Wheel Alignment Tech Talk – Camber, Caster, Toe-in
What is a wheel alignment? How does it effect handling and tire wear? When should I do an alignment? What causes alignments to go out? How would I know if my alignment is out?
A wheel alignment is nothing more than setting the angle of the hub/wheel so it tracks in the right direction. Most vehicles have four-wheel alignments, meaning each of the four wheels is separately aligned. Your basic alignment consists of three angles: camber, caster and toe-in. Camber is the tilt of the tire when viewed from the front of the car. Positive camber means the top of the tire is tilted away from the car. Negative camber means the top is tilted in. Camber has a lot to do with cornering performance. Too much negative camber will wear the inside of the tires prematurely. Too much positive camber will wear the outside tread.
Caster is the inclination of the front spindle. Picture the angle of the forks on a bike top to bottom. When the caster is out, it creates a pull or wandering condition and sometimes a slow responding steering wheel. Toe-in is measured in inches or degrees. Viewing from the front of the car, it is the difference between the front and rear center-line of the tire. Toe-in means the fronts of the tires are closer together. Toe-out means, the fronts of the tires are farther apart. Toe-in or out has the most effect on tire wear.
When your car is out of alignment, the tires will wear prematurely. In some extreme cases, new tires will be gone within 500 miles. At the price of tires, especially high performance tires with soft compounds, you want to keep your vehicle in alignment as long as possible. Other symptoms of an out-of-alignment car are poor handling, pulling to one side, or wandering from side-to-side. An alignment will also affect the steering wheel response and how quickly it returns to the center.
Your vehicle’s alignment should be checked every 10,000 to 12,000 miles. Any harsh impact such as potholes, curbs, objects in the road, or the damage of an accident, should prompt you to have your alignment checked. If you do any modifications to your suspension, raising or lowering your car, that will affect the alignment angles. Even changing the tire size will effect the alignment. Loose, worn or bent suspension parts such as ball joints, springs, bushings, and control arms will have an adverse affect on your alignment, too. In most cases you do not know if your alignment is out. The best way to check it is with a precision alignment machine. Laser optics combined with a computer allow for the most accuracy in alignment readings.
Remember you are aligning the hub of your vehicle. Check to see if the alignment shop or dealer has equipment that attaches to the hub, not the wheel. Many independent shops that do alignments have a specialty tool called “Tru Align” that attaches to the hub. This will make for a much more accurate alignment with the added bonus of not damaging the delicate finish on your wheels.
There is a lot more to suspension alignment, especially if you push your vehicle on the track. The modifications you make on your suspension are just the beginning. Once you start down this road you will be concerned with things like bump steer, weighting (vertical load), preloading, tire traction versus tire load, and more. Now you’re thinking under-steer, over-steer, tire compound, sway bar design, and other topics that can be covered in a later article. For now, just remember to have your vehicle aligned every 10,000 to 12,000 miles in normal driving conditions.
If you accidentally hit a curb, or drive through a nasty pothole or other road obstruction, that would be a cue to have your car’s alignment checked more often. Proper alignment is good for your car. It will save unnecessary wear on your tires. It will ensure that your vehicle is giving you the handling the factory designed the car to have. And, most importantly, a properly aligned car is safer and more fun to drive.
