Indeed, I have translated some taobao posts with babelfish.yahoo and it seemed to say that the product was not of best quality. But I am not sure, it was a babelfish translation.
My experience is that solid rubber is not too fast. Somewhat similar to pneumatic tires at 90 psi.
You want to use Polyurethane with 75% rebound or better and 83A or less hardness.
If you use PU of 50% or less rebound then you are in a situation similar to solid rubber.
Maybe one day a new small wheel will come out that will join together the advantages of PU tires with the advantages of the pneumatic ones.