The same argument would work for aluminum wheels.

Aluminum corrodes just like steel, just slightly faster.
No idea why they call them Mag wheels.
I doubt that wheels are made from magnesium.
They are actually forged aluminum alloy.
You would be driving around with four giant Thermite bombs under the frame if they were magnesium.
I will research this.

Well hush my mouth. Now THIS is lunacy!
Magnesium alloy wheels

Magnesium alloy wheel on a
Porsche Carrera GT
Magnesium alloy wheels, or "mag wheels", are sometimes used on
racing cars, in place of heavier steel or aluminium wheels, for better performance. The wheels are produced by one-step hot
forging from a
magnesium alloy known as ZK60, AZ31 or AZ91 (MA14 in
Russia). Cast magnesium disks are used in motorcycle wheels.
The
mass of a typical magnesium automotive wheel is about 5–9 kg (depending on size).
[2]
Magnesium wheels are flammable and have been banned in some forms of motorsport in the UK following fires which are very difficult to extinguish. Mag wheels have been known to catch fire in competition use after a punctured tire has allowed prolonged scraping of the wheel on the road surface.[citation needed] Some variants of magnesium alloy wheels may have low corrosion resistance.
They have the disadvantages of being expensive and not practical for most road vehicles. Aluminium wheels are often mistakenly called "mag wheels".