Proper selection of tyres is one of the most important factors affecting road safety. What you have to look for when buying tyres is primarily the type in terms of time of year, the size of the tyres, symbols and labels placed on it, but also ratings - for load and speed.
Each tyre features a special string of numbers and characters, e.g. 175/65R13 80T, which accurately describes the characteristics of the tyres, such as the width of the tyre (175), its aspect ratio (65) and the rim diameter (R13). Meanwhile, the end of this string includes ratings - load (e.g. 80) and speed (e.g. T).
Why is the selection of appropriately rated tyres for your car so important? The answer is simple - it means that the purchased tyres will assure safety and the ride will be a pleasure, not a series of problems. How to make the choice? "Be sure to check the car's manual. Its manufacturer selects the tyre size and rating for a particular model, and even the engine or type of suspension. And the car has received approval for just this type of tyres. This means that you can change the brand of tyres, but have to keep to the parameters specified by the manufacturer in the manual," says Piotr Sarnecki, General Director of the Polish Tyre Industry Association.
The speed rating indicates the maximum safe speed for the vehicle when a particular tyre is mounted. Most commonly it's marked with a single letter (in some cases, e.g. tyres for sports cars, this might be two letters), to which a speed in kilometres per hour is assigned.
In turn, the load rating shows the maximum load for one tyre when the speed permitted by the vehicle manufacturer is maintained. It's expressed in kilogrammes.
So, if you own a vehicle with a gross vehicle weight of 2 000 kg and a maximum speed indicated by the vehicle's manufacturer of 200 km/h, you should choose tyres with an H speed rating and a load index of 85 or other, as provided by the manufacturer.
It's worth noting that using tyres with ratings lower than specified by the vehicle manufacturer entails a significant decrease in safety. Tyres with an overly low speed or load rating pose a danger on the road, as they're not able to carry the loads foreseen by the car's manufacturer. In addition, they deform improperly and get used up quicker. They also have worse traction and may, for example, blow during driving. However, an improperly chosen tyre can also lead to legal consequences. "Polish law prohibits the use of tyres with ratings lower than specified by the vehicle manufacturer. It's worth keeping in mind that this can be checked during a roadside inspection and by the insurer in the event of an accident," Piotr Sarnecki adds.
Source: Polish Tyre Industry Association