How To Patch A Tire

Being a professional mechanic is waking up every day and not knowing what kind of issues or problems are going to roll into your garage. That being said there are a few issues when it comes to automobiles that stay pretty constant, and one of those is “flat tires”. By this point, I’m sure every mechanic or car enthusiast is nodding in agreement. Flat tires, well, they just happen. Millions of cars are on the road across the country at any given moment and per vehicle, you have four or more tires! With literally tons of debris in the form of rocks, nails, sharp metal, glass, and even bones, it’s just a matter of time before something inevitably ends up in a tire!

A punctured tire is absolutely no laughing matter and should be addressed as soon as the diver is aware and any automotive professional will agree. After all, your tires are what keep you in control of your metal cocoon that is barreling down the highway with you and your family inside! Mix in a tire that is losing air pressure into that situation and you have a recipe for disaster waiting to happen. Thankfully, this is where professionals like myself are here to save the day, or save your tire at the very least.

This page will go into detail with explanations and depictions of how to properly patch a tire like a professional. The type of tire patch we will be using in this article is what is called a “patch plug combo”. This type of patch is highly regarded as one of the best and safest on the market today.

Before moving onto the step-by-step process I think it is important to explain that step number 1 will begin where the tire has already been removed from the rim. After all, to use a patch plug combo you must remove the tire from the wheel. If you need instructions on how to remove a tire from a rim you are in luck because we have explained the process very carefully in a previous post here. That article also details how to properly mount a tire as well, which will be required at the end of this demonstration.

Lastly, this process is going to assume that you have a tire machine at your disposal to properly remove and mount a tire properly so that we can access the inside of the flat tire for proper fixing. If you do not have a tire machine and are interested in getting one for your shop or home garage we have already collected and cataloged the best ones on the market in this article here, “11 Best Tire Machines & Wheel Balancers“.

Now, without further a due let’s begin!

How To Plug A Tire

Step 1: Locate The Cause Of The Leaking Tire

(The image above shows a flat-headed nail in the tire. We have marked the area where the nail is at)

Well for starters, we have a flat tire so that means there must be something wrong with the wheel assembly in question. There are a few steps in which I personally go about locating this issue with the tire at hand. The first being that I live in the northeastern part of the US which means we see a lot of salt, mud, and slush which translates to corrosion and other sediment build-up being very common. So the first thing I do after pulling the problem tire off the vehicle is pumping the tire up to around 35 PSI.

This will hopefully make the tire force more air out of the location it is leaking from. After the tire is up to about 35 PSI, I give it a spray down with some soapy water. Making sure the entire tire including sidewalls and both beads are covered as well as the tire stem. After a good soaking in soapy water, it is your job to spot where the bubbles are appearing from. Finding bubbles means you have found your problem! If you find that the bead is creating very fine bubbles that means you need to remove the tire, clean the rim, and reseal the tire.

If you find a screw, nail, bolt, piece of metal, piece of wood, piece of bone, etc., mark the location so you will be able to easily find it later. In this demonstration it was quite easy to see that issue, we can clearly see and flat aluminum roofing nail in the middle of the tread. Bingo! I drew a box around it with a yellow crayon. After you have marked the location with a crayon or marker, remove the valve core to allow the tire to deflate. Also! Mark the location of the valve stem, I’ll explain later in the article the reasoning behind that step. For now, deflate the tire and move onto step 2.

Step 2: Remove The Tire From The Rim

As stated above we will begin our instruction on how to professionally patch a tire at the point where the tire has already been removed from the rim like the image shown here. If you need a refresher on how to remove a tire from its’ rim please visit our previous article, “How To Professionally Install A Tire Using A Tire Machine“.

Step 3: Move To Your Flat Tire Work Station

A key location in any garage or mechanic shop is the flat repair station. Here we have all the tools necessary to tackle almost any flat tire such as multiple types of patches and plugs as well as all of the hand tools and power tools we will need to get the job done.

One of the most frustrating things that can happen when working on a flat tire is trying to keep the tire from rolling around while you’re trying to drill delicate holes in it or buff the inside of the tire. Thankfully there are what’s called “Tire Spreaders” on the market and they come in many forms but all serve the same function. Holding the tire open and anchoring it into place while you work. Trust me, you will never go back to trying to hold a tire still after fixing a tire on one of these things. Now that the tire is anchored down you are ready to move on to the next step.

Step 4: Remove The Object In The Tire

Next, you want to find the easiest approach to removing the object that has punctured the tire. In this demonstration, we used a pair of plyers to grab hold of the head of what turned out to be a self-tapping screw. Removing the object in question will often not be this easy though. Sometimes you may need to get creative to remove a screw that’s head has worn off. For example, I have taken an old screwdriver and sharpened it to a point to help push objects through from the inside out or outside in.

You may also realize how important it was to mark the location where the puncture has taken place. Usually, after the object is removed it is hard to see where the original hole was, so marking it helps us return to the problem after looking away to fetch the right tools.

Anyways, the most important thing you must accomplish in this step is removing the object from the tire without making the hole any larger. Get the object out and move onto the next step.

Step 5: Scrape The Inside Of The Tire

This step could be considered optional if you do not have the right tools for it but will be very helpful and reduce the headache you could get from having to clean your tools. For this step you will need “pre buff” and some sort of metal scraper to remove the waxy layer from the inside of the tire. Removing this layer will help keep the buffing head on your drill from gumming up during the next step.

In this example, we are using Steelman Pre Buff and a Scraper tool in combination to remove the protective layer of wax from the inside of the tire. Removing this layer will help keep your abrasive buffing wheel from gumming up during the next step. Additionally, the rubber cement will adhere to the inside of the tire much better without the waxy inner coat present.

Moving on, thoroughly coat the inside area where the tire puncture has taken place with the pre buff and then immediately and aggressively scrape the inside of the tire with the scraping tool. You will notice that the waxy layer on the inside of the tire will begin to accumulate on your scraping tool and inside the tire, this is what you are going for. In the example pictured below, you can see the wax layer accumulating as it is being removed from the inner wall of the tire. After you begin to see that there is no more wax being removed with the scraping tool you can continue to the next step.

Your finished scrape job should look like the example below. As you can see the shiny waxy layer has been removed and the inside rubber of the tire is now exposed and ready for buffing. Additionally, the removal of the waxy layer will make it easier to see the puncture in the tire. It is very small in this example but if you look closely you can see the small through-hole the screw has left behind after wax removal in this image below.

Step 6: Drill Out The Through-Hole

For this step, the tools you are going to need is a hand drill, (corded or cordless), and a 1/8″ Carbide Cut Burr drill bit. The size of the drill bit may vary depending on the size of the plug/patch-plug you are using but for this example, we have 1/8″ patch-plug combos so the 1/8″ bit is what I am using.

Now it may seem counter-intuitive to drill out the hole wider than what was left behind by the screw but trust me, this process will ensure a proper fit to your plug and ensure minimal to no water penetration into the inner steel belts of the tire. The end result will be a plug that is guaranteed to last the lifetime of the tire.

Moving on, begin by locating the point at which the screw or object has pierced the inside of the tire, and at the exact angle of the hole through the tire, drill out the hole completely through to the other side.

As you can see in the image above I have pushed the drill bit completely through from the inside of the tire to the outside of the tire being careful to follow the same exact path the screw took through the tire. It is important to not get carried away when drilling out the hole however. You only want to drill the hole a maximum of three or four times total because you want to be sure that there is sufficient rubber left for the glue and plug to grab onto to stay seated.

The end result of drilling out the hole in the tire will look something like this. As you can see the hole is slightly larger than before which will allow the plug to be easily pulled through the tire in the following steps.

Step 7: Buffing The Inside Of The Tire

The next step can be performed a few different ways and I have seen some mechanics over the years get very creative with this process, but as long as the end result is the same you’ll be golden. Of course, having the tools described here will make this process as easy as possible.

In this step, you will be buffing the inner wall of the tire with an abrasive head and a dremel of some sort. In this instructional, I will be using an Air Dremmel, also referred to as an Air Die Grinder in combination with a 2″ copper buffing wheel. However, I have seen other mechanics use an electric dremel with other various buffing heads or wheels to achieve the same result. I have also witnessed some mechanics use very coarse grit sandpaper and some elbow grease to rough up the inside of the tire as well. No matter how you choose to buff the inner wall of the tire as long as your results look similar to mine you will be fine to continue to the next steps below.

Begin to buff out the inner wall of the tire around the area where the hole is located. Since I am using a patch plug combo and my patch is about an inch and a half in diameter I will buff about a one-inch radius from the hole in every direction to be sure that the entire patch is seated on the buffed rubber surface.

In the image above this is what your result should look like. Now it is VERY important for me to mention that this step in the tire repair process takes the most skill and a keen eye! This is because that if you get carried away and press too hard for too long in your buffing process you may accidentally buff through the inner liner of the tire and into the structural support of the tire. If you remove too much inner liner and expose or cut the inners of the tire I have some unfortunate news for you, you must throw away the tire.

Any mechanic or tire technician will tell you that if the structural integrity of the tire in question is compromised by any means, the tire must be disposed of and you are then responsible for the replacement of the tire. So like I said before, please be careful when buffing the inner wall of the tire! Take it slow and do not use a heavy hand and you will be fine to move onto the next step.

In the image above I am making certain that the patch fits within the buffed area of the tire before moving onto the next step.

I also forgot to mention that I use a small brass hand brush to brush away any rubber shavings from the buffed area. This is an important step because we want the rubber cement to adhere the patch directly to the tire and not the rubber shavings. You can see the brushed-away rubber shavings in the lower left-hand side of the picture above.

Step 8: Place The Patch And Plug

This is a fairly simple step in the tire repair process and you’ll be glad to know that we are almost done!

For this step, you will need chemical cement to ensure that your patch adheres to the inside of the tire as tightly as possible. This is because you do not want to have any air leaks! That would defeat this entire process of fixing the tire. I will be using Steelman Chemical Cement for this example but any chemical cement will do just fine.

Apply an adequate layer of chemical cement in and around the drilled out hole and the buffed area we have been working on. I have provided an example of what the cement application should look like above. After you have applied the layer of rubber cement to the inside of the tire, allow about one or two minutes for it to begin to cure before adding your plug and patch.

While I wait for the cement to cure for about a minute I like to remove the non-stick cover from my patch-plug combo in preparation for its’ placement.

It has now been slightly over a minute since the application of the chemical cement. The non-stick layer has been removed from my patch-plug combo and I have inserted the metal tip of the plug into the hole on the inside of the tire as shown in the above image.

As you can see in the image above the metal tip of the patch-plug combo is now protruding on the outside of the tire. Once the metal tip is visible you can then use a pair of pliers to pull the rubber plug through until the patch portion is seated flush against the inside wall of the tire. I would like to note that when you are pulling the rubber plug through the tire it helps to use a constant gradual pull rather than a fast jerk because the rubber plugs tend to snap before the patch is seated. If you find yourself in that situation simply removed to broken patch plug and retrieve another new one.

As you can see in the above image, the patch portion is seated against the inside of the tire and directly inside the rubber cement that we had applied prior. This step is now complete and you may move onto the next step.

Step 9: Stitching The Tire Patch

This step is very simple but will require you to have a Stitching Roller, also known as a Patch Roller similar to the one featured in the image below.

It is possible to use your imagination and figure out a way to roll on a tire patch to achieve the same result but it is much easier with this tool handy.

Now that you have you’re patch roller handy you may begin to press on and roll the patch into the chemical cement. Do not be afraid to use a fair amount of pressure when rolling on the patch, you want to make sure that there are no air bubbles trapped underneath the patch. Proper patch rolling technique requires the technician to roll the patch in at least three different directions where you completely cover the surface area before switching directions.

As you can see in the image above I have stitched the patch in multiple directions. With the amount of pressure I applied to the patch roller, directional indentations were left behind on the plastic film on the exterior of the patch. After you have finished stitching the patch in at least 3 directions you can now remove the inner plastic film from the top side of the patch as I have done in the image below.

Once you have removed the plastic film from the patch and discarded it you may move on to the tenth and final step!

Step 10: Finish Up And Test The Tire Patch

Congratulations you have made it to the final step! By now the chemical cement has had a few minutes to adhere to the patch and you are now ready to trim the plug on the exterior of the tire and mount it back to the rim.

In the image above you can see that I have trimmed the protruding tire plug portion leaving about a 1/8″ remaining. You may use any blade or cutting tool to trim the plug, in this example, I am using my extremely sharp pocket knife that I always have on me during my workday. You would be surprised how often you will use a pocket knife as a mechanic in your day-to-day.

If you are wondering why I have not trimmed the plug flush to the surface of the tread there is a reason. Leaving a small amount of plug showing will ensure that the plug does not pull back through into the tire during the reinflation process. In addition, the remainder of the plug will wear down flush on its’ own within a few miles of driving. And do not worry the customer will not hear or feel the small amount of rubber when driving.

We are now done with the tire repair and you may now remount the repaired tire to the rim in preparation for the final task!

After you have remounted the tire to the rim and added the appropriate amount of air pressure to the tire you can now test your tire repair. You will do this by getting a soapy water mixture and soak the area around the plug.

Apply the soapy water to the area where you have repaired the tire just like in the image above. You want to be looking for any bubbles emanating from the repaired area and as you can clearly see, there are none!

If you do see bubbles, you will, unfortunately, have to remove the patch and plug from the tire and begin from Step 7 by buffing the area removing any glue and rubber left behind by the patch.

CONGRATULATIONS! YOU HAVE SUCCESSFULLY REPAIRED A TIRE LIKE A PROFESSIONAL!

Important Mentions

It is important to mention that not all tires can be repaired and as a professional, you need to recognize when you should and should not attempt a tire repair. Below I will list some of the major ones that come to mind.

When Not To Attempt A Tire Repair

1. The object in the tire is larger than 1/4″ in diameter. There is no effective way to repair a tire that has a hold larger than 1/4″.
2. The object in the tire has punctured at more than a 30° angle in reference to the tread surface. If you are in this situation you can still attempt a tire repair but you must use a two-piece patch and plug repair kit, not the one piece I used in this demonstration.
3. There is anything other than a hole in the tire, such as a slice, tear, or cut. There is no effective way to repair a tire that has a slice, tear, or cut in it.
4. Any rupture to the sidewall of the tire! DO NOT ATTEMPT ANY REPAIR TO THE SIDEWALL OF A TIRE! I do not know how to make my point any clearer. It will not last and you will be held liable when the tire catastrophically fails. Have the customer purchase a new tire or mount the spare, this is non-negotiable!