You could assume that the manufacturer puts a tire under their truck which can carry the trucks rated capacity... Duals might have some overcapacity, but SRW usually has wider tires both front and rear. Speaking from where i come from (Europe that is) a Sprinter SRW 4.5 ton has 285 tires front and rear, while the 5 ton dually has 195 tires. That gives less flotation in the mud.
Also when the front wheels sink, the truck moves much easier if the rears follow the path, where the mud is already pushed aside.
The best driving rental truck at my previous employer was a 3.5t SRW VW Crafter (A Sprinter 2500 with VW 2.5TDI engine) with the 3-leaf spring pack of a 5 ton Sprinter (which we had left after a full air suspension conversion)
The SRW with heavy springs rode as good as the dually, because the same heavy 5t springs were mounted at a wider center distance (aside the frame rails instead of under them) which made up for more stability than what is lost by the flexing of a slightly higher tire sidewall.
And empty, the truck didnt float over rainy roads but kept holding a grip under all conditions.
unloaded DRW Sprinters will drift great through long corners or roundabouts, because there isnt enough contact pressure of the rubber to the asphalt, when the road is wet, snowy or iced.
Also the SRW was less bouncy when unloaded.
For those that report poorer cornering when towing a 5th wheel: They both might be a 1 ton truck, but did anyone ever check the actual spring ratings ?? It is more than likely that a manufacturer gives the SRW weaker springs for a smoother ride, though it has the same payload capacity.
Put some additional airbags on the SRW with its wide spring stance, and it will be equal or better than the dually LOADED. Unloaded, there is no question that the SRW gets further offroad.
