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Have you noticed a slow leak from your tire’s sidewall and wondering how to fix it?

This isn’t an easy question to answer as you can’t fix a tire leaking there on most – but not all – occasions.

If you look on forums, you will find posts from people that have patched or plugged their tire sidewall, whereas, on the main trade association and manufacturer’s sites, you’ll see that they say you can’t fix a tire that’s leaking from the sidewall and you need to fit a new tire instead.

It’s difficult to know who to believe. On one side, car drivers say they have successfully repaired a sidewall slow leak.

On the other side, you have tire trade bodies potentially interested in getting you to replace tires, saying it is not safe to repair.

There is one absolute exception that we will highlight further on.

Inside A Tire Sidewall

Looking at the picture below, you will see why repairing a sidewall is so problematic.

The tread section has steel belts and additional nylon ply. These structures underneath the tread provide additional stability to that section. Because of this additional strengthening, patching or plugging the center section of the tread is safe. 

As seen below.

Radial Tire Showing Belts and Ply

There is nothing behind the sidewall, and it relies solely on air pressure to maintain an element rigidity. I say an element because it does need to flex when you drive over bumps and potholes.

If it were rigid, like the tread section, you would experience a very firm ride. If you have driven a car with run flats  – which have reinforced sidewalls – you’ll notice a more firm ride.

Sidewalls are also load bearing, so they have to be flexible yet strong enough to take the weight of a car. That is why they are so vulnerable when they become damaged.

When you hit a large hole, your tire becomes slightly compacted, raising its air pressure not by much but enough to allow air to find weaker areas in the tire and force its way through.

This can happen suddenly and rip a large hole in the sidewall and making a car difficult to steer.

Often sidewall damage is more severe inside than out, and only removing it from the rim exposes it.

Furthermore, most blowouts are usually because of sidewall damage and not holes in the tread where it has steel belts to continue offering support.

Will Some Tire Shops Fix A Leak On A Sidewall?

You’re unlikely to find a professional tire shop willing to patch or plug a sidewall.  Any tire shop looking to be around and get a good reputation wouldn’t have to hesitate.

The answer will be no, they won’t repair it, and you’ll need a new tire.

Tire Expert’s Views Sidewalls and Slow Leaks

The Rubber Manufacturers Association (RMA), as it used to be before it became the US Tire Manufacturers Association (USTMA), states that approximately 88% of all tire repairs are done incorrectly. 

No one knows what percentage of these repairs have had sidewalls patched, plugged, or added sealant, but I reckon it’s a large amount.

“Repairs to the shoulders or sidewalls, other than for cosmetic damage, may not assure the structural integrity of the tire and are not approved.” 

British Tire Manufacturers’ Association 

The Tire Industry Association says:

“Puncture repairs are limited to the center of the tread area.  If there are punctures or damage in the shoulder or sidewall of the tire, it is not repairable.”

Is It Legal To Repair  A Slow Leak Tire Sidewall?

No specific law prevents anyone from patching, plugging, or adding sealant to their tire’s sidewall. But then the law gets a bit more general.

Some car safety laws state that a car should be kept in a roadworthy condition and maintained in line with the manufacturer’s guidance. 

Tire trade bodies don’t think this is good enough and want the law strengthened.

“There is a move by the RMA to legislate what would be an “improper repair,” but so far this has not passed in any State legislative session.”

Laws Regulating Tire Repair in the United States

All tire manufacturers state on their websites that tires with sidewall damage are irreparable and that a new tire is needed. 

So repairing a  sidewall does not appear illegal, although you should research it as laws often change over the years. 

Although it is not unlawful, driving with a repaired sidewall is certainly dangerous. 

A driver in charge of a car with a sidewall repair that blows out, resulting in a fatality, could be in a ton of trouble. 

The deceased’s family may make a civil claim for damages, and a car insurance policy that would usually cover the claim will refuse to pay out because the car wasn’t in a road worthy condition.

All car insurance policies will have a condition to cover this.

Slow Leak Between The Sidewall and The Rim?

Briefly, some people use the term sidewall for the bead. The bead is the ridged lip area the tires use to get a tight seal against the rim.

Sometimes air leaks from this area that people mistakenly call the sidewall. It usually results from bent rims or rim corrosion. The tire may need to be removed from the rim for the best repair.

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