Tyre Data Explained

[Desmond Hutchins]

Tyresare essential components of a race car, as they are the only direct link between the vehicle and the road. The viscoelastic characteristics of tyre compounds create an optimal window of operating conditions under which the driver can extract maximum performance, and race after race has demonstrated that achieving and maintaining this window is a critical differentiating factor between victory and defeat.

The teams are well-equipped to tackle this challenge and utilise various tools and methodologies to develop their understanding of tyre performance. Below we will discuss some of these tools and the considerations involved in unlocking tyre comprehension.

Tyre modelling can take several different approaches. A theoretical tyre model attempts to capture the physical behaviour of the tyre based on its construction and basic mechanical principles. Although these models capture a high level of detail, they are incredibly complex, computationally expensive, and require comprehensive knowledge of material properties. On the other hand, empirical models use collected data to construct a mathematical relationship or interpolation table. These models can achieve high accuracy without prior knowledge of the tyre design but require a large amount of data and provide no insight into fundamental tyre behaviour. Figure 1 shows a summary of these trade-offs.

Formula 1 tyres attain peak performance within a very narrow temperature band, so it is critical to understand and control heat generation. Thermo-mechanical models can capture these effects and are often combined with other models such as the Magic Formula using a grip correction factor, such as the example in Figure 4.

Collecting high-quality, relevant data is vital to achieving good model correlation, and there are various tools used on and off the track to characterise tyre behaviour. The most common indoor testing device is the flat track test, in Figure 6, which simulates the road surface using a rolling belt. A specialised machine applies a prescribed load and orientation to the spinning tyre and measures the resulting forces. This enables engineers to move efficiently through various operating conditions and create a complete characterisation of the tyre.

Teams often use a shaker rig test to evaluate the ride performance of the suspension. Here, all four tyres are on platforms that oscillate at prescribed frequencies and amplitudes. The resulting accelerations measured at the wheels and chassis can provide detailed information about the ride and handling performance for a given suspension configuration. Placing pressure-sensitive mats on these platforms allows engineers to measure the pressure distribution across the tyre in real-time, helping ensure full utilisation of the contact patch.

While lab testing allows engineers to control operating conditions and test plans, there is no substitute for on-track data to capture the real-world performance of the tyres. All Formula 1 cars are fitted with a wide range of sensors to measure the temperature distribution, pressure, humidity, and acceleration at each corner.

In conclusion, tyres are incredibly complex pieces of engineering, and the behind the scenes work to model and understand them is a time and resource-intensive process. The performance sensitivity of the Pirelli Formula 1 tyres makes this an important challenge for Formula 1 teams to achieve success in the sport. The 2022 season will be an exciting opportunity to shake up the competitive order, as we see which teams will be the fastest at getting on top of an all-new generation of the tyre!

Understanding tyre data can seem confusing at the best of times but, at Protyre, we are here to help! The code found on the sidewall of a tyre gives quite a lot of information, including the diameter, height, width of the wheel, and the load index rating. The single letter at the end of the code represents the tyres speed rating. For example, if the code is 205/55R/16/91V then it is the V that is the speed rating.

I find the internal tyre temp you get from mot motorsport TPMS systems useful for understanding the relative energy distribution between each of the tyres at each track and also for helping me get the hot pressures right - we're essentially estimating the internal air temp with the measurement. It's estimating because it tends to be quite influenced by rim temp.

External IR is helpful for understanding how the energy is being distributed over the surface of the tyre. We can use this to help tune tyre pressure and wheel alignment. Some downsides are that they can be challenging to fit while working properly. Especially on the front wheels with them being turned during cornering, if we want to keep them looking at the same parts of the tread, the sensors really need to be mounted to some part of the hub. This is a pain and often means you only test with them rather than having them on the car for races.

Internal IR is reading the carcass temp. In my opinion, this is probably the most useful for tuning the car and understanding how the tyre is working. It is giving similar info to the external tyre temp by instead we are understanding how the construction of the tyre is being loaded which I think is more useful than knowing how hot the tread is. It also helps that it's built into the sensor so nothing to mount externally.

I can see a value in both (probably why FI uses internal and external sensors) in that the internal sensors give data of how the tyre carcass is heating. This allows the driver/engineer to check that there is not too much heat being put into a particular region of the carcass as this can lead to blistering of the tread and/or tyre failure. The external temperature sensors will tell you how the tyre is working in transient conditions.

In one of the videos that Caleb from IZZE Racing has posted, you can see the effect on the tyre surface temperature that the exhaust pipe location (just in front of the LH rear wheel) has, with the surface temp increasing whilst going along the straight. This could lead to a handling imbalance at the next corner as one tyre has a higher tread temperature than the other.

I would still count internal IR as a transient measurement, it's true that it may not react quite as quickly as external IR. However, in my experience, the internal temperature spread of the carcass correlates more closely with setup and performance than external IR.

Hi James, Tim has actually moved on and doesn't work for HPA any more. That being said I have now spent quite a lot of time with the internal and external data. I find the external data to be more useful to validate setup changes as you get a much faster response from the sensor during cornering. Obviously there's a latency in terms of the heat transfer from the tread contact patch (what we're really trying to optimise) and the temperature in the carcass.

There are two places to find your tyre size. The inside of your door shows the installed size The sidewall of the tyre is used to replace the size that is currently on your vehicle.

Installing the right tyres on your vehicle is important to the overall performance and safety of your vehicle. Your tyre choice should reflect the conditions in which you drive and your preferences for vehicle response and handling. You should understand what tyre size is right for your vehicle to be able to make the right choice when it's time to buy tyres.

While actual, physical measurements like width and diameter are factors in finding the right tyre size, there are additional details you should consider. Things like load index and speed rating are also integral to finding the correct tyres.

Assuming your current tyres are the originally fitted, you can find tyre size data on the sidewall of your tyres. However, no matter where you find your tyre size, you will have to decipher a sequence of numbers and letters.

The final figure in a tyre size sequence is the speed rating, which is indicated by a letter: 225/70/R16 91S. Just as your load index number corresponds to a particular load, your speed rating letter corresponds to a particular speed capability based on a standardised laboratory test.

The percentage value indicates how much of the tyre performance capability has been used thus far in a stint. This value is not to be confused with tyre wear which instead refers to the amount of actual rubber removed from the tyre during the usage period. Lower values indicate a proportional loss in tyre performance via tyre degradation.

The graphic will also provide an insight into key race moments as well as a longer term view on tyre management. This includes the relative tyre performance difference between two cars locked in a battle and the implication of one car having to stop sooner than another, thus effecting race strategy outcome.

An emerging picture over the season of which cars are lighter on tyres than others, will allow the fans to become more immersed in not only the general conversation but also how particular battles could play out.

There is a variety of public data from a number of different sources that the Formula 1 team gathers in order to build the graphic and deliver the insights to fans in an engaging and digestible format.

This includes live race timing data (including lap, sector and mini-sector times for each driver), live telemetry data from all cars, tyre compound, stint length and total laps completed on each set, track status and marshalling information, weather information.

This new stat is delivered direct to broadcasters, via the Formula 1 International Feed, enabling commentators to give viewers added analysis into one of the key performance indicators throughout the race..

Automotive tires are described by an alphanumeric tire code (in North American English) or tyre code (in Commonwealth English), which is generally molded into the sidewall of the tire. This code specifies the dimensions of the tire, and some of its key limitations, such as load-bearing ability, and maximum speed. Sometimes the inner sidewall contains information not included on the outer sidewall, and vice versa.

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