The unmarked tyres are either Pirelli's prototype mediums or winter hards. Probably the latter with track temperature down at 16C and his stint before having been on hards
15:49 - Raikkonen pits. His final stint on unmarked tyres: 1:27.2, 1:28.0, 1:28.3, 1:28.1, 1:28.2, 1:28.1, 1:28.5, 1:28.2, 1:29.0, 1:28.3, 1:28.6, 1:28.4, 1:28.8, 1:29.9, 1:28.6, 1:28.6, 1:28.7, 1:28.6, 1:29.1, 1:29.7, 1:29.1, 1:29.2, 1:29.1, 1:29.7, 1:29.5, in lap 1:33.9