Five reasons why you should not put cheap rubber on your performance car

By Pritesh Ruthun Time of article published Oct 28, 2020

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JOHANNESBURG - Excitement filled the air, the day you drove out of the dealership with your hot new wheels. A proud moment, which you had looked forward to for a long time. You had done your research on the best luxury, high-performance car that would fit your lifestyle, give you the torque you needed to hit the open road, to enjoy your commute to work in style, and when you felt adventurous to drive roads for the sake of driving your machine. Freedom!

You knew what you wanted and knew the specs to fulfil those needs. You chose well. You looked after your car, tending to its every need. It came with a maintenance plan and you diligently ensured it stayed in tiptop condition. So far, the journey has been great, the mileage too. Importantly, the tyres have served you well, kept you safe – even at high speeds and in wet and cold weather. But the time has come to look at their replacement. How do you choose?

You know that tyres are the only part of your vehicle that contacts the road surface. They perform many different functions, of which safety and comfort are the most important. However, there are also other factors to consider.

When deciding, you need to ask yourself: Should I go for the tyre that came with the car? The cheapest replacement tyre or the most expensive? The ones with the racy sidewalls or the most intricate tread pattern? A soft or hard tyre compound?

To guide you through this process, we asked Riaz Haffejee, CEO of Sumitomo Rubber South Africa, manufacturer of the Dunlop, Sumitomo and Falken tyre brands for tips on how to choose the best tyres for your high-performance car:

1) How do tyres affect my car’s performance?

Tyres are required to perform many different functions. They need to ensure the safety of the passengers in the vehicle, enabling it to stay on the road in wet or dry conditions or stop quickly when required. Providing good steering ability, handling the speed capability of the vehicle, and ensuring stability while withstanding cornering forces are also key factors to think about.

Tyres need to be able to carry the load, not just of the vehicle, but of the passengers and the goods or luggage loaded on board. They need to offer a comfortable ride, cushioning the impact of bumps or corrugations on the road surface, while emitting low noise levels from contact with the road surface. Tyres are arguably the most highly engineered component on your car and have a significant role to play in the performance and functioning of your car.

2) How do I choose the best tyre for my vehicle?

The best tyre for your vehicle is the brand and size of tyre that your new vehicle came fitted with. This is the general rule. Manufacturers select Original Equipment, including tyres, for vehicles based on performance and strict testing protocols. It must be noted though, that for most vehicles there is more than one officially fitted tyre with most OEMs having multi-sourcing arrangements in place in their factory. Dealers and tyre manufacturers can help with identifying alternate options.

If you are either unhappy with the performance of the tyres fitted, or unable to fit those tyres for whatever reason, speak to a reputable tyre dealer and find out what the next best option will be. Ensure that you communicate your needs, the type of driving you do, and the specifications you have for the performance of your vehicle and tyres. This will help to prevent the selection of unsuitable tyres that do not meet your ‘on the road’ requirements. Our Dunlop Zone and Express fitment centre staff are trained in tyre selection and can assist you with making the best choice.

3) Why is the diameter of a tyre important?

The diameter of a tyre is extremely important as it impacts the vehicle’s steering and handling capabilities and the suspension set up. The correct fit will ensure that the vehicle will handle and perform to its optimum level. It is extremely important, when considering upsizing or downsizing wheels and tyres on your vehicle, that you try and stay within the diameter parameters set by the tyre manufacturer to avoid affecting the vehicles handling capabilities and characteristics.

When changing wheel and tyre diameter, or tyre size in general, there is a safety factor that allows for a change in the circumference. This allows the gearing of your car to stay within the right range without any drastic changes that could affect the traction control, ABS systems or fuel economy. To find the best fit for your specific high-performance vehicle, you can visit the Dunlop website www.dunloptyres.co.za and use the online calculator.

4) Why is the tread depth important?

The more rubber you have on the road, the better the grip the tyre has on the road. This relates directly to your tread depth. Low remaining tread will mean that you will have less control of the vehicle, braking distances will increase and there is a very good chance of aquaplaning or hydroplaning taking place on wet road conditions or sliding across the road surface in wet weather. In addition, tyres with a tread depth of less than 3mm have been shown to be less safe in wet conditions, with a significant increase in wet weather braking distances.

Remember to check your tyre tread regularly to ensure that all of your tyres are within the legal limit of 1.6mm and that the tread, across the entire breadth of the tyre, is above the tread wear indicator in the groove of the tread. Treadwear indicator heights will vary from manufacturer to manufacturer depending on the type of tyre and the casing construction and tread compound of the tyre.

5) What about rigidity?

The rigidity of the tyre will affect the comfort of the ride and your handling capabilities. Tyres can be manufactured from either a soft or hard tread compound. Soft compound tyres wear faster but offer a gentler, superior ride, better grip, and improved braking with reduced stopping distance.

Hard compound tyres, on the other hand, last longer and are better suited for difficult conditions, like rough terrain.

What else do I need to consider when buying replacement tyres for my high-performance car?

High-performance cars require tyres fitted with a high-speed symbol specification and a tread compound that will be able to handle heat generated at high speeds. As a rule, tyres with a high UTQG (Uniform Tyre Quality Grading) rating for temperature and traction are fitted to high-performance cars.

It is also important to consider the tyre load index and speed symbols when making your tyre selection. The load index is a numeral value indicating the maximum load weight that each tyre can carry. The maximum load-carrying capacity per tyre is indicated in kilograms (kg). The higher the tyre's load index, the heavier the load-carrying capacity. For example, a load index of 79 can carry up to 437kg per tyre and a load index of 84 that can carry up to 500kg per tyre.

Tyres with XL (Extra Load) or Reinforced imprinted on the sidewall are generally designed for heavy vehicles such as SUVs. These tyres have a greater load capacity due to their construction design and this makes it possible to maintain higher air pressure, to run at, within the tyre.

The speed symbol indicates the maximum speed at which the tyre can carry the load corresponding to its Load Index under service conditions specified by the tyre manufacturer. As an example, a speed symbol of T can travel at a maximum speed of 190km/h, whereas a speed symbol of H can travel to a maximum speed of 210km/h. Always check your user manual for the vehicle manufacturer’s recommended load index and speed symbol for your vehicle.

Making the right tyre replacement selection is key to ensuring that your high-performance vehicle continues to perform safely at its peak, giving you high-speed stability, more grip and driving pleasure.

DRIVE360

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