Great subject.. almost never addressed.
Let's face it, maxing out a truck in one area will most likely be pushing it's limits in others.
Brakes on 250's/350's are the same size. Big enough to do the job under normal circumstances. But there isn't anything extra, and sure enough for emergency.
Came back down from Waterville today on 2. Not notorious in the world of roads, but suffice to say it has it's own runaway ramp.
Wife was asking about the sign at the top (trucks must check brakes prior to descent). We talked about air brakes a bit and so on. Then ended up getting behind a 3500 with a 2 dink horse trailer, crawling down at 35 mph. Even at that, he was probably pretty warm by the time he got to the bottom, and I ask, did he have enough left in the system to complete an emergency stop if he needed to?
I was easily 50% heavier than him....and can assure you that stopping was not a problem.
Jim nailed it; bigger is better.
I read on this forum how folks are counting ounces. They travel without water to keep the weight off, then weigh their trucks with half tanks of fuel to make themselves feel better. Sure they can get down the road. Kind of like the guy who landscapes his yard, runs to the gravel pit and loads 2 yards of rock in his p/u and brags about how it works great....dragging the bumper all the way home. What happens when getting going isn't the problem? What are you going to do then?
Food for thought, great subject.