There’s a lot of discussion over the merits and disadvantages of both alloy and steel wheels. It ultimately comes down to what you want out of the wheel, but if you need some video evidence of how both react under extreme pressure and stress, then look no further than the Hydraulic Press Channel.
The alloy wheel, when stood straight up (like you would have it on a car), took a maximum of 23 tons of force for it to splinter. But when the host turned the wheel on its side and applied the force that way, it broke into pieces almost immediately.
The steel wheel, on the other hand, only needed about 10 tons of force applied while standing up to warp. What was a surprise, though, was how strong it was when laid down flat on its side: The press needed to exert a maximum force of 23 tons to crush it. Additionally, the tire seemed to stay intact even though the wheel was crushed.
The video also reveals a basic truth about steelies and alloys: That the former bends while the latter snaps.
There is a caveat to all of this, though, as Motor1 points out.
Basically, alloy wheels can differ from one another because they are comprised of different materials, though magnesium and aluminum are the most common ones. Different processes in manufacturing can also change the wheel’s tensile strength, which means that another set might yield different results from this particular set of wheels that the channel used in its experiment.
Steel wheels can also have some variation in strength, but not to the same extent as you’ll find with alloys. Steelies can also fall victim to rust, which most definitely compromises strength.
Anyway, to keep things realistic, the host kept the inflated tire on the wheel for the video. You can take a look at the experiment below.