REAL Answers By Popular Demand

While alignment can be quite a high-tech process involving lasers and computers in the hands of experts, one of the best tools for diagnosing alignment problems may be at the end of your arm. As we continue with the third letter of our “S.M.A.R.T.” acronym, “Align your vehicles on a regular basis,” we’ll see how some very low-tech techniques can help you identify areas that need high-tech attention.

How important is front-end alignment on trucks?
As we pointed out in the previous article, the real question is: If misaligned, which axle causes the most irregular wear? In the previous article in this series, we emphasized that drive axles seem to cause the most trouble, with trailer axles not far behind. Steer axles are usually the least troublesome.

How do we know when axles should be aligned?
Some fleets routinely align vehicles as part of the PM process. Others do it only when a wear problem develops. We recommend a regular program of checking tires for irregular wear, then taking follow-up action as necessary.

But once irregular wear appears, isn’t it too late?
Not necessarily. You can sometimes catch a problem in its early stages and correct it. And often, tires can be rotated to other positions to “even out” wear. (We’ll discuss that in the next article.)

How can we detect irregular wear?
One way is to “feel” it. If you run your hand across the surface of a tread, first one way, then the other, you will feel the edges of the tread elements. And, what you feel may tell you more than what you see.

How is that?
When a tire is new, the edges of the tread elements are usually very well defined—you might say “sharp.” Over time, those sharp edges are rounded off by wear. Chances are, you’ll be able to feel the difference before you can see it.

What does that mean?
Remember: “Rubbing Makes Round.” The side that is rounded (or less sharp) is the side where the rubbing force was applied.

How does that help?
Tires run best and longest in a straight line. Any time a tire is not in straight-line travel, wear forces concentrate on one side. This happens constantly during turns, but it can also happen when you’re not turning, because of misalignment. Imagine the tire is stationary, and it’s the road that’s moving. If the tire isn’t aligned with the direction of travel, the road “rubs” tread elements on one side more than on the other.
If you know which side is rounded, and how the tire was mounted, you may be able to tell a lot about the alignment.

For example?
If the right side of the tread elements is more rounded than the left, the tire was turned a bit to the left.
Remember: “Rubbing Makes Round.”
When you compare two tires, you can learn even more. If the right steer tire is rounded on the right, and the left is rounded on the left (more wear on the outside edges of both tires), you probably have a “toe-in” condition. If both have more wear on the inside edges, you probably have a “toe-out” condition.

How do we know how much to adjust the alignment? The test we’ve suggested won’t tell you that. You’ll have to rely on your alignment expert. Nevertheless, this kind of checking, which takes only a few minutes, can help you catch wear before it becomes a big problem, and can help you decide what to do when you align.

How so? First of all, whenever alignment is done, insist on a complete report of what the shop finds when they check the vehicle. You need to know where you are, compared to manufacturer’s specs, before you adjust.
For example, if your alignment check shows a toe-in condition, and tire wear confirms it, you’ll have a pretty good idea what to do. On the other hand, if toe is set to spec, or if you discover a toe-out condition, but tire wear points to toe-in, there may be something else causing the wear, perhaps a bearing or suspension part—or even a mismounted tire.

Why not just bring everything to spec?
Sometimes, the “If it ain’t broke, don’t fix it” rule applies. There are lots of variables, including caster, camber, toe and Ackerman, and they can interact. We suggest you only change a setting if you’re reasonably certain it will correct a problem.

Why go to all that extra trouble?
Because specs have tolerances, and Murphy’s Law says tolerances will sometimes accumulate in a direction that maximizes trouble. If everything’s in the middle, that’s much less likely.
Also, bear in mind that alignment equipment has tolerances, too, so if you’re on the edge of the range, you may actually be outside it because of the tolerances of the alignment equipment itself.
And, once the alignment is done, be sure to get a report on the final settings. This, plus the initial report, should be filed with your vehicle maintenance records. Once irregular wear starts, it can’t be reversed. (You can sometimes stop it or equalize it, as we’ll see in a future article.) So, if you put on new tires and the problem does not reoccur, what you did worked. If the irregular wear returns or worsens, you’ll have to look somewhere else.

Consult the equipment manufacturer and your alignment provider for details on front-end and total vehicle alignment. Next time, we’ll move on to the next letter in “S.M.A.R.T.”—our irregular wear-reducing acronym—“Rotate tires, if necessary, to equalize wear.”