DRW Stability

The only unstable truck that I own just so happens to be a tandem axle dual wheeled class 8 truck with a grain box and hoist mounted on its frame. This truck is stable until it gets heavily loaded at which point it becomes quite unstable. This seems to indicate to me that the suspension, rather than number of tires or track width, is the main factor in poor stability. It wouldn't surprise me in the least if some who are convinced that duals are much more stable than SRW trucks might actually discover that their old 2003 dually is less stable than a new SRW 1ton.