Chrome or lightweight aluminum?

If you don't want to roll the fenders, then 20's are out of the question I believe. Also, chrome might be heavier, but it won't strain your tranny. Now, if you want to street-race (which I do not support) or do track time, and you want pure performance, then hit up with the aluminums. They're marginally lighter. Also, before you buy, make sure offset and everything is correct. The brake calipers and schtuff should all be considered.

My two cents. I'm not a professional mechanic, so some others may disagree.

Yeah, chrome is for show only. If you ask me, I don't even like the look of chrome. Definitely go for aluminum alloy. Some aluminum wheels are pretty damn sexy.

I'd love to get a simple set of lightweight five-star forged wheels for my speed6, but forged wheels tend to cost $$$$ and frankly I think the stock wheels look fine. They're rather plain, but not unattractive and that doesn't bother me at all. Might be interesting to have them powdercoated black to match the paint some day though.