Tyre Punctures: String, Mushroom Plug, and the Holes Neither Can Fix
A plug seals a round hole in the centre tread and nothing else. How to tell the two common types apart, fit them so they hold, and recognise the puncture…
A puncture in the tread band is repairable; one in the shoulder or sidewall is not, and no kit on this page changes that. A plug costs a few euros, and a plug that fails costs a tyre, a rim, or a car. So: read the hole, choose the plug that suits it, fit it properly — in that order.
Read the hole before you open the kit
Three questions decide whether a plug is allowed at all. Any no, and the tyre comes off the rim for a workshop to look inside.
- Where is it? Centre tread only, the middle two-thirds of the running surface. Shoulder and sidewall flex every revolution and work a plug loose.
- What made it? A screw or a nail leaves a round hole. A cut, a tear or a pinch injury does not, and cannot be filled.
- Did it run flat? A tyre driven while soft has a damaged inner liner — invisible from outside, and permanent.
String or mushroom: the head does the sealing
Both kits work the same way: ream the hole, pull a plug through with the hardened carbon steel needle, cut it off outside. They differ in what presses against the inside of the tyre.
- Rubber string, 20 strips — cord through the hole, sealed by compression. The fastest roadside fix, the least permanent.
- Mushroom plug, 15 plugs — the stem fills the hole and the flat head sits against the liner, where pressure pushes it tighter instead of out.
- A soft needle doubles the work — it folds in a steel-belted tyre, and you ream the hole twice for one repair.
Three habits that shorten a plug's life
The plug is rarely the part that fails. The hole, the trim and the valve usually are.
- Reamed too little — the plug shears on the way in and leaves a channel that weeps.
- Trimmed too proud — a few millimetres of tail means a slow leak and a click at walking pace.
- The valve left alone — a stem split at its base reads as a puncture that keeps returning. New stems seat in the standard 11.3 mm rim hole; on a car, replace, don't re-tighten.
Where we would not plug at all
Two plugs in one tyre, a hole within 25 mm of the shoulder, a tyre past six years by its DOT code, or a run-flat driven flat: a kit is the wrong tool in each case. If the wheel comes off anyway, torque the bolts back to spec — see the socket and torque guide — and the tyre service range covers levers, spreaders and valves.
Delivery: we ship to the UK and the whole EU on a DDP basis — duty and clearance in the price, delivered to your door with nothing to pay on arrival. Sea freight runs 45–60 days door to door.
