As far as I know and have experienced, Advantage Powersports and Renos both will only replace Spyder tires with OEM Kenda. I have had work done at both dealer service departments and find them friendly and reliable. I don't know of any independent shops that will work on Spyders in the KC area but I am sure there may be some. Good luck.
Just had mine tires balanced at Big O tire and they stated that whatever tire you wanted to install they could get and install.
Might talk to your local BigO tire store or whatever its called in your area and see.