Mark McCormick
In a recent column, I discussed how tires should be mounted and balanced, and I briefly addressed wheel alignments and how the three settings (camber, caster and toe) are not always adjustable as the vehicle manufacturer may not have added one or more adjustable elements to your vehicle.
Camber, caster and toe are three settings that affect tire pressure.
If you have ever seen a NASCAR race, and the rear tires seem to be sticking out from the bottom of the cars and pushing in from the top, this is the camber adjustment. NASCAR race cars are set this way to get the best traction from their tires, and since they are adjusted to the extreme, the drivers wear out multiple sets of tires in a very short distance. If the camber setting on a vehicle’s tires is off, tires will wear out in a like manner.
Caster is the principal of moving the front wheels forward or backwards on an axis to get the best angle for a firm ride. Remember riding that bicycle and turning the handlebars 180 degrees? Well, the caster angle was changed, and there was a distinct difference in the ride. That is why the front wheel on a bicycle is angled forward to get the best ride.
The toe settings are made by looking at the tires from the front of the vehicle and moving the tires in or out from the center based on the preliminary readings taken from all four wheels.
Computerized alignment machines can take readings and adjustments made and recorded on the computer readout, ensuring the correct angles have been made. Other vehicles are aligned using a thrust angle, or four-wheel adjustment.
A thrust-angle alignment means the rear wheels have no adjustments, so based on the relationship of the front to rear wheels, corrections are made to the front adjustable wheels, which affects the rear wheel alignment.
A four-wheel alignment means all wheels have adjustable toe settings and possibly camber and caster adjustments as well. If the camber and caster are not adjustable, the aftermarket parts industry has addressed this issue by manufacturing parts that are used to make these adjustments. The upfront cost will be rewarded with longer tire life and a smooth ride.
There are many causes of alignment wear, from hitting potholes and curbs, to overloading weight capacities and weakening springs. Uneven tire wear should always be inspected by a professional.
McCormick has invested his skills in the automotive-repair industry for over 30 years, beginning as a full-service gas attendant and soon after learning how to service tires, brake and suspensions. He has worked for the past 20 years as a service manager.
