TREAD
At least 1.6 mm
Car tyres need at least 1.6 mm of tread across the central three-quarters of the tread, all the way round. Below that, the MOT treats it as dangerous.
Check a tyre
WHAT THE RULES SAY
Four small patches
hold the road.
Everything a car does reaches the road through its tyres.
Braking, steering and grip all depend on tread depth, the right pressure and a tyre free of cuts and bulges. UK rules set clear limits, and most of the checks take a few minutes on the driveway.
1.6 mm the legal minimum
Check a tyre- Tread above the limit
- Pressure checked cold
- No cuts or bulges
- A few minutes, four tyres
THE SHORT ANSWER
Tread, air,
condition.
Three things to look at on every tyre.
The law and the MOT check all three.
AIR
Weekly, and cold
The Highway Code says check pressures weekly, before a journey, when the tyres are cold. Under- or over-inflation affects braking and steering.
How to do it
CONDITION
Look for cuts and bulges
A lump or bulge from structural failure is a dangerous MOT defect, and a cut that reaches the cords is a major one.
See the numbers
FOUR CHECKS TO TRY
Five minutes
on the driveway.
You need a 20p coin, a pressure gauge or a forecourt air line, and good light. Do all four tyres, and the spare if you have one.
Try the 20p test
Put a 20p coin into the main grooves in a few places. If the outer band shows, have the tread measured.
Check pressures cold
Use the figure in the handbook, on the door shut or inside the fuel filler cap, before a journey and when the tyres are cold.
Run a hand round the sidewall
Look for bulges, lumps and cuts, and pick out stones or objects caught in the tread.
Watch for uneven wear
The Highway Code says uneven wear may point to faults in brakes, suspension or wheel alignment. Get those put right.
TWO NUMBERS WORTH KNOWING
Small rubber,
big stakes.
One figure on harm from tyre faults,
one on what an illegal tyre can cost.
190
Tyre-related deaths or serious injuries
Liverpool City Council, citing Department for Transport data, reports 190 tyre-related fatalities or serious injuries in 2023, up 29% from 147 in 2022 and the highest since 2018.
CASUALTIES · DFT DATA, 2023
£2,500
Maximum fine for each illegal tyre
Each illegal tyre can bring a fine of up to £2,500 and three penalty points. With all four tyres dangerous, that could reach £10,000 and 12 points, enough for a driving ban.
PENALTIES · PER ILLEGAL TYRE
Tyre age matters too: since a 2020 change to the rules, tyres over 10 years old must not be used on the front axles of lorries, buses, coaches and minibuses, because the Department for Transport found deterioration in older tyres cannot always be seen.
A QUICK TYRE CHECK
What does
the tyre show?
Pick what you found on a tyre to see what the rules say. The bar shows how urgently the guidance points to acting.
Based on the Highway Code (annex 6), the MOT inspection manual and UK council tyre safety advice. General information, not a vehicle inspection.
READING THE SIDEWALL
Every tyre has
a birthday.
A four-digit code on the sidewall gives the date the tyre was made: the first two digits are the week and the last two the year, so a tyre made in week 21 of 2020 reads 2120.
For lorries, buses, coaches and minibuses, tyres over 10 years old are banned from the front axles. The government also recommends that owners record and monitor tyre age, because structural deterioration in older tyres cannot always be seen.
Questions
Questions people ask
What is the legal tread depth for a car?
At least 1.6 mm across the central three-quarters of the breadth of the tread, around the entire circumference. Motorcycles and large vehicles need at least 1 mm.
How does the 20p test work?
Put a 20p coin into the main tread grooves. If the outer band of the coin is hidden, the tread is above the limit. If the band is visible, the tyre may be illegal and should be measured properly.
How often should I check tyre pressure?
The Highway Code says weekly and before a journey, when the tyres are cold, because warm tyres can give a misleading reading. Use the pressure in the vehicle's handbook.
What can happen if my tyres are illegal?
Each illegal tyre can bring a fine of up to £2,500 and three penalty points. In an MOT, tread below the limit or a bulge from structural failure is classed as a dangerous defect.
How do I tell how old a tyre is?
Find the four-digit date code on the sidewall: the first two digits are the week of manufacture and the last two the year. The marking must always be legible.
Sources
- GOV.UK: The Highway Code, Annex 6, vehicle maintenance, safety and security
- GOV.UK: MOT inspection manual, axles, wheels, tyres and suspension
- GOV.UK: Tyre age restrictions for goods vehicles, buses, coaches and minibuses
- Liverpool City Council: Be a tyre safety hero and ACT
- Torbay Council: tyre safety campaign news release
Updated