The tires that are on an automobile are actually attached to the vehicle with a complex network of suspension components that keep the wheels facing the correct direction. The general direction of the tires when measured in relation to the body of the car is known as the wheel alignment. Many different factors can change the wheel alignment of a car including the height of the body, physical contact with a curb or pothole and the age of the vehicle. The angles of the camber, caster and toe indicate the direction that a wheel is facing in each axis. Modern cars normally only allow adjustment of the toe because of new struts that make adjusting the camber and caster angles unnecessary.
The angle of the toe of the wheels refers to how far the wheels are slanted in relation to an imaginary line drawn down the center of the vehicle from front to back. Wheels are considered to be toe in or to have a positive toe if the forward edge of the wheels is aligned inward towards the center of the vehicle. Toe out or negative toe means that the tires are aligned so they are splayed outward away from the center of the car when viewed from above.
The alignment of the wheels of a car can help to change the handling properties of the vehicle. A toe in alignment of the wheels can help to reduce over steer problems and can increase stability in vehicles that have front-wheel drives. Alternately, a toe out alignment can help to mitigate issues related to under steering and can improve the handling on a vehicle that has a rear-wheel drive. The actual amount of the angle that the toe is adjusted for each wheel is incredibly small and is sometimes measured in fractions of a single degree.
Regular wheel alignment should be part of normal automotive maintenance. There are many reasons why a wheel might fall out of alignment. Improper toe angles can make the car less responsive and can increase the chance for an accident. Improper alignment can also cause a significant amount of wear on the tires that will dramatically reduce the lifespan of the treads. Alignment of the toe should only be performed by an experienced professional who is familiar with the tolerances of the vehicle and the recommended measurements provided by the manufacturer. Wheel alignment should be checked whenever the car has been in an accident or after periods of driving through severe weather conditions.