I exactly wouldn't call it a variation on USGT, as I believe it predates USGT, but it's almost exactly the same. We run on the hard Solaris premounts, which are a slick tire on a nice spoked rim. Other than that, it's exactly the same (21.5/zero timing/GT bodies).

I post the turnout here simply to show that support for 21.5 GT racing is growing steadily.

As USGT becomes more established I would probably be a proponent of a gradual transition to compliance, in the interest of a unified national structure. That being said, the Solaris tires are working great for us and I don't foresee changing anytime soon, as change is the enemy of growth.