If you are unsure as to whether a puncture can be fixed, this free printable repairable area gauge allows you to see in which area of the tyre tread it is possible to safely and legally repair a puncture. Simply click the image below and open the PDF file or save it to your computer. You can then print out the gauge and hold it up to the tyre to determine whether the puncture falls inside the repairable area. To open this file you need Adobe Acrobat reader. Most computers have this already, but if yours doesn't, it can be downloaded for free from get.adobe.com/uk/reader/.
The “repairable area” of a tyre is designated as that where a repair can be carried out to British Standards (currently BS AU 159f).
Because a tyre curves away from the middle of where the tyre rolls on the road, only the centre area is repairable. Sidewalls are not repairable.
Follow the printing instructions so that it is the right size, cut it out, read the tyre width off its sidewall, then put the centre line of the gauge in the middle of the tyre where the puncture is. If the puncture falls between the markings for that size tyre, it is probably repairable.
(Note that the tyre may not be repairable if the hole is larger than 3mm or there is other internal damage to the tyre.)
Click on the image below to download your free repairable area gauge in PDF format