Patching close to the sidewall may weaken the structural integrity of the tire, and so it should be closely monitored for any signs of failure. Though if it’s 1 inch away from the shoulders (towards the middle), it’s in the safe zone. Although I’d advice you go through the rest of the post to find some highly crucial info, if you are in a hurry, just know this:
Since sidewalls are not as thick (as they don’t have steel belts underneath), the patch won’t be strong enough to hold the pressure in, so a temporary solution is to “plug” the tire instead. However, if the hole is larger than 1 inch, even that is not advisable. And in that scenario, either get your tire replaced with the donut/spare tire, or wait for help.
Note: The above only goes for radial tire, if you have a bias ply tire (see sidewalls, it should say “B”, instead of “R”), you can actually get away patching the sidewalls.
Table of Contents
Difference Between Patching and Plugging
Both are different methods to repair the tire punctures.
Patching
This is the most common method of repairing, where a patch (piece of rubber) is applied over the puncture on the inside of the tire and then is melted with heat, so it can create a strong bond with the inner lining of the tire.
With this a tire gets to be permanently repaired, as the patch becomes an integral part of the tire.
If your tire is punctured from the middle part of the tread, the patching is the most suitable repairing method.
Plugging
As the name suggest, it’s a puncture repair by using a plug.
Here you just stuff a small piece of rubber inside the punctured hole from the outside of the tire. It’s anchored there usually with a tool (which pushes it in).
The excess rubber sticking outside is then cut off.
If you are in an emergency and have a sidewall damage, and there’s no other way but to fix it. You can do this temporarily by plugging. Though note, this method creates a temporary repair, as the plug only covers the hole and does not bond to the tire. So replace your tire as soon as possible.
Recommended: Different tread wear patterns.
Understand Tire Sections
First off, you need to understand the main sections of your tire, and how they are built, there’s central tread, shoulders, sidewalls and lastly the bead area.
Central Tread
The tread center is the only portion that is repairable on the tire, and since it’s the area that makes the most contact with the road surface, it gets punctured more commonly.
This part of the tire is most commonly construction with 3 ribs, having blocks in them, and they make 4 longitudinal channels.
Shoulders
On a majority of rib based designs, or even lug based designs, the shoulder lugs are prominently separated by the outer circumferential grooves.
These lugs get to have the most pressure on them during cornering. So if they get punctured, you are going to have a reduced cornering stability.
Overall, it’s not recommended that you patch the tire on the shoulder lugs, as they have a more complex shape compared to the center tread, and the patch may not be able to conform to the shape of the shoulder area, there’s a good possibility that the patch wont stay there for long as these lugs flex more.
Basically this has to do with the tire’s radial construction. On this type of construction, the sidewall lugs don’t get to have as many plies underneath, so they are softer. So these along with the shoulder lugs are more susceptible to bending, which reduced the bond efficacy of the patch.
Sidewalls
Sidewalls are not as thick compared to central part of the tread, and they are made that way to ensure the tire keeps its shape at all times (even on sharp turns).
They also get to create a slight bulge in them distributing the pressure off the central area, when carrying heavier loads.
So its a big fat NO, if you’re sidewalls are damaged, if you are asking to patch the tire there.
Bead Area
Bead area is actually just around the rims. And their job is to ensure the air stays in the tire at all times.
And although its very uncommon to see damage/puncture in this area, if that’s the case, you should replace the tire, as that area can’t be patched.
And this brings us to our next question.. Can you replace just one tire?
Conclusion
If you have any damage on the sidewall, shoulder, or bead, you should replace your tire.
Still, the inner part of the shoulder sometimes can be repairable. In this case, the limit is 1/2”. So, you can add 1/2” to each side of the tread center and find the exact location of the repairable area.
