I believe the owner's manual has a precise recommended torque of 80-100 ft lbs....
We torque to 90 based on the theory that that number allows for a +/- 10% variance in our torque wrench without over- or under- tightening. (When's hte last time anyone's torque wrench has been calibrated???)
Also, we only torque lug nuts once a day at the track (unless we remove the wheels, of course...) at the beginning of the day. I don't think that the time between run sessions really allows for enough cool down time due to all the heat in the rotors using all the wheels as big heat sinks - and thus still transferring too much heat into the studs. We have never had a problem with this torque or this method stretching the studs.