If you watch Formula 1 on a regular basis you may have noticed the race engineers asking some drivers to “pick up rubber” after the race has finished. This is common practice in Formula 1, but new and existing fans alike may still be confused as to why F1 drivers pick up rubber.
F1 drivers pick up rubber after a race to ensure their car meets the minimum weight limits. This limit ensures that all cars are the same minimum weight as lighter cars are faster than heavier ones. Picking up rubber adds to the weight of the car to ensure the car will be above the minimum limit.
However, drivers will avoid picking up rubber during a race as this can cause a severe loss in grip. The rubber left on the track is therefore both a good thing and a bad thing, and we discuss why this is the case in more detail below.
What Are Marbles In F1?
Marbles are small pieces of rubber that come off the F1 cars’ tires during the course of a race. You’ll often see them gather on the side of the circuit as they’re thrown off the tires. This becomes clearer towards the end of the race when there’s a particularly “dirty” side of the racetrack.
Drivers try to avoid marbles as much as possible during the race. Running over marbles can cause the tires to lose a lot of grip. This is because the marbles stick to the tires and make the surface of the tires uneven. For maximum grip, slick tires have a large contact patch with the road, and marbles disturb this contact patch.
The uneven surface on the tires, especially with slick tires, can cause a lot of vibrations as well, which may result in lockups and a loss of grip. It takes time for the tires to “clean up” after a car has run over the dirty side of the track.
Why Do The Tires Produce Marbles?
Formula 1 tires are extremely soft and have been designed to give the car as much grip as possible. This means that the tires also heat up a lot, especially under hard racing conditions. As the tires begin to wear out, the marbles are the small pieces of rubber that are ejected off the tires.
As the tires begin to wear out, they lose layers of rubber. These pieces of rubber are often so hot that they are extremely soft and malleable when they hit the track, much like a piece of play dough would be.
However, over time they begin to harden as they cool down. The harder marbles that have already been cooled have the worst effect on the drivers’ tires when they run over them. These marbles can be rock hard, and some of them are fairly large too.
Why Do Pirelli Tires Produce More Marbles Than Before?
Pirelli tires are still relatively new to Formula 1, being reintroduced into the sport in 2011. Previously we had seen Bridgestone being the sole tire supplier to F1 after the intense tire wars in the md 2000s between Michelin and Bridgestone.
During the grooved tire era where we saw Michelin and Bridgestone tires, we almost never saw graining or marbles being formed. This is because the tires were designed to withstand much more heat and last much longer.
Slick tires on the other hand have more surface area, therefore providing more grip and reaching higher temperatures. On top of that, the tires were also made significantly softer to make them sticker and grippier for the cars. This led to more marbles being produced than from previous tires.
Why Are F1 Drivers Asked To Pick Up Rubber?
At the end of the race drivers are often asked to pick up rubber by their engineers. The drivers will proceed to drive on the dirty side of the track over all the marbles at low speed, getting as many of them to stick to the hot tires as possible.
This might seem strange, considering the fact that driving over the marbles is bad for the tires. However, there’s a very good reason for this. Formula 1 drivers will try to collect as many marbles as possible during their cooldown lap in order to add weight to the car.
As the tires shed a lot of their weight over the course of a race, a good way to quickly add weight to the car is to try to regain some of that lost weight. Every couple of kilograms could make a big difference in the end in terms of staying above the minimum weight limits as per the FIA rules for Formula 1.
Why Is There A Minimum Weight Limit In F1?
Minimum weight limits are not just used in Formula 1, but also in other forms of motorsport as well. It’s not uncommon to see this rule being applied, and it’s merely to keep more of an even playing field for all cars.
Cars that are lighter, with all other variables kept the same, will be faster than heavier cars. Sometimes it’s not easy to make your car lighter, especially when you take into account all the components needed to build the car, and the variances in driver weights.
Having the minimum weight limit implemented ensures that all cars stick to the same weights, regardless of how heavy the driver is. If a driver is very light for example, they may have to drive with additional ballast to keep it above the minimum limit. This ensures that the sport is fair, and no car will have an advantage due to using lighter parts or having the lightest driver on the grid.
Sticking To Weight Limits
If your car is under the minimum weight limit, it’s an instant disqualification, which means all of your hard work for the weekend comes undone. It’s a strict rule, and being so much as a gram under the weight limit will result in disqualification.
Teams try to get their cars as light as possible for the race, providing them with just enough fuel to make it to the end, and ensuring that the car will be as light as possible to make it go faster. This can be difficult to judge, especially when there are safety cars or many restarts.
Ideally the car would be right on the minimum weight limit during the final few laps to ensure that the driver can extract maximum performance from the car. They can’t weigh the car while they’re racing to understand if they’re over or under the limit, so it’s better to be safe than sorry and pick up rubber anyway.
This means that picking up rubber at the end of the race is an absolute essential for most drivers if they want to avoid the risk of disqualification. But with all this talk of hot rubber, it’s worth considering whether or not the surface of an F1 track is sticky itself.
Are F1 Tracks Sticky Like A Drag Racing Track?
Formula 1 tracks are sticky, but not to the extent that a drag strip is. Drag racing tracks are treated with a special chemical before the event that makes it extra sticky. This is because the cars only race for a ¼ mile and need all the help they can get to put their massive amounts of power down.
Formula 1 circuits are not treated with chemicals to make them stickier, however the track does become grippier as the weekend goes on. The rubber from the tires gets laid on the circuit which makes the surface of the tarmac stickier. This rubber is engrained into the track surface, making it grippier, and is not like the chunks of marbles discussed earlier.
This is why we often see the racetrack becoming grippier throughout the weekend. On a Friday, when there has been no track action, the circuit is referred to as ‘green.’ This means that it has very little rubber on it, and therefore very little grip.
However, as Formula 1 cars (and the support race cars) go around the track, more rubber is laid down on it. This gives the track more grip, and we tend to see the lap times become considerably faster as well. However, some rain can wash all the extra rubber off the track, resetting it back to a green circuit.
The Effect Of Marbles On A Racetrack
Marbles will often come off the tires of cars and will be thrown out to the sides of the circuit. It’s rare to see marbles on the racing line because cars are constantly driving on the same racing line which keeps this section of the track clean. They do this by displacing the marbles either by driving over them and moving them, or moving them with the air coming off the car.
In this way, one or two marbles aren’t an issue, as the driver usually throws them off their tires to the sides of the racing line, just as a result of the air flows around the car and tires. It’s only when lots of marbles are able to collect in areas of the track that they become an issue at high speed.
Because marbles are thrown to either side of the racing line, it can make it a challenge for drivers to overtake or defend late into the race. If a driver has to go off the racing line in order to overtake or defend, they will pick up a lot of marbles. This is not an issue in terms of weight, as that only comes at the end of the race when the cars are going much slower.
Although the weight of these marbles is not an issue, the problem comes with the handling of the car. Once the car has picked up marbles it can begin to vibrate, and the driver can lose grip. The vibrations could even cause lock ups, which means that the driver who went off the racing line will be at a disadvantage for a small amount of time until their tires are cleaned off.
Final Thoughts
F1 drivers pick up rubber at the end of a race in order to ensure their car adheres to the minimum weight limit. Over the course of a race, F1 cars lose weight by burning fuel, through the driver sweating, and through tire wear, and picking up marbles adds some of this weight back on.
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