when is weight distribution hitch required

Boon Docker wrote:
I wonder what vehicle that owner manual belongs to, those recommendations seem a little unrealistic. A 150 lb tongue weight would mean a small pop up or a tear drop trailer would need a weight distribution hitch.

That is why the recommendation to look in "your" owner's manual was given. My Silverado 2500HD says none is "required" for more than double the weight of that for my F-150.