Tyres operate on a very simple basic principle: they provide a cushion of air between the wheel and the road surface to provide a smooth ride and protect the wheel against damage the road could inflict. But you might encounter a situation where you can't get the tyre to inflate, losing that cushion of air and leaving you stranded. There are a few possible causes why this could happen.
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Although you might be tempted to sell your car quickly and easily with our Instant Offer tool and start your search for new or used models on AutoTrader, let us first investigate to see what the possible causes could be for your vehicle's tyre not inflating.
Possible reasons for a flat tyre not inflating
1. The tyre is punctured or torn
This is the most probable cause, yet it could be surprisingly hard to diagnose. Punctures could be caused by an external object (such as a screw or a roofing nail) perforating the tyre, creating a small hole in the rubber through which the air could escape. Punctures can usually be remedied by applying a patch (also known as a gaiter) to the inner surface of the tyre (in other words, the inside of the tyre, facing the wheel) to seal off this hole.
You could also try using a can of tyre sealant: injecting this goo into a leaking tyre will often seal it off sufficiently to stay inflated long enough to get you home. Avoid the temptation of plugging the hole with a proprietary tyre repair kit (commonly known as a plug), unless you're really stuck in the middle of nowhere with no alternative – the action of inserting a plug into the tyre's tread could easily damage the tyre’s carcass (the metal- and fabric reinforcing weave which generates the tyre’s physical strength), leading to the formation of air bubbles in the tyre or even inducing a complete rapid deflation (blow-out). This is a safety risk and should only be considered as a last resort.
Torn tyres are something else entirely and usually occur as a result of a cut in the sidewall (the “upright” section connecting the wheel’s rim and the tread). This could be caused by a sharp rock or something similar slicing into the sidewall (something with which most serious off-roaders will be familiar). Such damage can unfortunately not be treated by the roadside, as there simply doesn't exist a patch or sealant strong enough to cover up a torn tyre.
2. The valve is leaking
Leaking tyre valves can cause tyre deflation in two ways: the rubberised valve housing could be leaking where it sticks through the wheel rim, or the actual valve core itself could have a sealing problem. The former can only be remedied by a tyre fitment workshop, as it requires specialised equipment to remove the tyre and then clean or replace the valve housing for an air-tight seal.
A leaking valve core is slightly simpler to remedy, but you will need a valve removal tool and an air compressor (to inflate the tyre after replacing or cleaning the sticking valve). Tyre valves can leak due to the ingress of dirt, causing a small gap through which air could escape or because it's physically damaged. Dirt is the most likely cause of a leaking valve, which means that you probably won't need to replace the valve itself – although reputable tyre repair workshops generally replace the valve.
3. The tyre doesn't seal against the wheel rim
The most common cause of this kind of leak is small gravel stones or dry grass getting stuck between the tyre and the wheel. This could happen while off-roading or even just when driving through a field with freshly cut grass. There isn't much you can do about this malady unless you have the equipment needed to remove the tyre from the rim before cleaning it of any such debris and refitting the tyre.
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There's another possible cause, however, involving reconditioned or re-painted wheels. If the surface preparation of the wheel isn't performed correctly before the paint is applied, the coat of paint may flake and break loose from the area where the wheel's metal surface meets the tyre. These flakes won't be enough to ultimately unseat the tyre, but they will introduce a route by which the pressurised air inside the tyre could escape to the atmosphere. Yet again, the repair for this problem falls outside the scope of the average motorist, and should ideally become the problem of the workshop which painted the wheels.
4. Physical damage to the wheel or its rim
We've already discussed damaged tyres, but tyres failing to inflate could sometimes also result from a damaged wheel. Alloy wheels are especially sensitive to this because they're easily damaged by potholes, which could develop cracks at the interface between the wheel and the tyre.
This poses an additional safety risk, as there's a chance that the wheel might disintegrate at speed, which will lead to a total loss of control of the vehicle. Always inspect the wheel carefully when facing a mysterious pressure loss or inflation failure. If it's not the tyre itself or the valve leaking, chances are that you could be faced with replacing the wheel itself.
Hopefully, this list will help you troubleshoot the next time you're faced with a tyre that refuses to inflate. Use this information when you visit the tyre repair workshop – it may save you money if you know exactly what's wrong beforehand.
