Boy, last winter sure was tough on the roads! It seemed that overnight giant, bottomless potholes with putrid, cavernous chasms opened in highways and byways all over the U.S. and promised to devour cars and trucks whole.
Did you notice? How could you not? While my car wasn't actually eaten, riding on miles of continuous smaller potholes made an alignment necessary and loosened the fillings in my teeth.
The big question remains: Will the roads ever get better?
Congress still has not passed a highway spending bill and the Highway Trust Fund is about to run out of fundinga scenario that will result in construction projects and road maintenance around the country grinding to a halt and highway conditions continuing to worsen...if you can believe that's possible. And here we are, right around the corner from another visit from Old Man Winter.
What are these roads doing to trucks that are pounding the pavement all the time? More truck tires are getting cut, snagged and ending up in the scrap pile with impact breaks and radial splits than ever before. In addition, wheels are piling up in scrap metal bins with bent flanges and excessive run-out caused by impact or run-flat damage.
Not only are tires and wheels taking it on the chin, but suspensions are getting beaten to death as well. Suspension damage results in misalignment of not just two axles like on my car but on all five axles of a tractor trailer rig, causing irregular treadwear on tires lucky enough not to already be in the scrap pile with pothole-induced damage.
Without a doubt your fleet accounts are feeling the costly pain of our nation's decaying roadways, especially since freight tonnage is increasing and trucks are on the road more now. In fact, freight is moving so well that fleets are starting to buy or lease more trucks to haul it. (Class 8 truck orders in June were 41-percent higher than last yearand this was the best June for sales since 2005.)
Your commercial tire and service business is no doubt on the rise, too, with escalating truck mileage and the impact of lousy roads on commercial vehicles. While your tire changes and road service calls are increasing, you should also be looking at tire wear and advising your commercial accounts when they have vehicles that need alignments, too.
A commercial tire dealer's job is getting more complex and demanding all the time as fleets exert their desires to remove themselves from the tire business and outsource tire maintenance, problems and concerns to their suppliers. You've got to hone your skills to a fine edge to protect your company's interests as well as provide the service your fleet accounts expect.
Irregular wear caused by vehicle misalignment is perhaps the most common tire problem. The key is determining the cause of this wear and correcting it to make your customers happy.
Toe-in wear, toe-out wear, full shoulder wear, one-sided wear, feather wear and thrust angle induced full shoulder wear are steer-tire wear conditions that are caused by some form of misalignment.
Toe usually refers to the angle of the wheels on the steer axle, but it also can be encountered on other axles. It is the difference in distance between the centers of the front and the rear of the wheels as seen from above. Toe-in exists when the wheels are closer together in the front than in the rear. When toed-out, the wheels are closer together in the rear.
Incorrect toe settings are the most common steer axle alignment problem, have the greatest effect on truck tire wear and probably are the easiest to correct. If there is a toe-in condition causing this wear, the outside shoulders of both steer tires will be worn, while if the axle is toed-out, the inside shoulders of both steers will be worn.
Feather wear is a condition in which the tread ribs are worn high to low on each rib across the tread face. This condition is the result of excessive side force scrubbing that is caused by excessive toe. It can also be caused by severe drive-axle misalignment, worn, missing or damaged suspension components, bent tie rods or other chassis misalignment.
If you find that this wear is identical on both steer tires, then drive axle or other chassis alignment should be checked. If the steer tires are worn in opposite directions, then the toe setting on the front axle should be corrected. If the feather is toward the center of the vehicle, then a toe-in condition exists, and if it is toward the outside of the tires, a toe-out condition is the cause of the wear.
Full shoulder wear appears as excessive wear across an entire shoulder rib to a major tread groove and usually is evident on one side of the tire only. This wear occurs as a result of side scrubbing and is generally caused by either an improper toe condition on the steer axle, drive-axle misalignment or trailer-axle misalignment.
A misaligned drive axle will push the vehicle in the direction the axle is facing, which forces the driver to turn the steering axle in the opposite direction to keep the vehicle going straight. As a result, the inside shoulder of one tire and the outside shoulder of the other steer tire are scrubbed and wear faster than the rest of the tread.
Damaged or poorly maintained suspension components such as torque rods, springs and spring bushings can produce the same type of wear. If this condition occurs on perhaps only one tire, check the seating of the bead. An improperly seated bead will cause this condition, too.
One-sided wear is similar to full shoulder wear except the excessive wear extends from the shoulder, goes past the shoulder rib and heads toward the center of the tread. The most common causes of this condition are improper camber and drive axle misalignment.
However, that condition also can be caused by worn kingpins, the improper adjustment of bearings and heavy axle loads.
Camber is the inward or outward tilt of the wheels when viewed from the front of the vehicle. It is the angle that moves the centerline of the tire from vertical and is built into the axle during the manufacturing process. It is not adjustable after the axle is installed on the vehicle.
Tires perform best when they run perpendicular to the road surface under typical operating conditions. Camber can be corrected by replacing worn parts such as kingpins and spindles, but axles or spindles should never be bent to correct camber.
Thrust angle-induced full-shoulder wear is another steer-tire irregular wear condition usually caused by misalignment of the drive or trailer axles. It appears as excessive wear extending across the entire shoulder rib to a major tread groove on the inside shoulder of one tire and the outside shoulder of the opposite tire.
Rear tandem axles that are not perpendicular to the vehicle's centerline but are parallel to each other create a thrust angle which pushes the vehicle off course.
The driver feels the vehicle pulling in the direction the drive axles are angled and must steer in the opposite direction to keep the truck traveling in a straight line, which subjects the tires to constant scrubbing.
This scrubbing results in fast and irregular wear. An indication of tandem thrust is having both steer tires feather in the same direction, as opposed to toe, which causes feathering in opposite directions. Irregular shoulder wear also will be apparent on the drive tires.
A similar out-of-alignment condition is known as tandem skew or scrub angle. Tandem skew or scrub angle occurs when tandem axles are not parallel to one another or perpendicular to the chassis centerline. Drive axles will fight each other as well as the driver to determine the direction the vehicle will go.
Trailer axles with tandem skew will be dragged in different directions. This causes every tire on the vehicle to scrub and wear fast. The steer tire on the same side of the truck on which the drive tires are closest together will wear into an out-of-round condition as well.
By the way, drive-axle misalignment will create irregular wear on drive tires as well as steer tires and is the second most common cause of alignment-related irregular wear.
While toe-in wear, toe-out wear, full-shoulder wear, feather wear, one-sided wear and thrust-angle-induced wear are pretty clear-cut conditions, steer-tire irregular wear can be complicated by having two or three conditions working on the steer tires at the same time.
For example, if you find a pair of steer tires that have full shoulder wear on three shoulders, it is possible that you have a toe-in condition that is wearing the outside shoulders of both tires. That's in addition to drive-axle misalignment that is wearing the outside shoulder of one tire and the inside shoulder of the other tire. The key is to look at the wear and figure out from where the forces are coming.
Besides steer tires, drive and trailer tires also can suffer from misalignment-induced irregular wear. Similar forces that scrub the tread off steer tires work the same on tires located behind the driver. On drive axles, rapid shoulder wear on one shoulder is commonly seen. This appears as excessive wear on the inner shoulder of the inner drive tires.
It will also show up on the inner shoulder of a wide-base drive tire. Usually this type of wear is more severe on the front-drive axle than on the rear-drive axle and can manifest itself in tires that are worn smoothly or irregularly. The cause of this wear is usually negative camber that may be induced by axle flex under load or misadjusted bearings. This condition also will occur if a tire is not mounted concentrically on a wheel.
Wide-base tires on drive axles have made many fleet owners crazy since they can develop rapid shoulder wear on both shoulders even when the alignment is perfect. The cause of this wear is not alignment related, but rather overinflation.
Trailer tires also can exhibit rapid wear on one shoulder, which can progress to a diagonal wipeout. Excessive camber is the usual cause of this irregular wear. But this mechanical condition also can be created by a misaligned or bent axle and improper bearing adjustment.
Trailer tires also commonly exhibit one-sided wear, which appears as excessive wear on one side of the tread. The usual causes are excessive toe, excessive axle deflection, non-parallel axles and improper bead seating.
If the trailer appears to be traveling at an angle to the tractor, it has a condition called dog tracking in which one or more of the axles is skewed in the same direction, allowing the rear of the trailer to be laterally offset from the rest of the tractor-trailer combination as it rolls down the road.
Tires on a trailer with this condition are literally dragged sideways a few feet for every mile the vehicle runs. This scrubbing results in fast and irregular tire wear on the outside shoulders of tires on one side of the trailer and the inside shoulders of the tires on the other side.
The third leading cause of alignment-related irregular wear is trailer-axle misalignment that will produce irregular wear on trailer, drive and steer tires.
So what do you do if you suspect you have a vehicle with an alignment condition? Well, if you have a portable alignment-measuring kit or a tandem axle-spacing caliper, you could check to see if the axles are parallel.
Most fleets have a toe-alignment check set needed to check toe and can do this fairly quickly. You also can just walk around and under the vehicle and look for areas of movement in the suspensionindicated, for example, by things such as rust around the U-boltsthat would indicate the axle has shifted, as well as cracks in the springs and spring hangers and wear in the bushings.
Tandem axles should be parallel to each other and all axles should be perpendicular to the vehicle centerline. Often these things are really obvious, but in some fleets no one ever looks at them.
If you are not comfortable checking basic alignment, then recommend to the fleet that the vehicle alignment be inspected. If the tractor is usually paired with the same trailer, also recommend that the trailer alignment be checked since it can be the cause of irregular wear on the forward axles.
Remember that total vehicle alignment is not just aligning the steer axle. It means aligning the drive and trailing axles, too, since they all will affect tire wear.
So how often should fleets be checking vehicle alignment? Many fleets perform pre-alignment checks on all new trucks and trailers to make sure they are properly aligned once out of the factory. The American Trucking Associations' Technology & Maintenance Council recommends that a post break-in alignment check be made at 15,000 to 30,000 vehicle miles but no later than 90 days after the vehicle goes into service.
This all-axle alignment on the vehicle should be done by a qualified alignment provider. After that, an all-axle alignment should again be performed every 80,000-100,000 miles or 12-18 monthswhichever comes firstby a qualified alignment provider.
However, with the condition of roads today, these intervals should probably be shortened. You definitely have to keep your eyes on tire wear and, if any alignment-related condition appears, recommend that a vehicle alignment be done right away.
Congress is moving slowly and can't seem to figure out how it's going to tax us to pay for the billions of dollars in road and bridge maintenance and construction that this country so desperately needs.
Even if legislators come up with the money that the Highway Trust Fund needs to fix all the roads tomorrow, it will be years before all the work can be done.
Until then, watch out for those vehicle-eating potholes, make your alignment service guy your new best friend foreverand don't miss your six-month visit to the dentist.