A blowout is one of the few things that can genuinely catch out a confident driver. Knowing the right reaction in advance is what keeps it manageable.
In short: Hold the steering wheel firmly, do not brake hard, and let the car slow down on its own. Ease off the accelerator gradually, keep the car pointing straight, and only steer gently towards the left once the speed has dropped. Braking hard or steering sharply is what turns a blowout into a loss of control.
A blowout is not the same as a puncture. A puncture lets air out over seconds, minutes or days. A blowout is a sudden structural failure, usually with a bang, and the car reacts immediately. It is unnerving, and the natural instincts, brake and steer away, are both the wrong response.
Why braking is the wrong reflex
When a tyre fails, that corner of the car suddenly has far more drag than the other three. The vehicle wants to pull towards the failed tyre. If you brake hard at the same time, you shift the weight forward and add another large, uneven force to a car that is already unbalanced. That combination is what causes cars to spin.
Letting the car slow gradually keeps the weight settled and gives the tyres that still work a chance to do their job. It feels counterintuitive to do less when something dramatic has just happened, which is exactly why it is worth reading this before it happens rather than after.
What to do, in order
- Grip the wheel with both hands. Firm, steady, at nine and three. Expect the car to pull, and resist it rather than fighting it. Your job for the next few seconds is simply to keep the car going straight.
- Come off the accelerator smoothly. Do not lift off suddenly and do not brake. Let engine braking and the drag from the failed tyre bring the speed down on their own.
- Keep pointing straight until the speed drops. No sudden steering input. Only once you are down to a slow, controlled speed should you begin steering.
- Indicate and move left gently. Once you are slow enough to steer smoothly, signal and ease over towards the hard shoulder, an emergency area or a lay-by. Brake gently now if you need to.
- Stop, hazards on, and get out safely. On a motorway, leave by the passenger door and get behind the barrier. Do not stand between the car and the traffic, and do not attempt to change a wheel on a hard shoulder.
- Call for help. A tyre that has blown out cannot be repaired, so you need a replacement. A mobile fitter can bring one to you and fit it at the roadside.
If you cannot get off the carriageway Stay in the vehicle with your seatbelt on and your hazards on, and call 999. On a motorway without a hard shoulder, do not attempt to get out into a live lane. Once you are on a hard shoulder or in an emergency area, get out of the left-hand side and stand behind the barrier.
What causes a blowout
Blowouts are rarely bad luck. They almost always trace back to something that was building up first, which is the encouraging part, because it means most of them are avoidable.
- Underinflation. The most common cause by a distance. A soft tyre flexes far more than it should, the sidewall overheats, and eventually the structure lets go. This is why a monthly pressure check matters more than most people think.
- Impact damage. A pothole or a kerb strike can break the internal cords without leaving an obvious mark on the outside. The tyre may look fine and fail weeks later. Around here, potholes do a great deal of quiet damage.
- Worn or aged rubber. Tread depth is only part of the picture. Rubber hardens and cracks with age, and a tyre that has been on the car for a decade is a risk regardless of how much tread is left.
- Overloading. A fully loaded car or van on tyres set to normal pressures asks more of them than they are rated for. Most handbooks give a separate laden pressure.
- Damage that was never inspected. Bulges, cuts and scuffed sidewalls are all warnings. A bulge in particular means the internal structure has already failed and the tyre should come off the car straight away.
Warning signs worth taking seriously
Most blowouts announce themselves first, if you know what to look for. Any of these means the tyre needs inspecting rather than monitoring:
- A bulge or blister anywhere on the sidewall
- Cracking or crazing in the rubber, especially on an older tyre
- A cut deep enough to expose the cords underneath
- A vibration or rumble that has appeared recently and is getting worse
- One tyre that always needs more air than the others
If you have hit a pothole hard, it is worth a proper look at both tyres on that side, not just the one that made the noise.
Can a blown tyre be repaired?
No. A blowout is a failure of the tyre’s structure, not a hole in it, and there is no safe way to repair that. The tyre needs replacing. It is also worth having the wheel checked, because a tyre that fails at speed often takes the rim with it, and any suspension component that was hit should be looked at too.
This is different from a straightforward puncture, where a repair to the BS AU 159 standard is often possible and much cheaper than a new tyre.
Blowouts on the M4
We are called out to the M4 corridor between Bristol and Cardiff more than anywhere else, along with the M48, M5 and M32. The pattern is fairly consistent: motorway speeds, a tyre that was already underinflated or damaged, and a driver who did the right thing and pulled onto the hard shoulder.
If that is where you are, get behind the barrier first and call from there. We carry tyres for cars, vans and 4x4s on the van, so most motorway call-outs are dealt with in a single visit without a tow.
Frequently asked questions
What should you do if a tyre blows out while driving?
Hold the steering wheel firmly with both hands, come off the accelerator gradually and do not brake hard. Keep the car pointing straight until the speed has dropped, then indicate and steer gently to the left towards the hard shoulder or a lay-by. Stop, put your hazards on and get out on the passenger side.
Why should you not brake during a blowout?
Braking hard shifts the car’s weight forward and adds a large, uneven force to a vehicle that is already being pulled to one side by the failed tyre. That combination is the main cause of losing control. Letting the car slow gradually keeps it stable.
What causes a tyre blowout?
Underinflation is the most common cause, because a soft tyre flexes excessively and overheats until the structure fails. Other causes include pothole and kerb impact damage, ageing or cracked rubber, overloading, and unrepaired cuts or bulges in the sidewall.
Can a blown out tyre be repaired?
No. A blowout is a structural failure rather than a simple puncture, and there is no safe way to repair it. The tyre must be replaced, and the wheel should be checked for damage at the same time.
Is a blowout the same as a puncture?
No. A puncture releases air over seconds, minutes or days and is often repairable. A blowout is a sudden failure of the tyre’s structure, usually with a bang, and always means a replacement.
How can I reduce the risk of a blowout?
Check your tyre pressures at least once a month when the tyres are cold, inspect the sidewalls for bulges and cracks, have any tyre checked after a hard pothole strike, and do not run tyres that are more than about ten years old regardless of tread depth.