Tyres – Understanding Them

Nov 11, 2019 | Articles, Tyres – Understanding Them

Tyres – Understanding Them Better.

Car tyres are so technologically advanced that they rarely call attention to themselves, so we hardly spare them a thought. However, there are certain things you have to know about these vitally important car components. Think for a moment about the following. You are driving along at maximum allowed highway speed. What do you think keeps you, your entire family, and your car on the road? Only four little tyre contact patches (also called tyre footprints) such as that in the image. That’s it, nothing more!

When you think about it that way, it may change your overall perception of the tyre. You may also then realise that you should be somewhat more educated about them. Tyre failure can cause a tragic accident, be sure of that.

Are you willing to gamble?

According to Discount Tire Direct, the design of the contact patch is an engineering feat. This feat is specific not only to each manufacturer but for each individual tyre. It is important to keep in mind that the design of the contact patch can affect traction, handling, and treadwear. There are two very important factors to consider that may affect the contact patch. They are carload and tyre pressure. The one has a direct relation to the other. The recommendation is to set your car’s tyre pressure to the specifications of the manufacturer.

Now I remember, my car has tyres!

The only times you probably think about your tyres is when they lose their grip. What do you think of when you approach a corner too quickly? The tyres start squealing, the steering lightens, and suddenly your car starts ploughing on straight ahead, ignoring your turning instructions. We call that understeer. You lift your foot off the accelerator in a panic, the front tyres bite, and your car resumes turning. You averted the crisis!

It may also happen that the weight transfer causes the rear end to lighten. This will result in the rear tyres losing their grip. You will then find the tail overtaking the nose. We call that oversteer and it is even more frightening than understeer. It is in these situations that you reconnect with your tyres, on a different level. Do not only, under such circumstances, remember that your car has tyres.

Tyre care.

As we said, always ensure that your car’s tyre pressure is correct. This is because underinflated tyres that deform under cornering, can cause your car to lose its footing. This will send you hurtling into a spin that may end in disaster. Keeping tyres inflated to the recommended pressures will prevent overheating (and subsequent blow-outs), and improve performance and economy. Do not use old tyres. Old tyres tend to dry out and lose the oils used in their construction – much like our skin when ageing. Therefore, an old tyre beyond its safe-use age should be discarded, irrespective of the amount of tread it has left. Do not use tyres that are older than ten years!

Unravel that code.

So, how do you know how old your tyres are? You look at the codes on the side of the tyre. Because of their different origins, these codes are an odd combination of figures. Let us use an example of a tyre with the following codes on the side: “195/65 R15 90H”. The 195 is the width of the tyre in millimetres. Then follows the 65, which refers to its profile as a percentage of its width. Its profile is the distance from the road surface to the wheel, and 65% of 195 mm is 126.75 mm. If there is nothing where the profile percentage is supposed to be, it is 82% by default.

The letter R stands for radial-ply, referring to the steel-ply reinforcement weaved into the tyre tread. After the R, is the number 15, and this refers to the rim diameter – in inches. The 90 is the load rating for the tyre and works according to a scale. This is typically from 50 (190 kg) to 130 (1900 kg). In this case, 90 constitutes a maximum tyre load of 600 kg. In conclusion, the letter H is the speed rating, for which there is also a scale. The scale is typically from N (140 km/h) to Y (300 km/h). In our example, the letter H constitutes a maximum continuous speed of 210 km/h.

Can a Unichip assist?

Fitting a Unichip will indeed improve performance and economy in a completely safe way, without having to modify your car. The next time you bring your car for a change of tyres, also fit it with a Unichip. It may be a surprise to you, but with the Unichip, there is almost always some room for vehicle improvement. Practice responsible car care. Become part of the Unichip family and buy your Unichip today. Click here to contact us.



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