Torque and Re-torque - Tire Review Magazine

Torque and Re-torque

Torque and Re-torque

Although we usually discuss tires and tire-related issues in this column, this month’s subject is the next closest thing – wheels. Specifically some important guidelines for remounting tire/wheel assemblies.

What’s so different or difficult, you may ask, about the simple task of mounting a wheel on a medium or heavy-duty highway truck? Not much, really. But as any parent will tell you about raising kids – tell them, re-tell them and re-tell them again.

Basic guidelines offered by vehicle and wheel equipment manufacturers usually include these important recommendations:

®′ Inspect used wheels and mounting hardware for any damage, excessive wear or corrosion, or any signs of abuse or neglected maintenance, and replace components as necessary.

®′ When replacement components are needed, use only known high-quality parts, preferably purchased from or approved by the wheel or vehicle manufacturer.

®′ Make sure that all wheel and mounting hardware components are compatible, as several wheel types and attaching systems are available for most applications. Parts of these different systems are generally not interchangeable and should not be mixed.

®′ Tighten lugs in a recommended sequence using a calibrated torque wrench to obtain the required torque setting.

Details of these basic but still vital recommendations and additional safety and servicing guidelines are readily available from just about every truck wheel supplier.

Several excellent sources are the National Wheel and Rim Association (904-737-2900), Alcoa Inc. (800-242-9898), and Accuride Corp. (888-626-7096).

In addition, free safety wall charts covering multi-piece rim matching, and mounting/demounting procedures for truck/bus tires are available from your local OSHA offices or from the OSHA Publications Office (202-523-9667). TIA’s Commercial Tire Service training program covers all these issues, and provides tremendous educational materials, as well.

All personnel in your shop involved with truck tire and wheel service should be trained and familiar with relevant safety and maintenance material.

Beyond the Basics

But the basics are, well, the basics. Astute commercial tire pros know there is a lot more involved, especially with current emphasis on optimizing vehicle performance (up-time) and with today’s legal atmosphere.

A few recent industry studies on common tire/wheel maintenance practices reveal a dire need to tell, re-tell and re-tell again. Here are two other vital recommendations your service staff should know by heart:

®′ Re-Torquing – Using a hand torque wrench, wheel and rim attaching nuts must be torqued to the manufacturer’s recommended values AND they must be re-torque to those values after approximately 50 to 100 miles of on-road operation.

®′ Lubrication of Flange Nuts – Two-piece flange nuts (commonly used with newer generation hub pilot single nut attaching systems) should be sparingly but positively lubricated with oil as recommended by the manufacturer prior to re-use.

Why Re-torquing?

Once the wheel attaching nuts have been properly tightened, why should re-torquing be necessary? According to Paul Levering, vice president of Webb Wheel Products Inc., this is due to "joint settling."

There are as many as 12 different mating surfaces in attaching a wheel – from the stud seat outward to the hub, drum, inner wheel, outer wheel, washer, hex nut, and finally to the stud threads. If each of these joints takes only a minimal set after initial tightening, some clamping force will be lost. If painted or coated wheels are used, additional compression may occur in these protective coatings, which could lead to loosening.

Industry studies have shown that a re-torque after the first 100 to 500 miles of service in either new or replacement situations is a very desirable maintenance practice and is recommended for both flange nut and ball seat mounting systems.

Is Lubrication Okay?

Other than to clean off any rust or corrosion, few would think that wheel fasteners should be lubricated. After all, wouldn’t a well-oiled nut easily work its way loose over time? The short answer is: The right lubricant used sparingly in the right places improves the clamping forces of a fastening system.

Actually, the subjects of torquing and lubrication are closely related by the common thread of an engineering term called "clamping force." The purpose of tightening bolts (for example, on a cylinder head, or lug nuts when attaching a wheel to a hub) is to create tension in the bolt or stud. This tension, in turn, creates clamping forces that hold the different pieces together.

The clamping force is actually friction at the interface that restricts movement of the joined surfaces relative to one another. Since clamping force is impractical to measure accurately in the field, torque of the fasteners is measured to approximate the desired clamping force.

This provides a practical fastening solution, since there is a close relationship between torque and the clamping force generated. However, that relationship can vary depending on the amount of friction between the bolt head or nut and the surface it is sliding against while being tightened.

The type or amount of lubricant applied to the threads and/or mating surfaces at the point of fastener contact – if any ®“ is why bolts torqued to the same value can deliver different clamping forces.

Good quality lug nuts are manufactured with coatings designed to deliver consistent clamping forces for given torque values. Typical coatings are Teflon phosphate and oil for the newer two-piece nuts used with hub-pilot mounting systems.

As these type nuts are tightened, the cone or washer seats on the wheel and the hex nut slides relative to the washer. It is this interface between the hex nut and the washer that manufacturers recommend be slightly lubricated at each reuse. The goal of lubrication is to restore the designed-in relationship between torque and clamping force. This clamping force relationship may have changed over time as the nuts have been exposed to moisture, salt, and other contaminants that invite corrosion at the sliding surface interface.

Most manufacturers advise against lubrication of the wheel or thread surfaces, but stress that the wheels should be clean and dry and that threads should be clean and free of any burrs or nicks. Also note that manufacturers generally do not recommend the use of any lubricant on the cap nut seating surfaces of ball seat mounting systems.

Be certain to follow the manufacturer’s recommendations for the particular service equipment you are using. Proper initial lug torque and maintenance of torque through the life of your customers’ vehicles can contribute significantly to the life expectancy of wheel end components and, most importantly, to highway safety.

You May Also Like

Training and Technology Will Lead the Way in OTR Tires

When we look at how OTR tires keep up with innovations in equipment, it’s all about maximizing productivity.


After two years of probably the strangest logistics we've lived through—and a roller coaster ride of an economy—the OTR tire market is surprisingly robust. The construction industry has slowed down slightly, and there's a lot of talk about a recession, but so far, we haven't seen a lot of publicly or privately funded projects pull back, and quarries and mines are running hard. All that activity is good for the tire industry.

Last-Mile Delivery Tires Set to Outpace Long-Haul Tire Volumes

Prior to the pandemic, the last-mile delivery (LMD) market was booming. So, when COVID-19 hit, and newly-homebound consumers placed even more online orders — retailers like Amazon shortened delivery times to two days, one day, or even same-day services — and the segment exploded. Related Articles – Maxam Tire Completes Core Size Range for Agrixtra

Global Tire Manufacturer Ralson Enters US TBR Market

Global tire manufacturer Ralson is entering the U.S. commercial tire market with a new medium/heavy truck tire manufacturing facility and a team of veteran American sales and marketing tire professionals. Ralson debuted its products for the US with its American team at the 2022 SEMA Show in Las Vegas. Related Articles – Hankook Tire Launches

Michelin Releases Agilis HD Z as New Urban and Regional Tire

Michelin North America has released the Michelin Agilis HD Z 19.5 in two sizes to offer fleets with light and medium-duty vehicles durable, long-lasting tires optimized for the stresses of urban and regional environments. The Agilis HD Z 19.5-in. tires will replace the Michelin XZE in two current sizes (225/70R19.5 LRG and 245/70R19.5 LRH) in

Yokohama Tire Launches the 716U UWB Regional Drive Tire

Yokohama Tire’s newest commercial tire – the 716U ultra wide-base – is a weight-savings drive tire that carries more profitability for fleets, the company says. It is available now in the US in size 455/55R225. Related Articles – Vredestein Launches New Pinza H/T in US – Goodyear Adds Wrangler HT Tire to Light Truck Lineup


Other Posts

Continental Debuts Enthusiast-Driven ExtremeContact Sport 02

From timed autocross laps to drifting on a skid pad and mastering knee-jerk braking and turns on a raceway, dealers, influencers and members of the media were treated to a crash course in performance racing while testing out Continental’s newest UHP summer tire, the ExtremeContact Sport 02. Related Articles – BKT Tires Launches Agrimaxfactor Tire

BKT Tires Launches Agrimaxfactor Tire For Tractors

BKT has launched the Agrimaxfactor, a new tire series for tractors for transport and soil tillage operations. Related Articles – Continental Tire Launches ExtremeContact Sport02 – BKT Launches EM 933 Super Excavating Tire – Kenda Unveils Vezda Touring 4S, its First ‘Four-Season’ Offering The company says it developed the series in response to the request

Michelin’s Enviro System Unveils Tire with 58% Sustainable Materials

Michelin says its subsidiary Scandinavian Enviro Systems is the first tire manufacturer in the world to unveil tires with a high proportion of environmentally sustainable materials that have been approved for use on ordinary road vehicles. These include tires for buses and cars containing recovered carbon black from Enviro, among other materials. Related Articles –

Cooper Unveils Largest Tire in its Discoverer Rugged Trek Line

At the annual SEMA Show in Las Vegas, The Goodyear Tire & Rubber Company unveiled the biggest tires yet in its Cooper Discoverer Rugged Trek tire line. Designed for lifted pickup trucks, these all-new, large-sized tires feature signature Cooper Knife-Edge and Mountain Pass customizable sidewall designs and will be available to consumers in early 2023.