Likely the clearcoat has been breached on the rims allowing water to infiltrate under the protective layer.I bought my 2013 XTS-4 Premium almost 2 years ago, a few issues here and there. But, I noticed after getting the car washed yesterday that the wheels looked like they were still dirty. No, it's the paint/coating is rough. The wheels aren't chrome, so which would be the better option? Getting them re-painted or replacing them? I saw on another Cadillac forum that it's a defect, but those posts were from 2015 and none since.
Your options are DIY refinishing, sourcing new rims, or having your existing wheels professionally refinished.
I recently had 2 rims on my Escalade refinished for $175/ea and they turned out beautifully.