Joel,
If they are cracked, have a dusty finish of metal powder, have a slight
yellowish tint to them, it is a good clue they are magnesium. Slice off
less than a flat toothpick's worth of material and stick it into a hot
flame. If it burns like a rocket, it's magnesium. Which is why they
use them if flares.
If it is shiny, bright, cleans well, it is probably aluminum. Magnesium
can be polished, but to a much lower sheen.
You could always weigh them, find the wheel volume by submersing in a
bathtub and calculating volume of water displaced (Archimedes did this,
but early Greeks did an awful lot of unique things).
It should be magna fluxed for cracks, if there is any doubt, before
trusting your life to them. While lighter than an equivalent sized
aluminum part by a little, it is also much more brittle even when new.
A sharp impact can cause cracking. Most aluminum is ductile enough to
bend a good deal before cracking. What could you hit? Any curb, speed
bump, SUV, Miata, iron lawn dwarf, lots of stuff.
Steve Laifman
joel harris wrote:
> Gents,
>
> I have a set of these original Silverstone mags on our car, forgive
> me if I sound dense but how can I tell if they are Magnesium or Aluminum?
> they are pretty light.
>
> do you think it may be risky to run them on the street?
>
> Best Regards,
>
> Joel
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Steve Laifman
Editor
http://www.TigersUnited.com
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