Problems At The Wheel Ends Can Cause Irregular Tire Wear And Premature Failure

December 2010, - Feature

by Jim Park • Equipment Editor

SHARING TOOLS        | Print Subscribe
From HDAJ's sister publication, Heavy Duty Trucking.

We focus on tires here, mostly, but wheels and hubs, and the other gear that attaches tires to trucks, deserve attention too.
Wheel-ends function as a system: the spindle, hub, and rim (or wheel), as well as the bearings and the fasteners, all work in concert to keep the wheels in place and the tires running straight and true. If one part of the system is out of whack, the results will be seen and felt elsewhere in the system - usually at the tires themselves. When that happens, tire dealers often get angry phone calls - though the problem usually has nothing to do with the tire. It's just a victim of circumstance.

From irregular wear caused by negative camber on a trailer axle to non-concentric tire mounting, how you maintain your chassis and wheel-ends, and how you install your wheels and tires, will have a greater impact on tire wear than any defect that might be present in the tire. I'm not letting the tire people off the hook easy here, but few manufacturing defects are found in tires anymore. The process is highly managed and tightly controlled to ensure product consistency. There are poor quality tires that don't wear well, and there are tires used in applications they were not designed for, but bum tires are probably not to blame for your irregular wear problems.

I'll note here that both alignment and wheel balance have a great impact on tire life too, but we won't delve deeply into those in this issue. We'll be writing on tire balance in the December issue, and have an alignment story scheduled early in the new year.

Prevention At The Wheel-End

Beginning with the components farthest back in the system, axles, spindles, and hubs affect tires in not-so-subtle ways. Loose axle U-bolts or worn bushings can allow axles to wiggle and shimmy as the vehicle travels. Any movement other than straight forward simply scrubs rubber off the tire. Worn shock absorbers can play havoc with tire wear, too.

"Any component that allows a tire and wheel assembly to wander off center or run any way other than vertically true will affect tire life," says Guy Walenga, director of engineering-commercial products for Bridgestone Bandag Tire Solutions. "A little preventative maintenance at the axle and wheel-end will improve tire life in most cases."

The same applies to the hub and the wheel bearings, though perhaps to a lesser extent. Loose wheel bearings allow for poor alignment between the cone and the cup, which causes the hub to wiggle on the spindle. That allows the wheel to run off center - perhaps only by a tenth of a degree or so, depending on how loose the bearing is. Mike Becket of M.D. Alignment Services in Iowa says toe adjustments should be set to within 1/32 of an inch. "If steer axle wheel bearings are loose, the toe setting can vary by as much as 1/4 inch," he says.

"Bearing adjustment is a sensitive issue and one where we often see disagreement," Becket says. "Some bearing manufacturers' specs allow for a little too much tolerance in my opinion - and TMC's too - at up to 15 thousandths of an inch of spindle endplay. TMC (the ATA's Technology and Maintenance Council) says one to five thousandths, and I think that's the way to go."

Becket says as long as the endplay is within the bearing manufacturers' tolerance, you're okay. "I set bearings in the one- to three-thousandths range when I can."

Another approach Becket endorses is to torque all bearing adjustments to 50 foot-pounds without backing off. He does the same for axles with wide-single tires, but torques them to 75 foot-pounds and doesn't back them off.

"That's necessary because the weight of the wheel, drum, and hub assembly takes more load to center them on the spindle," he notes.

Check with your wheel-end suppliers if there's any doubt about this, and see also TMC's soon-to-be revised recommended practice guide on wheel ends, RP 644.

With axles and wheel-ends firmly mounted and going in the same direction, tires will wander less, and you'll see less cupping on the tire shoulders. As well, loose wheel bearings are suspect in many cases of advanced shoulder wear in wide-single tires.

"Loose bearings allow for some degree of negative camber, which will wear the inside shoulder of an inside dual tire or a wide-single tire," says Walenga.

When Wheels Wobble

Even if your wheel bearings are perfectly torqued, and all your bushings and U-bolts are tight, if your wheels aren't round or if they wobble on the hub, they aren't going to roll properly.

Lateral run-out, or a wobble, is more common on spoke wheels where the wedges have seated unevenly, pulling one part of the wheel closer to the hub than its opposite side. On disc wheels, it could indicate either a bent rim, improper seating, or some foreign material has lodged between the rim and the hub face.

It's easy to detect. Jack the wheel up and spin it, using some object (preferably a runout gauge or a dial indicator) placed close to the tire to mark the gap between it and the wheel. As the wheel spins, the gap should be the same all around the tire. If not, retighten the nuts on a spoke wheel, allowing the wedges to seat properly before torquing them down to the final setting.

You can check radial runout the same way, except you measure between the tread face and the object. If the gap differs, the wheel is out of round or bent, or the tire is not concentrically mounted.

You can check the rim by measuring across its face at several points. The diameter should be equal anywhere you measure. Take the rim out of service if it's bent, or check with the wheel manufacturer for runout tolerances.

You can check for non-concentric tire mounting by observing the mold ring near the tire bead. It's located about 1/4 of an inch from the edge of the rim with the tire mounted. Observe any change in the distance between the ring and the rim by examining the bead area all around the tire.

"If the rim checks OK, and the tire you're working with is a new one, you can try rotating the tire 90 or 180 degrees on the rim to see if you can match the minor variations of the tire and rim better to get an acceptable assembly," advises Becket.

To prevent non-concentric mounting, a bead lubricant should be used to ease the bead onto the rim. It should be inflated to 25 psi or so while sitting flat on the floor, not standing vertically, leaning against a wall, or with the rim sitting raised on some other object. The pressure will push equally in all directions from within the tire, forcing it away from the rim equally in all directions. If it's vertical or leaning against a wall, the weight of the rim inside the tire will cause it to seat off center.

Once the tire is seated, place it in a tire cage and continue inflating to 120 psi. Then, deflate the tire to your standard operating pressure and the tire will seat itself properly.

These steps alone are no guarantee that your wheels will run true and trouble-free, but seeing the wheel end as a system rather than a collection of parts headed in the same direction can help troubleshoot some tire wear problems.

Torque Your Nuts

Attaching wheels to a truck hub is serious business. Yet it's not uncommon to see some big bruiser of a mechanic, one foot against the bottom of the tire, whaling away with a one-inch-drive impact gun driving the wheel nuts home. As with anything technical, there's a process for ensuring the job is done properly and safely. The above procedure is not recommended.

Wheel nuts must be torqued to specified values, and the stud, nuts, and wheel must be in good condition, otherwise torque values could be compromised and the equipment damaged.

When mounting wheels on a hub and securing them with a typical M22x1.5 stud and 33 mm two-piece flange nut, the clamped material will compress slightly and the stud will stretc


  1. 1. mike vinal [ May 26, 2016 @ 05:43PM ]

    I have a 2013 f350,bought it with 8300 miles,at 12,000 I changed oil and rotated tires and noticed that 1 set were worn more than the other,so I left them on the front,now has 19,500 miles did oil at 17,000 did rotate cuz I need good tires up front!my tires spin in the rain front are cupped,when I hit a bump truck skips,hit highway exspandition joint steering wheel whobble of death ,I put new steering damper 4 gas skyjackers,dealer changed steering gear box its a little better,but they don't know why its whobbling and why my tires are so bad it wont pass for a sticker when it is coming up!ford denied me tires,continental are a soft compound don't belong on it,tire pressure on door says 65lb front 80 in back,that I would say is the problem?! 2015-2016 pressure is 65 front n back!! they use toyo and Michelin tires,that says a lot!!! so it will cost me $1400 for tires ford should eat that!!!!the f350 deseils swd have same coils as my gas job!!! diesels weight more than the gas motor,bet spring is to stiff that my wobble!! they cant answer that!!! I had it I should have stuck with gm!!! this is my first n last ford truck!!!!


Comment On This Story

Comment: (Maximum 2000 characters)  
Leave this field empty:
* Please note that every comment is moderated.


We offer e-newsletters that deliver targeted news and information for the entire fleet industry.


ELDs and Telematics

sponsored by
sponsor logo

Scott Sutarik from Geotab will answer your questions and challenges

View All

Sleeper Cab Power

Steve Carlson from Xantrex will answer your questions and challenges

View All