In previous seasons, Pirelli has received some criticism as to the performance of their tires. What changes have they made to try addressing the issues they have faced?
Most of the criticism revolved around the lack of durability and large amount of “clag” or rubber “marbles” that would accumulate on track due to tire wear. Pirelli have decided to make some changes for the 2014 season. “The 2014 tyres are more consistent and wear less than their predecessors, without compromising performance.” (Paul Hembery, Pirelli Motorsports Director) But what exactly have they changed?
In the most basic sense, F1 tires are made up of a carcass of Kevlar coated in various compounds of rubber. The various compounds give the handling and wear characteristics to each class of tire; super-soft, soft, medium, hard, winter, intermediate, and full wet. Each of these compounds will wear out at a different rate and will provide different levels of grip. Once a tire has worn, it reaches its “cliff”; the performance of the tire will reduce significantly.
Pirelli has approached the problem of clag from two different angles. The first is that the wear particles will be smaller. Instead of the large marble sized balls, the debris will be more like a dust. It will not be nearly as fine as a household dust. However, the particles will be small enough, that the air movement from the cars should keep the track relatively free from large amounts of debris.
The second is to reduce the amount of debris that comes off the tire in the first place. Tires previously degraded due to a large amount of material coming off of the surface of the tire. Pirelli have designed the new rubber compounds to degrade more significantly with thermal wear, instead of loss of material. This thermal wear (hardening), will cause the same loss in performance, while eliminating the large buildup of debris.
Because the tires will not lose as much material over the course of a race, their durability increases. There will no longer be as large of a concern over the tire catastrophically failing due to wear. This focus on tire compounds, has allowed for a tire that maintains the racing requirements, while increasing the competitiveness of cars and drivers in other areas.