You're wrong. Bolts, tapered or not are NOT sufficient for wheel centering. That's why in engineering design we use bore pilots on components that need to be aligned raidally!
Have you even checked to see if the bore of the wheels you have possibly is already the correct size, thus eliminating the need for rings?
I bet when you're wheel is put onto the hub there is litle to no radial play in the interface thus you're set. But in the rest of the cases, wheel manufacturers will make the bore of their aftermarket wheels the largest size to suit the largest hub size of the vehicle that same bolt pattern, and then use hubcentric rings to resize the wheels to suit all the cars with consequently samller hub diameters.
