The Arithmetic of a Pit Stop
A pit stop costs time in three parts: slowing to enter the pit lane, traversing it under a mandated speed limit far below racing speed, and standing still while the tyres are changed, then rejoining and getting back up to speed. In racing terms that total is enormous, far larger than the gaps that usually separate cars on track, and it is paid in full the moment the car turns in.
Everything in strategy follows from comparing that fixed cost against a variable gain. Fresh tyres are faster than old ones by an amount that grows as the old set degrades, so the longer a car stays out on a fading set, the more per-lap advantage a new set would deliver. A stop makes sense when the accumulated per-lap gain over the remaining distance exceeds the one-off cost of stopping, and adding a second or third stop only pays when degradation is severe enough that the extra fresh-tyre advantage clears another full pit-lane penalty. This is why high-degradation circuits push teams toward more stops and low-degradation circuits reward stretching a stint. The pit-lane cost barely changes. The value of fresh rubber changes a great deal.
