A puncture's position is one of the first things a fitter checks, but the visible tread is not one large repairable area. Routine minor repairs use a defined central zone, often called area T. The tyre must also pass an internal and external inspection.
The repair area is not the legal tread-depth band
The central three-quarters used in ordinary UK car tread-depth rules is a different measurement. It should not be used as a shortcut for deciding whether a puncture can be repaired.
BTMA's published minor-repair guidance defines the width of area T using the tyre's nominal section width. Its table uses 60% for widths up to 155mm, 65% above 155mm up to 200mm, and 70% above 200mm. The area is centred on the tyre. A fitter should apply the relevant repair guidance to the actual tyre rather than estimate the boundary from a photograph.
What happens near the shoulder?
The shoulder is the transition between the tread and sidewall. An injury that looks as though it is still in the tread can fall outside the permitted minor-repair area. A groove or a tread block is not a reliable boundary marker.
An ordinary puncture repair should not be used to work around an injury outside the permitted area. Ask the fitter to explain the position and the inspection finding. More specialised repair categories are not interchangeable with a routine passenger-car puncture repair.
Location is only one condition
The prepared injury size, angle, earlier repairs and tyre condition all matter. Damage caused by driving while flat can make a small central puncture unsuitable for repair. So can structural deterioration or exposed reinforcement. A tyre holding air after inflation is not proof that its structure is sound.
The tyre needs to come off the wheel for a proper assessment. Tell the fitter how the pressure was lost, whether you drove on it and whether a sealant or external plug has been used.
What to ask the fitter
Ask whether the inspection and quotation cover a permanent repair, refitting and balancing, and what happens if the tyre fails inspection. If replacement is needed, confirm the complete specification and the appropriate matching arrangement for the vehicle.
Source for the repair-area definition: BTMA tyre-industry repair guidance.
Further reading
Common questions
Is the repair area the central three-quarters of the tread?+
No. That is associated with the ordinary car tread-depth rule. Minor-repair area T is defined separately using nominal section width.
Can a small hole outside the repair area be plugged?+
A small diameter does not override the location and inspection requirements. Ask a qualified fitter to assess the tyre; do not substitute an external plug for a refused permanent repair.