One of the study leaders, H.E. "Bill" Knee, said researchers put a tractor-trailer with traditional duals, dynamic sensors and outriggers through a series of tests to emulate three events that lead to rollovers: evasive maneuvers, driving around curves with a constant radius, and running off the road. The same tractor-trailer was re-equipped with singles and a wider slider trailer suspension in various configurations and put through the same paces.
The result? In most cases, new generation single tires and slider suspensions reduced rollover propensity, at least in van operations. In evasive maneuvers, the new-generation combination decreased the maximum trailer roll angle per lateral acceleration ratio by 45 percent, a significant amount, Knee said.
Some anomalies need further investigation, Knee said. For example, a truck equipped with duals coupled to a trailer equipped with singles and a wider slider suspension performed best in the evasive maneuver test. That may have something to do with driver feel from having dual tires on the tractor, Knee said.
My theory would be that the tractor's suspension width did not change and so the wide based singles didn't have much of a positive effect. Now what would be real interesting would be to see a tractor custom built with wider rear suspension attachment points and Super Singles, my hunch is it would perform very well. Of course another theory could be that the tractor suspension/ tread width is a relatively unimportant rollover factor, since the typical turn rollover starts with the trailer tandems tipping and then the trailer pulls the truck over.