RV Tire Safety: Lug nut torque – a critical safety item

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With RV tire expert Roger Marble

Those that have read their owner’s manual may recall seeing a mention of the need to check the lug nut torque. In this case, we are talking about how “tight” the nuts should be to ensure the wheels stay on our vehicles. Others may have a warning label on the inside of their RV. This is from my Class C Coachmen:

RV Tire Safety: Lug nut torque – a critical safety item
(Click to enlarge.)

NOTE: Class A’s and RVs with 10-bolt wheels probably require a service truck and torque in the 450 ft-lbs range, so this info may not apply to you as you will need significantly different tools.

First, the simple answer:


RV Tire Safety: Lug nut torque – a critical safety item
(Click to enlarge)

• Look up the specification in the Owner’s Manual.

Here is a sample page from Heartland RV. Note they tell you how often to check and how tight to make the lug nuts and even the pattern for the sequence of tightening the lug nuts.

• With your torque wrench, follow the instructions for both frequency and how tight the lug nut should be.

• What to do if you don’t know what a torque wrench is? Watch this video

• What to do if you don’t own a torque wrench? Check this video for a comparison of different wrenches. You do not need to buy the most expensive wrench as, hopefully, you will be only using the wrench a couple times after a tire or wheel was changed on your RV, or maybe a couple times a year per your Owner’s Manual instructions. For infrequent use I have found Harbor Freight non-digital torch wrench adequate.

Now some background:

Do not lubricate the stud or lug nut with oil. This can affect the torque reading and could lead to stripped threads in lug nuts ($) or broken wheel studs ($$$).

This website gives a technical background on why not to lubricate lug nuts.

Some Technical Info for those that want to know more:

Torquing a bolt is to get a certain amount of stretch out of the bolt. If torquing a bolt to 80 ft-lbs, it is technically more accurate to say, “When you torque this bolt to 80 ft-lbs, it will cause it to stretch by .0030 inches.” In critical applications such as race engines, many engine builders use certified bolts and actually measure the stretch of the bolts rather than using a torque wrench.

Think of the bolt like a spring. When you torque it, you’re stretching it so that it exerts force on what you’re holding together. This video goes deep into bolt stretch vs. torque.

When I was driving my race car, confirming the torque of the lug nuts was MANDATORY before each track session. With this as a standard practice, I never had a wheel come lose in 30 years of racing.

 RV Tire Safety: Lug nut torque – a critical safety item

Read more from Roger Marble on his blog at RVtiresafety.net.

 ##RVT906

 

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Wolfe

This may not be the official method, but in a pinch (like changing tires roadside), I torque based on the English language… for 250ft-lbs, I step on my standard wrench at 1 foot from the socket, 375Emily″, etc. Anytime I’ve checked with a calibrated torque-wrench, it’s pretty close. Confirm when safely at a tireshop again.

Also, if unsure of precise torquing sequence, most tires do fine with repeatedly tightening the “furthest loose bolt from the prior one,” so 15736284 for 8bolts, 146325 for 6bolts, a star (13524) for 5bolts, etc… and then go around TWICE.