OTC Tools OTC 1921 2-1/2" Truck Wheel Bearing Locknut Socket. These sockets have a 3/4" square drive opening, permitting the use of an extension and torque wrench to tighten the locknut as required. Locknut removal and installation is simple, even when wide-rim wheels are involved, since a long extension may be attached to the socket to provide the necessary clearance. Sockets are made of high-strength steel; openings resist "rounding out." Socket is 6-Point.