# How to fix a slow leak in a car tire?



## milkyspit

One tire on our car has a VERY slow leak. I typically inflate all the car's tires to 36 psi. After a week, this particular tire will be around 20-23 psi, while the other three will still be very close to the original 36 psi. My uncle is a mechanic (and a very good one!) but was unable to find the leak. I haven't found it, either, but clearly something's wrong. BTW, the usual soapy water test doesn't seem to reveal the leak, either. /ubbthreads/images/graemlins/frown.gif

I vaguely remember some sort of spray one can put into a tire, where it essentially revulcanizes (?) the rubber, or something like that. My wife mostly drives this car, and the handling is affected by the leak, making the steering less safe than it should be. Since my wife is also the one who often drives my kids places, I want the car to be as safe as possible, and this leak is driving me crazy! /ubbthreads/images/graemlins/banghead.gif

For all you car folks out there, is there something fairly inexpensive and simple that I can do to cure the leak, without throwing the balance of the tire off or causing any more harm to it? If so, please advise! /ubbthreads/images/graemlins/ooo.gif

Thanks. /ubbthreads/images/graemlins/smile.gif


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## Lightraven

I had a rental car with a slow leak. Lost about 10 PSI per day, so I had to air it up every other day. I took it to the shop and they said the same thing--can't find the leak. I said, "It's there. The tire is almost flat when I come out in the morning."

After some careful looking, they found a nail buried deep in the tread. Fixed, no problem.


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## Brock

I would take it to a garage and have it checked and remounted. Many times the seal has shifted enough to allow a slow leak. 

I wouldn't suggest the tire fix spray stuff. Many tire guys will refuse to fix a tire that has had flat fix sprayed in. It really makes a mess inside the tire.

Of course if you in the middle of no where and that’s all you have, it's a good thing.


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## Lurker

There is some gunk you can put inside the tire, but it may or may not work depending on the location of the leak. 

I would think that finding the leak is your best bet. Once found you can probably repair it pretty easily. It is leaking fast enough that you should probably be able to locate it but slow enough that you will really have to scrutinize the tire. I am surprised the soapy water trick didn't work. Did you put it in a spray bottle and cover the whole surface of the tire? Really look down in between the treads. Also don't forget the valve stem and valve itsself as well as the places where the tire and wheel mate. It could even possibly be a defect in the wheel rather than the tire. You will have to remove the wheel from the car to really do this right. Good luck.


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## Darell

Tire shops usually have a tub big enough to submerge the entire tire - at least half of it - to check for the leak. You describe a very slow leak though, so that'll be a tough one for sure. The first thing I do, is check the valve stem. Put some spit /ubbthreads/images/graemlins/eeew.gif across the top of the stem and see if it survives a few seconds. If yes, then the air is coming from elsewhere. If no, the valve core is suspect. The air can come from the stem, the tire or the wheel - tires aren't always the responsible party!

Personally, I'd avoid putting goop into the tire that messes with the innards. Your best bet is to have the tire removed and have the wheel and tire inspected from the inside. This is assuming that the tank trick doesn't work (of course the soapy water trick should have worked as well!)


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## _mike_

Yea...it might be coming from the bead on the inside or outside of the rim. You just take it off, clean up the rin a bit and re-mount the tire, then re-balance it. Problem with the seal-a-leak type products is that if you ever need to actually patch the tire....that stuff might make it more difficult or impossible to.

Besides, if it is the bead.....that stuff won't help or at least not for very long.

Have you carefully checked that the valve stem is not cut, cracked or broken?


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## tiktok 22

Hi Milky,

I have fixed a ton of tires in my life. My father used to work in a shop when he was a teenager and taught me a great deal about working on tires. Usually I break down a tire and patch a leak, but it's not always necessary. Unfortunately slow leaks are the hardest to find. The bubble test is still a great test though. Remove the wheel from the car. Test around the bead on both sides of the tire, it may take some time. If you find a leak at the bead, have the tire broke down(removed from the rim). Clean the bead and apply some bead sealer. Air up the tire until you hear the bead pop back onto the rim. Check around the air valve. It may need replaced. Check the tread by dunking the tire into a tub of water. check for slight bubbles. If a leak is located, mark it. If your not comfortable doing it yourself, Take it to a local tire shop and have them patch it. If you choose to plug it, make sure to clean the hole with the rasp at the same angle the object went into the tire or you might end up with two holes. Clean with rasp and lighter fluid or alcohol. Apply cement to rasp and work in cement. Apply cement to plug and use plug tool to push plug into hole. Grab shaft of plug tool with a pair of pliars to keep from pushing plug completely through tire. Pull plug tool out swiftly. Trim plug. Check for leaks.


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## LEDmodMan

I did a spell as a tire mechanic, albeit a short one. That job can really suck! /ubbthreads/images/graemlins/smoker5.gif

Darell hit the nail on the head. Most shops (esp. the chain stores) have large farm-type tanks to fully submerge the tire in the tank and hold it under water. It works well to find the leak, even a slow one.

I'd say 8-9 times out of 10 the leak you describe is somewhere in the valve stem, possibly even at the base where it goes through the rim.

Don't put any of that fix-a-flat kind of crap inside your tire!

PS - If you're a member, Costco does FREE tire repair even for tires purchased elsewhere as long as they're in a safe, working condition.


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## Darell

[ QUOTE ]
*LEDmodMan said:*
PS - If you're a member, Costco does FREE tire repair even for tires purchased elsewhere as long as they're in a safe, working condition. 

[/ QUOTE ]
Wow, really? That's some good info to file away!


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## Lux Luthor

It's also possible the tire isn't balanced properly. If that's the case, a little air squishes out each time the tire makes a revolution.


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## TheBeam

I used to take the tire off, fully inflate it and dump soapy water on it. It bubbles more with the dishsoap.

Around here, Les Schwab will fix flats for free.


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## LEDmodMan

[ QUOTE ]
*Darell said:*
[ QUOTE ]
*LEDmodMan said:*
PS - If you're a member, Costco does FREE tire repair even for tires purchased elsewhere as long as they're in a safe, working condition. 

[/ QUOTE ]
Wow, really? That's some good info to file away! 

[/ QUOTE ]

Yep!!! /ubbthreads/images/graemlins/grin.gif I've used that service many times over the years. Of course, it's polite to tip the guys for that.

Costco rules!!! /ubbthreads/images/graemlins/grinser2.gif


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## Nitroz

I agree with everyone else here, no fix a flat in the tire unless it is an absolute emergency and the extreme last resort. Ie. (Being in east bumble) /ubbthreads/images/graemlins/smile.gif


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## CNC Dan

You might try the soapy water around the valve stem, while bending the stem outwards. When the tire is spinning the stem will be pulled to the outside. This can cause a tire to leak when the car is in use, but not when parked.


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## Lumenous

Have you checked the valve and rim carefully?


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## cannon50

I think it is more likely that you have a small nail in the tread of the tire. Use a soap solution with a stable high foam such as cheap bubble soap for kids and dilute about 50% and pour not spray over the treads. Watch for a small patch of frothy foam from the small leak that may take a few minutes to develope. A larger leak may leave a stream of bubbles and will show up quickly.


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## Wingerr

I shouldn't be hard to find a leak that goes from 36 to 20 in a week; that's not all that slow.
Solution is to use the soapy solution, with dish detergent like Dawn for good bubbles-. You don't have to immerse the whole tire, just use a brush and scrub all the surfaces with it for good film coverage, and look for the frothy foam cannon50 mentioned. If you simply pour the solution on, you can easily miss it, so use a brush, or a spray bottle-
I was lazy looking for a leak one time and checked with the wheel on the car, and couldn't find it; checked the entire tread, outer rim, valve stem. Nothing. It turned out to be on the inner sidewall, and easily showed up with the soapy solution- new tire time. 
Take the tire off if you have to, to get to all the surfaces. Some wheels had problems with porosity, but the speed of the leak you have makes that improbable.


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## smokinbasser

I have a safety tip for seriously looking for leaks once one side of the tire is off the rim, take a shop towel and CAREFULLY run the rag around the inside of the tire, it will snag in a heartbeat if something is in there. A little known factoid; hedge apple thorns have an unnatural attraction or affinity for air under pressure. It's main source seems to be lawn tractor tires. But 4X4s aren't immune, I wouldn't be wearing those Air Jordans in the same county with those thorns around.


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## cobb

All good ideas. I just wanted to add, if its a mag wheel, sometimes it can leak through the rim. Over time rims can develop small holes and the air can leak through them. 

I also agree with te soapy water method. If it is leaking it will bubble up where it is going so. 

With my wheelchair, the tires stretch. So, when I get new tires and jack them up to 36psi. Next week they read 30. This can go on for a few months then they level off. I used fix a flat and man, that was one gooey mess. Not to mention the danger as they use propane or some natural gas, gas in the can to force the fluid out of the can. The goo can also mess up your valve stem so it quits working and you en dup with good squirting on you. BTW< dont use green slime either, same reasons. nothing like checking the air in a tire with green slime in it just to have the valve stick open and slime you.


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## doubleganger

interesting thread
It occurs to me that overinflating the tire might make the leak faster and easier to find.


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## cobb

Careful, over inflating the tire could case the bead to leave the rim, and lots of damage. Before I was hired at the chrysler dealer in 92 they had a guy do that to set a bead on a tire on their old tire machine. It poped off both sides. THe machine was destroyed, the wheel and tire left teh machine despite being screwed down and went up and damaged the celling. THe guy had a broken arm, but was lucky to be alive. 

Best bet is to follow what your door panel says, not the tire or some guy.


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## UncleFester

Another thing to consider is the seal between the valve stem and the rim. I have heard of them not leaking at a standstill, but when driven, the cetrifigul force bends the stem a little and it leaks. See if bending it around causes the soapy water test to bubble.


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