More often, a puncture is not only caused by a foreign object penetrating the tyre (e.g. a nail). Reduction in tyre pressure may also be caused by valve failure or the breakage of the link between tyre and rim (often caused by a collision such as hitting a curb with force).
Tyre repairs are only permitted in the treaded area of a tyre i.e. the area that makes contact with the road surface – these are deemed as ”minor repair zones”. Repairs are not permitted in ”major repair zones” i.e. the sidewall or any other areas of the tyre. In certain situations it may be advisable to fit a new tyre as opposed to repairing the current one. For example; if the tread depth is illegal (less than 1.6mm across the central 75% of the tyre), if there is evidence of deterioration or damage (e.g. exposed cords or bead damage) or if a poor quality repair has been carried out on the tyre previously. Tyres will always be thoroughly checked before a repair is carried out. Unfortunately not as it is difficult to ascertain how long the tyre has been driven on with a puncture or how damaged the tyre wall has become. Tyre manufacturers recommend not to repair and run flat tyres.