It goes without saying that damage to truck, bus and coach tires may be caused by a variety of external forces. Being able to identify common damage can provide insight into the possible causes of the problems. Armed with this information, the necessary repairs and adjustments can be taken to help prevent avoidable damage.
Here are some tips on how to “read” common types of damage to a tire’s tread, along with suggested corrective actions. This is information that should be shared with all technicians.
Abnormal one-sided wear -- This condition arises as a result of tire constrainment caused by wheels being inclined to the direction of motion. Scale-like or feather-edged wear is often seen at the shoulders.
This wear pattern comes about by excessive toe-in/toe-out values or crooked axles. It also occurs if corners are regularly taken at excess speeds.
The recommended corrective action is to correct axle and wheel alignment.
Abnormal one-sided wear in the shoulder area -- This condition occurs predominately with trailer tires as a result of several conditions: a high center of gravity of the vehicle, unsteady loads, one-sided load distribution, bent trailer tow bar or play in the trailer coupling ring.
When wear patterns of this sort are found, the vehicle should be checked to see if any of the aforementioned causes apply.
In order to stabilize the tire cross-section, maximum permitted tire pressure needs to be maintained in all tires.
Abnormal one-sided wear on both sides in the shoulder area -- Wear patterns of this nature are caused by high lateral strain. For example, by fast cornering and by underinflated tires.
A high center of gravity of the vehicle further increases this tendency toward pronounced wear.
The suggested fix is to ensure sufficient tire pressure to stabilize the tire cross-section for the load condition.
Abnormal center wear -- This state is caused by tire pressure too high or a high proportion of trips without a load or with only a partial load.
This condition can be addressed by simply adjusting tire pressure to the load situation.
Scale-like wear -- This type of tread wear is caused by slip as a result of high circumferential or lateral forces. It is increased by excessive tire pressure or insufficient wheel load.
As with abnormal center wear, scale-like wear can be prevented by adjusting tire pressure to the load situation.
Tramline wear -- This results from the unfavorable combination of various vehicle vibrations in low wear use on roadways, and only occurs on tires on non-driven axles (front or trailer axles).
In the case of tractor tires, the recommendation is to move the tires with tamline wear to the driven axles.
Spotty wear -- This condition comes from a difference in diameter on dual tires resulting from varying tire pressures or different size tires. The tire with the lower pressure or smaller diameter is subject to excessive slip.
Spotty wear can also be caused by irregularities on the vehicles, such as too much play in gearings or joints or issues with the suspension system.
To remedy spotty tread wear, only fit dual tires of approximately the same diameter. Keep both tires in a dual arrangement inflated to the same specific pressure levels.
Furthermore, remove any play in bearings and/or joints and repair any broken or defective suspension components.
Circumferential damage -- This is caused by cuts from bent or protruding vehicle parts or foreign objects trapped in the wheel house.
This type of damage to the tread can be avoided through regular inspection of the vehicle and its tires.
Exposed steel cords -- This is typically caused by too deep re-grooving down to the belt. Damage of this nature, combined with the effect of dirt and moisture, causes a tire’s steel belts to rust. This may render the tire unsuitable for repair. Advanced stages of rust can lead to premature tire failure.
If circumferential damage is discovered, the tire should be removed immediately and repaired, if possible.
Better management and training will help get the most out of your tires.