- 11 Apr 2017
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A Geeky Guide to Tyres
Those numbers speak volumes. They explain your tyre's composition (usually layers of steel and polyester), its traction rating (the Mercedes-Benz tyre is rated at the highest level – AA), its operating temperature range, plus its maximum pressure for inflation. Coded in universal tyre language, these geometric specifications might read "265/35/20".
This means the tyre is 265mm wide, the height-to-width ratio (or aspect ratio) expressed as a percentage of the width is 35% of 265mm, and the inner diameter measures 20 inches to fit a rim of that size.
But most significantly – especially helpful when it comes to the replacement of tyres (every seven years, regardless of the distance covered) – is that these figures tell you when your car's batch of boots were made. The final four digits following the US Department of Transport (DOT) number show the week and year of manufacture.
But there's more. The tyre's load index number specifies the maximum load that can be carried at its given speed rating. For the Mercedes-AMG GT S, this number is 98 (as classified by the industry-standard load index, which ranges between 62 and 126) and signifies a weight-per-corner carrying ability of 750kg.
And as it's a super high-performance car, only the highest speed classification will do. Its tyres get a Z rating, which means safe travel at speeds in excess of 300 kph.
In short, these four round hoops are the most overlooked and underrated safety kit on your car. They have to grip, steer, power and brake – and can save your life. Isn't it worth getting to know yours a little better?
Here’s more on how to care for your car’s tyres – and how to save on fuel.
By Braam Peens