Wet Weather

Slick tyres have no grooves, so they aquaplane the instant the track is wet. When rain comes, teams switch to grooved wet-weather tyres designed to pump water out from under the contact patch — a full wet can clear tens of litres of water a second at racing speed.

Aquaplaning is the danger the grooves exist to fight: above a certain speed a film of water lifts the tyre clear off the asphalt, and with no contact there is no grip, no braking and no steering at all. The grooves cut channels for that water to escape, which is why a wet tyre can keep working in conditions where a slick would simply skate straight on at the first corner.

A drying track is the most treacherous: a dry line forms where the cars run most, getting quicker and quicker, until suddenly slicks are faster than inters — but only on that narrow strip, and only if you dare. The first driver brave enough to switch can leap up the order, or run wide onto the wet part and lose everything. The crossover window is often just a lap or two wide, so teams watch rivals’ sector times obsessively for the moment to jump.

Rain also brings a second enemy: spray. The wall of water thrown up by the cars ahead can blind a following driver completely, and it is often poor visibility — not a lack of grip — that forces officials to neutralise a race behind the Safety Car or stop it with a red flag until conditions improve. For that reason the full wet is used less than you might expect: by the time the track is wet enough to need it, the spray is often too dangerous to race in at all, so most wet running happens on intermediates.