Theory

E. Tires

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Tires play an essential role in a vehicle’s safety and performance. In direct contact with the road surface, they must withstand the stresses of weight, speed and road conditions, while ensuring good grip and optimum driving comfort.

E. Tires

Chapter 4: Vehicles

Tires are the part of the vehicle in contact with the road. They must be able to withstand the load and speed of the vehicle without deteriorating, guaranteeing reliability, safety and performance. They absorb shocks and vibrations, providing comfort. Tires have a radial or diagonal structure under the tread, which solidifies the tire. Radial tires are found on most vehicles, offering robustness, longevity, better material work in the tread and lower energy consumption.

Tires are the part of the vehicle in contact with the road. They must be able to withstand the load and speed of the vehicle without deteriorating, guaranteeing reliability, safety and performance. They absorb shocks and vibrations, providing comfort. Tires have a radial or diagonal structure under the tread, which solidifies the tire. Radial tires are found on most vehicles, offering robustness, longevity, better material work in the tread and lower energy consumption.

Tread

The tread is a thick layer of rubber in contact with the road surface, carved to evacuate water, snow and dust, limit aquaplaning, improve grip and evacuate heat. The wear indicator is a small rubber block on the tread called the Tread Wear Indication (TWI). The thickness limit is 1.6 mm for summer tires and 4 mm for winter tires. When the tread reaches this level, the tire must be replaced.

The tread is a thick layer of rubber in contact with the road surface, carved to evacuate water, snow and dust, limit aquaplaning, improve grip and evacuate heat. The wear indicator is a small rubber block on the tread called the Tread Wear Indication (TWI). The thickness limit is 1.6 mm for summer tires and 4 mm for winter tires. When the tread reaches this level, the tire must be replaced.

Wear indicator

The tread wear indication (TWI) is a small rubber block on the tread. Its thickness limit is set at 1.6 mm for summer tires and 4 mm for winter tires. When the tread reaches this thickness, the tire must be replaced.

The tread wear indication (TWI) is a small rubber block on the tread. Its thickness limit is set at 1.6 mm for summer tires and 4 mm for winter tires. When the tread reaches this thickness, the tire must be replaced.

Tire markings

Tires vary according to the vehicle and are marked: 195 is the tire width, 65 is the ratio of height to width, R or D indicates the structure, 15 is the rim size, 95 is the load code, V is the speed code, DOT indicates the 4-digit production date (e.g. 1520 means manufacture in the 15th week of the year 2020).

Tires vary according to the vehicle and are marked: 195 is the tire width, 65 is the ratio of height to width, R or D indicates the structure, 15 is the rim size, 95 is the load code, V is the speed code, DOT indicates the 4-digit production date (e.g. 1520 means manufacture in the 15th week of the year 2020).

Tire pressure

Check tire pressure regularly when cold (5 km after setting off). They can be over-inflated by 10% for long journeys and when carrying a heavy load. Never under-inflate by 10%. Follow the manufacturer’s recommendations. An under-inflated tire reduces grip, which is dangerous when cornering and braking, causes faster wear, risks bursting and increases fuel consumption.

Check tire pressure regularly when cold (5 km after setting off). They can be over-inflated by 10% for long journeys and when carrying a heavy load. Never under-inflate by 10%. Follow the manufacturer's recommendations. An under-inflated tire reduces grip, which is dangerous when cornering and braking, causes faster wear, risks bursting and increases fuel consumption.

Changing the tire

To change a tire: loosen the bolts counter-clockwise, tighten the bolts clockwise in a crosswise sequence.

To change a tire: loosen the bolts counter-clockwise, tighten the bolts clockwise in a crosswise sequence.

Winter tires

When the temperature drops below 7°C, tires harden and become less efficient. Snow tires are designed for good performance in extreme winter conditions. Winter tires are marked M+S (Mud and Snow).

When the temperature drops below 7°C, tires harden and become less efficient. Snow tires are designed for good performance in extreme winter conditions. Winter tires are marked M+S (Mud and Snow).

Proper tire maintenance – checking tire pressure and wear, and adapting tire type to the season – is essential for safe, efficient driving. Knowing their characteristics and how they work enables drivers to optimize their vehicle’s performance and safety.