Flat tire that doesn't leak?

Honda Civic 2021 with one of those low-profile tires. Got up in the morning to find one tire flat. As in ZERO pounds of pressure. OK, there’s a leak. Need to patch. Filled it enough to get to the shop and… it held pressure. Howzzat? Can you do a tire patch if you can’t find the leak?

1 Like

If your car was parked outside, I suspect that someone pulled a prank on you by deflating that tire. Carefully monitor the pressure of all your tires for a few days, and if they all continue to hold the proper inflation pressure, then I think you have to conclude that human intervention was the cause of that flat tire.


If there’s a leak, the tire shop will find it.



It might be a slow leak that doesn’t go flat for a week or more. I’ve had those and if I wasn’t watching the tires diligently, it could go flat while I wasn’t watching for a week. Also, low profile tires leave less sidewall and it should be more difficult to see a low pressure bulge than on a 55% sidewall.

I had a tire that leaked and the leak just did not show at the tire store . After the 3 rd try the tire shop found a really small brad nail . It was so small they showed around the shop because it was just had to believe that caused a leak . It was one on mine of the size I had used on a cabinet trim.

Being as you have either a Direct or Indirect TPMS, you still have a TPMS (system) and as long as you don’t ignore the light, it will tell you when your tire is low…
So keep an eye on it… If it is a fast leak, you will know pretty fast, but those really slow leaks can at times be very hard to find…
As someone that used to see 15-20+ flat repairs a day, yes a day, I have seen them go flat in the parking lot and it still be hard to find… Sometimes it can be just a small puncture and nothing in the tire, other times I have seen the tire have to be parked just right for it to leak, or the weight of the vehicle be on it to leak… You could have corrosion around the bead area and the lower the air pressure the faster the leak… If a direct TPMS it could be leaking from a pinched seal or dry rotted seal…
And I could wright a book on the different things I have seen in tires, I don’t think anything would surprise me anymore…

So time will tell…


That’s exactly right about less sidewall. It really isn’t that conspicuous when these tires are flat, so it could have been that way for a while. Amusingly, this car has an indicator on the dashboard that lights up when the tires are low. It was lit up for a long time when all tires were up to pressure, and you’re supposed to go to the dealer to get it “readjusted” if that happens. We haven’t done that, and have just been ignoring that indicator. Such an indicator that just doesn’t work is pretty worthless.

Up to pressure - I just have to ask - How did you determine that ? - Did you use the correct PSI that is listed on your drivers door plaque ?

Of course. I have a decent gauge, and anyone can see the plaque. If I didn’t know how to establish correct tire pressure, I wouldn’t be here.

If you hang around this site for at least a few weeks, I can guarantee that you will see posts/questions from people who have no clue about how to determine the correct inflation pressure for their tires.

1 Like

People here have occasionally mentioned a leak that happens only when the tire is in a certain position, so that’s a possibility here.

You could spray the tire with soapy water and watch for bubbles each time you park if that’s not too much of a pain.

1 Like

Have you checked your owners manual?? I did a quick Google and all kinds of info popped up and videos on how to reset your TPMS, you do not have to go to the dealer unless the system is malfunctioning…

As part of that, lay tire horizontally on ground, use a level and shims to get it exactly horizontal, then paint the soapy water along the bead area using a paint brush. Watch it over the course of an hour or so, you may see some tiny bubbles forming at the bead. I had that problem on my truck, very frustrating, had to remove the tire and wire brush the rim to clean metal, no rust, rim sealant when reinstalling tire on rim. This sort of leak can be difficult for shop to find b/c it leaks very slowly.

its possible that the valve stem core had a leak, and the simple act of you adding air reseated it to the point it isn’t leaking (or leaking as fast,) any longer.


Hmm. Very interesting. (I didn’t understand this thing was called TPMS) The owners manual says to go to the dealer to get the TPMS “calibrated”. I don’t have a TPMS reset button,and without it, you’re supposed to drive for 50 miles to reset it. That doesn’t work in this case.

That’s interesting. Do valve stem cores leak? The stem had a tight cap on it, so if it was leaking, you’d think that would stop any leaks through the core.

Your car does not have tire pressure sensors. The tire pressure monitor system (TPMS) monitors the rolling diameter of each tire to determine if one is underinflated.

If one or more tires are replaced, tire are rotated or tire pressure is adjusted, the system must be calibrated to register a baseline tire diameter.

The calibration procedure is shown on pages 442 - 445 of the owners manual.


Yes Schrader valves (valve stem cores) can leak as well as loosen sometimes, the cap is basically a dust cover to keep the elements out…

And it sounds like you have indirect TPMS which uses the ABS system to approximate tire pressure…

A lot of new tire shops have a tool used to reset TPMS systems, if you are having trouble resetting it yourself…

1 Like

I had a tire on one of my trucks doing this. I went out to drive it and it was flat. This one had just been checked not long ago. The cap had been left off and the valve area was full of dirt. I filled it and then let air out to help blow the dust out, then found a cap to put on. It would go a month without losing air, then be flat the next day. I just assumed it was the valve not seating so planned to keep an eye on the pressure and take it to a shop to have a new valve stem installed whenever it was convenient. Then it started losing air overnight no matter what.

The tire shop found a nail or screw in the tire. I told them to replace the valve stem at the same time as this was super cheap. I don’t know if I had two problems or only the nail or whatever it was.

1 Like

OK, I reset my TPMS, which was easy peasy. Though on a Civic 2021, you have to figure out how to get to Settings, whether on your touch screen or behind your steering wheel. Now, what was odd was that you select TPMS Calibration, press go, and one is led to believe that it does it, with the car not moving. Now, I don’t understand that. If the TPMS is measuring wheel circumference, which I’m sure it’s doing, it needs to count wheel rotations as a function of speed of rotation.So how does it do that when the car is stopped?

BTW, the tire is still holding pressure. Weird. Now I do recall the other day cutting a corner a little close, and hitting a curb on that side. Could that depressurize a tire?