Flat Tire Repair: Plug, Patch, or Replace?
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Most nail-in-the-tread flats are repairable for $20–$40 at a shop — or about $15 with a plug kit at home. But some damage makes a tire scrap: know the difference before you spend anything. This guide covers the rules, then walks through a temporary plug repair.
A plug inserted from outside is widely considered a temporary repair — the industry-standard fix is a patch (or plug-patch combo) applied from inside the tire, which requires removing the tire from the wheel. Never repair sidewall or shoulder damage, and never repair the same tire more than twice. When in doubt, replace. If you do take the wheel off to reach the puncture, never put any part of your body under or beside a car supported only by a jack — see our tire-changing guide for jack points and jack stands.
What you'll need
- Tire plug kit (reamer, insertion tool, plugs, cement)
- Pliers (to remove the object)
- Tire pressure gauge and air source
- Soapy water in a spray bottle (leak check)
- Jack and wrench (if the wheel must come off)
The steps
Tap through one step at a time — built for one-handed use at the roadside — or switch to all 8 steps to read ahead or print.
Step 1 of 8: Find the puncture and assess it
Step 1: Find the puncture and assess it
Look for the nail or screw in the tread, or spray soapy water and watch for bubbles. Note the location precisely — repairability depends entirely on where and how big the hole is.
Step 2: Rule out unrepairable damage
Do NOT repair if the puncture is in the sidewall or shoulder (the curved area past the tread edge), larger than 1/4 inch (6mm), if the tire was driven on while flat (internal damage), or if the tread is already near the wear bars. In all those cases the tire must be replaced — no exceptions worth your life.
Sidewall repairs fail catastrophically because the sidewall flexes constantly. Any shop offering to patch a sidewall is a shop to avoid.
Step 3: Remove the object and ream the hole
Pull the nail or screw straight out with pliers. Push the reamer from the kit into the hole and work it in and out several times — this cleans the channel and sizes it for the plug. Expect a hiss as remaining air escapes.
Step 4: Insert the plug
Thread a plug strip through the eye of the insertion tool so it's centered, coat it with the kit's cement, and push it firmly into the hole until about a half inch remains outside. Pull the tool straight out quickly — the plug stays behind, sealing the channel.
Step 5: Trim and reinflate
Trim the excess plug flush with the tread. Inflate the tire to the door-jamb pressure — you may need to do this where the car sits, so a portable inflator earns its keep here.
Step 6: Leak-check with soapy water
Spray the repair and the valve stem with soapy water. Steady bubbling means it's still leaking — the plug needs to be redone or the tire needs professional attention. No bubbles: you're sealed for now.
Step 7: Get a proper internal patch soon
Drive gently to a tire shop and ask for an internal patch or plug-patch combo. The tire comes off the wheel, the interior is inspected for hidden damage, and the liner is sealed — the only repair the tire industry considers permanent.
Step 8: If it's unrepairable: replace in pairs when possible
A scrapped tire should ideally be replaced together with its axle-mate so both sides have matching tread depth — critical on AWD vehicles, where mismatched circumferences strain the drivetrain. Some shops can shave a new tire to match on AWD cars.