The compound is a reference to the rubber that the tyre’s wearing surface is constructed from.

Pirelli has developed a suite of compounds from C0 (hardest) to C5 (softest) and they select three of these compounds for each race weekend. The selection is based on factors such as track surface, track temperature, speeds, corners and the number of pitstops targeted.

Typically three consecutive compounds are used but this is not always the case. In Melbourne 2022 Pirelli supplied a step in the range as noted in

This weekend will see the teams use an unusual mix of compounds: the C5 (soft tyres x8 sets) for the first time this season, then a step to the C3 (medium tyre, x3 sets) and the C2 (hard tyre, x2 sets

Andrew Burden

The author Kiwi F1 Fan