Try to stick one of your refrigerator magnets on one of your wheels, if it sticks, the wheel is steel.

In General -
Alloy wheels are often lighter than steel wheels, (they have less unsprung weight, allowing better handling over bumps and pavement irregularities)
Alloy wheels are often mose susceptable to damage - dents, curb rash ,bent wheels, etc.
most people think that alloy wheels are more attractive. Volvo only offers a couple of wheel cover designs for steel wheels. (EVERYONE has alloy wheels now!)

Personally, I like to have some fun with wheel covers - paint them body color, or any color you like. I have painted wheel covers yellow, burgandy, and white.

In the gallery, search for 700s and look 1/3 of the way down page two to see "Evander in his winter plumage" Evander, a black 1990 740 Turbo sedan has white wheel covers and a white reflective stripe around his flanks.

Wheel covers are cheap, have some fun with your car.
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2 8s & 2 7s 600,000 miles total