Super-single tires are a great thing for tractors and trailers, but there are two considerations.
First, if you have a flat on a tire, you only have that one tire -- you can't slow-roll to the tire shop, and it's hard to carry a spare, so you are DOWN until you find a shop that has a super-single in stock.
Second, you can't swap between steers and rears, unless you like the Big Daddy Roth look on your coach.