Screw-in studs should not be "tightended" once they are threaded in to the hub. Think about what you are doing. If the studs threads are 'topped out' in the hole in the rotor, if you continue to turn the stud, are you putting more threads on the stud? No. You are twisting the stud. This can lead to all kinds of problems.
Here is a link to ARPs website:
http://www.arp-bolts.com/pages/products/pa...ks/how_tos.html
I know this is for head studs, but the principle is the same.

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Rodney Williamson
#93 IT7
www.titaniummotorsports.com