You know how some cars have wheels with hub caps, and you would see the black rim if you took the hub cap off? I thought someone told me that this rim was called a mud flap.
I later told this to one of my teachers, who had two wheels on her car with missing hub caps, and she finally told me what mud flaps actually are.
A childhood belief about cars

others believed things like this
- i used to believe that the hard toe caps on rugby boots were made from giant ants found in the amazon!— eryll
- I used to believe that when people talked about 4x4 trucks, I thought it meant all the wheels turned.
— tracy - I used to believe that there were lots of hamsters in the wheels of the car, and that's what made it go.— Jade
- I used to believe that training wheels were the different colored beads on the spokes.— Samantha
- i used to believe that my brain worked like the inside of a clock. How the wheels cranked and turned.— Becky
- I use to beleive that Motorways had special tarmac on the road that made the wheels go faster— Nada