Sad to say, for many RVers, they know more about peanuts than lug nuts. That could be a real problem. While you can get fat eating too many peanuts, you can get seriously injured or worse with loose lug nuts.
“Welding you can later take apart”
Lug nuts and their mates, the lug studs, are designed to be torqued or “tightened up” to a given point. The nut and stud—which is the threaded chunk that’s permanently fixed to the wheel—react a certain way. When put under twisting pressure (loosely translated, “torque”), they actually stretch a bit. When the pressure is taken off, the metal snaps back, allowing the nut and stud to mate. One technician describes this process as a sort of welding that can later be taken apart.
Some use the “quick and dirty” method: They just jump on the lug wrench. Others, some so-called professionals, rely on slamming the lug nut with an impact wrench until that clattering noise stops. Danger, Will Robinson! You’ll very likely have a lug nut that’s either too tight or too loose. Either one can lead to problems—even to disasters. Too loose, the wheel’s bolt holes can be scoured and create damage, unwelcome vibration, or uneven tire wear. Too tight, the stud can be stretched too far, weakening it. And in the catastrophic category, too loose or too tight can actually lead to the old “drive ’til the wheels fall off” scenario. Think we’d rather get fat eating peanuts!
Do it right!
Here’s the right—and safe—way to proceed. When you, or your tire technician, put a wheel back on your rig, be sure this is done. First, the lug studs should be free of dirt and dust and the wheel put in position. Next, using an impact wrench or standard lug wrench, snug up the lug nuts.
Next, and critical to safety, use a torque wrench to do the rest of the job. A “clicker”-type torque wrench may be your best bet. Here the wrench is set to the number of foot-pounds desired. When that specification is reached the wrench clicks, giving an audible acknowledgment. Dial-type torque wrenches are easily damaged by being dropped or tossed around, and can go out of calibration easily.
A torque wrench is an essential member of your tool box
Don’t have a torque wrench? Then get one! This is an essential tool that every RVer should have in his storage compartment. Most RVers will need a 1/2″ torque wrench, and a socket that fits your rig’s lug nuts. Amazon carries a suitable 1/2″ wrench for a reasonable price. Read the instructions included with your torque wrench. And when not in use, DO NOT leave the wrench set for your lug nut specifications. “Unwind” the torque setting—but NOT to zero. Rather, leave the wrench set at the minimum reading. Why so? Torque wrenches are precision instruments, and leaving them set at the minimum scale value will help ensure their accurate calibration.
If a clicker-style torque wrench is used, put the socket on the lug nut and apply steady, even pressure. The nut should turn at least a quarter-turn before the “click” is heard. If the nut doesn’t move but the wrench clicks, it indicates the lug nut is already too tight. Back it off and reapply torque to get it right. It’s best to do the tightening in three stages.
Set the torque for a third of the total value. Tighten one nut, then tighten the next in a star-like pattern. We talk about the right order down below (with a link to the method). After you’ve tightened all the nuts, start back at the first nut, and repeat the process using two-thirds of the total value. Repeat the process around the wheel, and finally, reset for the “full” measure of torque and go around the circle the last time. This will ensure a safe job.
And a quick recheck a short way down the road
It doesn’t hurt to check your lug nuts to make sure someone hasn’t already “goofed them up.” Thread the lug nut onto the stud by hand. If there are irregularities in how the nut threads on, you’ve found indications of “bottlenecking,” meaning that the stud diameter is a little smaller. Somebody’s over-tightened the lug nut before. It’s best to replace any stud that shows bottlenecking.
After you’ve torqued the nuts and put the rig back in service, it’s always wise to recheck the torque after driving a few miles. Many recommend going 20 miles, then doing the recheck. Things can happen that can cause you to find the torque on the nuts “off” after a little while. A bit of a hassle, but a lot better than losing a wheel!
Bag those chrome lug nuts!
Got chrome lug nuts? These can be handled in the same fashion, but here’s a tip to keep them from getting dinged up in the process. Make sure the lug nuts are clean and free of dirt and grit. Cover the lug nut with a section of plastic freezer bag while tightening. This keeps from direct metal-to-chrome contact. Be sure to use a “fresh” section of freezer bag over each lug nut.
Finally, where do you find the proper torque specifications for your lug nuts? Check your rig’s owner manual or contact the company’s tech folks. If you’ve got an orphan RV and no owner manual, here’s a link to tirerack.com with suggested torque specifications based on lug nut size. This same page also shows you the correct order to tighten your lug nuts.
Having your lug nuts properly secure will let you RV—without going nuts with worry about loose wheels! Tune in next week for more “Know Your RV” tips. And if there’s something about your RV that you’d like to know, drop us a line. Use the form below, and insert “Know Your RV” on the subject line.
photo courtesy modenadude on flickr.com by creative commons license