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Wheel Alignment 101

Tire Wear and Alignment

Wheel alignment means a lot of things to your car and its performance. The more tightly the wheels are aligned, the higher your fuel economy, the lower your tire wear, and the better your vehicle will drive. Recommendations for tire and wheel alignment intervals vary, but it's generally a good idea to have it done at least once a year. Especially if you're having your tires changed or balanced.

Wheel alignments can be "eyeballed" in the garage, but should be done professionally, on a rack, with specialized equipment made for the job. Tolerances for an alignment are often within tenths of a degree. This kind of accuracy cannot be had with straight edges and eyeballs alone.

What Alignment Is

Alignment is how well the tires of the vehicle are positioned relative to one another and the vehicles' chassis. The object is to have all of the tires have the same amount of rolling resistance and to have them "in line" with the car's frame. This makes the car go straight and gives the driver intuitive control of the vehicle's direction.

Misalignments can occur for a variety of reasons. Accidents, changes in tires or wheels, or even routine maintenance can change alignment.

Within Tolerance vs Preferred

The first thing to know is the nomenclature. When your alignment tech tells you that your wheels are "within spec,' this does not mean that they are aligned. It merely means that they fall within the tolerances the manufacturer has given. You want your alignment to be as close to the preferred positions as possible. This position is the "perfect" sweet spot for your vehicle's alignment, per the manufacturer's design.

Toe

Toe is the angle of the tires relative to one another. When all four tires are on the ground, the tires will either sit perfectly straight forward or, more often, "toe" in one direction or another. Think of the tires as a person's feet when standing straight. If they angle somewhat inwards so that the big toes can have a line drawn forward that intersects at some point, there is "toe in."

Toe is the angle that most directly affects steering and tire wear. If one tire (or a set) are off by an eighth of an inch, that can mean the tire is being effectively dragged for 28 feet for every mile the car drives. That's significant tire wear and is probably creating a fair amount of driver fatigue compensating.

Camber

Camber is the angle of the tires relative to the road. Tires should be sitting flat and pointing straight up and down when the vehicle is on flat pavement. Any change in camber will affect this.

Some vehicles are off-camber on purpose. Sports and racing cars, for example, often "camber in" so that they are riding on the outer portion of the tire on the front axle. This is to allow the tire to camber outwards (flex away from the car) on hard cornering, improving traction. On most passenger vehicles, however, this is not normal.

Caster

Similar to camber, caster is the tire's vertical position relative to the car rather than the road. Wheels should ideally be straight up and down, making a line parallel to the car's frame. When caster is off, a vehicle often leans.

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