Back when we made the switch from bias to radials on the steering axle, we changed caster. Its been so long that I can't remember how much or which direction. But all of the trade magazines of the day had articles on the subject. But I receive about a dozen trade magazines a month, and needless to say I didn't keep any of them. Bias tires do not react as violently as radials when you hit a drop off such as dropping off on to the improved shoulder. Changing the caster eliminated a lot of this. But for many years, we ran bias on the steer and radials on the drive and trailer just for this reason. When we made the switch from duals to super singles, it just about eliminated the violent reaction of a drop off.
