The basic tyre regulations for the 2013 season have stayed unchanged from last year. Each car is allowed to have 11 sets of slick tyres over the course of every race weekend: six sets of the harder compound and five sets of the softer compound.
For every race, Pirelli will nominate two out of the four available dry compounds in advance: one softer compound and one harder compound.
One set of the harder compound is returned before the start of the second free practice session, while one set of the harder and one set of the softer compound are returned before the start of the third free practice session. From the remaining dry-weather tyre sets one set of each nominated compound must be returned before the start of qualifying. This leaves the teams with three sets of each compound for both qualifying and the race. The way in which they use these six crucial sets of tyres forms the basis of the tyre strategy for the weekend.
At the start of the race the top 10 cars must be fitted with the tyres on which the driver set his grid time. This rule will only apply if dry weather tyres were used to set the grid time and if dry weather tyres are used at the start of the race. Those drivers in the top 10 who for whatever reason did not set a time are free to choose which tyre they want to start the race with.
During the race, the drivers have to use each type of tyre at least once (unless it rains, in which case this rule does not apply). If they do not do this, they will be excluded. If a dry race is suspended for any reason before the drivers have used both types of tyre, 30 seconds are added to their cumulative race time.
During Friday practice Pirelli has the possibility to provide teams with one additional set per car of either the harder or the softer compound, if it is a new circuit or high wear is expected. Alternatively, Pirelli also has the possibility to supply teams with two additional sets per car of prototype tyres for development reasons. In each case these sets must be returned before the start of the third practice session.
Wet tyres
Teams are allowed four sets of intermediate tyres and three sets of wet tyres per car per race weekend. If it rains during Friday free practice, one extra set of intermediates is given to each car.
This set has to be returned before the start of the third practice session.
If the race is started behind the safety car, then the teams must all start on the wet tyre. If it starts raining during the race, then the teams are no longer obliged to run both slick compounds, and they can change over to either the intermediates or wets, as they feel is appropriate for the conditions.
Both the wet and intermediate compounds are available at each round of the championship and are given to the teams before the start of Friday practice.