Tow Vehicle - Dual tires in back or single? Which is best?

Dually can carry roughly twice the weight on the rear axle as the same model with single rear wheels. In pickups, this would be the nominal "one- ton" class (30-350-3500 moddel numbers), which not so long ago were all dualllys, SRW one tons have been around for only the past 25 years.

Any bigger, all dual rear wheels. Any smaller, single.

So it comes down to how much weight you need to carry, cargo and tongue or hitch weight of what you tow.