They say that the Ultimate-style spinner is the only one that will work in that size (2.25") due to the length of the adapter.

A complete set-up, with the special cut for the 16x4W, ready to install, is $63.90 shipped, like coomarlin quoted.

That's a case of fuel; think I'll just spend five bucks on a 2.5" Dubro and whittle it out.

Steve