admin
advice on getting the best out of your tyres whilst ensuring legal compliance.
Tyre Maintenance and Safety
Experience has shown that tyres are the most neglected safety feature on vehicles despite the fact that tyre-related accidents are often catastrophic.
Combined with the increase in tyre-related road traffic accidents being reported, tyre maintenance is of paramount importance.
Safety in acceleration, steering, cornering and braking depend to a large extent on the small area of road contact provided by the tyres.
It follows therefore that the quality, application, design capacity and condition of a tyre has a major influence on tyre and road safety.
Choosing a Tyre
Good tyre maintenance begins with the choice of tyre. In choosing a tyre one must pay special attention to the size, application, rating and quality of the tyre.
It is important to ensure that the size of tyre is in line with the vehicle manufacturer’s specifications.
The application for which a tyre is designed is also a critical element for safety and service life.
Application may refer to vehicle use (passenger or commercial), road condition (tarred, dirt, mud, snow, etc).
Each tyre is manufactured with three critical rating considerations. These are the load, speed and temperature ratings.
Operating a tyre above any of these ratings will diminish the useful life, performance and safety of the tyre.
The side-wall of a tyre contains a lot of critical information to help in determining it’s suitability for a chosen vehicle and use.
The quality of the tyre has a bearing on its reliability and performance.
Poor quality tyres are responsible for many of the premature tyre failures on our roads. It has often been said that “when you buy cheap, you are likely to buy twice” and this has been proven many a time by motorists who put initial purchase price ahead of quality.
Looking After Your Tyre
Once the correct tyre has been chosen, it must be maintained in a good condition to avoid damage and abuse that may result in premature failure.
Failure of a tyre is often manifested through punctures, cuts, impacts, cracks, bulges, run flats and disintegration.
The service life of a tyre, on the other hand, is a cumulative function of the storage, rotation and service conditions, which a tyre is subjected to throughout its life.
Service conditions refers to load, speed, inflation pressure, road hazard, driving habits, etc.
Inspections
A key element of tyre maintenance is regular inspections of all tyres including the spare wheel. It is recommended that this be done at least monthly.
If tyre damage is suspected or found, it is recommended that the tyre be inspected by a tyre service professional to determine if the tyres can continue in service.
Stones and other objects embedded in the tread must also be removed and oil and grease wiped off with detergent.
Motorists are strongly encouraged to be aware of their tyres’ visual condition, such as cracking/crazing of the tread/side-wall rubber and be alert to changes in dynamic performance such as increased air loss, noise or vibration.
Motorists are further urged to recognise a severe in-service impact to a tyre (usually when one “hits” a pothole) and to ensure that the tyre is inspected almost immediately thereafter.
The tread depth of the tyres must be routinely monitored to ensure optimal grip especially on wet roads and compliance with the law. Generally, wet grip decreases as the tread depth decreases
Inflation
Tyre and road safety specialists prefer to define a tyre as a “vessel for the air that carries a vehicle’s load”.
The significance of this definition is that it explicitly points to the fact that it is the air (pressure) inside that tyre that carries the load.
Thus correct tyre inflation pressure is the cornerstone of in-service tyre maintenance. An under-inflated tyre increases fuel consumption, reduces tyre service life (50 percent under inflation results in a 60 percent decrease in service life) and makes the tyre vulnerable to heat induced disintegration.
An over-inflated tyre is more susceptible to impact fractures, makes handling more difficult, makes the ride less comfortable and has a reduced contact area with the road.
Tyre inflation pressure should be checked at least every two weeks and only when the tyre is cold, since there is an increase in pressure when the tyre has warmed up after being run.
A reliable and accurate pressure gauge should be used.
A new valve should be fitted when replacing tubeless tyres as well as a new cap of the sealing type.
Most vehicles have the recommended tyre pressure marked on a sticker placed on the driver’s door.
The vehicle manual also contains this important information.
Overloading is a menace and should be avoided as it has the same effect on the tyre as under-inflation
Wheels and Rims
It is essential the wheel size is an approved fitments for the tyre and vehicle concerned.
Tyres must not be used on damaged, distorted or modified wheels since this could result in tyre damage, deflation and possible loss of control of the vehicle.
Removal and Fitting of Tyres
These operations should only be entrusted to a trained tyre specialist who has the necessary equipment and expertise to avoid bad practices that can result in injury and damage to tyres and wheels.
Repairs to car tyres must only be carried out by a reputable tyre specialist and in accordance with SAZ standards
Wheels should be balanced after tyres are fitted or replaced.
Ageing of Tyres
Whilst there is no known technical data that supports a specific tyre age for removal from service, most vehicle and tyre manufacturers recommend that tyres (including spare tyres) must be removed from service when they reach a certain age from the date of manufacture even when they appear to be usable from their external appearance and the tread may not have reached the minimum wear out depth.
This age ranges between five and seven years.
To help in determining the chronological age of a tyre, the side-wall provides the year and week of manufacture in the last four digits following the “DOT” symbol.
The first two of these four numbers identify the week of manufacture while the last two identify the year of manufacture (e.g., a tyre with the information “DOT XXXXXX2111” was manufactured in the 21st week of 2011).
Directional And Asymmetric Patterned Tyres
Some tyres have patterns where their direction of rotation is important to achieve their full performance.
The direction of rotation is marked on the tyre’s side-wall.
Additionally, some tyres have patterns which are different on the inner half of the tread than compared to the outer half and will be marked “Outside” and/or “Inside” or similar wording on their side-walls.
- Tyre Maintenance Tips
- Careful brand and supplier selection
- Regular inspections
- Regular pressure checks
- Strict minimum tread depth Standards
- Brake maintenance to ensure even distribution
- Curb excess speed
- Accurate alignment throughout
- Driver participation
- Correct application
- Tyre balancing and rotation every 5 000km
- Control of ageing tyres, e.g. spare wheel
- Good general mechanical maintenance
- Care and proper application of rims
- Proper storage of tyres and avoidance of direct sunlight, ozone, oils, grease and high temperatures
Conclusion
The president of the Irish Tyre Industry Association, Mr Brian O’Neill, succinctly put it:
“We all know it’s a good idea to check our tyres regularly, but the truth is the average Irish motorist doesn’t always give tyres the attention they deserve.”
Overlooking your tyres is a mistake. When it comes to the road-worthiness of your car, and the safety of the people travelling in it, few things are more critical than a good set of properly selected, professionally fitted, correctly inflated tyres.
Finally, remember you do not have to be a tyre expert, you simply have to know one who will help you to get the best out of your tyres and ensure you are safe on the road, comply with the law and save money.
Tafadzwa Choto is a tyre expert and writes in his personal capacity. He can be contacted on [email protected]. For your views and comments you can contact the Traffic Safety Council of Zimbabwe on 04-751208 or 0772 110 898.
Online Reporter