SAFE DRIVING AND TYRE FEATURES
SIDEWALL MARKING
On the tyre sidewall there are several different inscriptions. As well as the name of the brand and the range, the size and characteristics of the tyres are marked: nominal width, ratio between nominal section height and nominal section width, structure or construction code, rim diameter and load and speed index.
TYRE FITTING AND MIXING
Pirelli strongly recommends the following rules are followed.
- Always fit the same identical tyre with the same size, structure, brand and design on the same axle
- Follow the vehicle manufacturer’s recommendations as to replacing 2 or 4 tyres at the same time
- Always respect the rolling circumference ratio between tyres and axles when fitting tyres to a 4WD or AWD
TYRE PRESSURE
The tyre pressure has a strong influence to the safety and economy of a vehicle.
As such, tyre pressure when cold (never try to adjust the pressure while the tyre is hot) must be checked regularly (every month), especially before a long trip.
Inflate the tyre to at least the minimum cold pressure for that size tyre as shown on the vehicles tyre placard.
Braking distance is related to the tyre pressure. At a driving speed of 100km/h, the braking distance with correctly inflated tyres will be 40m compared to 42.4m with deflated tyres. Performance is therefore improved by almost 6%, equal to 2.4m.
Incorrect inflation pressure causes irregular tyre wear. Pressure that is too low causes shoulder wear and carries the risk of structurally damaging the tyre from impact damages. Low pressure also increases fuel usage. Pressure that is too high causes wear to the centre of the tyre.
TYRE INTEGRITY
A tyre is made of rubber, steel and fibres. Steel and fibres are structural materials whilst the rubber has the function of protecting them against environmental influences. The rubber itself can be damaged by chemicals or other environmental influences:
- Sharp objects, strong impacts or other mistreatment can cause visible and invisible structural defects
- Tyre pressure that is too low causes structural defects
- High temperatures and sunlight will destroy the rubber
TYRE TREAD DEPTH
The tread depth is a substantial safety factor in wet conditions. It has an important influence on the vehicle’s contact with the ground.
While braking, the Anti-lock Braking System (ABS) is controlling the wheel at the slip threshold and water is collected. The tyre tread becomes saturated and the braking distance increases drastically.
Aquaplaning depends on water depth, tread depth and driving speed. To measure aquaplaning, a car is driven into a basin with 8 mm of water and speeds up. As soon as the motor works harder without speeding up, aquaplaning starts.
The tread’s depth should never be less than the legal limit, which for cars, caravans and heavy vehicles is 1.5 mm. Other than the legal limit requirements, to stay within the safety margin, Pirelli recommends that you replace your tyres when the tread is about 3 mm. Performance on wet roads decreases in proportion to the tread’s groove depth.
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