Winter driving asks more of your tyres than any other season. Cold roads, standing water, and the occasional icy morning all reduce grip, and the one thing standing between your car and the road is a contact patch roughly the size of your palm on each tyre. Tread depth is what keeps that patch working when the road is wet. This guide explains what the law requires, why many motoring organisations recommend changing tyres well before the legal limit, and how to check your own tyres in about five minutes.
What the law actually requires
In the UK, car tyres must have at least 1.6mm of tread across the central three-quarters of the tyre, all the way around. That is the legal minimum, and driving below it can mean a fine and penalty points per tyre, as well as a failed MOT. But the legal minimum is a floor, not a target. A tyre at 1.6mm has already lost most of its ability to clear water from the road surface, which is exactly what you need most in winter rain.
This is why many tyre professionals and motoring bodies suggest considering replacement at around 3mm. At 3mm, a tyre still has meaningful wet grip in reserve. Below that, stopping distances in the wet start to grow noticeably. You do not need to memorise the physics to act on it: if your tread is approaching 3mm as winter arrives, start planning a replacement rather than waiting for the MOT to flag it.
How to check tread depth at home
You do not need specialist tools for a first check. The simplest method is the 20p test: place a 20p coin into the main tread grooves. If the outer band of the coin is hidden, your tread is above the legal minimum. If you can see the band, your tread may be below 1.6mm and the tyre needs professional checking right away. Check several points around each tyre, not just one spot, because tyres can wear unevenly.
For a more precise reading, a tread depth gauge costs very little and gives you an actual number in millimetres. Measure the inner, middle, and outer sections of each tyre. Uneven readings — for example, heavy wear on the inner edge — can point to alignment or pressure problems worth fixing, since a new tyre fitted to a car with an alignment fault will simply wear out the same way.
Pressure matters just as much in winter
Cold air contracts, so tyre pressures drop as temperatures fall. A tyre that was correctly inflated in September can be several PSI under-inflated by December, and under-inflation increases wear, fuel use, and the risk of damage. Check pressures at least once a month in winter, when the tyres are cold, using the pressures listed in your door jamb or handbook — not the maximum printed on the tyre sidewall. If you are unsure, a mobile tyre fitting service can check pressures and tread as part of a visit, which saves a trip to a garage in bad weather.
What else to look for before winter
Tread depth is only part of the picture. Look for cracks in the sidewall, bulges, cuts, or objects embedded in the tread. Check the age of your tyres too: the DOT code on the sidewall shows the week and year of manufacture. Tyres older than five or six years deserve a closer look even if the tread looks fine, because rubber hardens with age and grips less well. And if you drive in an area that regularly sees snow and ice, ask a professional whether winter or all-season tyres suit your driving — the right compound can make a real difference below about 7°C, when summer rubber starts to stiffen.
The five-minute winter check, summarised
Once a month through winter: check all four tread depths with a gauge or the 20p test, check cold pressures against the handbook figure, walk around the car looking for sidewall damage, and make sure your spare or repair kit is present and usable. Five minutes, once a month, is a small price for the grip that keeps you safe when the road turns wet and cold.
If any tyre is near or below 3mm, damaged, or unevenly worn, get it looked at before the worst of the weather arrives. Tyre Repair Near Me offers mobile tyre fitting across Glasgow and surrounding areas, so a worn tyre does not have to mean a garage trip in the rain.
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