TYRE AGE

Tyre age is often overlooked and should be considered when driving your vehicle over short or long distances.

Often the tyre seems to be within legal limits but the overall quality of the tyres has degraded with time.

Your tyres may become brittle and deteriorate without your knowledge. It is best to have your tyres inspected annually to prevent flat or exploding tyres.

Rubber ages differently in each climate, so your region and temperatures needs to be considered. In South Africa, it is generally expected for your tyres, and their integrity, to last between 5 to 6 years.

It is important and advised to note the date on your tyres.

LEGAL REQUIREMENTS

There is a lot of confusion regarding the correct way to measure tyre tread depth. Even so-called tyre experts, such as the fitment centres disagree on the correct manner.

Insurance companies often incorrectly reject claims on the basis that tyres did not comply with the roadworthiness requirements, when they in fact do.

The correct manner is however described by law (South Africa), and although some sections are somewhat ambiguous when read in isolation, when one considers all the normative references in the National Road Traffic act and the applicable standards, such as the SABS 1550 and SABS 047, one is able to understand the correct procedure, as it applies to passenger vehicles/tyres.

NATIONAL ROAD TRAFFIC ACT AND REGULATIONS

Regulation 212 of the National Road Traffic Act, Act 93 of 1996

212. No person shall operate on a public road motor vehicle:

Which is fitted with a pneumatic tyre unless such tyre displays throughout, across its breadth and around its entire circumference, a pattern which is clearly visible, and has a tread of at least one millimetre in depth; or

Which is fitted with a pneumatic tyre which contains a tyre tread depth indicator, if the tread is level with the tyre tread depth indicator:

• Is applicable, where the tread depth is specified as at least 1mm
• Relates to industrial tyres with no tread pattern. The tread depth indicator, differs from the “tread wear indicator” (TWI). The tread wear indicator is used on passenger tyres and is present inside the main grooves (where the tread depth is measured), to indicate that approximately 1.6mm of tread is still present, when worn to the level of the TWI.

THE VEHICLE EXAMINERS HANDBOOK

ARP 007: The care, maintenance and use of motor vehicle tyres and rims.

The tread of a tyre must therefore be measured in the main grooves of the tyres and in other areas where the tread wear indicators indicate that the tread depth should be measured, as prescribed in ARP 007: 1992.

Paragraph 3.3.1.3 states: “It is recommended that no vehicle be operated with tyres that do not have a minimum tread pattern depth of 1,0 mm in all the main grooves across the full width of their tread contact area and around the full tyre circumference, with the exclusion of areas where tread-wear indicators or tiebars (or both) exist.”

IMPORTANT: If there are no main grooves, as in the case of some directional tyres, tread depth can be measured anywhere on the main tread surface, with the exclusion of areas where tread-wear indicators or tiebars (or both) exist.

BASICALLY

This basically means that the tyre must have a tread depth of more than 1mm over the breadth of the tyre and around the tyre’s circumference.

Depending on the design of the tread on some tyres, the breadth may exclude the shoulder area.

This is because it is common practice to have reduced depth of the grooves on the shoulder area of the tyre to increase the stiffness of the shoulder of the tyre. This increased stiffness reduces tread squirm and associated wear.

It therefore serves a specific purpose.

ADDITIONAL REQUIREMENTS

Additional to the above, there is a requirement that a tyre should not be worn to a level where any part of the tyre construction is compromised. This is due to the fact that a tyre can be worn or may suffer damage in an area to expose parts of the tyre construction. In such a condition, the tyre is weakened in many ways:

• The tyre has reduced penetration resistance
• The tyre has reduced impact resistance
• The tyre is less stable due to the weakening of sections of the construction
• Cords are exposed to the elements and may corrode or rot

This means that even if the tyre tread depth (in the main grooves) was measured and complies with the specific requirements relating to tread depth, the tyre must be rejected.