The tyre is the only part of the car that touches the road. Tyres must strike a balance between traction, comfort, durability, energy efficiency and overall cost. As a result of these competing needs, tyres are more complex to design and build than you might think.
Take, for instance, a smart phone. It seems far more complex than a tyre. But actually, throughout development a similar amount of research and technology goes into the tyre.
The steps of the tyre making process
1- Understanding through research
We study peoples' tyre usage and driving habits to make sure that our tyres meet everyone's needs.
2- Developing and mixing materials
Over 200 ingredients go into a tyre. They play vital roles in safety, fuel efficiency, performance and eco-friendliness.
These components fall into five groups:
- Natural rubber: the main component of the tread layers
- Synthetic rubber: part of the treads of car, van and 4x4 tyres
- Carbon black and silica: used as a reinforcing agent to improve durability
- Metallic and textile reinforcement cables: the "skeleton" of the tyre, forming the geometric shape and providing rigidity.
- Numerous chemical agents: for unique properties like low rolling resistance or ultra-high grip
We create many different designs and use simulations to test and select the best tyre concepts to be developed.
We expertly build each tyre through both hand-made and machined processes. When necessary, we invent our own machines to reach our goals.
5- Quality control
Quality control is not only an end step. We measure quality throughout the process.
We do over 1 billion miles worth of tyre testing per year – the equivalent of driving around the planet 40,000 times.
How does the design of a tyre impact its performance?
A tyre’s tread design – the grooves and patterns in the rubber on the top surface of the tyre – is crucial to its performance. The tread design plays an essential role in your tyre’s grip in different types of driving conditions and can impact both your safety and your driving pleasure.
Safety – wet road grip example
To understand the role of the tyre tread on wet roads, it's useful to think of a water pump. The more channels in your tyre's tread, the better it pumps water away from between the tyre and the road. Remarkably, it can displace water in just a few milliseconds. A 195/65 R 15 tyre, for instance, can displace almost 15 litres of water per second.
Design elements that impact wet grip:
- Groove ratio: The more/larger grooves a tyre has, the better the tyre pumps out water.
- Shape and layout: The shape of the tread patterns (symmetrical, directional, asymmetrical) contributes to how quickly water is drained.
- Sipes: These are thin slits in the rubber surface of the tread. They improve traction in wet or icy conditions. Acting like windscreen wipers, sipes help the edges and grooves of a tyre to drain away water.
Driving pleasure – dry road grip example
One of the main factors contributing to precise steering control and reactivity is the stiffness of the tread design.
Design elements that impact dry grip:
- The tyre's profile (shape): A flat profile with square shoulders provides good support in turns.
- The amount of grooves: The smaller the percentage of grooves in the tread pattern, the more rubber there is in direct contact with the ground and the better the level of grip.
- Tread blocks: The larger the individual blocks of tread rubber in the design, the better the traction. But this can also generate more road noise.
- Self locking sipes: Tread blocks with many sipes will reduce the rigidity of the tread pattern. To counter this effect, we have introduced complex 3-dimensional sipes, which lock together under load.
What is the structure of a tyre?
The typical radial tyre consists of nine main parts.
- Inner liner:
A layer of airtight synthetic rubber (this is the modern equivalent of the inner tube).
- Carcass Ply:
The layer above the inner liner, consisting of thin textile fibre cords (or cables) bonded into the rubber. These cables largely determine the strength of the tyre and help it to resist pressure. Standard tyres contain about 1,400 cords, each one of which can resist a force of 15 kg.
- Lower bead area:
This is where the rubber tyre grips the metal rim. The power from the engine and braking effort is transmitted from the rim of the tyre to the contact area with the road's surface.
They clamp firmly against the tyre’s rim to ensure an airtight fit and keep the tyre properly seated on the rim. Each wire can take a load of up to 1,800 kg without risk of breaking. There are eight of them on your car – two per tyre. That’s a massive 14,400 kg of resistance strength. An average car weighs about 1,500 kg.
It protects the side of the tyre from impact with curbs and the road. Important details about the tyre are written on the sidewall, such as tyre width and speed rating.
- Casing ply:
It largely determines the strength of the tyre. It's made up of very fine, resistant steel cords bonded into the rubber. This means that the tyre can resist the strains of turning, and doesn't expand due to the rotation of the tyre. It's also flexible enough to absorb deformations caused by bumps, potholes and other obstacles in the road.
- Cap ply (or "zero degree" belt):
This important safety layer reduces friction heating and helps to maintain the shape of the tyre when driving fast. To prevent centrifugal stretching of the tyre, reinforced nylon based cords are bedded in a layer of rubber and laid around the circumference of the tyre.
- Crown Plies (or belts):
They provide the rigid base for the tread.
It provides traction and turning grip for the tyre, and is designed to resist wear, abrasion and heat.