Securing lug nuts—the pro way

Confession: I came late to the discipline of properly torqueing the lug nuts on my vehicles—and checking them regularly.

Very late.

For years I never gave them a thought except when I had a puncture or I was reinstalling a wheel after maintenance or a repair. And when I put them back on I simply cranked really hard on my T-handled lug wrench and called it good.

I had a wake-up call a few years ago, when Roseann and I were hauling a pair of Expo cargo trailers to Flagstaff. I was driving my FJ40 and pulling a 14-foot box trailer that probably weighed 3,000 pounds or so. Only a couple of days before I’d had new tires installed at a local tire store. We’d decided to go the back route to Flagstaff: from Tucson to Globe via Highway 77, then to Payson via 188, then through Pine and Strawberry on 260 and up 87 to Mormon Lake Road. We stopped in Payson for fuel, and as I pulled in at low speed I heard a distinct clicking sound coming from the left rear of the Land Cruiser. A short search led to the source: lug nuts on that wheel that were barely finger tight and the wheel was shifting fractionally back and forth.

I shudder to think what could have happened if I’d experienced a catastrophic failure on the steep, winding mountain road uphill from Strawberry. I tightened the lug nuts on that wheel, checked all the others (which were fine)—and changed my attitude. Now I include checks of the lug nuts in my normal maintenance routine, especially when traveling in the backcountry on rough roads.

While I was changing my attitude I decided to change my approach as well, and use a proper torque wrench to ensure correct and even tension on the nuts. I know, I know: I already admitted I was behind the curve on this. 

Checking torque at home is easy: I have a superb Snap-on digital torque wrench worth about a zillion dollars, which a company PR rep simply gave me when I was doing another article that involved torque settings. (That rep, sadly, is no longer with the company, probably in large part due to all the tools he sent me whenever I emailed him that I had a new article coming out. It was a great ride while it lasted.) 

However, the Snap-on wrench is a full 24 inches long, and simply overkill for a traveling tool kit, even though a torque wrench has many uses in the field besides tightening lug nuts. A simple mechanical torque wrench would more than suffice, but I wanted decent quality without spending, well, a zillion dollars. And I found what I needed at Tekton Tools.

I became aware of Tekton by accident when I stumbled on their booth at the west Expo last year. As a self-appointed tool connoisseur/snob (take your pick), I approached the brand like a sommelier sniffing an unfamiliar cabernet. And came away impressed.

The Tekton website offers more detailed information on the company’s tools than any other site I’ve seen—including Snap-on’s. The page for their 3/8ths inch socket and ratchet set, for example (here), informs you of not just features, but each socket’s minimum failure point compared to ANSI specifications. The country of origin—in this case, Taiwan—is also clearly stated. (The quality of Taiwanese-made tools is excellent in my experience.) They note that the set does not skip any sizes—one of my pet peeves about many sets I’ve tried.  The ratchet is a fine, 90-tooth unit, and the ANSI measurements are published for that as well. Nice.

So, on to Tekton’s 1/2-inch torque wrench, which employs a simple but precise rotating handle adjustment and click/bump alert when the selected value is reached. The company claims plus or minus four percent accuracy, which is more than adequate for any task including engine assembly. In the hand it compared favorably to my memory of a similarly configured Sears Craftsman American-made torque wrench I had decades ago, which if I recall cost more even back then. The first thing I did was to compare it to the Snap-on wrench at identical settings on the same nut; the two were within the probability of error of my ability to respond to either the click of the Tekton or the beep and buzz of the Snap-on. Like all mechanical torque wrenches, it is important to reset the wrench to its minimum value in between uses to avoid stressing the mechanism and throwing off the accuracy (this is not necessary with digital wrenches). It’s also important to remember that a torque wrench—whether Tekton or Snap-on—is not a breaker bar; it should be used only for tightening nuts or bolts to a specified setting. The Tekton wrench is all-steel, so I expect it to be durable. And at $40 for the 18-inch 10 to 150 ft-lb version it is an outstanding bargain.

Back to my lug nuts. What exactly is the correct setting? Good luck obtaining the figure from your vehicle manufacturer. Obviously proper setting vary with the vehicle and the wheel size, but as a very general rule, for vehicles in the general mid-size overlanding category—Land Cruisers, Land Rovers, pickups, etc.—about 80-90 ft-lb is proper for a steel wheel. If you prefer to go by stud size, here is a chart.

Alloy wheels are more problematic. Some charts I’ve seen list higher torque than for steel wheels torque—around 100 ft-lb. Others list lower figures—70-75 ft-lb. Why the higher figure? I have yet to find a definitive answer, but possibly it is because steel wheel lug nut holes are typically raised a tiny bit and thus retain fractional elasticity to grip the nut more effectively, while alloy wheels must be clamped flat against the hub. For both steel and alloy wheels the primary effect you are achieving with tightening is to fractionally stretch the threaded lug itself, creating a powerful clamping mechanism.

Lug nuts should always be tightened (or loosened) in an alternating sequence across the wheel, thusly:

Like so many other habits I’ve adopted, being lug-nut conscientious makes me feel like I’m approaching travel in a serious, professional manner, and adds just one more layer of peace of mind to any journey. 

Edit: A question came up regarding using anti-seize lubricant on lug-nut threads, as many people do who live in areas where snow and salted roads are common. While manufacturers—and thus I—recommend installing lug nuts on clean, dry threads, this chart from Fastenal shows that effective torque increases if one lubes the threads (or if those threads are zinc-plated). Note that if used, anti-seize compound should only be applied sparingly to the threads, not to any mating surfaces of the wheel or nut.