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In 2022 the FIA applied a major overhaul to the regulations that define F1, and the cars adopted 18-inch wheels with a lower profile Pirelli tyre. The 305mm front and 405 wide rear tyres are matched to the track surface, and circuit type through a range of compounds and are run at pressures prescribed by Pirelli. 

Consider this, F1 involves a driver in a $3.0m car (chassis, aero, technology and safety system) powered by a $10.0m power unit, producing 1000 hp and setting speeds over 330 kph, while cornering at 310 kph and up to 5.0 g’s. 100% dependent on a small contact patch from four $700.00 tyres (a set costs $2,700.00).

Assembly

The wheel assembly is a critical part of the car set-up, holding in the track and enabling it to corner at astonishing speeds. The wheels must withstand immense forces of acceleration, braking and cornering. Fixed to the car with wishbone suspension they are adjusted through push-rod or pull-rod systems and dampers. Ride height, rake, toe, camber and castor can all be adjusted to fine-tune the car and gain those critical fractions of a second.

Safety

Safety is as important here as any other aspect of the sport. A wheel ripped from the car in a 300 kph impact is a potentially devastating missile threatening the lives of other drivers, marshals and spectators. To combat this, the cars have two tethers within the wishbones, significantly reducing the chances of a wheel flying off. 

Brakes

F1 cars use carbon fibre brakes on all four wheels that don’t begin to work effectively until they reach 400 degrees C and are optimal around 1000 degrees C. To keep weight at a minimum, there is no mechanical cooling so F1 cars must move forward to push air through the brake ducts. When stopped, you will see cooling fans placed on each hub and in very hot climates, dry ice is added.
The brakes on an F1 machine will slow the car rapidly from 315 kph to 80 kph with the braking point less than 50 meters from where the driver initiates the corner. Experienced drivers from F2 or Indycar are often surprised by how late they can brake at such high speeds. But, get this wrong, and the car could understeer, lock up or crash, costing valuable time.

Contact Patch

Contact patch size is incredibly important in F1. The size of a contact patch is the area of the tire physically contacting the track. The larger the contact patch, the more grip the car will have, which is affected by the tyre pressure. As tread decreases the size of contact patches, a slick tyre is the most effective. 
 
Slicks are completely ineffective when there is water present, so tread is used in the form of Intermediates (i and Full Wets. These tyres will move 30 and 60 litres of water per second respectively so a set of four will shift a whopping 120 and 240 litres respectively. The team’s race engineer needs to judge when to make the change from one tread style to another very carefully as an extra pitstop is costly.

Compounds

The compound is a reference to the rubber that the tyre’s wearing surface is constructed from. Pirelli has developed a suite of compounds from C1 (hardest) to C5 (softest), from which they select three for each race weekend. Referred to as Hard, Medium and Soft, the tyres have different performance characteristics. The soft will be the fastest, but it will not last as long, whereas, the hard will have longevity but a second a lap slower. 
The selection is based on factors such as track surface, track temperature, speeds, corners and number of pitstops targeted
The compounds are designed to degrade at different rates, and the shredded rubber can be seen accumulating off the racing line.

Tyre Allocation

Teams are provided with an allocation of 13 sets of dry weather tyres for the weekend – two set of hard tyres, three sets of medium tyres and eight sets of soft tyres. They also receive three sets of intermediate tyres and four sets of wets. If FP1 and FP2 are wet and FP3 looks like it will be wet, then the teams may return a set of slicks and take an extra set of interest.

Pitstop

F1 regulations state that each car must use two different tyre compounds during a race, enforcing a mandatory pitstop. Teams will assess the tyre combinations to calculate the optimum combination to get to the finish line in the shortest time.
The new tyres are preheated to help ‘switch them on’ as quickly as possible. This means getting them up to their optimum temperature, and as sticky as possible, to maximise grip.

In a pitstop, all four tyres are replaced in a little over 2 seconds but the total time lost is around 20 seconds due to the reduced speed in the pit lane (generally 80kph).

In the Window

Looking after the tyres is a critical part of a driver’s racecraft. If the tyre is not hot enough, there is a lack of grip, and if they are overhead, they will deteriorate too quickly.
The cars have sensors that measure the tyre’s temperature in several locations. Under current regulations, tyres are preheated using tyre warmers, and then the driver will drive in a certain manner to induce additional heat. It is easier to heat the rear wheels, using power from the PU, than it is to heat the fronts, as they can’t be spun up. 
When the tyres are at their best, they are considered to be “in the window”. 

Tyre Management

Each tyre compound will have a predetermined level of performance unique to the track surface and temperature and teams will match this to a “pit stop strategy”. Pundits will talk about the “pit window”, which is the optimum lap range before a pit stop is required and new tyres are fitted.
A driver will greatly improve his strategic options if he can manage his tyres and extend their effective life. Running longer on one set may be the difference between a one-stop, two-stop strategy or even three-stop strategy, with each pit stop costing roughly 20 seconds.
As the tyre age builds, you will hear drivers tell their engineers that the grip is dropping off and the car is starting to slide. Pundits will note the tyre is blistering or graining, contributing to its decline in performance.
The call to come in for fresh tyres is Box or Box, Box.
Pit stop strategy is complex and needs to be flexible to changing conditions throughout the race. Faster tyres over shorter distances or an undercut may be the ‘secret sauce’ to get the car to the finish line first…

Logistics

Pirelli is the exclusive supplier to F1. 20 teams, each with 21 sets per weekend and 23 races equates to 9,660 sets or 38,640 tyres for the races plus spares. They also need to supply tyres for testing and media days
As part of Pirelli’s ‘green technology’ programme for the betterment of the environment, the tyres are ‘ecologically disposed’, which means they are recycled. The tyres are crushed to fit more of them in fewer containers and then shipped to a cement factory near Didcot, Oxfordshire after each Grand Prix.
There, the tyres are finely shredded, along with other road car tires. The shredded tyres form small pellets, which are then burnt at extremely high temperatures as a fuel-source for cement factories. Moreover, the extremely high temperatures mean that no harmful fumes are released during the process, and the only particle that remains is non-poisonous ash.
 
Andrew Burden

The author Kiwi F1 Fan

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