broken the 20,000 rpm limit on track in December 2005. Tyre changes returned to Formula One in 2006. Each driver is limited to 14 sets of tyres per race weekend. This consists of seven sets of dry-weather tyres, four sets of wet-weather tyres and three sets of extreme-weather tyres. The thinking behind this is that the reduced engine size will offset any performance gain. The number of constructors who were supplied tyres by Michelin was down from seven to six while Bridgestone increased from three to five. Michelin announced they would withdraw from the championship after the 2006 season. All Formula One cars and entrants began to utilise mandatory 7-speed + 1 reverse semi-automatic gearbox configuration from 2006 to . To keep costs down, the fuel tank capacity of all Formula One cars were mandatorily standardized to . Sporting regulations A new qualifying system consisting of three sessions of varying length was introduced. A 15-minute session was held first, in which the six slowest cars from that session were eliminated and thus set in grid positions 17–22. After a five-minute break, another 15-minute session was held with the remaining cars, and again the six slowest cars were eliminated and set in positions 11–16. These twelve eliminated drivers were placed in parc fermé, but allowed to modify fuel loads as they see fit. During a further five-minute break, the remaining 10 cars declared their fuel loads to the FIA. A final 20 minute session then decided the top 10 grid positions. Teams were allowed to run their fuel load low by making as many laps as possible, and thus improve their times as the weight falls. This was considered an improvement for TV audiences because teams needed to run as many laps as possible to lower their fuel loads. Following this session, the top ten cars were placed in parc ferme and required to refill their fuel load to the level of that at the beginning of the final 20 minutes. Starting with the 2006 French Grand Prix, qualifying for final session was cut short to just 15 minutes, making all of the sessions the same length, and the ability for drivers to complete a flying lap after the chequered flag drop now applied in the first two sessions as well. A loophole was detected by the FIA, in that teams could declare a large fuel load but on the out