What is a wheel alignment?

November 28, 2016

Everyone has hit a curb or a pothole before; most people know that either of those can cause wheel misalignment; but few people actually know what a wheel alignment is, much less why it’s needed. Wheel alignments sound awfully important and awfully complicated. The most annoying part about an alignment is how much it costs for what may seem like an unnecessary service. While they aren’t particularly expensive, it’s nice to know what you’re paying for, and why it’s important to your car’s ability to run properly.

I was talking to a friend about my blog, and she mentioned her confusion on the topic of wheel alignments. She explained her limited knowledge, (which was based solely on her definitions of the words “wheel” and “alignment,”) and asked me what I knew. Much to my shame, I knew no more than she did. It wasn’t until a few days later that I thought to look into it.

So, what is a wheel alignment? According to Merriam-Webster's Dictionary, a wheel alignment is “the alignment or adjustment of the front wheel suspension and steering mechanism of an automotive vehicle.” Simple enough, right? Not really. On the simplest terms, there are three main problems that can occur with your wheels’ positioning on the vehicle: camber, caster, and toe. Just as there are three dimensions that can be measured by angles, there are three angles that can go wrong with your wheel alignment.

Camber is the angle at which the tire touches the road. (Though it’s technically described as the number of degrees between the perpendicular of the driving surface and the angle of the wheel in relation to it.) This kind of misalignment can be most easily viewed from the front of the vehicle, looking straight at the tires. If your tires are angled the wrong way in relation to the road, they’ll wear unevenly as you drive. For example, if the top of the tire is angled out, then your camber is described as positive, and the tires will only wear on the side that makes contact with the road. and if the top of the tire is tilted into the wheel well, then your camber is negative. Perfect camber is 0º and will result in even tire wear.

Caster is the angle of the steering axis in relation to the ground. In simpler terms, it’s the angle of the steering pivots that hold the wheels in place. When viewed from the side, if the axes are angled toward the front of the vehicle, the caster is positive; if towards the rear, it’s described as negative caster.

Toe is the angle of the tires when viewed from the top. If they are angled towards the center of the vehicle, the toe angle is understandably called “toe-in.” Likewise, if they are angled outward, the difference is called “toe-out.”

For the most part, these problems are easy to understand, but they are somewhat difficult to see, and even more difficult to fix. When you bring your car into a mechanic to get your wheel alignment, they’ll pull your car into the bay, and connect each of your wheels to a calibrating machine. The machine will read the angles of your rims, and show whether or not you’ll even need the service. If your camber, caster and toe don’t fit within the manufacturers’ specifications, they'll be adjusted by the mechanics, and you'll be ready to leave with perfectly aligned wheels.

So, why does this even matter? Who cares if my wheels are crooked, anyway? If you leave your camber, caster, or toe problems without correcting them, your tires can wear too quickly or unevenly, and your car may even pull to the right or left while you're driving. These are among the many problems that will occur if your alignment is too far off. (YoSpeed gives a pretty simple explanation on their site.  Auto Dimension Inc. showed a more in-depth explanation that included images to illustrate the concepts.)

In general, wheel alignments aren’t too complicated. Unlike some car-related services, after you get an alignment, you can’t show off crisp black tires, or shiny new rims. Despite this, alignments help you keep your car safe and on the road day after day. They are a vital factor in helping your car run properly, and longer.