Tyre Law for Trucks: Tread Depths, Age Limits and the Defects That Cost Points

Tyres are the only part of a truck that touches the road, and the law treats them accordingly. The Highway Code’s annex on vehicle maintenance, safety and security sets the tyre rules for every vehicle on UK roads - and several of them are different, and stricter in specific ways, for the large vehicles haulage fleets run.

Tread depth: the number depends on the vehicle

The rule most drivers half-remember is 1.6mm. That figure applies to cars, light vans and light trailers: they must have at least 1.6mm of tread across the central three-quarters of the breadth of the tread and around the entire circumference.

Large vehicles and passenger-carrying vehicles sit in the other category: they must have at least 1mm of tread across three-quarters of the breadth of the tread, in a continuous band around the entire circumference. Motorcycles share that 1mm standard, and mopeds just need visible tread.

The lower legal minimum for large vehicles is not permission to run tyres to the cords. The legal floor is where enforcement starts, not where grip ends - most fleets replace well before 1mm because a steer-axle tyre at the legal limit in standing water is a skid waiting for a braking zone.

Inflation and condition

Tread is only one of the three legs:

• Inflation. Tyres must be correctly inflated to the vehicle manufacturer’s specification for the load being carried - “for the load being carried” matters in haulage, where the same truck runs empty and full in the same week. The vehicle’s handbook or data plate is the reference.
• Condition. Tyres should be free from certain cuts and other defects. A bulge, exposed cord or deep cut is a defect regardless of tread depth.
• Warning. The annex warns that some vehicle defects attract penalty points - a bald or defective tyre is not just a prohibition, it can put points on the driver.

The 10-year age rule

The rule fleets most often miss is about age, not wear. Tyres over 10 years old must not be used on:

• the front axles of goods vehicles over 3.5 tonnes maximum gross weight
• the front axles of passenger vehicles with more than 8 passenger seats
• the rear axles of passenger vehicles with 9 to 16 seats, unless fitted with twin wheels

To make the rule enforceable, the tyre’s date of manufacture marking must always be legible. Vehicles excluded from tyre roadworthiness regulations, and historic vehicles not used commercially, are exempt.

For a haulage fleet this rule has a real edge case: the spare. A spare that has sat under a trailer or in a rack for a decade is a 10-year-old tyre the day it goes on a steer axle. Fleets need the manufacture date in the tyre inventory, not just the tread gauge reading.

If a tyre fails on the move

The annex’s driving advice is short and worth drilling: if a tyre bursts while driving, grip the steering wheel firmly and let the vehicle roll to a stop at the side of the road - no stabs at the brake. With a flat, stop as soon as it is safe, and only change the tyre if it can be done without putting anyone at risk; otherwise call a breakdown service. On a motorway, “without putting yourself or others at risk” almost always means the breakdown service.

One more wrinkle worth a line in the policy: tyre rules are policed at the roadside as well as at the annual test. A roadside examiner does not need an appointment to check tread with a gauge, read a manufacture date, or spot a perished sidewall, and the findings feed straight into the operator’s compliance record.

The fleet’s tyre system

Tyre compliance is a process, not a gauge:

• Walkaround checks catch the daily stuff: cuts, bulges, obvious under-inflation, embedded debris.
• Scheduled measured checks - tread depth across the tread and around the circumference, pressures against the manufacturer’s spec for the planned load - go in the maintenance planner with the 15-month records every other inspection generates.
• Age tracking belongs in the tyre inventory: manufacture date in, and no tyre older than 10 years anywhere near a front axle or a minibus rear axle.
• Defect reports closed out. A driver-reported tyre defect that sits unfixed is an operator problem, not a driver problem.

Tyres are where roadworthiness becomes literal. Keep the tread, the pressure, the condition and the age inside the rules, and the most common mechanical prohibition in the industry never lands on your OCRS.

Sources

• The Highway Code - Annex 6: Vehicle maintenance, safety and security (GOV.UK)