Stephen King is really bad with numbers. Apparently in the book they had to constantly walk at 4-5MPH, but they dropped it to 3 for the book. But sometimes King will just pull numbers straight out of his ass and his editor just lets it fly.

Similar case, in IT, he constantly described Ben as fat, as wider than he was tall, etc., basically fat shaming the kid, but his actual weight was just a bit over average. It’s just in 1958 when the book took place, there really weren’t fat kids, and the “fat kid” was the one who didn’t look starved. Not like now where everyone’s thick and fat really means fat. It’s a matter of perspective, but the fact of the matter is, we might even consider Ben to be normal or underweight compared with the 11 year old boys (what he was) of today. King just liked to fat-shame. (But he also gave Ben a huge member in the train scene. Like shockingly big. So he didn’t do the boy entirely dirty!)