This classic riddle sounds like it should have a complicated answer. Something with four wheels immediately makes you think of a car, truck, or another vehicle—but the word “flies” is the clue that changes everything.
Instead of thinking about something that flies through the air, think about something that might attract actual flies while traveling on four wheels.
Once you interpret the clue that way, the answer becomes surprisingly simple.
Answer: A garbage truck. It has four wheels, and flies can gather around the garbage it carries.
