What are the causes of inside tire wear?
By
Vroomouk
This blog will explain the causes and remedies of inside tire wear. The answers to the following questions are also provided: What are the other types of tire wear patterns? How to prevent uneven tire wear and prolong tire life?
What are the causes of inside tire wear?
The causes for the inside tire wear are listed below. Any uneven wear on the tire is not desired as it leads to improper contact with the surface of the road.
- Excessive negative camber
- Worn out suspension components
- Incorrect toe angle
Let’s take a closer look at each of the causes of inside tire wear.
Excessive negative camber
Camber is defined as the angle between the vertical axis of the tire and the road surface. If this angle is acute then it is a positive camber and if the angle is obtuse the camber is on the negative side. Inside tire wear is mostly caused by incorrect or excessive negative camber.
It is a common misconception that the tire must always be perpendicular to the road surface. It is mechanically not possible as the weight of the vehicle changes depending on the number and the amount of fuel or luggage in it.
Therefore, the manufacturer tunes the suspension setup and sets a limit for the max permissible load for the vehicle.
The camber is kept slightly on the negative side as it increases the contact patch of the tire and improves handling in the corners. If the camber is set too much on the negative side or the driver is frequently overloading the vehicle, the inner side of the tire will wear out more quickly.
The vehicle can also pull towards one direction if the camber is more on that side. For example, if the camber reading on the front left is -1.0 and the front right is -0.5 then the vehicle will go towards the right. The driver has to use constant force on the steering wheel to keep the vehicle going in a straight line.
Excessive camber can be corrected by adjusting the cam bolts to turn knuckle bolts located in the upper or lower control arms. In some vehicles, additional washers or shims may be required to bring the camber within the tolerance set by the manufacturer.
Worn out/ damaged suspension components.
The suspension components like ball joints, control arms top bearings, shock absorbers, and rubber bushes are subjected to a lot of stress. As the age and mileage of the vehicle increase, the components like ball joints and bushes get worn out.
If these components are not replaced then the wheel alignment of the vehicle changes. For example, ball joints are used to connect the upper and lower control arm to the steering knuckle. The wheel hub is connected to the steering knuckle and hence a worn-out ball joint can lead to excessive camber angle on that particular wheel.
Similarly, the shock absorbers can leak or get weaker over time and are unable to support the weight of the vehicle. Since the lower portion of the suspension strut is connected to the steering knuckle or the lower control arm, it changes the camber angle as the weight of the vehicle comes closer to the ground.
A closer visual inspection of the suspension components must be performed before a correction of the camber is carried out by performing a wheel alignment. The suspension strut must always stay perpendicular to the control arm.
There should be no grease leaking from the ball joints. The lower and upper control arms are connected to the front subframe and vehicle body through rubber bushes. If there are cuts or oil leaking from the bushes then they must be renewed first before performing the wheel alignment.
During replacing suspension components like control arms or thrust arms, the final tightening torque is applied when that particular component is supporting the weight of the vehicle. For vehicles with pneumatic components, a ride height calibration is performed before adjusting the camber.
Incorrect toe angle
A toe angle is the angle of the left and right wheels with respect to the central axis of the vehicle. If wheels on both sides are pointed towards each other, it is known as toe-in and when the wheels are pointed outside of each other the toe angle is known as toe out.
Inside tire wear is caused due to excess toe-out angle. Toe out is preferred on the front wheels for handling as it makes the steering more responsive. However, it has a direct effect on the inside edge of the tire. The suspension geometry is designed in a way that there is a balance between tire life and vehicle handling characteristics
The toe angle at the rear wheel is always towards the inside as it improves the high-speed stability. The tie rod ends are directly connected to the steering knuckle. Adjusting the tie rod end can pull the inner side of the wheel towards or away from each other.
During measuring and correcting the toe angle of the wheels a toe press bar is attached to the front wheels. This toe press bar replicates the natural position of the wheels when the vehicle is moving or accelerating.
It also helps in adjusting the correct toe angle as the reading measured by the hawkeye of the wheel alignment machine is true to the operating condition of the wheels.
What are the other types of tire wear?
The other types of tire wear patterns and their causes are listed in the table below:
| Tire wears pattern | causes |
| Feathered or sawtooth wear | Improper alignment, toe out |
| Wear on the one edge | Incorrect camber |
| Scalloped or copper wear | Worn out suspension components |
| Bald spots | Wheel runout or not balanced correctly |
| Both edges or center wear | Incorrect tire pressure |
| Cuts on the sidewall and chipped threads | Bad driving habits, use on the rough road |
How to prevent uneven tire wear and prolong tire life?
Following are important tips to prevent uneven tire wear and extend tire life:
- Always use the correct tire and wheel combination, car makers also mention the compatible tire and wheel sizes in the owner’s manual or behind the fuel filler cap.
- Check the tire pressure at least once a month. Most cars have a tire pressure monitoring system that can warn the driver if the tire pressure is too low. Many aftermarket tire pressure monitoring systems are also available that work as stand-alone devices.
- Perform periodic inspection of the suspension component and wheel alignment every 500 to 1000 miles.
- Perform wheel balancing and rotate the tires according to the manufacturer’s specifications and replace the tires if the thread depth is 2-3mm.
Conclusion
This blog listed the causes and the remedies of inside tire wear. Driving a car on an uneven or worn-out tire can be very dangerous especially on slippery roads or in snowy conditions. Therefore, inside or uneven tire wear must be corrected as early as possible.
