Way back in the 60’s my English grandpa taught me you drive down a hill in the same gear you’d drive up it.
That was true of older large trucks. In more recent years, though, engines are more powerful and you can climb in higher gears than the older ones. If you try going down in too high of a gear, you're going to have trouble. Those runaway truck escape ramps are there for those who try it. That rule no longer applies.
