Originally Posted by blair
i really don't see the benefit.
it doesn't increase the amount of weight you can pull.
does it increase your tongue weight?
Yes, it effectively increases towing capacity, by increasing load carrying capacity for the tongue weight. It's less of an issue with boats, but RV and car hauler trailers can have heavy tongue weights. The trailers I pull usually have 2500-3000 pounds of tongue weight, which would overload the rear tires on a SRW van. And it allows for more capacity for other stuff too. I generally have around 1500 pound loaded on the roof.
Basically, I've upgrade my running gear to E450 spec, and load it accordingly. Last trip over the scales I as 13,500 on the van and 22,000 combined.
For somebody that doesn't need the capacity, I don't recommend it because it is harder to park, and there's more tires to buy. But the extra stability from the wider track width is nice.
The only driving situations where duals are detrimental is deep ruts in mud or frozen slush. Otherwise, it handles everything else as well or better than before. In sand, my front axle always sinks in first.