In any racing series that permits scheduled pit stops, pit strategy becomes one of the most important features of the race; this is because a race car travelling at 100 miles per hour (160 kilometers per hour) will travel approximately 150 feet (45 meters) per second. During a ten-second pit stop, all of a car's competitors will gain approximately one-quarter mile (one-half kilometer) over the stopped car.
However, the car that made the additional pit stop will run faster on the race track than cars that did not make the stop, both because it can carry a smaller amount, and thus lower weight, of fuel, and will also have less wear on its tires, providing more traction and allowing higher speeds in the corners. In racing series where teams have their choice of different compound tires, the lower tire wear may be enough to allow the team to choose to use a tire with a softer rubber compound that provides increased grip at the expense of faster wear; going longer between stops may even cause enough wear on the softer tire to cause the tires to fail.
Because of this, race teams plan a pit strategy prior to the start of every race. This is a schedule for each car's planned pit stops during the race, and takes into account factors such as rate of fuel consumption, weight of fuel, cornering speed with each available tire compound, rate of tire wear, the effect of tire wear on cornering speed, the length of pit road and the track's pit road speed limit, and even expected changes in weather and lighting conditions. The pit strategy does not just include a schedule of when pit stops will happen; it also includes what service and adjustments are scheduled for each pit stop, particularly in endurance racing, where scheduled changes of wear-limited parts such as brake pads may be planned for specific points during the race. The pit strategy is calculated carefully so that the amount of time to be "given away" to other competitors in pit stops is balanced out by the time gained while on the track, resulting, theoretically, in the shortest possible time to cover the scheduled distance.
However, a team's pit strategy is not a fixed, immutable thing; it is subject to change during the race to take into account the unpredictable events that happen in every race. In road racing, for example, if the weather changes from dry to rain, teams will be forced to recalculate their pit strategy based on the unscheduled stop to change from dry-weather "slick" tires to treaded wet-weather tires. Full-course caution periods often see mass pit stops by many teams, hoping to take advantage of the slowed pace to reduce the ground lost to other teams while making pit stops; this forces teams that do so to immediately recalculate their pit strategy to optimize it for the remaining race distance after the stop.
Even when a team chooses not to take advantage of the opportunity to stop during a full-course caution, it can still result in significant changes to pit strategy; under caution, the cars run at a reduced speed that results in greatly reduced tire wear and fuel burn for a distance traveled. Depending on the circumstances, this may be enough for a team to gain more by choosing not to pit, hoping that the reduced fuel burn and tire wear will allow them to make one pit stop fewer than the other teams, allowing them to gain distance and time on their opponents. At tracks noted for frequent full-course cautions, teams may even plan their entire race strategy around this, using a suspension and aerodynamic setup suited to short sprints instead of extended runs to gain positions in the short bursts of green-flag racing, and planning their pit strategy on the assumption that cautions will extend their fuel mileage and tire wear enough to make fewer stops than would otherwise be needed to complete the race distance.
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