Got a nail, screw or puncture? Answer five quick questions to see whether it’s likely to be repairable under BS AU 159, or whether you’re probably looking at a new tyre.
Puncture checker
Check your tyre in five quick questions
Tap the answer that fits best. If you’re stuck at the roadside, skip it and call us.
Quick guide: a nail or screw up to 6mm across, in the central three-quarters of the tread, can often be repaired to BS AU 159. Damage in the sidewall or shoulder, bigger cuts, bulges or exposed cords, a tyre driven flat and most run-flats usually mean a new tyre.
This checker is a guide only. The final repair-or-replace decision is made by the fitter after taking the tyre off the wheel and inspecting it inside and out.
Has the tyre been driven on while flat or very low?
Question 4 of 5
Is it a run-flat tyre?
Question 5 of 5
Can you see any bulges, cracks or exposed cords?
Your result
Likely repairable
Probably needs replacing
Needs checking
From what you’ve told us, this sounds like damage BS AU 159 allows to be repaired: a hole of 6mm or less in the central three-quarters of the tread, with no sign the tyre was run flat or that the casing is damaged. A proper repair means taking the tyre off the wheel, checking the inside and fitting a combined plug and patch from the inside. Leave the nail or screw in place until the fitter arrives.
Damage near the edge of the tread or on the shoulder falls outside the BS AU 159 repair zone, which only covers roughly the middle three-quarters of the tread. The shoulder flexes constantly as the wheel turns, so a repair there can’t be relied on to stay sealed. If the fitter confirms where the damage is, a new tyre is the safe option.
BS AU 159 does not allow repairs to the sidewall. The sidewall flexes on every turn of the wheel and carries much of the load, so a cut or puncture there weakens the structure of the tyre. Expect a replacement tyre, and avoid driving on it.
For car tyres, BS AU 159 limits repairs to damage of 6mm or less across. Bigger holes, cuts and gashes damage too much of the steel belts and cords underneath for a repair to be safe, so the tyre normally needs replacing.
Driving on a flat or very low tyre usually damages it from the inside, as the sidewalls fold and rub against each other. BS AU 159 does not allow a repair where running flat has caused internal damage. The fitter will take the tyre off and look inside before deciding, but be ready for a replacement.
Many run-flat tyre makers advise against repairs, or only allow them in narrow conditions, because the stiff sidewalls can hide damage from being driven without air. AH follows the tyre maker’s guidance, so a punctured run-flat usually needs replacing.
A bulge, crack or exposed cords means the structure of the tyre is already damaged. That can’t be repaired under BS AU 159, and the tyre could fail without warning. Don’t drive on it. Call us and we’ll come to you with a new tyre.
You’re not sure whether the tyre was driven while flat or very low. That matters, because running flat can damage the inside of a tyre even when the outside looks fine, and BS AU 159 does not allow a repair if it has. The fitter needs to take the tyre off the wheel and look inside.
You’re not sure if it’s a run-flat. Look on the sidewall for a marking such as RFT, ROF, SSR or ZP, or check the vehicle handbook. Run-flats usually need replacing after a puncture, in line with the tyre maker’s guidance.
This checker is a guide only. The final repair-or-replace decision is made by the fitter after taking the tyre off the wheel and inspecting it inside and out.
BS AU 159 is the British Standard for repairing car and van tyres. It sets out where on a tyre a repair is allowed, how big the damage can be and how the repair has to be done, so that it’s safe and permanent rather than a quick fix that just holds air for now.
Repairs are only allowed in the central three-quarters of the tread. Picture the tread split into eight strips across its width: the outer strip on each side is the shoulder, and that’s off limits along with the sidewall. Those areas flex on every turn of the wheel, so a repair there can’t be relied on.
For car tyres, the damage must be no more than 6mm across, which covers most nails and screws. The tyre also has to come off the wheel so the inside can be checked, because driving on a flat or very low tyre can damage the inner liner even when the outside looks fine. If there’s internal damage, it can’t be repaired.
The repair itself is a combined plug and patch fitted from the inside. A plug pushed in from the outside is not a BS AU 159 repair. Run-flat tyres are a special case: many makers advise against repairing them, and AH follows the tyre maker’s guidance. Read the full BS AU 159 repair guide for more detail.
Safety first
When not to drive on it
If the tyre is flat or clearly low, don’t drive on it. Even a few miles on a flat tyre can wreck it from the inside and turn a simple repair into a new tyre, and it can damage the wheel too. If you’re on the move when it happens, slow down gently and stop somewhere safe and off the road.
Don’t drive on a tyre with a bulge, a deep cut, cracking or exposed cords. Those are signs the structure has failed and the tyre could give way without warning. The same goes if you can hear flapping or feel heavy vibration through the steering.
A slow puncture with a nail in the tread may still hold air for a while, but it’s a gamble. Leave the nail in, keep speed and distance down, and get it looked at as soon as you can. If you’re stranded, our emergency mobile tyre fitting team comes to you 24/7. On a motorway, read our motorway flat tyre guide first.
Puncture questions
Tyre repair FAQs
For a car that can’t be moved, call from somewhere safe.
Can a tyre with a nail or screw in it be repaired?
Often, yes. If the nail or screw is in the central three-quarters of the tread, the hole is 6mm or less and the tyre hasn’t been driven flat, a BS AU 159 repair is usually possible. The fitter takes the tyre off the wheel and checks the inside before repairing it.
Can a puncture in the sidewall or shoulder be repaired?
No. BS AU 159 doesn’t allow repairs to the sidewall or the shoulder, because those areas flex on every turn of the wheel. Damage there means a new tyre.
Is a plug pushed in from the outside a proper repair?
No. A BS AU 159 repair is fitted from the inside, after the tyre has been removed from the wheel and inspected. An outside plug can hide damage and isn’t a permanent repair.
Can run-flat tyres be repaired?
Usually not. Many run-flat makers advise against repairs, or only allow them in narrow conditions, because the stiff sidewalls can hide damage from being driven without air. AH follows the tyre maker’s guidance.
Should I pull the nail out before you arrive?
No. Leave it in. It may be slowing the leak, and pulling it out can leave the tyre completely flat before help arrives.
What happens if my tyre can’t be repaired?
We quote for a brand-new replacement tyre in the right size, and the price is agreed on the phone before we set off. Wheel balancing is free with fitted tyres.
Is the checker’s answer final?
No. It’s a guide based on what you can see. The final repair-or-replace decision is made by the fitter after taking the tyre off the wheel and inspecting it inside and out.
