A practical guide to slow puncture for UK drivers, from the CarPal mobile tyre team.
What a slow puncture looks like
The classic sign is one tyre that needs topping up every week or two while the others hold pressure fine. Normal loss is 1–2 PSI a month across all four.
You may also see the TPMS light appear repeatedly on the same corner, or notice the car pulling slightly to one side when the tyre is at its lowest.
Common causes
A small object in the tread — a screw, a staple, a piece of wire — that seals well enough to leak slowly rather than deflate fast.
A leaking valve or valve core, which is common on older valves or where the cap has been missing.
A corroded or kerb-damaged wheel rim preventing a good bead seal.
Occasionally a leak only under load, which seals when the car is parked and makes it harder to find.
Finding it
Soapy water sprayed across the tread, the valve and around the bead edge will bubble at the leak point. Submerging the wheel is more thorough.
Either way it needs the wheel off the car to check properly, which takes a few minutes with the right equipment.
Why not to ignore it
A tyre you top up weekly is running under-inflated most of the time — wearing on both shoulders, using more fuel, and building heat.
It will also eventually deflate somewhere inconvenient. Finding the leak now is cheaper than a new tyre later.
Frequently Asked Questions
What is a slow puncture?
A slow puncture is a gradual loss of air pressure caused by a small leak in the tyre. Unlike a sudden puncture, it may take several hours or days for the tyre to become noticeably under-inflated.
How do I know if I have a slow puncture?
Common signs include one tyre repeatedly losing pressure, frequent need for inflation, or a tyre pressure warning light appearing on your dashboard. Check your tyre pressures regularly using a reliable gauge and follow your vehicle manufacturer's recommended pressures.
Can a slow puncture be repaired?
In many cases, yes. A puncture in the central tread area may be repairable following a proper internal inspection. Damage to the tyre's sidewall, shoulder, or internal structure may make repair unsafe. Leaks from the valve or wheel rim may also be repairable.
Is it safe to drive with a slow puncture?
Driving on an under-inflated tyre can cause overheating, increased stopping distances, poor handling and further tyre damage. If you suspect a slow puncture, check the pressure before driving. If the tyre is significantly under-inflated, visibly damaged or losing pressure rapidly, do not continue driving. Arrange a professional inspection and repair.
Concerned about a slow puncture?
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