Land Line
March, 2000
(excerpt)

"Over tightening stretches the studs..."

Wheel-off accidents have gained more than their fair share of headlines lately.  When wheels come off at highway speeds, people get hurt or killed.  Wheels let go for several reasons.  Loose lug nuts, cracked wheels and worn or damaged bearings are among the most frequent.  You can check wheels and nuts quickly and easily by hand.  One of the most frequent reasons lug nuts are loose is because they were over-tightened with an air impact wrench.  Over tightening stretches the studs, reducing (not increasing) clamping force.  That lets nuts back off.  Final tightening should always be done with a torque wrench by hand.  If your inspection finds one nut loose, chances are more will work loose on that wheel, and any other wheels hit by the impact wrench that day.  You may have to replace the studs, too, if they’re found to be stretched.

by Paul Aberson