The tire wear pattern is an intuitive representation of vehicle performance and how the owner maintains the vehicle.

Customers may lie about maintenance practices, but tires tell a different story.

The tire wear pattern is an intuitive representation of vehicle performance and how the owner maintains the vehicle. The tread pattern reveals the alignment angle, the condition of the suspension components and the ride control components. Learning how to read tires and communicate your findings to customers is the key to sales riding control.

What is tire wear? A perfectly worn tire will have a perfect contact surface and the weight will be evenly distributed side by side. However, in order to obtain the ideal tire wear, its toe angle, camber angle and caster angle will never change. In the real world, tires must go around corners and deal with uneven roads. Suspension and ride control systems must strike a balance between handling and comfort. Engineers can design the suspension so that the geometry minimizes uneven wear, but they cannot design for worn parts.

The tire contact area is controlled by the geometry of the suspension. The movement of the body and suspension is controlled by shock absorbers, struts and springs. If the ride control cannot control the movement, the body or the suspension, the tires will be affected.

As the pitch and yaw of the vehicle change, the geometry of the suspension and the pick-up point will change as the road changes. In addition, when the driver turns the steering wheel, angles such as caster, camber, and toe angle will affect each other. Another factor is the flexibility or compliance of the suspension and steering system. If the bushing is soft, it will compress and effectively change the suspension pickup point.

If a customer in your store is looking for a new tire because the old tire has worn out, please check the original tire for obvious conditions to determine if they still need new shock absorbers, struts or springs.

The shoulders of passenger car tires are designed to withstand a lot of abuse. However, if there is a problem with the way the tire contacts the road, the shoulder is the first area to wear.

Inner edge wear is usually related to negative camber and wheel eversion. The camber angle and toes change with the vertical movement of the suspension and the movement of the body. This helps improve the traction of the vehicle when turning.

If the vehicle's springs are weak and cannot be maintained at the proper ride height, negative camber and camber suspension angles may occur.

If the outer edge of the tire is worn, it indicates that the anti-sway bar, springs and shock absorbers cannot control the movement of the body. When the vehicle turns, the body can lean. For vehicles with a high center of gravity, such as crossovers, SUVs, and pickup trucks, the situation may be worse.

When the body of a car or truck is tilted, it creates a positive camber angle on the outer wheels. The positive camber and the transferred weight scrub the outer edges of the tire.

Excessive loads can also cause the outer edges of the front tires to wear. The weight of the rear of the car or truck will cause the rear to squat and the front to lift. When the front part is raised, it will produce a positive camber angle.

If the shock absorbers, struts, and springs are gone, the body will shake more than usual in corners. Leaning the body will produce enough positive and negative camber to wear the edges of the tire. Another problem may be joysticks and links. In some cases, this may simply be a lack of rotation.

Under-inflated tires are the main cause of tire shoulder wear. If the tires are below specification, the sidewalls will not be able to bear the weight and wear prematurely.

An indicator of excessive positive or negative toe angles is tire feathering or scratches, which can be detected by touching your fingertips on the edge of each tread strip or block. The feathery edge on the inner side of the tread rib indicates too much toe, and the feathery edge on the outer side indicates too much toe. Since the toe angle is affected by changes in the camber and caster angles, the toe angle is always the last adjusted angle during the wheel alignment process. In addition, any change in the camber or caster angle will immediately change the toe angle. The geometry of the toe angle is also greatly affected by changes in suspension height, such as an uncalibrated aerial riding system.

Cup-shaped or fan-shaped depressions around the tire tread may indicate loose, worn, or bent suspension components. Worn shock absorbers or unbalanced tires can also cause cup-shaped protrusions, but cup-shaped protrusions are usually more indicative of concentric patterns. Worn shock absorbers and struts are the most likely culprits because they provide damping force to control tire movement. When the tire moves excessively, a fan-shaped pattern appears. Insufficient spin can cause this condition on the rear tires.

The health of the spring determines the health of the tire. When the spring is compressed, a little bit of life is taken out of the spring and energy is released. What matters is not the number of trips, but the frequency of the cycles. Over the years, bending and frequency can cause fatigue, which can be measured by lowering the ride height, which weakens the alignment angle.

Some springs may fatigue, but still do not significantly reduce the ride height. These springs can be progressively designed and use coil geometry to provide smooth straight-line travel, but become stiffer as the body and chassis begin to shift weight. The only way to inspect these types of springs is to test drive and visually inspect the springs and tires.

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