When it comes to wheel maintenance, paying attention to detail is key and following recommended manufacturers’ procedures is vital. Safety is at stake – for the service technician, the customer and all who share the truck’s operating environment, both
on- and off-road.
Today’s wheels – both steel and aluminum – are robust components, but become susceptible to failure through poor maintenance practices or an undesirable operational event, such as overloading or overheating. Of these two primary causes, however, improper maintenance is more frequently the culprit. Luckily, according to Dave Walters, manager, field service and warranty, Alcoa Wheel Products, it is also more easily avoidable. Case in point: removing and installing wheels.
“If you try to take off a wheel but it’s stuck onto the hub because of corrosion, some technicians will take a hammer and beat on the tire,” Walters says. This frowned upon practice can, of course, damage the wheel so the proper tools and a tire cage should always be used when dismounting a tire.
Before putting the wheel back on, be sure to clean the studs and hubs with a wire brush. “There could be debris behind them, which can break up and cause loose wheels,” explains Walters.
Applying the proper torque when mounting a wheel is another area of common, yet avoidable, mistakes.
Torqueing is critical, according to Ken Duval, president, Canadian Wheel, Edmonton, Alberta, Canada, as “it translates into clamping force.”
Walters says that most people don’t understand that when you put torque on the wheel, you’re actually stretching the wheel stud. The torque places tension onto the stud, and then that stud in return holds the wheel onto the hub on the wheel assembly.
Too little torque and the stud doesn’t stretch, possibly causing wheel nuts to become loose and fall off. Too much torque and the stud is stretched too far. This can yield the stud, stretching it beyond what it was designed to handle and causing it to crack.
To achieve the desired balance, the Technology And Maintenance Council (TMC) specifies the appropriate torque range as 450 ft.-lbs to 500 ft.-lbs for 33 millimeter hex nuts with 22 millimeter studs, which are typical in a hub-piloted wheel system.
When TMC made this recommendation about 10 years ago, Walters says it was “a monumental step in the right direction, and was a great help to technicians.”
Safety in the Shop
Tire and wheel failure can be just as dangerous in the shop as on the road. So much so that Occupational Safety and Health Administration (OSHA) Regulation 29 CFR 1910.177 dictates all employees who service truck tires and wheels must be trained. “Since the OSHA definition of ‘service’ includes the installation, removal and inflation of truck tires already mounted on rims, all heavy-duty technicians must receive the proper training in order to be OSHA compliant,” says Kevin Rohlwing, senior vice president of training, The Tire Industry Association (TIA).
This is why TIA, in conjunction with Alcoa, recently developed a wheel maintenance training video that addresses the importance of disc wheel inspection prior to mounting a tire, including how to avoid wheel-offs and injury to the technician.
“There are a number of hazards created whenever a technician handles an inflated truck tire, so safety training is necessary for anyone who comes in contact with an inflated truck tire,” Rohlwing says.
That’s where attention to detail is necessary. The technician has to read the inflation pressure printed on the wheel and the tire, and make sure he doesn’t go over the maximum, which will cause excessive stress on the wheel, resulting in failure, explains Dale Overton, field engineer, Accuride.
Likewise, too little inflation can be just as detrimental. One undesired result of underinflation is a condition known as flange wear, where a tire has a tendency to roll over the edge of the rim and the resulting abrasion wears down the top of the aluminum wheel, causing sharp edges to form that could damage tires on a subsequent tire mounting, Overton says.
Another problem of too-low pressure is excessive heat buildup. “The tires that you see blown up along the road are underinflated,” Walters adds. “They build up heat and they blowout, ruining the wheel if they aren’t in a dual wheel.”
The key to prevent blowouts is to check the air pressure regularly with a tire gauge; thumping won’t do. Inspections don’t have to be performed daily, but should be done once a week or at least once a month.
And in the event of tire failure, fast action can save the wheel. Tell your customer that if he sees or hears what he believes is a flat tire, he should pull over immediately. Although roadside maintenance can rack up the dollars, it is more ideal than driving to the closest truck stop and risking wheel damage.
Remember, as a rule, compromised wheels need to be replaced, not repaired. Customers who keep this in mind can minimize the financial impact of a blowout, keeping repair costs limited to only the tire.
Operational Damage
The other cause of wheel damage is operation-related, and it too can be monitored and mitigated by the technician. An example of this type of damage is overloading, which, according to Walters, doesn’t just damage one component; it harms all components, from the axle to the wheel ends. The tell-tale signs of damage caused by overloading are fatigue cracks and if present, the wheel should typically be replaced. Aluminum wheels are generally less prone to overloading damage.
A heat related incident also can be defined as operation-related damage. Tire fires can cause wheels to warp or lose their structural integrity. “Don’t try to put another tire on, because it will just blow off,” Walters says. If you know there’s been a fire affecting the wheel bearing, tire or brakes, roll the wheel across the floor.
If the wheel rolls in a straight line, that indicates that the bead stop flanges have not been damaged, but if it starts to turn, they more than likely have been weakened or distorted and replacement is necessary.
Walters also suggests referring to the TMC Recommended Practice (RP) 241 that explains how to use a common carpenter square to check the wheel’s condition.
“It’s easy,” he says. “Take a basic carpenter square – they only cost seven dollars – and as long as it touches the inside bead and the outside bead you’re good to go.”
