How Can I Tell If I Have Aluminum Alloy Wheels on My Tires?by Richard Rowe
Aluminum alloy rims came into the forefront of automotive styling back in the 1970s. Aluminum rims were a lightweight alternative to steel rims, offering better performance and a more sculpted look than steel rims and hubcaps. There are a number of ways to tell if your car has aluminum allow rims, some a little more straightforward than others.
This is the easiest part; if your wheel uses a hub cap, then it's almost certainly steel. The same holds true if the rim is painted black and isn't obviously an aftermarket wheel.
Steel is magnetic and aluminum isn't, so any magnet will tell the tale if the wheel is steel. If the magnet doesn't stick, then the wheel is either aluminum or magnesium.
The Acid Test
Magnesium was once a commonly used wheel material, but its tendency to corrode and to burst into flame when overheated made aluminum the better and safer option. Magnesium is an extremely reactive metal, especially where acids are concerned. Find an inconspicuous spot on the back of the rim and apply a drop of vinegar to it; if the vinegar bubbles up, then the wheel is magnesium.
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