Driving in snow and ice: the Highway Code rules, technique and when not to travel

What the Highway Code actually says

The Highway Code deals with snow and ice in four rules, 228 to 231, and the first of them settles the biggest question before you reach for the keys. Rule 228 says to check the forecast for warnings of icy or snowy weather and — in the Code's own capitals — "DO NOT drive in these conditions unless your journey is essential". Everything the Code then says about technique assumes you have already decided the journey genuinely needs to happen.

The wording matters. Where a rule says MUST or MUST NOT, it describes a legal requirement backed by a named regulation, and breaking it is an offence. Where it says "should", it is advice — though advice that can still be cited in evidence in court to help establish liability, careless driving included. Rules 228–231 contain both kinds, and this guide flags which is which.

Before you set off: clearing the car is a legal duty

Rule 229 sets out the pre-departure checks, and two of them are law. You MUST be able to see, so clear all snow and ice from all your windows — not a letterbox-sized patch on the driver's side. That traces to regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986, which requires all glass to be kept so that it “does not obscure the vision of the driver while the vehicle is being driven on a road”. You MUST also ensure your lights are clean and your number plates are clearly visible and legible.

The roof is the question everyone asks. There is no offence called "driving with snow on your roof", but Rule 229 tells you to remove all snow that might fall off into the path of other road users. That line is advice rather than a MUST, though the Code can be used in evidence in court, and if snow slides over your windscreen or onto the car behind, the police could consider careless driving or using a vehicle in a dangerous condition, depending on the circumstances. A soft brush clears a roof in under a minute.

Demist the inside thoroughly, clear your mirrors, and budget ten unhurried minutes with a scraper and de-icer rather than pulling away half-blind. A winter driving kit that lives in the car from November makes this routine rather than a scramble.

Tyres and pressures: the legal floor is not a winter target

Cars MUST have at least 1.6mm of tread across the central three-quarters of the tyre, around its whole circumference, and tyres MUST be correctly inflated to the manufacturer's specification — both requirements sit in Annex 6 of the Highway Code, under the Construction and Use Regulations. Grip on snow falls away as tread wears long before the legal limit, so tyres near 2mm going into winter are better replaced ahead of the season than after it.

Ignore the persistent tip about letting air out for extra grip. It does not improve traction on ice, it worsens braking and stability, and it takes you outside the manufacturer's specification the law requires. Check pressures weekly when the tyres are cold, as the Highway Code advises, and before any long winter journey; a small plug-in inflator makes this a two-minute job. Winter tyres are not required by UK law: their softer compounds are designed for temperatures below about 7°C, and they earn their cost on rural, hilly or untreated roads far more than on short, gritted urban runs.

On the road: high gear, gentle inputs, ten times the room

Rule 231 is close to a checklist: drive at a slow speed in as high a gear as possible, and accelerate and brake very gently. A high gear keeps the torque reaching the wheels low, which is exactly what you want when grip is scarce. The Code stops short of naming a gear for moving off, but the technique driving instructors and breakdown organisations teach is to pull away in second, easing the clutch to avoid wheelspin. Automatics with a winter or snow mode should use it.

Leave enormous room. Rule 230 warns that stopping distances can be ten times greater than on dry roads, and Rule 126 says the gap to the vehicle in front — at least two seconds on high-speed roads — should be at least doubled in the wet and can need to be up to ten times greater on ice: twenty seconds, not two. Treat bends as no-braking zones: brake progressively on the straight before the bend, then steer smoothly round it with no sudden inputs.

Black ice announces itself by silence. Rule 231 notes that on ice, tyres make virtually no noise — if the road goes quiet and the steering suddenly feels light and unresponsive, you are on it. Do not brake; ease off the accelerator and keep the steering as straight as you can until grip returns. Rule 230 fills in the rest: be prepared for conditions to change over relatively short distances, take care when overtaking vehicles spreading salt or de-icer, and do not overtake a snowplough unless the lane you intend to use has been cleared — ploughs throw snow out to either side.

Snow socks and chains: a fair test

Neither is required by UK law, and neither is the cure-all the marketing implies. Chains give real traction, but only on a compacted snow layer; on cleared or gritted tarmac they need to come off, because they damage both road and tyre. Most UK roads you would actually use are treated within hours, so the realistic chain user is someone on upland rural roads that stay snow-covered — not a commuter.

Snow socks — fabric covers for the driven wheels — are the pragmatic middle option. They genuinely help you pull away and hold grip on packed snow, fit in minutes without tools, and cost a fraction of a winter tyre set. Their limits: they wear fast on bare tarmac and manufacturers typically cap speeds at around 30mph, so they are a get-out-of-a-side-street tool, not a travel-through-a-warning tool. If you park on a hill or visit rural relatives in winter, they earn a place in the boot alongside a proper car emergency kit — but they do not change the arithmetic of an amber or red warning.

The decision framework: when not to travel

Match the decision to the Met Office warning, not to how the road looks from your window. Under a yellow warning, most journeys can go ahead with extra time, a planned route and a check that no further snowfall is forecast along it — the final item on Rule 229's checklist. Under amber, the Met Office advice is to think about changing your plans, and the Highway Code's "essential journeys only" test starts to bite: ask whether the journey has to happen today at all.

A red warning means dangerous weather is expected, it is very likely there will be a risk to life, and the Met Office advice is to avoid travelling where possible. If a journey genuinely cannot move, carry Rule 228's kit — de-icer and scraper, torch, warm clothing and boots, first aid kit, jump leads and a shovel, plus a warm drink and food — keep your phone charged, and tell someone your route and arrival time. Check the live picture on our weather warnings tracker before you commit, and if a thaw has left standing water on the route, read our guide to driving in floods first.