Aluminum is lighter, but also weaker so they have to use more of it. If you look at an aluminum rim there is ALOT more material there than with a steel one. Usually aluminum rims come out being heavier than steel, along with a noticable power loss. But they also act as a huge heat sink for your brakes and help them cool better. As usual there isn't really a clear winner.
Steel rims work great (they should, they just about have been used since the begining of time), both my trucks have steel rims and hold a balance fine. I wouldn't mind finding a set of alloys for each truck though, I find both sets tolarable but I wouldn't pick them out of a catalog (they are factory) Black rims really don't do much for me, and aftermarket chrome rims like to rust... so that is about all that is left for me.
I haven't either bent an steel rim or broken a aluminum rim, unless you are pretty hardcore at wheeling or like to biff curbs at high speed it really isn't that big of a deal. Either way you are looking for a new rim once you get home.
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