You have most likely heard of a tyre plug, which is a self-vulcanising repair cord that is used to ‘plug’ the hole where a tyre has been punctured. While fast and convenient, plugging a tyre should only be used when there are no other options, and should only be considered a temporary or emergency repair.
A tyre plug is a sticky, malleable object that is slightly longer and slightly narrower than a cigarette, and it is forced in to a tyre using a special insertion tool.
When in place, it plugs the hole in a tyre caused by a foreign object such as a nail or screw, or a hole caused by a sharp object such as a rock or a tree root. Tyre plugs can only be used to temporarily repair tubeless tyres; you will need a vulcanising patch to properly repair a punctured tube.
If you make a repair to a tubeless tyre using a plug, you should ensure the tyre is repaired permanently as soon as practicable by removing it from the wheel and patching it from the inside.
Finally, plugs should only be used across the tread face of the tyre. If you get a puncture in the shoulder or the sidewall of the tyre, a plug is not a suitable repair choice. In fact, a tyre damaged in either of these areas will most likely be unserviceable and will need to be replaced.
Detecting deflation
When you are driving at high speed on the road, you probably won’t have any problems detecting a deflating tyre, as it will affect the way the vehicle handles. If it’s a front tyre that is deflating, it will affect the vehicle’s steering, pulling it to the direction of the deflating tyre.
If it’s a rear tyre that’s deflating, chances are you will feel the vehicle move around unpredictably, especially when cornering. When tyre pressure drops very low, you will hear the tyre make a flapping sound, by which stage it’s likely being subjected to irreparable damage.
It can be more difficult to detect a deflating tyre when driving at low speeds off road; as the terrain is uneven anyway, it can be more difficult to feel any effect a deflating tyre has on vehicle handling.
Of course, if your vehicle is equipped with a Tyre Pressure Monitoring System (TPMS), this should alert you to a deflating tyre well before any irreparable damage occurs. If you don’t have a TPMS fitted, you should consider equipping your vehicle with an aftermarket one.
A good quality TPMS only costs a couple of hundred bucks, which is less than the price of one good quality off-road tyre, so it will pay for itself even if you are only ever alerted to one deflating tyre.
Finding the cause
Once you have detected a deflating tyre, you should pull up as soon as it is safe to do so, and well off the road or track so that you are not in the way of other vehicles. You should also look for a level area to pull up in case you need to jack the vehicle up to remove the wheel with the deflated tyre.
You now need to find what caused the damage. Sometimes this is easy, as the object that caused the puncture can be an obvious protrusion. If the tyre is still partially inflated, there’s a good chance you’ll be able to hear air escaping at the puncture point. You will also be able to feel this with your hand. If the tyre is completely deflated, you’ll probably need to dig out your air compressor and pump it up to find the puncture point; you will need to reinflate the tyre to make the repair anyway.
If you can’t hear or feel the leak, you might be parked on top of the puncture, so drive forwards or backwards half a wheel turn and check again for the sound of escaping air. If you can find the leak, and it is in a repairable part of the tyre, mark it with some chalk. If you can’t find the leak, you will need to pour water over the tyre and look for bubbles that will indicate where the leak is. This task will be made easier with the wheel removed from the vehicle; it will also be easier to insert the tyre plug with the wheel off the vehicle.
Always ensure the park brake is on, the transmission is in gear/park, and the wheels are chocked before jacking up the vehicle to remove a wheel. You should also ensure the vehicle is secured and chocked if you are going to attempt the repair with the wheel still on the vehicle.
Tyre repair kit
You’ll obviously need a tyre repair kit to plug the tyre. Most four-wheel drive aftermarket companies sell tyre repair kits, and they all come with similar contents, so you might wonder why some are more expensive than others.
The answer lies in the quality of the tools in the kit, and when plugging a tyre you don’t want a crappy reamer or insertion tool that’ll fall apart in your hands, so always go for quality gear.
So, what will you find in a basic tyre repair kit? A plug insertion tool, a reaming tool, a pair of needle-nose pliers, an Allen key (for tightening the insertion and reaming tools when necessary), a small knife, a handful of self-vulcanising repair cords, a tub of lube, and several valve stems, valves and dust caps.
Of course, you will also need an air compressor and a tyre gauge, and once again, always opt for good quality units rather than cheapies.
Pump and plug
As mentioned, the tyre will need to be inflated to make the repair. Don’t be afraid to overinflate the tyre as you can set the correct pressure afterwards, and the higher the pressure, the easier it will be to insert the plug.
Once at the desired pressure, using the pliers, remove the object that caused the puncture and quickly insert the reaming tool in the hole to stop air escaping.
The next step is to push and pull on the reaming tool a few times to force it in and out of the hole; this will make the hole big enough to insert the plug. It will also clean the hole, which will be through several layers of the tyre including the tread face, and the various plies and belts.
When using the reaming tool, and later when inserting the plug, always follow the direction of the original puncture; so if it’s at an angle, clean the hole at that same angle.
Leave the reaming tool in the tyre while preparing the plug. Grab one of the plugs and dip one end in the tub of lubricant, then feed the plug through the hole in the needle of the insertion tool. Now apply a generous coating of lubricant to the plug and pull each side of the plug back so it is almost flush with the needle.
Remove the reaming tool and force the loaded insertion tool in the hole. Sometimes it will go in easily and sometimes it will require a fair amount of effort, aided by some grunting, swearing and sweating. If it’s a big struggle to get the plug in, try inflating the tyre a bit more.
Remember, it will be easier to insert a plug with the wheel removed from the vehicle, as you will be able to use more of your body weight to force the insertion tool in to the tyre.
Once fully inserted, push down on the collar of the insertion tool as you pull back on the handle to remove the tool. The collar will ensure the plug stays in the tyre. Have a listen for air leaks and pour soapy water over the repair and look for any bubbles that will signify a leak. Saliva is a good substitute if you don’t have any soapy water on hand.
If there is still a leak, it may need another plug (or even more) until the hole has been successfully repaired, but if you need more than one plug there is a higher risk of the repair failing, so you’d be better off fitting the spare.
If there are no leaks and the repair has proved successful, trim the excess plug so that it is flush with the tread face. Ensure the tyre is inflated to the correct pressure and refit the wheel (if removed).
Then drive for about 10 minutes and check the air pressure to ensure it’s not leaking, and that the wheel nuts are tight.
A permanent fix
As mentioned, a tyre plug should only ever be considered a temporary or emergency repair, and you will need to remove the tyre from the rim and inspect it thoroughly, both externally and internally, for structural damage.
If the tyre was run for any length of time while deflated, chances are the sidewalls will have been damaged, in which case the tyre should be replaced.
If there is no sidewall damage, and a visual inspection reveals that that area around the puncture can be safely repaired, the plug should be removed and a vulcanising patch applied internally to the punctured area.
If you don’t have the tools required to remove the tyre from the rim, or the know-how to perform a permanent patch repair, take the tyre to a specialist tyre repair centre for evaluation/repair.
Do
- Install a TPMS in your vehicle
- Always travel with a tyre repair kit and air compressor
- Handbrake on and chock wheels when jacking a vehicle
- Check that the tyre repair is holding air
- Tighten wheel nuts to correct torque settings (and recheck)
Don’t
- Try to plug a tyre sidewall
- Rely on a plug as a permanent repair
- Buy an el cheapo tyre repair kit
- Drive on a deflated tyre
- Forget to check you have plenty of plugs/lube in your kit
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