Yeah, there were several web sites with 17" listed and after I talked to Hensim and some of the dealers they have started updating their sites to say 16".
I'm going to use the stockers as well for a while, but when they wear out I would suggest looking at the Michelin Starcross Mini -- they are super for traction in soft dirt and mud.... which I encounter a lot of in my woods riding. They really hook up great: