I have driven these trucks at 90+ mph, and it can be one scary ride. In high school the lumber yard I worked for had a 52 1/2 ton, it was 18 years old, and I pegged the speedo (90 for a 52). Could barely hold it between the ditches, literally. And my 52 3/4 ton has recently gone that fast, but I certainly didn't stay at that speed. Held the road straight and true, but I wanted to see just how fast she would go. I do drive to work daily on the interstate at 60, about 2600 rpm with gears and tall tires. But I have to leave lots of room for manuvering.
When I spoke of being designed to drive at 50, I meant realistic driving conditions. Big thing at the time was roads, which really limited you. I do engineering work daily, and know there is a huge difference between actual design conditions and the real world.
