Why do the wheels on a car look like they're rolling backwards when the car is moving forward?

Answer 1

I think you see that more in old movies actually. The illusion occurs because the movie projector is displaying something like 24 frames each second. For something like a wagon wheel, that can make the wheel appear to spin backwards if it is spinning at certain speeds, kind of kind how a strobe light works.

Answer 2

I have seen this happen in real life, not in movies.... sometimes hubcaps are designed to look like that. Yes, of course it is an optical illusion, I don't suppose it could be seen during the day, though. At night, the streetlights (if they are sodium vapor or flourescent, which most are) are a bit like strobe lights, they flash at 120 Hz..... so if the hubcap is moving fast enough and is designed to look just right, it may appear to have moved backwards..... then reverse direction again as it speeds up more.

Answer 3

It is an optical illusion.