Back in the day, cars were much simpler, and operating them was more straightforward. And I'm not only talking about electronics here – the full-size spare tire has gone for good and will probably never come back. In its place, we have a donut spare (also on the chopping block), tire repair kits (the new norm), and run-flat tires (the darling of premium car brands).
All of those solutions are more complex than the original spare tire. In the past, you would replace your tire with the spare one and travel until you found a tire shop to repair shop. Then, the tire technician would just patch the punctured tire and leave it in the trunk – no need for replacing the tires again.
The donut spare, tire repair kits, and run-flat tires, though, all come with various limitations. For starters, you can't use them for more than 50 miles (80 km) after a puncture, which can be very restricting if you are far from a populated area. Moreover, they will usually limit your top speed to 50 mph (80 km/h), which is another bummer.
Many owners of premium vehicles that have run-flat tires also wonder whether they can plug them. On a regular tire, you could easily plug the puncture and continue driving, but is it the same for run-flats? Can you plug a run flat tire and call it a day?
It's not an easy question to answer since there are many variables, so let's dive into the world of run-flat tires and see whether you can repair one or not.
What is a Run-Flat Tire?
A run-flat tire, as its name suggests, allows you to continue driving after a puncture or a loss of pressure. Most run-flat tires will limit your top speed to 50 mph (80 km/h) and let you drive for up to 50 miles (80 km) before you need to repair the tire.
The reason why run-flat tires can work at zero pressure is their stiffer sidewalls, which can hold the weight of the car by themselves. However, they can't do that indefinitely, and prolonged driving can seriously damage the internal components and make them inoperable. This is the biggest concern of run-flat tire owners, who have already paid a fortune for a new set, and rightfully so.
Based on the brand, there are currently two run-flat technologies – self-supporting and with a support ring system. The self-supporting run-flat tires use a reinforced sidewall construction and are the most prevalent today. Due to their stiffer sidewalls, tires with this technology also tend to be sharper to drive, though at the cost of ride quality.
Meanwhile, the support ring system employs a rubber ring attached to the inside of the rim, which is only utilized when the tire completely loses pressure. Thus, this technology doesn't alter the tire's performance at the manufacturer's recommended pressure but also adds more weight and complexity.
Regardless of the technology, each run-flat tire must be paired with a Tire Pressure Monitoring System (TPMS) to alert the driver when a loss of pressure occurs.
Run-flat tires do have many advantages, but the primary one is safety. Namely, in case of a blowout, a run-flat tire will continue to support the vehicle and let you control it, while a regular tire could destabilize it. Moreover, having no spare tire in the trunk leaves more space for the stuff you need and also cuts weight, which is great for fuel economy.
However, run-flat tires are also heavier and add unsprung weight, which increases inertia, which has many negative side effects, including worse performance, less agile handling, longer stopping distances, and a harsher ride.
The higher weight also accelerates tread wear (the reason why run-flats come with shorter treadwear warranties) and reduces fuel economy (though this is negated by removing the spare tire).
What Does it Mean to Plug a Tire?
Plugging a tire is a popular and convenient option for repairing a puncture while on the road. It involves inserting rubber plugs inside the punctured area of the tire, which helps to maintain tire pressure.
Tire plug kits are widely available in most auto stores and gas stations, making them an easy option for drivers. The kit typically contains rubber plugs, rubber cement to secure the plugs in place, and a reamer tool to open the hole, making it easier to insert the plugs.
However, while tire plugging is a common practice, it is not without its drawbacks. One of the primary concerns with tire plugging is that the reamer tool used to open the hole can potentially damage the polyester casing or steel belts in the tire, leading to a significant weakening of the tire's stiffness. This weakening can result in reduced performance and, in some cases, a complete failure of the tire.
Additionally, if the plug does not work, drivers may need to repeat the process, causing further damage to the tire. Therefore, while plugging a tire may seem like an easy and convenient option, it should not be considered a permanent solution.
In general, it is recommended to only plug a tire with punctures up to 1/4 inch in size. Anything larger than that would require the services of a professional technician for proper repair. Furthermore, drivers should exercise caution when plugging a tire, as even a small mistake during the process can lead to significant damage.
So, tire plugging is not without its limitations and risks. While plugging a tire may be a quick solution, it should not be considered a permanent fix. Drivers should exercise caution when plugging a tire and only do so when necessary and appropriate. For anything beyond a small puncture, drivers should seek the services of a professional technician for proper tire repair.
Should You Plug a Run-Flat Tire?
Okay, now we come to the million-dollar question – can you plug a run flat tire? And to that, my answer is – yes, you can, but you probably shouldn't do it. In other words, you can use your tire plug kit to seal the puncture and continue driving, but just like with regular tires, you might do irreversible damage to the run-flat tire.
But here, the issue is even more pronounced because run-flat tires rely on their structural rigidity to support the vehicle in case of a puncture. Therefore, damaging its internal components can reduce its safety and leave you stranded without any means of repairing the tire.
Furthermore, tire manufacturers advise against repairing a run-flat tire and will certainly void the warranty. This is especially true if you plug a run-flat tire instead of patching it, which is a safer method that doesn't compromise the internal components.
So, yeah, you could plug a run-flat tire, but you probably shouldn't do it. Instead, I would advise using its self-supporting ability to go to the nearest gas station, re-pressurize the tire, and continue to the nearest tire shop. There, the professional tire repair technician will remove the tire from the rim, inspect it thoroughly, and patch it from the inside.
The technician will also tell you whether you can continue using that tire; the structural rigidity of run-flat tires can be compromised because of very large punctures or blowouts, but also from using their self-supporting ability for longer than 50 miles (80 km) and at speeds higher than 50 mph (80 km/h).
Is it Better to Patch a Run-Flat Tire Instead?
Yes – patching a run-flat tire is a safer option that won't damage the internal components. However, it's also much more time-consuming and requires significant DIY experience and special tools. Basically, you would need to remove the tire from the rim, find the puncture, patch it, and put everything back on. For this reason, professional tire shops always use patches to repair tubeless tires and not plugs.
Which Brand of Run-Flat Tires Can be Repaired?
Every tire brand will let you repair a run-flat tire, but only at a professional tire shop. Moreover, most companies will void the warranty if the damages on the tire are too extensive and advise you to buy a new tire.
When You Should Not Repair a Run-Flat Tire
You should absolutely not repair a run flat with a damaged sidewall because it's the most important structural part of these tires. However, holes with a diameter larger than ¼ inches should also not be repaired, especially not by amateurs or DIYers. Run-flat tires require special care, and you should treat them differently than regular tires.
Run-flat tires were designed to make it easier for the driver in case of a puncture, but that's only true if you look at the matter from the surface.
Dig into the fine print, and you'll see that reputable tire brands like Michelin, Bridgestone, Continental, Goodyear, and Pirelli are all very strict about plugging a run-flat tire and won't let you do it. They are even cautious about letting technicians without proper training repair these tires.
So, my advice is to be cautious with your run-flat tires after a puncture and never exceed the manufacturer-recommended limitations and then find a reputable shop to patch the tire from the inside. That way, you'll ensure the tire lasts longer, which saves you money in the long run.
I’m Ivo Gievski, the content writer for Tireer. We built our website with over 15 years of experience and extensive research in the automotive and technology sectors. My dedication to delivering high-quality content is unwavering, and I strive to continuously hone my skills to stay ahead of industry trends and provide readers with informative, engaging, and valuable insights.