F1 tyres: What are the compounds and what do they mean?
Tyres are the only parts of a Formula 1 car that touch the ground, but what are the different compounds and what do they do? Find out here.
For as long as cars have raced each other for grand prix wins, tyres have played a crucial role in securing victory. As the only contact points between the vehicle and the road, through which every piece of engineering wizardry must ultimately be channeled, that’s logical enough.
And although the technology has progressed in line with everything else in Formula 1, the fundamental challenge around tyres has remained virtually unchanged since the very first world championship event in 1950. How do you get the most grip (and thus corner speed) from your rubber – without wearing it out too fast or too soon?
What are the tyre compounds used in Formula 1?
Tyre compounds refer to how hard or soft the rubber is on a particular type of tyre – and they introduce a critical variable to the Formula 1 tyre equation.
On any given weekend, drivers can choose from soft, medium and hard compounds for dry weather conditions. These ‘slicks’ are marked red, yellow and white respectively. There’s also a full wet compound (marked blue) for racing in serious rain, along with an intermediate (marked green) for a damp, in-between track surface.
All of these are supplied by Italian manufacturer Pirelli. While there have been periods of ‘tyre war’ competition in the past, and no less than nine manufacturers have shod cars in world championship races, Pirelli has taken exclusive care of F1’s rubber needs since 2011.
Pirelli tyres in blankets
Photo by: Steven Tee / Motorsport Images
What’s the difference between a soft, medium and hard tyre?
As we mentioned up top, the essential challenge with tyres is to get as much road-holding performance (grip) as possible – and maintain it for a reasonable length of time. If tyres provide excellent handling but wear out after a lap or two, that’s not going to be much good for winning races. Because once tyres are worn, handling deteriorates and the danger of a blowout increases. Which in turn means pitstops become necessary sooner rather than later. And you don’t want to lose time making too many of those, no matter how fast your car is when the tyres are fresh.
So, tyres are always a compromise between performance and endurance. In Formula 1, the different tyre compounds mean teams have the choice of which way they want to shift this compromise. In theory – which doesn’t always match practice! – a softer tyre is faster but wears out sooner. A harder compound lasts longer, but doesn’t provide the best performance.
· Soft tyres – These represent the fastest rubber, but are likely to wear out before the harder compounds do.
· Medium tyres – This is the compromise compound. It’s usually slower than the softs but faster than hards. And it should last longer than the softs, but not as long as hards!
· Hard tyres – These provide the least grip, but are supposed to remain in working order the longest.
Pirelli tyres, from left to right: soft (red), medium (yellow), hard (white), intermediate (green), wet (blue)
Photo by: Erik Junius
How many tyres can a driver use over an F1 weekend?
The tyre plot thickens when you consider that resources are limited by the rules. For a start, each driver can use a maximum of 13 sets of dry-weather tyres for the full three-day weekend. The allocation of slicks is broken down by compound, so each driver gets two hard sets, three medium sets and eight soft sets.
Even before you consider additional wet-weather tyre allocations and the slightly different numbers governing weekends with the sprint format, there are further twists. Drivers must return two sets following each of the three practice sessions, leaving only seven for qualifying and the race. And they have to keep at least one set of soft tyres for possible participation in the Q3 session. Those who make it that far have to return this set after qualifying, whilst those who don’t get to keep theirs for the race.
If that’s not enough to consider when planning the weekend, drivers are also required to use at least two different slick compounds during a fully dry race. That means at least one pitstop will be necessary on raceday. Drivers are also free to change tyres more than once if they feel it makes sense strategically – and have saved enough sets during practice and qualifying.
To cover wet weather, each driver can also draw from an allocation of four sets of intermediates and three sets of wets.
Finally, sprint race weekends see the number of dry sets for the weekend reduced to 12. Drivers are also obliged to use the soft tyres throughout qualifying. After the sprint race, drivers must return the set with which they completed the most laps in this short race.
Alpine F1 mechanics with tyres
Photo by: Carl Bingham / Motorsport Images
Can drivers share tyres?
The tyre allocations mentioned above are strictly on a per-driver basis. If one of a team’s drivers drops out of the race – or even has to pull out of the race weekend at an earlier stage – that doesn’t mean his team-mate can help himself to an extra few sets of tyres. Tyres are strictly marked according to their allocation, so policing this is straightforward.
This rule offers no sympathy for mix-ups either. George Russell was mistakenly given Valtteri Bottas’s tyres when the Mercedes drivers pitted one after the other at the 2020 Bahrain Grand Prix – and the team picked up a €20,000 fine.
Can drivers use different compounds at the same time?
Fans of other categories or forms of motorsport are used to seeing competitors hit the track with a mix of different tyre compounds on their vehicles. In MotoGP, for example, it’s not unusual for a rider run a soft front and a hard rear, for example. Formula 1 doesn’t allow for this. You have to run the same compound on all four wheels at all times.
What does scrubbed, blistering and graining mean for F1 tyres?
Formula 1 has a jargon all of its own. And plenty of that has to do with tyres. Here’s a brief glossary covering some of the terms you’ll hear when watching F1.
· Scrubbed: Sometimes using a brand-new tyre is tricky as it heats up for the first time in its life. When this is the case, teams often ‘scrub in’ a set of tyres by running them for a couple of laps in practice. That means they’re ready to hit the ground running on raceday.
· Slicks: Completely smooth tyres with no grooves. Designed for dry-weather use.
· Compound: How hard or soft the rubber on a particular tyre is. Harder tyres last longer, but softer tyres grip the road better.
· Blistering: When the inner part of the tyre overheats in relation to the outer part, creating a minor explosion from the inside and damaging the surface.
· Graining: When the outer surface is hotter than the inside of the tyre, it leads to the outside rubber flexing, breaking off and sticking on top of the tyre surface.
· Flat spot: As the name suggests, this is a patch where the surface of the tyre loses its curvature. Typically happens when a driver ‘locks up’ by braking too late for a corner, causing the wheel to momentarily stop turning and the tyre to scrape along the ground.
· Deg: Short for ‘degradation’, this refers to a steady loss of tyre performance due to wear.
McLaren Google Chrome tyre detail
Photo by: Erik Junius
How do teams decide on a tyre strategy?
While the rules governing tyre strategy are framed in terms of drivers, the tyre plan for the weekend is a team decision. Teams usually use the first practice day to try different compounds and get a feel for the best tyre strategy for the race.
This decision is generally a mix between information provided by Pirelli, degradation observed over a ‘long run’ simulating a large chunk of the race, the nature of the circuit and the weather forecast for Sunday. If rain is expected later in the weekend, there’s less of a squeeze on dry tyre resources because drivers can then draw from their wet-weather allocation and keep their dry allocations intact.
Conversely, if hot weather (which usually translates to higher tyre wear) is on the cards for the race, teams will have to make sure they have enough rubber to cover plenty of tyre changes.
The track layout’s role in tyre strategy plays out on a couple of levels. If overtaking is tough and getting stuck behind another car is highly likely in a race, a team may err on the side of more pitstops because that’s a handy way to get their driver running on a ‘clear’ track rather than losing time behind a slower rival.
Also, if it’s a track where the walls are close and a safety car is thus more likely in the event of an incident, teams may plan for more stops because changing tyres costs relatively little time when your competitors are required to drive around the track slowly.
Once the target resources for Sunday have been worked out, teams can then plan their tyre use for the rest of practice and qualifying accordingly. In an ideal world, they would all throw soft tyres on their car for all three parts of qualifying, since nailing a lap time is mostly about performance rather than endurance.
But the rules call for compromises whose consequences – in terms of available tyres – might only become apparent at the back end of the race the following day.
Red bull Racing pitwall
Photo by: Erik Junius
What do the C1 – C5 scorings mean?
As we’ve already seen, each weekend sees Pirelli bring soft, medium and hard compounds to the track for dry-weather use.
However, the range of those tyres can be tailored to the circuit’s characteristics. That’s why the tyre supplier actually manufactures five dry compounds for the season.
They’re coded C1 (the hardest) to C5 (the softest). It can then nominate three of those compounds for each particular Grand Prix weekend.
For example, Pirelli may decide a harder range of tyres are called for due to an abrasive track and/or high temperatures. This is a safety and marketing decision as much as anything, because blowouts are dangerous and tyre failures resulting from excessive wear don’t make for good publicity. In this example, it would probably bring the C1, C2 and C3 tyres.
In this way, compounds in the middle of the scale can actually get a different marking on different weekends. Where C3 would be the soft, red-marked tyre in the example above, it could equally be
the hard, white-marked tyre on a weekend when Pirelli decides to bring the softest possible range, C3-C5.
The wet-weather tyres don’t vary in terms of their softness or hardness, and simply carry the designated colours outlined above.
Why do some tyres have grooves and others don’t?
The primary role of grooves on a tyre is to disperse water from a wet road surface. That’s the reason everyday consumer cars all have grooved tyres: they need to work safely in all conditions!
But grooves actually also compromise dry-weather handling to a degree, because having them reduces the amount of rubber touching the road. This isn’t critical in a road car, but in the close and competitive world of Formula 1, a completely ‘slick’ tyre is desirable for getting around corners as fast as possible in dry weather. For race fans, a slick tyre is synonymous with ultimate performance.
Formula 1 cars ran grooved tyres in the early decades of the world championship, but slicks began to appear in the early 1970s. These caught on fast.
However, teams were once again compelled to run grooves from 1998 until the end of 2008. This measure was introduced in an attempt to slow the cars down – but few look back on that era’s tyres with fondness.
Lewis Hamilton, McLaren MP4-23 Mercedes, leads Kimi Raikkonen, Ferrari F2008
Photo by: Glenn Dunbar / Motorsport Images
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