Tire Tread Wear Causes - Choppy, Scalloped (Inner and Outside)

Tire Tread Wear: Causes And Symptoms

Tire tread wear can tell you a lot about a suspension. Most specifically, it can tell you if the angles, inflation and components are within specification. Here are the most common tread wear patterns and what causes them.

Understanding Tire Tread Wear

Tire tread wear can tell you a lot about a suspension. Most specifically, it can tell you if the angles, inflation and components are within specification. Here are the most common tread wear patterns and what causes them.

Over-inflated Tires

Tire tread wear in the center of the tread pattern tells you that the inflation patterns are too high. Too much pressure can cause the contact patch to shrink and the center of the tire to carry the entire load.

Over-Inflation Wear

Under-inflated Tires

Tire tread wear on the edges of a tire will typically indicate inflation pressures are lower than specified. When a tire is underinflated, the contact patch grows and the load is carried by the outside edges of the patch.

Under-inflated tires

Tire Feathering

The indicator of excessive positive or negative toe angle is a tire feathering or scuffing that can be detected by stroking your fingertips across the edge of each tread bar or tread block. A feather edge on the inside of the tread bar indicates excess toe-in, while a feather edge on the outside of the tread bar indicates toe-out. Because toe angle is affected by changes in camber and caster angles, it’s always the last angle to be adjusted during the wheel alignment process. In addition, any change in camber or caster angles will immediately change the toe angle. Toe angle geometry can also be greatly affected by changes in suspension height.

Tire Feathering

Scalloped Tires

Cupped or scalloped dips appearing around the surface of the tire tread wear could indicate loose, worn or bent suspension parts. Worn shock absorbers or unbalanced tires can also cause cupping, but the cupping would typically be more indicative of a concentric pattern. Shocks and struts are the most likely culprit because they provide damping force to control tire movement. When the tires move excessively, the scalloped pattern can appear. A lack of rotation can cause this condition.

Scalloped Tires

Outer-Edge Tread Wear

Tread wear on the outer edge of a tire is rare these days, but it does happen. Positive camber, caster and toe can lead to wear on the outer edge. If you see edge wear on one side, check the thrust and setback.

But, it should be noted, the leading cause of outer edge wear on modern vehicles is over-enthusiastic cornering.

Outer-Edge Tread Wear

Inner-Edge Tread Wear 

Inner-edge tire tread wear is the most common tread wear problem most technicians see. The angles causing this type of wear are typically negative toe and camber. For parts, there are three component sources of the inner-edge tread wear: bushings, springs and loads.

Inner-Edge Tread Wear

• Bushings

Ozone, extreme temperatures and other atmospheric issues tend to destroy rubber bushings and cause the alignment angles to change. Some vehicles have hydraulic bushings on the rear lower control arms. Some bushings will leak when they fail. When a bushing in the rear fails, the extra movement causes the wheels to toe out and the camber to go negative.

Bushings, Springs, Loads

• Springs

As a suspension compresses and rebounds, the alignment angles change. Engineers tune alignment angles for a specific ride height to maximize handling and tire tread wear. If a spring can no longer support the vehicle, the alignment angles will suffer. Most engineers tune the suspension to toe out when the rear suspension compresses. This increases vehicle stability. But, it also causes the inner-edge tread wear. Springs are made of metal that is heat-treated, but can still fatigue. This includes leaf, coil and torsion bar springs. If you see a vehicle that needs considerable adjustments for camber on both wheels of the same axle, inspect the springs.

• Loads

Loads in the rear of the vehicle will cause changes to toe, caster and camber in the front (and possibly the rear). The camber and caster will become positive in the front, and if the vehicle has an independent rear suspension, the camber will become negative and it will be toed out. This could lead to outside-edge tire tread wear in the front and inside-edge tread wear in the rear.

Courtesy Brake & Front End.

You May Also Like

Updating Your TPMS Tools Regularly Matters

You can ensure your read is accurate by updating your tool regularly.

Courtesy of Tire Review by Yanick Leduc

Picture this: Mark, an experienced tire service technician, is on the phone with a technical support representative from his TPMS supplier, inquiring why his new sensors don’t seem to work properly with the 2019 Silverado he’s servicing.

Mark: “The truck doesn’t seem to pick up the signal from the new sensor!”

Cabin Air Filters

Cabin air filters will protect the health and well-being of the driver and passengers.

Diagnostic Procedures For Stop/Start Systems

Stop/start technology is more than just a switch wired to the brake pedal and starter.

Brake Pad Wear Sensors

Brake pad wear sensors have been around for years and continue to evolve.

Topology and Your Scan Tool

Topology influences how you access the modules with your scan tool.

Other Posts

Ride Control Diagnostics From Tire Wear Clues

Learning how to read the tire and communicate your findings is the key to ride control service.

Understanding Engine Timing- Chains, Gears and Belts

Engine timing is critical for overall performance.

Air Filters and Fuel Trims

Modern engines rely on precise airflow and oxygen sensor data for optimal performance.

Mercedes Ignition Coil Pack Diagnostics

Replacing a single coil might not be the best approach to curing an engine of a chronic misfire.