I haven't found any pics, but I can picture it pretty clearly in my mind and, yes, the black wheels look out of place with the chrome trim. They don't complement the rest of the car and it kinda exaggerates their "aftermarketness".
Personally, I like black on silver. My Tahoe isn't silver, but it's a metallic gray. I toyed with the idea of black wheels, but I, too, have an LTZ with the chrome trim. I wanted to keep the chrome trim because it fits the trim level and is a bit of a status marker (take that as you will), which means I'd have to stick with chrome wheels. But now, I'm considering swapping the chrome door handles and mirror caps for color-matched and doing something with the grille to tone it all down some. This would sway it's appeal more to the sporty side than the luxury side, which would be more befitting once lowered. The body being more "neutral" would give me more wheel color options- chrome, gloss or satin black, gunmetal gray, brushed/machined aluminum, silver or gray painted... damned-near anything would look good.