Mercedes and McLaren are both taking only 8 sets of the soft (C3) tyres to Spa-Francorchamps for the Belgian Grand Prix.
On the other hand, Ferrari, Red Bull, Renault and Haas take the full complement of ten, while the rest take nine.
In terms of the C1 (hard) tyres, Williams driver, George Russell stands alone as the only driver to take more than one set.
Most opt for two or three sets of the C3 (mediums), though the Silver Arrows pair and Lando Norris take four sets.
Last year the supersoft, soft and medium was available, while in 2017 it was the ultrasoft, supersoft and soft.
Last year's race was won by Sebastian Vettel on a one-stop strategy, with thirteen of the top fourteen finishers also stopping just once.
The German started on used supersofts before switching to new softs, as did seven of the leading eight finishers.
Fourth-placed Valtteri Bottas was the only driver, other than Stoffel Vanddorne, to stop twice, the Finn having started from the back of the grid following an engine change.