Tuesday, June 6, 2023


Is a “plug” or “liquid sealant” an acceptable tire repair?

RV Tire Safety

with RV tire expert Roger Marble

I got a reply to a post in an RV Forum regarding the use of a “plug only” type repair to a tire. I had posted a couple of pictures of examples of tires that had been run when significantly under-inflated and the owner used a “plug only” type repair.

Here is a picture (right) (click on any image to enlarge) of a tire showing the cracks through the inner liner due to the tire being run severely under-inflated because of the air leak, and run for hundreds of miles.

Here is another tire (left) that had significant damage from the puncturing object but the damage went undetected because the tire was not dis-mounted and inspected.

Here is an example (right) of a tire that was “plugged” three times but apparently continued to leak and the owner put some type of liquid sealant into the tire trying to stop the leak. (Note: I don’t think this is Fix-a-Flat brand sealant, but you understand what I am talking about here.)

Would you feel comfortable driving on either of these tires?

These examples show why the proper method of repair is to first dismount and inspect the tire. Then if the tire is OK, a patch and plug can be used to seal the air chamber and to protect the steel belts from rusting due to water entering the belts from the outside. If you don’t inspect, how would you ever know the extent of the damage that has been done to your tires?

The person asking the initial question about the advisability of using a plug (I assume he wanted to do plug repairs) continued:

“I’m still not sure what point you are making, especially if the cracks and the puncture are unrelated.

If the plug repair was successful, as most are, or if there had never been a puncture anyway, then a tire interior would never be inspected and so cracks caused by, say, running over a curb or large rock would never be noticed unless they caused air loss that resulted in testing or inspection.

Your second exhibit shows a tire with a plug repair (that we don’t know if it was successful or not) and again, probably or possibly unrelated damage that could have been there for hours or years and may or may not have been the reason for the tire being dismounted. So, again, your point? Tires get damaged, tires fail, and as your photos clearly show, a simple sharp object penetration isn’t the most serious injury tires are subjected to.”

I agree it may be “possible” to do a “plug” repair that will allow a tire to hold air. The main problem is that most people who do a plug repair as a “temporary fix” to allow them to stop the leak, reinflate the tire and continue to travel to get off the highway, will never go the next step to have the interior of the tire inspected.

Inner liner cracks come from operating a tire for many hundreds of miles with the excess deflection that is probably due to running significantly underinflated. Such operation can not only damage the inner liner but also compromise the belt integrity.

Many times if there is a belt separation later, the owner does not associate the decision to not have the tire inspected and replaced if the damage is discovered, so simply blames the tire manufacturer for the failure.

The second picture shows the damage to the interior of the tire when the object (maybe a piece of wire) was left in the tire and it cut through the inner liner. This will result in high-pressure air being forced into the body of the tire and again possibly leading to a separation that, again, the owner does not associate with the puncture weeks or months previous.

Some points to consider:
1. The use of a plug only will void any tire warranty according to most tire companies (Goodyear, Michelin, Bridgestone, etc.).

2. The use of a plug only is specifically not approved by DOT so don’t try and make a claim of a tire being “defective” to NHTSA or in any court of law.

3. Unless you have personally inspected a few thousand tires and can provide evidence that tires with improper repairs do not suffer secondary catastrophic failures, I suggest you include a warning with your posts that your observations are only based on your experiences with a few tires.

I agree that we are all entitled to our personal opinion but not our own facts, especially when others may be relying on our statements for the safe operation of their vehicles and specifically their tires.

Go ahead and use a plug if the situation warrants, but just be sure you have the tire dismounted, completely inspected and, if possible, properly repaired. But please be clear that without a complete inspection it is possible that the tire has suffered irreparable damage and should be removed from service.


Read more from Roger Marble on his blog at RVtiresafety.net.




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Keira B
4 years ago

Those that are raised in farm country tend to fix every tire they can with the cheap methods. If we bought new tires every time we got a puncture, we would go broke. I suspect some of your readers are low budget folks who would like some advice on making do with the cheap repairs.

Roger Marble
4 years ago
Reply to  Keira B

Keira, I understand. I will even admit to using “sealant” but I used it on my wheelbarrow. Using plugs and sealant on tires that see highway service above 15 mph is where the problems occur. Also long term use with tires that can go 20,000 miles. Bet you don’t do that with your farm equipment.

3 years ago
Reply to  Roger Marble

Low cost repairs are not limited to the farm or “low budget folks”, they are the mainstay of most government operations around the country, heck around the world. It would be wonderful if there was enough money in the world to make everything safety first. However, in the real world there isn’t enough money to even get close.
I had my first encounter with tire plugs in 1985. We were on vacation in the mountains of Colorado and got a flat on a rear tire on our 1 ton single wheel Dodge camper special truck. At the time there was a 12 1/2′ pickup camper on the back. The Continental tire dealer never took the tire off of the off of the truck. I asked the manager if that was a good repair and he said “yes, that they used Oakum and that the plug would outlast the tire. 30,000 miles later he was proved right.
I retired from a major municipality and plugs were the number one repair solution for our crews in the field. Sure if your crew could get the tire back to the central maintenance facility they would patch it but most repairs were done with a plug kit. They couldn’t handle all of the tire repairs otherwise.
The one thing you said in your example was that the plugged tire was operated underinflated. Even though your example had a tire with internal damage are you sure the under inflation didn’t have as much to do with any catastrophic failure as the internal damage? We hear from the tire manufactures that under inflation is the number 1 cause of tire failure,

Vanessa Simmons
4 years ago

Purchased all new tires for my TT a few months ago and installed a TPMS. Driving through nowhere NM the alarm went off. I pulled over with 40 psi remaining. When roadside service arrived (almost 2 hours) he removed the tire and found a screw in the tread. Was surprised it wasn’t shredded and I pointed out the TPMS. Instead of putting the spare on he said “let me repair it”. He patched, reinstalled it and I was on my way. Tire is still holding air.

Is this a safe tire to be traveling on?

Roger Marble
4 years ago

If he did an internal patch and a plug to protect the steel belts per established industry practice then the tire is probably OK.

4 years ago

Been plugging tyres since the 60’s. You only plug in the tread area, NEVER in or near sidewalls. Never double plug. I have never had a failure on a correctly plugged tyre.
Never use the inflator-flat fix junk on a RV or car tyre, never/ever !
If you run underflowed you are setting your self for disaster if a new tyre or a plugged tyre.

4 years ago

While I acknowledge that this article (and your opinion) stresses the goal of safety, it also tends to emphasize that a puncture situation must be solved with a new tire. Which in the case of at least one popular brand of all-wheel drive vehicle, means replacing all four or having the new tire ‘shaved down’ to match the surviving three. A reputable repair and tire business where we live actually did insert a “plug” in one of my wife’s tires to fix a nail puncture. Or they could have argued to sell us four new tires, putting three on the used tire market.

Roger Marble
4 years ago
Reply to  Graybyrd

Did they dismount and inspect the tire before plugging it? Do you know there was no internal damage done to the tire?

Guy Wood
4 years ago

Thank you for your article. I have not plugged a tire yet but I plan on buying a kit so I can have it for emergencies. I cannot imagine not taking the tire to a shop once you are back to civilization. I plan on using it to get me out of the situation and then have the tire properly repaired.

Roger Marble
4 years ago
Reply to  Guy Wood

Yup, that would be the time to consider using a temporary plug. “Emergency” is the key word.

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