Tyre bulge at the MOT: which cars fail on it most
1.5% of failed initial MOT tests in 2025 recorded this defect: 137,990 of 9,185,328. By age, it was most common on vehicles 3 to 5 years old (3.4%) and least common on vehicles 20 years old and over (0.6%).
It is one of the 10 most common MOT failures on 30 of the 332 car models we cover. Against vehicles of the same age, it was most common on the BMW 8 Series, the BMW 6 Series and the BMW 4 Series. On the BMW 8 Series, 19.7% of failed tests had it, against 3.2% for all vehicles of the same age.
The DVSA records it as “Tyre has a bulge, caused by separation or partial failure of its structure”. A failed test can have several defects.
What the MOT checks
A lump or bulge in a tyre where its structure has separated or partly failed.
The MOT inspection manual lists “A tyre with a lump, bulge or tear caused by separation or partial failure of its structure, including any lifting of the tread rubber or with cords exposed or damaged” as a dangerous defect, so the vehicle fails.
Car models where it is most common
| # | Car | Share of failed tests | Against same age |
|---|---|---|---|
| 1 | BMW 8 Series833 failed tests | 19.7%164 tests | 6.2×all: 3.2% |
| 2 | BMW 6 Series3,650 failed tests | 7.9%287 tests | 5.9×all: 1.3% |
| 3 | BMW 4 Series18,389 failed tests | 9.7%1,785 tests | 4.8×all: 2.0% |
| 4 | Porsche Taycan966 failed tests | 12.8%124 tests | 3.7×all: 3.5% |
| 5 | Mercedes-Benz CLS4,504 failed tests | 4.2%190 tests | 3.1×all: 1.3% |
| 6 | Audi A72,394 failed tests | 4.9%118 tests | 3.1×all: 1.6% |
| 7 | Jaguar F-Type1,233 failed tests | 5.8%71 tests | 3.0×all: 1.9% |
| 8 | MINI Clubman5,109 failed tests | 5.7%291 tests | 2.9×all: 1.9% |
| 9 | Toyota Aygo X686 failed tests | 10.5%72 tests | 2.8×all: 3.8% |
| 10 | BMW 2 Series21,991 failed tests | 6.0%1,329 tests | 2.8×all: 2.2% |
| 11 | Porsche Cayenne3,436 failed tests | 4.8%165 tests | 2.7×all: 1.8% |
| 12 | Jaguar XE7,965 failed tests | 4.8%384 tests | 2.5×all: 2.0% |
| 13 | Mitsubishi Mirage2,055 failed tests | 4.0%82 tests | 2.4×all: 1.6% |
| 14 | Volkswagen Arteon1,223 failed tests | 6.6%81 tests | 2.3×all: 2.9% |
| 15 | BMW X22,975 failed tests | 5.6%166 tests | 2.0×all: 2.8% |
Only models where this defect is one of their 10 most common MOT failures, with at least 50 failed tests, have a figure. So a model that isn't listed can still have it, just less often than its other faults. Vans, pick-ups and taxis are left out, as in our rankings. × is the model's share divided by the share for all vehicles of the same age.
How common it is by car age
- Under 3 years, first used 2023 to 20243.3% of failed tests, against 1.5% for all ages359 failed tests
- 3 to 5 years, first used 2020 to 20223.4% of failed tests, against 1.5% for all ages23,010 failed tests
- 6 to 9 years, first used 2016 to 20192.1% of failed tests, against 1.5% for all ages44,480 failed tests
- 10 to 14 years, first used 2011 to 20151.3% of failed tests, against 1.5% for all ages44,068 failed tests
- 15 to 19 years, first used 2006 to 20100.9% of failed tests, against 1.5% for all ages20,778 failed tests
- 20 years and over, first used 1985 to 20050.6% of failed tests, against 1.5% for all ages5,295 failed tests
All-vehicle figures cover vehicles first used from 1985 to 2024: 9,185,328 of the 9,193,164 failed initial tests in 2025.
How these figures are counted
These are failures recorded at initial MOT tests in 2025. Retests are not counted. A defect found on more than one wheel, lamp or joint at the same test counts once. "Same age" is the defect's share of failed tests for all vehicles first used in the same years, weighted by the model's own failed tests in each year.
An MOT checks safety and emissions on the day of the test. These figures show where a defect was recorded, not why, and not what a repair costs. Figures: DVSA anonymised MOT tests and results, 2025. Contains public sector information licensed under the Open Government Licence v3.0. What the MOT checks: MOT inspection manual: cars and passenger vehicles, GOV.UK, read 1 Nov 2026.
How we choose and rank these defectsOther tyres faults
- Tyre tread depth7.9% of failed tests
- Tyre cut5.0% of failed tests
- Tyre cords exposed4.8% of failed tests
- Tyre pressure monitoring1.7% of failed tests
Share of all failed initial MOT tests in 2025.