A tyre puncture is a natural part of any rally. Even this seemingly routine situation, however, can cause serious damage to the car, meaning it retires from the rally or incurs insurmountable time loss. What does ŠKODA Motorsport do in case of puncture, how do the crews decide whether to change the tyre or not, and what equipment do they have on hand?
The crew is in perfect symbiosis with their car, and experienced drivers and co-drivers can tell immediately when there’s a puncture from the changes in the car’s behaviour. At this point, they need to decide whether it’s necessary to change the tyre or just slow down and try to finish the stage. The engineers have calculated that if you have less than seven or eight kilometres to the finish, the tyre change usually won’t pay off – the time loss caused by stopping for at least a minute would, in the end, be bigger. It can also make a big difference whether it’s a “slow puncture”, where the tyre loses air pressure gradually, or a fast one, where the tyre is flat basically in an instant.
It also depends on the character of the rally and the track surface. On tarmac, the car is still able to drive reasonably fast but in demanding gravel rallies, like Turkey or Portugal, the effect of a flat tyre on the speed is much greater. In these cases, the crew may decide to change the tyre only five kilometres before the finish. It’s also important to take into account the possibility of the tyre shattering, because the debris could damage the car significantly.
“Extra hard, metal-reinforced gravel tyres can damage or destroy the fender, wheel well, bumper or even the headlight. This can cause significant complications for the mechanics in the service area. Once, a puncture cost us the whole rear door. Parts of the tyre can also get into the interior and even damage the rollcage, which would disqualify the car from the rally,” Miroslav Šlambora, the coordinator of rallycar and service area builds for ŠKODA Motorsport, explained.
If the crew decide to change the tyre, they first need to find a safe place to stop. Even though the cars start with two-minute gaps, which should give the crew enough time, unexpected complications can still occur. Usually, the wrench is mounted on the rear door behind the driver, while the jack is behind the co-driver. While the driver is loosening the nuts, the co-driver jacks the car up and then he hands the spare tyre to the driver. The driver then tightens the nuts again, while the co-driver is fastening the damaged wheels into the trunk.
They can only set off again after their safety belts are fastened. In the past, the crews often jumped into the car and fastened their belts on the go. However, the driver may well have lost his focus because of the puncture, which increases the risk of an accident; without safety belts, the consequences could be much more serious. There are plenty of cameras to observe whether or not these rules are followed, and even seemingly minor infractions, like not plugging the connector into the helmet before setting off, can result in penalisation.
Still, the whole puncture can be dealt with in under a minute. “Each crew has their own well-rehearsed procedure. Our crews practice their tyre change before every rally. In training, they are able to change the tyre in around a minute and ten seconds, but during a rally, it’s more difficult because of stress and demanding conditions. Anything under a minute and a half is good and means that the crew will not cause problems for the car behind them,” Šlambora told us.
As in every aspect of rallying, seconds matter, so ŠKODA engineers are trying to make the whole process as effective as possible. During the development of the modernized ŠKODA FABIA Rally2 evo, they experimented with moving the wrench from the spare wheel well to the side door behind the driver, where it’s on hand more easily. “We realised that a puncture could cause damage to the rear door and if this happened, then the crew would be left without a wrench. It’s always necessary to take everything into account,” Šlambora explains.
The right equipment
The standard equipment in a rally car is one spare wheel, but the rules allow for carrying two, which teams do in the more difficult rallies where the risk of a puncture is higher. Taking two spare wheels is not a decision to be taken lightly, as every kilogram makes a difference. The tarmac spare wheel for the FABIA Rally2 weighs about 19 kg and the gravel one is even heavier at 23 kg. In a road car, that’s not much; in motorsport, it makes a huge difference.
“We have calculated that in one 70-kilometre leg, this much weight can mean the loss of up to seven seconds. On the other hand, it’s always better to lose time than not to finish the race. We also have to take the additional spare wheel into account when setting up the car – we raise the rear shocks by two millimetres to compensate for the extra weight and retain the correct balance,” Šlambora explains.
Every team chooses their tyre-changing tools according to their preferences. For example, ŠKODA Motorsport has developed its own jack, which is supplied not only to factory crews, but also to customer teams. Its main advantage is that, besides weighing very little, it has a double-acting piston, which raises the car both when you move the lever up and when you move it down, saving valuable seconds.
Finishing is not enough
The crews also have to keep in mind that it’s not enough to finish the stage. They need to drive all the way to the service area – often tens of kilometres away. In the past, the spectators could often see cars driving on the wheel rim or with the wheel broken off, but the current rules dictate that all four wheels have to be intact and able to turn. This means that the tyres cannot be destroyed, although they can be flat because the racing tyres have stiff enough sidewalls to keep the car controllable.
An example of this kind of situation is the heroic struggle of Kalle Rovanperä and Jonne Halttunen in last year’s Rally Turkey, when the Finnish ŠKODA Motorsport crew had to use both spares and then had another puncture. That forced them to drive almost two whole stages as well as the transport stage on the flat tyre. They kept switching the wheels around to keep at least some rubber to get to the team’s mechanics.
Working with tyres is one of the key strategic aspects of rallying: from choosing the right compound, to choosing between higher speed or lower risk of a puncture, to both teams and crews being ready for a tyre change. Nothing is ever certain in rally, but it’s always true that luck is on the side of those who have prepared properly.