1/2-20 thread, 60-degree cone. FSM range 80-110 ft-lb depending on year. Steel wheels 95 ft-lb, aluminum 90 ft-lb, in a star pattern.
XJ uses 1/2-20 lug studs with a 60-degree conical seat across all years. Factory torque specs varied: 1986 FSM lists 75 ft-lb, 1994 FSM lists 80-110 ft-lb, 2000 FSM lists 85-115 ft-lb. Practical middle-ground: 95-100 ft-lb on steel wheels, 85-90 ft-lb on aluminum. Always tighten in a star pattern (1-3-5-2-4 on 5-lug) in two passes - first to 50%, then to full. Re-torque aluminum wheels at 50-100 miles after install or wheel rotation since they compress and settle slightly. Never use an impact wrench to tighten - impact only to loosen. Avoid anti-seize on studs (changes friction coefficient and over-torques the joint by 20-30%); a single drop of dry lube on the cone face is acceptable to prevent corrosion seizure but not on threads. Replace any stretched or rusted stud and matching lug nut as a set.
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.