You come out to the parking lot after work and discover you have a flat tire and no spare. You aren’t going anywhere. You call roadside assistance. The tech arrives, installs a tire plug and reinflates the tire and you’re back on the road again. But what is a tire plug, and how long does a tire plug last? Is it something you can count on?
What is a tire plug?
A tire plug is a strip of leather covered in a sticky rubberized compound that is then attached to a tool and inserted into the tire’s casing through the hole in the tread. From there, the plug can adhere to the lining of the tire and provide an effective repair.
Tire plugs have been used for at least 100 years since the earliest days of automobiles.
How long does a tire plug last?
In theory, a tire plug can last 7-10 years or 25,000 miles. But that depends on a lot of things. A plug is generally considered to be a stopgap repair until you can either have the tire patched or replaced with a new tire. In other words, a plug can indeed make for a good repair, but it may not be one you want to count on long-term.
Tire plug vs. tire patch–what’s the difference?
The biggest difference is that plugs are applied from outside the tire while patches are applied from the inside. Plugs are considered less reliable, though they have the advantage of not needing to remove the tire from the rim in emergency situations. That means they can be applied roadside with little in the way of equipment.
A plug is inserted from the outside and seals itself to the tire through pressure, centrifugal force and inflation. This mushroom-shaped seal should keep moisture from infiltrating the tire and keep air from escaping. The excess plug material is then trimmed so it’s flush with the tire tread.
A patch, on the other hand, is installed on the inside of the tire liner after roughing up the liner surface and applying a vulcanizing cement to ensure a positive seal.
Some plug/patch hybrid systems are also available, using both methods for tire repair. This is considered a superior repair method, but it’s no longer an either/or question.
When should you not plug a tire?
So, do tire plugs work? Yes, but there are definite caveats as to when a plug can be used successfully, even as a temporary repair.
A plug absolutely shouldn’t be used if:
- The puncture is anywhere near the tire shoulder or sidewall.
- The puncture is at an angle.
- The hole is any bigger than one-quarter of an inch.
- The hole is irregularly shaped.
- There’s a bubble or bulge in the sidewall.
- The tire was driven on after full loss of pressure, even for a block of so.
In addition, while it’s tempting to just get a tire plug kit and pull off a DIY repair, you really should remove the tire from the rim even for a plug job. It’s the only effective way to get a good look at the tire and see if there’s any additional damage other than the puncture. Most DIYers do not have tire irons and a tire mounting/balancing setup.
Tire plug alternatives
A plug isn’t an optimal solution for a flat tire—but neither is a patch. A plugged or patched tire is always considered compromised, regardless of how minor the damage might have been. The same goes for fix-a-flat and other tire repair products. Your best bet is to replace the tire completely, especially if the tire is already worn.
If you have to bite the bullet and replace the tire, that’s a good time to take a look at the condition of the other tires as well. In a perfect world, you’d replace all four tires simultaneously. Mismatched tires of different sizes, states of wear, tread patterns and even different brands can affect handling.