How Do Tire Plugs Work? [Answered]

It’s always nice to know how something works before using it, especially regarding something as important as road and tire safety.  

Below we will look in detail at how tire plugs work and whether they are a long-term safe solution.

What is a Tire Plug? 

A tire plug is an inexpensive and easy way to repair a punctured tire. It involves inserting a plug, usually made of leather encased in rubber, into the puncture. The plug will often be aided by cement to lubricate and bond the plug to the tire forming a tight seal to prevent air from escaping.

To use a tire plug, there is no need to remove the tire from the rim to insert it.  

Tire plugs are a great way to repair a puncture quickly and easily, but unfortunately, they don’t offer a permanent solution. The plug can eventually allow water and moisture into the tire to fall out or start leaking again.

How does a tire plug differ from a tire patch?

A tire patch is a more permanent solution for repairing a punctured tire. 

To use a tire patch, you’ll need to remove the tire from the rim, locate the puncture then apply a patch/plug combination.

This also gives a chance to inspect the inside of the tire for other damage. Not something that can happen unless the tire is taken off the rim.

The best patches are a combination of a plug and patch. These provide a vulcanized seal on the inside and the plug to protect from water and moisture entering the tire from the outside.

Tire patches are more reliable than tire plugs and offer a more permanent solution. However, they take more time, and the kits are more expensive.

Tire plugs are an inexpensive and easy way to repair a punctured tire, but they are less reliable and not recommended by tire manufacturers and industry bodies.

So How Exactly Do Tire Plugs Work?

There are two types of plugs used in tire repair.

A tire mushroom plug is a rubber plug inserted into a hole in the tire from the outside. The plug looks like a mushroom hence the name, and has a stem.

It works by the mushroom part of the plug getting forced through the hole and into the inside of the tire by a special screw mechanism tool which, when tightened, acts as a rivet to hold itself in place. The stem then plugs the injury site.

The hole still needs to be reamed to ensure it is circular and less than 6mm for these plugs to work. 

Although some kit manufacturers state that these are permanent repairs, remember that although the tire has been sealed, it hasn’t been inspected on the inside for further damage or vulcanized or sealed like a patch repair.

On the other hand, a tire rope/string plug does not seal the inner lining of the tire. 

String plugs work the same way as mushroom plugs in that they plug a hole in the tire that stops air from escaping.

 A string plug will not rivet tight or seal the tire’s inner lining but rely on pushing through the string into the hole so tightly that it prevents air from escaping when the tire is inflated.

Often cement is used for two reasons.  

Firstly it helps lubricate the string plug and helps it slide into the hole, and secondly, it bonds the plug to the tire’s rubber.

These kits are cheaper than mushroom plugs kits as you do not need a screw device but a needle tool. 

What makes both tires plugs less permanent is that the inside of the tire is never inspected. 

There is often further damage inside that makes repair dangerous, but this can’t be seen unless the tire is removed from the rim.

Here’s what Michelin says about tire plugs

The proper way to have a tire repaired is to patch the tire from the inside and fill the puncture hole. Do not have your tire plugged. Ever.

Plug repairs do not involve taking the tire off the wheel for a proper inspection. A plug is simply inserted into the punctured area, making it unreliable.

Michelin Tire Repair Advice

A mushroom plug is often confused with a tire combination patch/plug repair. They are not the same. A patch can be permanent a plug never is, according to the tire manufacturer themselves.

For this reason, tire shops never plug tires and insist on doing a proper patch.

Related Articles: Is your tire already plugged?  How Many Times Can You Plug A Tire? [ANSWERED]

In Conclusion

Both string and mushroom plugs work by sealing the tires’ injury site and stopping air from escaping. Both are considered – by tire makers – as temporary fixes, although many drivers use them as permanent repairs