Alignment is one of the key maintenance factors in getting the most wear and performance from your tyres. In addition, wheel alignment provides safe, predictable vehicle control as well as a smooth and comfortable ride that’s free of pulling or vibration. Today’s modern suspensions require a precise four-wheel alignment that can only be achieved through a modern alignment system. This applies to both front and rear wheel drive vehicles.
Alignment Basics
The direction and the angles that the tyres point in after the alignment is critically important. There are four factors involved in setting the alignment to specification: caster, camber, toe and ride height. The following brief discussion of each aspect will help you understand the process and spot potential problems.
Caster
Positive and Negative Caster Graphic Caster is the angle of the steering axis (the part of the suspension that supports the wheel and tyre assembly). Viewed from the side of the vehicle, an imaginary line drawn between the centers of the upper and lower ball joints forms an angle with true vertical; this is defined as caster.
Camber
Positive and Negative Camber Graphic Viewed from the front of the vehicle, camber describes the inward or outward tilt of the tyre. The camber adjustment maximizes the tyre-to-road contact and takes into account the changes of force when a vehicle is turning. Camber is the one adjustment that can be set according to driving habits.
Toe
Viewed from above the vehicle, toe describes whether the fronts of the tyres are closer (toe-in) or farther (toe-out) apart than the rears of the tyres. Toe settings vary between front and rear wheel drive vehicles. Stated differently, toe is set to let the tyres roll in parallel (at zero toe) when the vehicle is in motion.
Ride Height
Ride height is simply the distance between the vehicle’s frame and the road. This is the reference point for all alignment measurements. This rule applies if you put a taller or shorter tyre on your vehicle.
Misalignment and Tyre Wear
It is pretty evident that poor tyre wear and misalignment are closely related. Many of these misalignment conditions can be easily “read” by your tyre dealer; and they can recommend the appropriate solution, which will be “get an alignment.” For your assistance, the following troubleshooting guide will help you see what your tyre expert sees.
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Misalignment Condition |
Tyre Wear Symptom |
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Incorrect Camber Setting |
Premature smooth wear on either inside or outside shoulder |
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Incorrect Toe Setting |
Feathered wear ac
ross tread, raised tread block edges |
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Incorrect Caster Setting |
Excessive shoulder wear, tread blocks show "heel-toe" wear pattern |
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Unequal Caster setting (either right or left side is out of specification) |
Sharp pulling necessitates steering compensation and feathered wear |
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Unequal Toe setting (either right or left side is out of specification) |
Sharp pulling necessitates steering compensation and feathered wear |
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Combination of two or more settings are out of specification |
Irregular tread wear with feathering and smooth spots |
Worn Parts
Very often a worn suspension part is the cause of an alignment problem. On older vehicles, worn springs can lower a vehicle’s ride height, altering its geometry and creating misalignment (all alignment settings refer to ride height). Weak springs and worn ball joints can also contribute to uneven or “cupped” tyre wear. The symptoms here are erratic handling, slow steering response, and irregular tyre wear etc. Again, this is not an exhaustive listing, but if you stay alert to these common problems, it may help you schedule an early visit to your mechanic and save on tyre wear.
Want to know more about better tyre wear? View our articles on Balancing and Tyre Rotation.
