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How To Use a Torque Wrench on Lugs

Torque With Wrench

One of the more common issues a DIY mechanic or first-time tire change motorist has is tightening the lug nuts. Too much force can damage the lug or the wheel and too little can mean the wheel literally falling off the car. If you're lucky enough to have a shop outfitted with an electric or pneumatic torque wrench which you can set to the specifications for your car, be grateful. For the rest of us, here's how to do it manually.

Wait? Lugs Can Be Too Tight?

Most people understand that loose lug nuts can mean them rattling off the lug bolt, allowing the tire and wheel to wobble and literally fall off the car. But too tight is also a problem.

When over-tightened, lug nuts can cause the lug bolt's threads or the nut's internal threads to stretch. This can eventually lead to failure of the nut and bolt, either by sheer (breaking in half) or by compromising the integrity of the thread hold.

Over-tightened nuts can also cause a steel wheel to go out of balance when one or more lug holes are bent or compressed. Worse, it can cause an aluminum or alloy wheel to crack, eventually leading to failure.

It's also possible for over-tight lugs to pull against their mounts, causing fractures or failures at that point.

In short, if your lug nuts are too tight, you're eventually going to have issues.

Properly Tightening Lug Nuts

Grab your trusty lug wrench and put the lug nuts on tightly, but do not "jerk," stand on, or use a cheater bar to continue tightening them. Aim for that "guten tight" feel without resorting to tricks.

Now use a torque wrench capable of measuring torque to the specification for your lug nuts (you'll find this in your owner's manual and perhaps on the sticker inside the door specifying tire pressures). Tighten the nuts to within specification, in a cross pattern (make a star or X).

The cross pattern lets the wheel "settle" against the brake rotor or seating evenly as you tighten it. Then return to the original two nuts and double-check their torque to be sure they didn't loosen as the settling took place.

Most vehicles with steel wheels expect those wheels to "compress" somewhat when the lugs are tightened. Aluminum wheels should not.

The point is, use your torque wrench and get the right amount of pressure without going too far. To learn more about using a torque wrench, go here.