Originally posted by Stazi:
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? 
Have you seen the hub size of a Miata? It ain't big. Please explain to me why four tapered bolts (remembering that three define a plane) are insufficient to centering a lugnut onto a stud? Because, after all, that's what we're truly doing. Even a hub centering ring only sets the radius, the lugnuts still could be several degrees off radially until they're torqued down.
Some calculations here: http://www.idsfa.net/miata/lugnuts/page1.jpg and http://www.idsfa.net/miata/lugnuts/page2.jpg
Whirling dervish of FFOG.
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