I contacted Bridgestone/Firestone back in September regarding retrofitting my single-axle rig with super singles. Here's their reply:
The ultra wide base tires, reasonably new to the market here in the USA, are very popular in Europe, and have been widely used on single drive applications, which is also popular there. From a performance standpoint, there is probably no definite reason that you should not be able to use these tires in a single drive axle application here in the USA.
However, from a practicality standpoint, they may not be desirable to use in such application. The ultra wide base tires have a about a 13% smaller footprint than a set of duals being replaced, and typically also have less tread depth than a standard dual type drive tire; as a result, there is literally less rubber on the road, and overall removal mileage may be significantly less than dual tires. Also, when used in single drive axle configuration, there should be concern for vehicle downtime should the tire become unusable on the road; this is not quite such a concern with a tandem axle configuration.
Factoring in the reply above and the cost to retrofit (new wheels and tires), I decided to stick with duals.
And, FWIW, super singles were a factory option on dual axle Freightliner trucks when I ordered my rig in 2005. However, they would not install super singles at the factory on a single-axle truck.