I hear this across multiple transit forums, I think most of them are used vehicle owners and they do not know what they have boughten. I do not think they make super singles that small.I don't know that I've whined, but it definitely does add up (just replaced mine a month ago, so it's fresh in my mind). Especially when they age out and you have to replace them even though they still "look newer." And tire problems are just that much worse, plus typically a heavier vehicle which can be more of a challenge if you do need a tow -- so there is definitely motivation to keep them fresh.
What I wonder about the Super Singles is.... do people then carry two spares? One spare Super Single and then the regular spare for the front? Or do you just hope the Super Singles don't have a problem? I'm sure on a semi or huge vehicle then two spares is no big deal; but it would be kind of a lot to find room for on a smaller dually such as a T/E-350 or even 450.