Tyres Fail at 60 MPH. Brakes Fail at 35.

Owners remember how fast they were going. It appears in the text constantly — "I was doing about 65 when", "at approximately 30 mph the".

147,733 complaints contain a speed. Extracting them gives each component a signature.

Twenty-five miles an hour separates the top of the table from the bottom, and the ordering is not random.

Tyres are a heat problem

Sixty miles an hour is the highest median on the list, and tyres are the only component where the speed is part of the mechanism rather than the circumstance.

A tyre carrying existing damage — a bruise from a pothole, a slow leak, tread separation starting inside — survives low-speed driving indefinitely. What kills it is sustained heat in the sidewall, and heat comes from flexing at speed over time.

That is why tyre failures cluster on long drives at motorway speed rather than in town, and why they carry the highest death rate per complaint of any component we have measured — 14.94 per thousand.

Brakes are a demand problem

Thirty-five miles an hour is the lowest median among major systems, and it does not mean brakes are safer at speed.

It means brakes are discovered. A hydraulic fault, a corroded line, worn pads — none of these announce themselves while the car is moving. They are found at the moment the pedal is pressed, and most braking happens at moderate speeds in traffic.

The speed did not cause the failure. It is simply where the demand occurred.

Seat belts at 35 mph are the same logic taken further: a belt is tested only in a collision, and the collision speed is what gets recorded.

The airbag row is the one to read carefully

40 mph, 7,382 readings — the second-largest sample on the table.

Airbag complaints split into two kinds that this median blends together. Ones where the bag failed to deploy in a crash, which records the crash speed. And ones where it deployed without a crash, which records whatever the car was doing at the time.

Both are serious and they are different failures. The single number cannot distinguish them, which is worth knowing before anybody quotes it as "airbags fail at 40 mph".

What the distribution says overall

Across all 33,218 readings the median is 45 mph, with a quarter below 30 and a quarter above 60. Only 5% happened under 15 mph.

So failures are overwhelmingly reported at road speed rather than in car parks — which sits interestingly against our finding that faults occurring at junctions and in car parks are more than twice as likely to end in a crash.

Both are true. Most faults happen at speed; most crashes from faults happen where there is no room. The dangerous combination is a failure that starts on the motorway and is still unresolved when the car reaches a junction.

Whether a specific vehicle has a known fault of either kind is checkable in a minute. A free VIN check returns the open campaigns for that VIN.