year would use something that is "soft" and "delicate?"
no. they use it because it is strong, and resiliant. Why do you think the first thing a trucker does to his truck is spend $10,000.00 to chrome the power unit? so they never have to worry about rusted out exhaust stacks, rusted out front bumper, headlights falling out of their sockets, etc. etc. etc.
use a soft cloth on your chrome. not because chrome is a sissy substance that needs babied and its "soft" but because its good practise.
dont buy black chrome wheels unless you want to replace them in 5 years or so. decorative chrome will last between 7-10 years.
edit: they use chrome on Diesel cylinder liners and jet engine components for ****'s sake... lol.