Dissecting rubber damage

Irregular tyre wear can be a tell-tale sign of underlying mechanical problems. WILLIAM GEORGE finds out about the root causes of tyre damage and ways to manage them.

The relationship of tyres to a vehicle is similar to that of the heart to the human body. If a tyre is worn or damaged, it could result in malperformance of the other parts of the vehicle.

Old and worn tyres are common causes of accidents, which makes it critical to keep the tyres well maintained. According to a study by the Council for Scientific and Industrial Research, nearly 20 percent of accidents involving minibus taxis have tyre failure as a contributing factor.

Automotive parts manufacturer, Meyle, has created a video tutorial, which troubleshoots tyre damage and analyses the common root causes of the damage. Meyle explains that there are six different types of tyre damage and provides information on each one with the aim of helping vehicle operators to spot a defect instantly without having to consult a tyre professional.

“Tyres are an easily accessible and reliable source of information when troubleshooting vehicle damage, and scrutinising tyre wear patterns can reveal whether or not the damage was caused by other components. Furthermore, these types of damage are easy to fix, thus protecting customers from future tyre problems.” the company notes.

For example, the possible root causes of unilateral tyre wear include incorrect axle alignment, local wear of defective shock absorbers, or local wear caused by incorrect braking behaviour.

These are some causes and solutions of different types of tyre damage highlighted by Meyle:

The tyre centre is worn

The possible cause is likely to be high tyre pressure, or continuous driving at excessive speed. This can be solved by reducing tyre pressure to the level specified by the manufacturer.

Tyre has worn shoulders

This is a possible result of insufficient tyre pressure or aggressive cornering. This can be fixed by increasing
the tyre pressure to the level specified by the
manufacturer.

Both over or under-inflation of tyres can shorten the life of the tyre.

The cupped-tyre wear 

This is typical of defective shocks, or incorrectly balanced wheels. The remedial action is to perform regular shock tests, replace defective shocks, and/or balance the wheels properly.

All tyres on the vehicle should be the same prescribed size, of the same speed rating, and from the same tyre manufacturer.

Flat-spot wear

This could be the result of bad driving behaviour, heavy braking, a defective ABS sensor, or absence of an ABS sensor. Therefore, simply replacing the defective ABS sensor could help resolve the issue.

Saw-tyre wear

This problem is caused by various issues, such as incorrect tyre pressure, incorrect load capacity indices, wheel misalignment, incorrect tyre size used on the vehicle and poor driving technique. This can be fixed by replacing the tyre.

More ways to better manage tyre damage

It might seem obvious, but it is always important to ensure that the tyre pressure is correct. A time-saving method could involve the use of a tyre monitoring device. Companies that offer these devices were covered in issue 11 of 2017 of FOCUS.

There are other remedial actions to keep in mind, such as inspecting the spare tyre. Having a problem-free spare tyre will make it easier to get back to the road if one tyre fails.

Frank Burger, business unit manager for Eqstra Tyre Management, advises operators to treat commercial vehicle tyres as assets to be managed from cradle to grave. He recommends these methods to correcting mechanical irregularities:

• Daily pre-trip inspections (to identify developing tyre wear patterns and visible defects);

• Regular preventative maintenance inspections for damage and wear;

• Correction of mechanical defects; and

• Correction of steering geometry (wheel alignment).

Monal Naik, marketing manager at Bandag, says tyre casing management is key to achieving the best return on a retreading programme, which ultimately produces the best cost per kilometre. He explains: “There is no magic number to be used across all fleets, but, in many instances, a good place to start is replacing scrap tyres with new tyres, which, in turn, generates casings for retreading within the fleet.”

Since the disposing of tyres could have adverse effects on the environment, it is ideal to recycle the older rubber. Naik mentions that in South Africa retreading is well accepted and provides savings while reducing tyre landfills.

He says: “Customers have become accustomed to premium retread options including stock retreads. Retreaded tyres, including stock retreads, offer fleets a cost-effective solution without compromising on mileage performance and vehicle downtime.”

There is important information inscribed onto the tyre to which operators need to adhere. This includes the temperature resistance of the tyre; the tread number, which helps in determining the wear rate; and load capacity, which indicates the maximum load that can be carried by the tyre.

Naik concludes: “The key areas that need to be rectified are poor tyre maintenance, lack of a proper tyre policy, unsatisfactory road conditions and driver abuse.”