>One way to tell cast from forged is by looking at the bare alloy surface with
>a magnifying glass (best with jeweler's loop used for checking out
>gemstones). Anyway, forged aluminum will look tight and less porous
>to their more common
>counterparts. The pores are airpockets left from casting. Forging the wheel
>forces most of these airpockets out or makes them very small resulting in a
>stronger wheel.
>
>Forged wheels are also generally much lighter than a comparable cast wheel.
>Since forged wheels are stronger, manufacturers will often use less
>material to
>accomplish the same thing. In one example, I found a 15" X 7" forged alloy
>wheel weigh 50% less than a cast wheel in the same style and size.
>Furthermore,
>the weigh capacity of the forged wheel was 33% higher than the rating for the
>cast counterpart.
>
>Unfortunately, forged wheels are much more difficult to make. As a result few
>designs are available. Some due to lack of demand (due to cost), most because
>the forging process limits (aesthetic) designs. So there are more
>good-looking (yeah, I know it is a relative term) cast wheels
>available vs. forged
>wheels. Forged wheels tend to have flatter dish and spoke designs.

I believe Mercedes alloy wheels are forgeries?
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
<andrew.grebneff@stonebow.otago.ac.nz>
Fossil preparator
Seashell, Macintosh & VW/Toyota van nut