'The Tire of Lourdes', or, help me solve this apparent miracle repair

Monday night, as I drive home from the restaurant where I eat most nights, the tire pressure indicator comes on.

Great, I think to myself: for the third time in around a year, I have to wait in line at the tire place to get a tire patched (although I’m again glad I bought the road hazard warranty for all four tires when I bought them).

When I get home, I check the pressure. The left rear tire is indeed down (from 32 to 20 psi).

Tuesday morning, I pump the tire up at a gas station and buy one of those cigarette-lighter-powered tire pumps at an auto parts store.

I drive to work. After work I check the tire. It’s still full.

Tuesday night, the low-pressure indicator comes on again. I check the left rear tire, and again, it’s back down to around 20 psi. I pump it up with my new pump.

Wednesday morning, I check the tire. It’s still full. I drive to work and call the tire place. They tell me I can come in that afternoon. I leave work a couple hours early and wait in line at the tire place.

After several hours, they finally get to my car. They inform me that there is nothing wrong with the left front tire.

I re-inform them that it’s the left rear tire that’s been deflating slowly.

They go back to work.

After about 20 minutes, they inform me that there’s nothing wrong with the left rear tire either.

I strongly suspect that they’re incompetent, lazy short-handed, or some combination of the three. I politely remind them that it’s a slow leak. The store manager tells me that if the tire deflates again, he will give me a new tire (I will pay 16 bucks for the installation, as per the road hazard warranty terms).

Fine, I tell him (POed that he wouldn’t replace the tire now, after I’ve waited all these hours).

I smile and thank him, confident that the tire will be down tomorrow. At which time I will drive back and hold him to his offer.

This took place about 7:30 Wednesday evening.

It’s now Sunday evening - and the tire has not needed inflating since Wednesday morning - almost four and a half days.

WTF happened?

Did you bump a curb any time recently? A relatively mild bump can push the bead off the rim just long enough to lose 20% or so of the pressure.

Did the car sit without the valve cap on that tire? The Schrader valve is NOT designed to hold air in by itself and if there’s no cap, vibration and other things can cause leakage through the valve.

Prank by someone?

What method was used by the tire shop to inspect the tire for a slow leak? It would have to be removed from the car. Normally, they overinflate the tire before doing that, to magnify the bubble release in the bath. Over-inflating might have reseated a gap in the rim.

I while back, I had the same experience. A tire would hold pressure for days or weeks, then suddenly go down overnight. Inflate, wait, repeat. Then an oil-change guy said he could hear it leaking. He had me drive forward a few inches, and it stopped.

It turned out that the tread would squish to open a little hole just in that position of rotation, when the leak was just past the footprint. A few degrees further, the tread would un-squish, and the hole would close. He marked the sidewall right there, and a mechanic found and plugged the hole.

My Guess: Someone with a tire gauge is pranking you where you park. They are dropping the tire pressure a little bit on occasion.
The air was there, the pressure did lower, but the flow of its loss isn’t constant. Since the only other exit is at the valve, someone is operating that valve that you are not aware of.

I’m just not sure how either you or your mechanic can fix that.

You could have a screw in the tire. Sometimes a screw will randomly act as a patch.

Maybe they squirted a can of Fix-A-Flat into the tire?

I’m not sure exactly what they did, but my money is on this answer. A tire-knowledgeable friend suggested it as well.

One suggestion. Instead of “left” and “right” try using “driver’s side” and “passenger side”.

My gf took her car in and her use of “left” and their use of “left” were different. :wink:

I’m on board for your third suggestion. I think someone is trying to gaslight F.U.


I worked in a car repair place after the military for a little while. We saw this ALL the time. If the rim is even slightly bent or dented, it doesn’t take much to break the bead and cause a slow leak. You may have curbed it, or hit a pothole, or even a large rock, or taken a speed bump a bit too fast. We’d do everything we could to find the leak, and sometimes couldn’t. Since we do overinflate a little before putting it in the water (if a visual inspection didn’t find anything), we’d assume it was at the bead. Depending on how fast the customer said it was leaking, and what kind of shape the rims appeared to be in, we might let the air out of the tire and spread bead sealer (black stuff halfway between tar and rubber cement) on the bead and the rim, and the fast-inflate it to seal the bead, and overinflate by about five psi, then let the extra air out, just to make sure it seals. After that, we’d balance, and replace.

They may or may not have put bead sealer on your tire, but I think leaking around the rim is pretty likely. What shape are your rims in?

So I’m reading this, and I’m thinking “They have tire pumps powered by cigarette lighters?”, so I google it and … disapointment. That would have been cool.

I do a lot of mounting and dismounting of my Jeep tires by hand at home, and strongly agree with post #12. I have a nice big can of that bead sealer, and when all else fails, apply enough of that stuff and the problem usually goes away.

But, yeah, I feel your pain. I have experienced many of the “Miracle Self-Repairing Tires” that seem to defy the established protocol and makes you crazy and question what is real and if we are all just an illusion in someone’s fever dream.

One time, I had a cracked valve stem that was fine when parked, but the centrifugal force of the tire rotating would cause it to flex and leak. Go drive, come back low. Fill it, it stayed full. Go drive, come back low, lather, rinse, repeat. I WOULD NOT leak when the vehicle was parked (I use the soapy water squirt bottle to find leaks). Found that one by accident. I went to check the valve, and knocked it sideways and heard the air escaping.

When I was 18, I owned an old VW with the softest rims ever.

Anytime I hit a pothole, the rim would deform and I’d get a flat. I carried a ball-peen hammer and a little cig-lighter air pump. I’d jack the car up, pound the rim back, inflate the tire, drop the car and drive off. I became pit-stop fast at it.

I loved/hated that car.

F. U. is welcome to correct me if I’m wrong, but I’m gonna say they’re round.


(but every happiness, you two!)

I heard them called air pigs and I picked one up for 30 bucks, bout 7 years ago. Its been a real asset to have, between pumping mine and others cars, and also one flat tire that a mom had on her baby pram. When gas stations cost a buck to use theirs, which may or not be working in the winter, they are handy to have around.