How to Plug a Tire on the Trail
Most flats on the trail are a nail, a screw or a sharp rock through the tread. A string plug fixes that in about ten minutes without pulling the spare, and you are back to rolling once the tire is aired up. Here is how to do it.
What you need
- A plug kit: reamer, insert tool, repair strings and rubber cement. The SAO 53-piece kit has all of it plus pliers and valve parts.
- A way to put the air back in: an onboard compressor or a portable one. See air & recovery.
- A knife to trim the plug.
Step by step
- Find the leak. Look for the nail head or the cut. If you cannot see it, put some air in and spray or pour soapy water over the tread. It bubbles where it leaks.
- Pull the object. Use the pliers. Note the angle it went in at.
- Ream the hole. Push the T-handle reamer into the hole at the same angle, then work it in and out several times. This cleans the hole and roughs it up so the plug seals.
- Load the plug. Thread a repair string through the eye of the insert tool until it sits in the middle, and coat it with rubber cement.
- Insert it. Push the insert tool into the hole until about a third of the string is left showing. It takes real force.
- Pull the tool straight out. Do not twist it. The string stays in the tire.
- Trim. Cut the tails off flush with the tread.
- Air up and check. Inflate to pressure, then put soapy water on the plug again. No bubbles means it is sealed.
When a plug is not the fix
- Sidewall damage. Never plug a sidewall. The sidewall flexes with every turn of the tire, and a plug there will not hold. That tire needs replacing.
- Big cuts and tears. A plug fills a puncture. It does not hold a gash together.
- Driven flat. If the tire was driven any distance with no air, the inside can be damaged where you cannot see it.
A string plug is a field repair. Once you are home, have a tire shop look at it.
The kit
The 53-piece tire plug repair kit is $32.99: a T-handle spiral reamer and insert tool, 15 repair strings, 10 mushroom plugs in two sizes, 2 tubes of rubber cement, needle-nose pliers, 4 valve cores and a valve core tool, a lock-on air chuck, 14 valve caps and gloves, all in a zip case that rides behind a seat.
Can you plug a tire on the trail?
Yes, for a puncture in the tread of a tubeless tire. Ream the hole, insert a cemented string plug, trim it and air up.
Can you plug a tire sidewall?
No. The sidewall flexes and a plug will not hold. A sidewall puncture means a new tire.
Is a tire plug permanent?
Treat it as a field repair and have a tire shop inspect it when you get home.
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