Rain changes three things at the same time: how much grip the tyres have, how well you see and are seen, and how far you need to stop. Sweden has no separate "rain speed limit". Instead, the Traffic Ordinance (Trafikförordningen 1998:1276) makes the driver responsible for adapting speed, distance and lights to the conditions. That is exactly how the theory test asks about it.

What the law says about driving in rain

Three paragraphs in chapter 3 of Trafikförordningen cover most rain questions:

  • 3 kap. 14 §: speed must be adapted to road, weather and visibility conditions. You must always be able to stop within the distance you can see ahead, and before any obstacle that can be foreseen.
  • 3 kap. 15 §: you must keep a sufficiently low speed when visibility is reduced by light or weather, on slippery roads, and where a dirty road could splash other road users.
  • 3 kap. 2 §: the distance to the vehicle in front must be such that there is no risk of hitting it if it slows down or stops.

The posted limit is a maximum for good conditions. On a 70 road in heavy rain, the legal speed may be well below 70.

What aquaplaning is and why it happens

Aquaplaning (vattenplaning) happens when the tyre cannot push water away fast enough. A thin layer of water builds up between the tyre and the road, and the tyre starts to ride on the water instead of the asphalt. You lose steering and braking ability at the same moment.

The risk grows with:

  • higher speed, because the tyre has less time to clear the water
  • worn tyre tread, because the grooves that carry water away are shallower
  • wrong tyre pressure
  • standing water, especially in the wheel ruts (spår) that form on heavily used roads

Early signs are that the steering suddenly feels light, or that the engine revs rise without the car going faster.

Transportstyrelsen sets these minimum tread depths for cars:

  • Summer road conditions: at least 1.6 mm.
  • 1 December to 31 March, when there are winter road conditions: winter tyres or equivalent equipment with at least 3 mm tread. Winter road conditions means snow, ice, slush or frost on any part of the road, and the police decide on the spot.

The minimum only tells you when a tyre becomes illegal. A tyre close to 1.6 mm clears much less water than a new one. Transportstyrelsen also advises checking tyre pressure often (the correct value is in the owner's manual) and fitting the tyres with the most tread on the rear axle to reduce the risk of skidding when braking and cornering.

Lights, fog lights and visibility

Rain makes you harder to see, so the light rules matter:

  • Dipped headlights are the basic rule when driving a motor vehicle on a road (3 kap. 69 §).
  • Daytime running lights are not enough in bad weather. Other lights may replace dipped headlights only when it is not dark, not dawn or dusk, and weather does not require dipped headlights (3 kap. 71 §). Many cars also show no rear lights when only daytime running lights are on, which the rules allow in daylight (3 kap. 68 §), so in heavy rain the car can be almost invisible from behind.
  • Front fog lights may be used instead of dipped headlights in fog and heavy precipitation (3 kap. 71 §).
  • The rear fog light may only be used in fog, heavy precipitation or similar poor visibility, and never so that drivers behind are dazzled (3 kap. 72 §). Switch it off when the rain eases.

Wipers and washer fluid are not formalities either. Trafikverket lists both among the items the examiner can ask you to check at the start of the driving test.

If the car starts to aquaplane

This is standard driving instruction rather than a legal rule, but it is what instructors teach and what the theory test expects you to understand:

  • Ease off the accelerator gently.
  • Hold the steering wheel steady and keep the wheels pointing where you want to go.
  • Avoid hard braking and sudden steering while the tyres are on water.
  • Wait for grip to return as the car slows. If the wheels are turned when grip comes back, the car can jerk in that direction.

Prevention is far better than recovery. Lower your speed before large puddles, drive beside water-filled ruts rather than in them when it is safe, and increase your distance to the car in front.

Rain on the theory test and driving test

On the theory test, rain questions usually combine several rules: speed adaptation, following distance, lights and tyres. On the driving test, Trafikverket says the examiner assesses how you adapt your speed and how you drive in poor visibility or slippery conditions. A wet test day is not bad luck. It is a chance to show planning.

Typical theory test traps

  • "The limit is 70, so 70 is fine." Not in heavy rain. 3 kap. 14 § and 15 § require lower speed when visibility or grip is reduced.
  • "Daytime running lights are enough." In weather that requires dipped headlights, they are not.
  • Rear fog light in ordinary rain. Only in fog, heavy precipitation or comparable visibility.
  • "1.6 mm means good grip." It is only the legal minimum for summer conditions.
  • Splashing pedestrians and cyclists. The law specifically requires low speed where dirty roads could splash other road users.

FAQ

Is there a lower speed limit in rain in Sweden?

There is no fixed rain limit in Trafikförordningen. You must adapt speed to the conditions yourself. Variable signs can show a recommended maximum speed (sign E13) when conditions are temporarily poor, and that speed is always lower than the legal limit.

Can I use fog lights in heavy rain?

Front fog lights may replace dipped headlights in fog and heavy precipitation. The rear fog light is allowed only in fog, heavy precipitation or similar poor visibility, and must not dazzle drivers behind you.

What tread depth do I need?

At least 1.6 mm in summer conditions and at least 3 mm on winter tyres when the winter tyre requirement applies (1 December to 31 March in winter road conditions). More tread gives better protection against aquaplaning.

You can practise questions on wet roads, lights and tyres in Körkort Hero, which is available in 16 languages, so you can check the Swedish rule in your own language before you meet it in Swedish on the test.

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