I have had my RS5's for almost a year now and I have had an ongoing problem

. My studs keep breaking when I go to tighten the lug nuts. I have been torquing them to 85 lbs and I have torqued them to 90 in the past and they still want to back off (meaning getting loose) so when I go to torque them they turn a little bit then they break. Has anyone had a problem like this? I'm using the lugs they sent w/ the wheels. I have noticed after each lap or run they get loose and at first it was just the front and now the rear are doing the same thing as well

. And yes the do have the hub setric rings on them.
Any suggestions or comments?