As I've noted many times in the past, the main factor has always been Harley's choice of a rim size that limits the choice of tires to the ones they conveniently had Dunlop design to fit the rim and with Harley molded into the sidewall. In other words, setting up a little monopoly. Now we are finally seeing some light at the end of the tunnel, with Dunlop just releasing their American Elite version of the Harley tire and Metzler soon to do the same. But for those who want something different, or different sizes, there has always been the ability to buy different size rims and then choose from a wide assortment of tire brands and models (limited only by speed and load ratings as well as physical clearances to other parts of course). Since very few seem to have taken that route, I have to assume the typical CVO owner would rather keep the stock CVO wheels and put up with the limited availability of tires.
Jerry