I think you can only get nylon sidewalls on passenger-type tires with a large sidewall. On low profile tires you must have a stiff sidewall. Does that make sense? So a soft sidewall on performance tires is really not possible, I don't think.
I was just saying that if you were willing to downsize your wheels, you would have that option.
Edit: it's the Kumho brand I was referencing, which is what I have. Not sure if any other brand even has this.