Key takeaways
- Water reduces traction even before it causes aquaplaning, when a film of water lifts the tyre off the surface and steering stops working.
- F1 brings two treaded wet tyres: the intermediate (green) for damp tracks with light standing water and the full wet (blue) for heavy standing water.
- The 'crossover' to a different tyre comes when the lap-time gain over the remaining laps outweighs the time lost in a pit stop.
- In the 2026 F1 rules, rear lights must be on with wet tyres, the two-compound rule falls away, and a race can start behind the safety car with wet tyres mandatory.
- If rain stops a race early, points scale down with the distance completed, and none are given without two green-flag laps.
Rain cuts grip, throws up spray and forces a decision about tyres. This guide explains what water does to a racing car, how wet tyres work, how teams decide when to change tyres, and which rules change in a wet Formula 1 race under the FIA's 2026 sporting regulations.
What water does to grip
Wikipedia's article on aquaplaning separates two problems:
- A lubricated surface. Traction is reduced on any wet surface, even without aquaplaning.
- Aquaplaning. When a layer of water builds up between the tyres and the road, the vehicle loses traction and stops responding to steering, brakes and throttle.
Dry-weather racing tyres are slicks, with no tread at all, which is why racing switches to treaded wet-weather tyres once water stands on the track.
The two wet tyres
Wikipedia describes the two treaded wet-weather tyres supplied at every Grand Prix:
| Tyre | Sidewall | For |
|---|---|---|
| Intermediate | Green | Damp tracks with light standing water |
| Full wet | Blue | Heavy standing water |
The 2026 regulations allocate each driver five sets of intermediates and two of full wets at a standard event, and in practice sessions intermediates and wets may only be used once the race director has declared the track wet. Racing tyre strategy covers the dry compounds.
The crossover
As a track dries or gets wetter, there comes a moment when a different tyre becomes faster. This guide calls that moment the crossover, and changing is worth it only if the lap-time gain repays the pit stop.
An illustrative example. A pit stop costs 22 seconds. The track is drying, and slicks would now be 2 seconds a lap faster than intermediates.
| Laps remaining | Gain from slicks | Pit stop cost | Decision |
|---|---|---|---|
| 15 | 15 × 2 = 30 s | 22 s | Pit: 8 s better off |
| 8 | 8 × 2 = 16 s | 22 s | Stay out: 6 s better off |
Real decisions are harder: the first laps on new tyres may be slower, the track keeps changing, and a rival who gambles first can gain or lose a race. A safety car makes any stop cheaper; the safety car explained covers why.
What changes in a wet F1 race
The 2026 sporting regulations include several wet-weather provisions:
- Rear lights. A car's rear lights must be illuminated at all times when it is on intermediate or wet-weather tyres, so following drivers can see it in the spray.
- No two-compound rule. A driver who uses intermediate or wet tyres during the race no longer has to use two dry specifications.
- Safety-car starts. If conditions are unsuitable for a standing start, formation laps can take place behind the safety car, and the race director can make wet-weather tyres compulsory.
- Visibility. Behind the safety car, the race director may increase the maximum gap between cars from 10 to 20 car lengths in poor visibility.
- Qualifying. The 107% rule for Q1 does not apply if the race director has declared the track wet.
Marshals warn of slippery patches too: under the FIA's Appendix H, a yellow flag with red stripes, shown motionless, signals deteriorating grip from oil or water ahead. Racing flags explained lists every flag.
When rain stops the race
Heavy rain can end a race early. Points then depend on how far the leader got: under Article A2.2 of the 2026 general regulations, a race that runs less than 25% of its distance pays 6 points for a win, rising to full points only at 75% distance, and no points at all are awarded unless the leader completes two consecutive laps without a safety car or virtual safety car. Racing points systems has the full tables.
A wet start, step by step
The regulations set out how a rain-affected start works when the race director decides a standing start is unsafe:
- Ten minutes before the start, if wet tyres are to be mandatory, the safety car's orange lights come on and teams receive the message "FORMATION LAP(S) BEHIND SAFETY CAR - WET WEATHER TYRES MUST BE USED".
- If wet tyres are not mandated, the same lights and a shorter message come at the five-minute signal.
- When the start gantry lights turn green, the safety car leaves the grid and the cars follow in grid order, no more than 10 car lengths apart, or 20 in poor visibility.
- The safety car leads until the race director judges conditions suitable for racing, and the race is shortened by the number of laps the safety car led, minus one.
Marshals keep the yellow-and-red "slippery" flag out for at least four laps, depending on circumstances, unless the surface returns to normal sooner, according to Appendix H.
In Car Racing - Pro Career Racer, one of our sports career games, dry and wet races, changing grip, rain, cautions and safety periods all change which strategy is right; the game guide explains how.
Good to know
Frequently asked questions
What is the difference between intermediate and full wet tyres?
What is aquaplaning?
Why do F1 cars show rear lights in the rain?
Do F1 drivers still have to use two compounds in a wet race?
Sources
- 2026 F1 Regulations, Section B [Sporting], Issue 09 (opens in a new tab)Fédération Internationale de l'Automobile — accessed
- Formula One tyres (opens in a new tab)Wikipedia — accessed
- Aquaplaning (opens in a new tab)Wikipedia — accessed
- Appendix H: Recommendations for the supervision of the road and emergency services, 2026 (opens in a new tab)Fédération Internationale de l'Automobile — accessed
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