Standard torque for a 1/2-20 bolt is 90 ft/lbs. with the threads lubricated, or 120 ft/lbs. dry. I've always used 100 ft/lbs. as a rule of thumb for 1/2" lug nuts and I've never lost a wheel due to the lugs backing off.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!