The MOT Files

MOT defect file

Tyre worn close to the legal limit

Last updated

Quick answer

There is little usable tread left. Replace before it reaches the 1.6mm legal minimum across the central three-quarters of the tyre.

Typical cost
£70–£140 per tyre
DIY viability
Garage job
Tyre tread depth measured against the 1.6 mm legal minimumA cross-section through a tyre tread showing five grooves of differing remaining depth, drawn to scale against a dashed line marking the 1.6 mm legal minimum. The two shoulder grooves retain 7 mm and 6.5 mm but sit outside the measured zone. Within the central three-quarters of the tread the grooves measure 3 mm and 2.5 mm, which are legal but close to the limit, and the centre groove measures 1.2 mm. Because that groove is below the 1.6 mm minimum and falls inside the measured zone, the tyre fails the MOT even though the shoulders are barely worn.1.6 mmlegal minimum1.2 mm — below the limitCentral three-quarters of the treadMeasured here, around the entire circumference
Tread must be at least 1.6 mm deep across the central three-quarters of the tread, all the way around the tyre. A single worn band inside that zone fails the test even where the shoulders still look healthy.

What you might notice

  • Tread blocks visibly shallow against the moulded wear indicator bars
  • Noticeably longer stopping distances in the wet, and standing-water aquaplaning
  • Wear concentrated on one edge, which points at alignment rather than age

What causes it

  • Normal wear — most tyres cover somewhere between 20,000 and 40,000 miles depending on compound, position and driving style
  • Under-inflation, which wears both shoulders while leaving the centre intact
  • Over-inflation, which does the reverse and wears the centre band
  • Misaligned tracking or worn suspension components, producing rapid wear on one edge only

Advisory or failure?

An advisory is recorded when tread is close to the limit but still legal. Below 1.6mm across the central three-quarters of the tread, around the entire circumference, it is a major defect and an automatic failure. Exposed cord or ply, a bulge, or a cut deep enough to reach the structure is a dangerous defect.

Can you fix it yourself?

Garage job

Fitting a tyre requires a machine, and the wheel must be rebalanced afterwards. Checking tread and pressures yourself is worthwhile and takes minutes — a 20p coin gives a usable rough guide, since the outer band of the coin is close to 1.6mm.

What it costs

Budget tyres for a common size start around £50 to £70 fitted; mid-range and premium sit between £80 and £160. Always replace in pairs across an axle, and if wear is uneven have the alignment checked at the same time or the new tyre will go the same way.

What happens if you ignore it

Driving on an illegal tyre carries a fine of up to £2,500 and three penalty points per tyre, so a car with four bald tyres can attract twelve points and a ban in a single stop. Wet braking performance falls off sharply in the last couple of millimetres of tread, well before the legal limit.

Common questions

What is the legal minimum tyre tread depth in the UK?
1.6mm, measured across the central three-quarters of the tread and around the entire circumference. Below that it is a major defect and an automatic failure. Tread that is close to the limit but still legal is recorded as an advisory, and wet braking performance already falls off sharply in the last couple of millimetres.
How do I check my tyre tread with a 20p coin?
Push a 20p coin into the main tread grooves. If you can see the outer band of the coin standing above the tread, the tyre is close to or below the legal limit, because that band is roughly 1.6mm wide. Check several points around the tyre and across its width rather than one spot, since wear is often uneven.
What is the penalty for driving on an illegal tyre?
Up to £2,500 and three penalty points, and both apply per tyre rather than per car. A vehicle with four illegal tyres can therefore attract twelve points and a ban in a single roadside stop, which makes tread depth one of the least sensible things on a car to gamble on.
How much does a new tyre cost fitted?
Budget tyres in a common size start around £50 to £70 fitted, while mid-range and premium sit between £80 and £160. Larger diameters and low-profile fitments cost more. If the wear is uneven, have the alignment checked at the same time, or the new tyre will wear out in exactly the same pattern.
Do I have to replace both tyres on an axle?
It is the sensible approach even though only one may be worn out. Replacing across an axle keeps grip balanced left to right, which matters most in the wet and under heavy braking. If one tyre has worn out early on a single edge, treat that as a sign to have the tracking and suspension checked first.

Cars this happens to most

Of every model with at least 2,000 tests in the DVSA data, these record tyre worn close to the legal limit on the largest share of their MOTs. Across all of them the typical rate is 2.8% of tests.

  1. Tesla Model 37.4%

    6,487 times in 87,484 tests

  2. Citroen DS47.4%

    703 times in 9,558 tests

  3. Maserati Ghibli6.7%

    225 times in 3,334 tests

  4. Citroen Grand C4 Picasso6.3%

    215 times in 3,438 tests

  5. Chevrolet Matiz6.0%

    490 times in 8,112 tests

  6. Hyundai IX355.9%

    2,928 times in 49,770 tests

  7. Vauxhall Antara5.5%

    1,008 times in 18,445 tests

  8. Mercedes-Benz Citan5.4%

    1,070 times in 19,945 tests

A high rate here is a property of the fleet as much as the car: these models skew old, and almost everything fails more with age. It is a reason to check the item on a used example, not proof the model is badly built. Models with fewer than 2,000 tests are left out because a rate drawn from a few hundred cars moves too much to rank.

Pass rates for every make and model

This is general guidance, not a diagnosis. The severity DVSA records depends on the specific fault found, so the same item can appear as an advisory on one test and a failure on another. Ask a qualified tester or mechanic to inspect the vehicle.

Has this been recorded on your car?

Check the full MOT history for any UK registration.

Spaces are optional

Other common defects