The only REAL use of the hubcentric ring is to accomodate for people-and mostly shops- that rush their wheel installs, and don't take the proper torquing procedures of bolting down the lug nuts in a cross pattern, and in steps. When you just tighten the lug nuts one at a time, in a non-cross pattern, you essentially tighten the wheels on unevenly, and the wheels end up going on a little off-center. Hubcentric rings prevent this from happening by centering the wheels before you even tighten the lug nuts... but they are not really necessary. People have been having no problems for decades before the advent of the hubentric rings... and usually, when you're running an expensive aftermarket wheel, you already should be torquing down the wheels correctly anyway. So whether you run with or w/o rings, just make sure you torque your lug nuts in a cross pattern, and in several steps before the final torque down (doing this assures the conical section of the lug nuts do the job of centering the wheel), and you will be safe. Oh yah, and you will also want to torque the wheels in the air. Once you let it sit on the ground and place weight on the wheels, they will shift slightly...
1995 Supra T