How To Assess Your Truck's Steering Tires To Verify Their Toe Settings

Automotive Blog

All tires will wear out eventually due to the forces of friction and compression against the road surface. Steering tires on almost all vehicles, semi tractors included, will tend to wear faster due to increased friction caused by cornering. However, steering tire lifespans can be extended by proper maintenance and by learning how to diagnose signs of potential trouble before they drastically shorten the life of tires. Below is how you can assess tire wear caused by improper toe settings and gain an understanding of how to stop wear from eating up your tires prematurely: 

Toe and how it affects steering tire wear

Despite first appearances, the front end wheels of a semi tractor can be adjusted in a variety of subtle directions beyond mere right-angle alignment with the truck and surface of the road. These various alignment perspectives include toe, camber, and caster, and all of these can affect tire wear to some degree. However, the most important of these that influences wear in steering tires is toe, which is sometimes called tracking.

Simply put, toe is a comparison of the distance between the leading edges of the two steering tires against the distance between the trailing edges. If a semi tractor's steering tires are demonstrating a toe-in stance, that means the distance between the leading edges is less than the trailing edge distance. Conversely, toe-out stances occur when the leading edge distance is greater than the trailing edge.

How to know if your semi tractor's steering tires are being affected by toe alignment

If your semi tractor's toe is out of adjustment on the steering tires, you will be able to assess the impact of this misalignment by feeling the tread of the tire. Excessive toe-in and toe-out causes a phenomenon known as feathering, which is the presence of thin, but sharp, edges along the tread blocks.

To make this assessment, simply place your fingertips on the inside edge of the tread surface and lightly rub your fingertips across the tread toward the outside of the tire. Next, repeat the process, but rub your fingertips across from the outside toward the inside of the tire. Below is how to know what the results indicate:

• Smooth toward the outside/smooth toward the inside - A tire tread without feathering will feel smooth to the touch in both directions, and this indicates proper toe-in is present on the steering tire assessed.

• Smooth toward the outside/sharp edges toward the inside - If you detect feathered edges when feeling from the outside toward the inside, then your tire has excessive toe-out wear.

• Smooth toward the inside/sharp edges toward the outside - Should you feel feathering when rubbing your fingertips toward the outside of the tire, this indicates the presence of excessive toe-in wear.

Keep in mind the relationship between steering tires is a "mirror image" whenever toe-in and toe-out issues are present. Should there exist a conflicting pattern where feathering occurs in a one-way direction, other issues may be the cause of your misalignment and excessive steering tire wear. For example, tandem axles must be parallel to one another, or their effect on the vehicle will be to pull it to either the right or left and introduce unidirectional feathering.

Regardless of whether your truck's steering tires are demonstrating a pattern of excessive toe-in, toe-out or even tandem axle misalignment, tire wear is accelerated and control can be compromised. These parameters are adjustable, but keep in mind the proper adjustment of toe requires the use of precision equipment and should be performed by a professional.

Share

12 July 2016