Feature F1 Unlocked
EXPLAINED: What does the maximum tyre stint length rule mean for the Qatar Grand Prix?
Concerns over tyre interactions with the kerbs in Qatar have left the teams with a small window to work out their ideal race plans after Pirelli and the FIA implemented safety measures for today’s race. Here’s what that will mean for the teams and drivers, and what strategic options are open to them for the Grand Prix…
What are the rules for the race?
Teams will only be able to use a new set of tyres for a maximum of 18 laps, with used tyres having individual limits to the stint lengths defined by Pirelli and the FIA based on the way they have been used before. For example, a tyre used in qualifying is likely to only count fast laps towards the limit, with slow out-laps and in-laps not part of the 18 that are permitted.
The limit is the same across all three tyre compounds, so teams still need to use at least two different compounds during the race, and any car deemed to have exceeded the tyre life lap limit will be reported to the stewards as being run in an unsafe condition.
What does this mean for strategies?
In basic terms, if the race runs to its full distance then the first two pit stop windows are relatively wide but the first stop can be taken no later than the end of Lap 18 and the final stop can be taken no earlier than the end of Lap 39.
The earliest a pit stop can be taken is at the end of Lap 3 but that would lock teams into a specific strategy with exact stop laps from then onwards, so is very unlikely to be used. Similarly, the soft tyre showed in the Sprint it is not suited as a race tyre due to graining on the low grip surface, so teams are likely to prefer the medium and hard compounds.
Most drivers have only one set of new hard tyres, with Williams, Haas, AlphaTauri and Alfa Romeo the only pairings with two sets of hards available.
That means the majority are likely to do one stint on hards and three on mediums, although for someone such as Lewis Hamilton that comes with bigger restrictions as he only has 10 and 13 laps respectively available on two of his medium tyre sets (see the chart below), limiting when he can make his pit stops even further.
It makes for a complex set of potential combinations that teams are still working out, not only for their own strategies but also for what is available to their rivals.
How did we get here?
In Pirelli’s usual analysis of tyres after Friday practice, a separation in the sidewall between the topping compound and the carcass cords was discovered on many sets of tyres that had completed around 20 laps.
The very early signs of damage were not visible to the naked eye but were consistent with repeated high-speed impacts with aggressive kerbs.
The FIA said: “This issue has likely been caused by the high-frequency interference between the tyre sidewall and the 50mm ‘pyramid’ kerbs used extensively at this circuit, aggravated by the propensity to ride those kerbs.”
Those kerbs are used at many venues on the calendar, but cars are not running on them for the same length of time or at such high speeds, with the combination of factors believed to be causing the issue. The same kerb design was installed as the second row of kerbing in Qatar two years ago but have since been revised in many places to be the initial exit kerb and therefore used far more heavily.
Track limits changes were made on Saturday to try and reduce how heavily the kerbs are used, with the outside of the track brought in by 80cm at Turn 12 and Turn 13, preventing the highest parts being used regularly. However, the number of Safety Car interruptions in the Sprint limited the amount of data that was able to be gathered from the 19-lap race.
Pirelli still noted the initial onset of the separation on some tyres used in the Sprint, so after discussions between the tyre supplier, the FIA and the teams, the mandatory stint length has been introduced for the Grand Prix.
Why aren’t three stops mandatory?
If the race runs to its full distance and without interruptions, then the rules mean a three-stop race will be an automatic consequence. However, if there are unforeseen incidents such as an aborted start, in-race restarts or reduced laps then it could be possible for teams to reach the end on two stops.
As such, the FIA has opted against imposing a direct mandate for three stops as this would then potentially have led to teams able to get to the end without exceeding the maximum laps on each set of tyres but being forced to do an extra stop regardless.
Wait, but what’s the weather doing?
If you’ve been following any of the Qatar Grand Prix weekend so far you will know it has been extremely hot throughout, with air temperatures regularly climbing above 40C in Lusail.
But those temperatures have thankfully had little impact on competitive sessions, with FP1 taking place as the sun started to drop and then qualifying under the lights.
Saturday’s Sprint was also after dark, and that’s going to be the case again for the Grand Prix itself with the 8pm local time race start ensuring temperatures have dropped by as much as 10C towards the 30-32C range.
There’s an even bigger drop-off in terms of track temperatures though, with the 55C levels of daytime reducing by over 20C once the sun goes down, making it a little easier to avoid overheating.
But it’s still a challenge, and there’s the added variable of the wind. Extremely gusty conditions caused real headaches and handling issues on Friday – with lots of drivers suffering unpredictable snaps and running off track – but then the wind calmed significantly by the Sprint and that led to the likes of Williams being much more competitive in those conditions.
The race should see relatively similar temperatures and wind speeds to Saturday night, giving the teams that little bit of added confidence in the data they gathered during race conditions in the Sprint.