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What is it?

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The tread of your tyres (the rubber pattern on their surface) has to transmit all the forces that pass between your vehicle and the road. Tyres have to support the weight of your vehicle, steer it, transmit drive and braking force, grip the road and even assist your vehicle's suspension. Tyre grip determines the ability of the wheels to follow the road without slipping or skidding. Underinflated, worn or hard tyres reduce stability on bends and can make your vehicle dangerous in the wet and under braking.

Friction and therefore grip at the patch of contact between tyre and road influences:

  • Stopping distances under braking
  • Road holding on bends
  • Vehicle stability
  • Vehicle response in emergency manoeuvres
  • Steering accuracy
  • Safety in all driving conditions

Understanding the basics of tyre design contributes to your safety in all driving situations. Tyres are not made from rubber alone. They have quite a complex internal structure.

  • Tread: this is the surface that comes into contact with the ground. The tread must resist wear and protect the inside of the tyre. It is made from rubber and features a pattern that varies from one type of tyre to another.
  • Sidewalls: these protect the internal structure against side impact and attack by atmospheric agents; they are marked with useful information on tyre size, tread pattern name, manufacturer's name, date of manufacture, etc.
  • Bead: this is a ring of rubber coated fabric the same shape as the wheel rim, and is designed to stop the tyre slipping on the wheel.
  • Ply or warp: this is the structure that defines the shape of the tyre. The warp comprises one or more overlapping layers (plies) of fabric arranged to provide the necessary flexibility while also absorbing all the forces involved, including driving, braking and inflation forces. "Radial" tyres are tyres in which the plies of the warp extend crosswise between the beads.
  • Belts: these are steel or nylon belts bonded between the carcass and the tread to improve strength, stability and impact and penetration resistance.
  • Filler: this part is generally made of rubber and extends from the bead into the sidewall; it provides a gradual transition between the hard bead and the flexible sidewall.
  • Inner liner: this is the layer of rubber inside tubeless tyres that stops air from leaking out.
  • Bead wires: these are wires that run through the bead to prevent it slipping off its seat in the wheel rim.

Tyre designs differ according to the season of the year for which they are intended. There are three main types including:

Summer tyresDiscover

Winter tyresDiscover

Four Season TyresDiscover

The European Union has introduced a new, obligatory tyre labelling system to ensure the diffusion of clear and authoritative information on:

  • Energy efficiency
  • Wet grip
  • Tyre noise

Starting from November 2012, all new tyres sold in the European Union must be marked with the information needed to evaluate their performance.

EC Regulation 1222/2009 specifies various performance ratings for:

  • Rolling resistance
  • Wet grip
  • External rolling noise
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ROLLING RESISTANCEDiscover

Wet gripDiscover

Noise LevelDiscover

Did you know?

Markings and sizes

Markings and sizes

The markings on tyre sidewalls precisely identify tyre characteristics. This information is important because each vehicle can only be fitted with tyres of the size and type specified in the Owner Handbook.

Each number marked on the tyre identifies a precise physical characteristic. For example, the Owner Handbook may specify tyres of size 215 65 R 16 95H where:

  • 215 is the width of the tyre in millimetres
  • 65 is its height/width ratio
  • R identifies the arrangement of the plies. In this case the tyre is a radial ply model
  • 16 is the diameter of the tyre in inches
  • 95 is the load rating, a numeric value identifying the maximum load the tyre can withstand at the speed identified by the manufacturer's speed rating
  • H is the speed rating, a value identifying the maximum speed at which the tyre is able to withstand the load identified by the manufacturer's load rating
The date of manufacture (DOT) is also marked on the side of the tyre. The week and year of production are specified in the form a four figure code. For example, the code 4712 identifies a tyre made in week 47 of the year 2012.

How to control aquaplaning

How to control aquaplaning

Aquaplaning is one of the greatest risks involved in driving on wet roads. When a vehicle aquaplanes, its tyres start to float on a cushion of water, immediately losing contact with the asphalt beneath. Aquaplaning is a dangerous phenomenon, typically caused by driving at high speed over a very wet road or an asphalt surface with puddles of water. Under these conditions, the channels in the tread are no longer able to expel all the water from under the tyre; a cushion of water forms as a result, causing the tyre to float over its surface. In most cases, aquaplaning can be avoided by careful driving combined with good, correctly inflated tyres, since tread patterns are designed to drain large volumes of water in order to maintain an effective grip. If your vehicle starts to aquaplane, applying the brakes is useless because your tyres are no longer in proper contact with the road. Braking could even cause the vehicle to swerve violently when the first tyre regains grip, causing you to lose control.

The best thing to do is keep a firm grip on the steering wheel ready for the moment the tyres regain their grip, while maintaining directional control for as long as the phenomenon persists. Also, gradually release pressure on the accelerator pedal, since engine speed will have increased as soon as the wheels began to float.

The right pressure

The right pressure

In addition to being unsafe, underinflated tyres also increase fuel consumption. Because they offer greater rolling resistance, they require more energy to turn, which translates into increased fuel costs. Once fitted to wheels, tyres inevitably deflate over time. It is therefore important to check tyre pressure regularly and respect the values specified in your vehicle's Owner Handbook. Correctly inflated tyres can save you up to 5%* in fuel costs.

* Source: U.S. Environmental Protection Agency (EPA)

FIAT’s tips

Underinflated, worn or hard tyres significantly reduce stability on bends and can make your vehicle dangerous in the wet and under braking Respect the tyre sizes specified in your vehicle's documentation. It is illegal to fit tyres of a size not permitted by your vehicle's registration document. While it is not permitted to fit tyres with a lower speed rating than that of the ones fitted as original equipment, it is permitted to fit tyres with a higher speed rating. You are also allowed to fit your vehicle with winter tyres with a speed rating one letter below that of its summer tyres. Keeping your tyres inflated to the right pressure can save you up to 5%* in fuel. Correct inflation and use of tyres suitable for the season make a major contribution to safety and tyre life. Have your tyres checked regularly by an Authorised Fiat Service Centre. They can also change your tyres if necessary. Their specialist personnel will also be able to recommend the best tyres for your requirements.

* Source: U.S. Environmental Protection Agency (EPA)

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Self-diagnosis

It is good practice to check your tyre pressure regularly. The correct pressure is specified in your vehicle's Owner Handbook.

Tread depth

Tread depth varies from one type of tyre to another, but its minimum value is established by law. Tread must be at least 1.6 millimetres deep across the surface of the tyre.

Tyre condition

Cuts and lacerations in the sidewalls of a tyre can be dangerous, especially if they penetrate to the plies of the structure. Replace the tyre immediately if you notice this kind of damage.

Rim

Dents in the rims can cause vibration in the steering and even lead to the tyre coming off the rim.