A repair to a tyre is covered by a British Standard — BSAU159f:1990
— which splits repairs into two categories - minor repairs and major repairs.
The British Standard also defines limits to the location, size and number of repairs
that can be carried out and makes recommendations also on the repair materials to be used.
A tyre must always be checked thoroughly before it is repaired.
If the tyre shows any of the following, it should not be repaired;
Illegal tread depth (below 1.6mm across the central ¾ of the tyre tread throughout the entire circumference)
Run flat damage - breakdown of the tyre's structural integrity
Secondary damage - caused by the injuring object
Ageing/deterioration of tyre rubber
Faulty/poor previous repairs