lokokkee

While examining my Speedlines for the offset figure (ET55, which is also the OEM figure for MY97), I noticed a "Mg" marking on the inside of the wheel. Does this indicate that it is a magnesium alloy wheel? I don't know which model is mine (there is no marking to indicate), but it is a 8-spoke affair, with the spokes straight and parallel (i.e. not curved or tapered). Any info will be much appreciated, as if so, may have to check the tyre pressure more frequently then.
Thanks.