Explain a flat tyre with no puncture
May 3, 2017 5:44 AM
I got back to my car after a lunch in a cafe to discover that the tyre was flat. I filled it full of air and continued on my way home. I stopped on the way back to check it's pressure but it hadn't gone down at all. It still hasn't the day after. What could have done this?
During a journey home I stopped at a slightly shady cafe for lunch with my family. I'd been driving four a half hour and had noticed no problems. When I returned to the car I noticed one tyre was nearly flat, and, on inspection, the edge of the cap had come away slightly.
It was a public holiday and I knew I'd have to wait ages for a break down service, so I filled the tyre and decided to check it on the way home but saw it hadn't lost air. It still hasn't.
Now at the start of my journey I had scraped the car near the affected wheel but feel like any damage I might have done to the tyre then wouldn't be just temporary, right? My only feeling at this point is that someone must have let the tyre down deliberately. Can anyone think of another way this could have happened?
During a journey home I stopped at a slightly shady cafe for lunch with my family. I'd been driving four a half hour and had noticed no problems. When I returned to the car I noticed one tyre was nearly flat, and, on inspection, the edge of the cap had come away slightly.
It was a public holiday and I knew I'd have to wait ages for a break down service, so I filled the tyre and decided to check it on the way home but saw it hadn't lost air. It still hasn't.
Now at the start of my journey I had scraped the car near the affected wheel but feel like any damage I might have done to the tyre then wouldn't be just temporary, right? My only feeling at this point is that someone must have let the tyre down deliberately. Can anyone think of another way this could have happened?
Another possibility is that when a tire gets low enough, things like parking with car tires on uneven surfaces or up against a curb can flex the sidewalls enough that the seal of the tire could be breached such that it would leak air until it was properly filled.
posted by mmascolino at 5:59 AM on May 3, 2017
posted by mmascolino at 5:59 AM on May 3, 2017
I had the same case last year. It took me several hours to figure this out but as it turns out, someone had apparently tempered with the valve. I can only assume that someone didn't agree with my choice of parking space and instead of causing permanent damage on my car, decided to teach me a lesson by letting out the air from one of my tyres.
Just keep observing your tyre and maybe don't go on the highway right away and you should be able to know whether your tyre is really damaged after all.
posted by Fallbala at 6:04 AM on May 3, 2017
Just keep observing your tyre and maybe don't go on the highway right away and you should be able to know whether your tyre is really damaged after all.
posted by Fallbala at 6:04 AM on May 3, 2017
Tyme will tell. :-) As JoeZydeco said, you could have a small, slow leak due to a pinhole, there could actually be a problem with the rim or the valve. Fallbala's "slightly less nasty vandalism" theory makes sense too.
I'd take it by a garage at your earliest opportunity
posted by randomkeystrike at 6:06 AM on May 3, 2017
I'd take it by a garage at your earliest opportunity
posted by randomkeystrike at 6:06 AM on May 3, 2017
Every now and then some mischievous young person lets the air out of someone's tire for their own amusement. There's always that possibility.
posted by Pater Aletheias at 6:06 AM on May 3, 2017
posted by Pater Aletheias at 6:06 AM on May 3, 2017
Schraeder valves can leak, they have a removable valve core that can be tightened. "Scraped the car near affected wheel" is probably your culprit - bent rim will leak air.
posted by fixedgear at 6:10 AM on May 3, 2017
posted by fixedgear at 6:10 AM on May 3, 2017
It is possible that you pushed the tire away from the rim when you scraped it - modern (i.e. the last 50 years) tires are tubeless and it is air pressure that holds the tire bead against the rim making the seal. The less the pressure, the less the seal. By reinflating the tire you would have reseated the bead. I would keep an eye on the pressure, some grit could have gotten between the rim and tire causing a slow leak.
posted by 445supermag at 7:15 AM on May 3, 2017
posted by 445supermag at 7:15 AM on May 3, 2017
I once had a nail puncture one of my tires in such a way that it was essentially sealed unless I parked with the tire in a position so that the nail was bent between the tire and the road surface, in which case it would go flat very quickly. Took me forever to figure it out. JoeZydeco's approach would have been a good place to start.
posted by Rock Steady at 7:51 AM on May 3, 2017
posted by Rock Steady at 7:51 AM on May 3, 2017
It's possible that contact with a curb (kerb?) or other obstacle can make a bad seal between the tire and the rim, and create an air leak. Then just by refilling it, the pressure reseats and realigns the rubber and it doesn't leak again. But yes, keep an eye on it, I wouldn't assume it's 100% fine. But it might be - or at least 95% fine, that seal might be weakened a bit if there was a bend to the rim.
posted by aimedwander at 7:53 AM on May 3, 2017
posted by aimedwander at 7:53 AM on May 3, 2017
You can easily have pushed a tyre (especially a slightly underinflated tyre) away from the rim against a kerb and cause it to lose a puff of air. This is a likely way that you can lose a decent amount of air in a short period. Also, you can have a leaky valve or a puncture that only lets out air at certain temperatures or depending on how the car is sitting etc, but these are usually much slower leaks.
The chances of one tyre being let down sound pretty high to me, though. That or the kerb pop did the deed, to me, if there is no subsequent leak. Refill the tyre, visually inspect it and monitor it closely - every day until no difference can be seen, then every other day, then every third day etc. If there is no change in a week then I'll bet it was some kid/arsehat at the cafe.
posted by Brockles at 8:31 AM on May 3, 2017
The chances of one tyre being let down sound pretty high to me, though. That or the kerb pop did the deed, to me, if there is no subsequent leak. Refill the tyre, visually inspect it and monitor it closely - every day until no difference can be seen, then every other day, then every third day etc. If there is no change in a week then I'll bet it was some kid/arsehat at the cafe.
posted by Brockles at 8:31 AM on May 3, 2017
I once had a garage find an otherwise-invisible leak in one of my tires once by squirting the whole thing with a mixture of water and a bit of dish washing liquid and watching for where it bubbled - might be worth a try?
posted by DingoMutt at 9:15 AM on May 3, 2017
posted by DingoMutt at 9:15 AM on May 3, 2017
This was years ago in old Saabs that I used to own, but a possibility that is worth looking into is having the rim inspected (and the other 3 as well) to see if there might be any rust on the edges that come into contact with the tires. Even in seemingly small amounts, rust can cause the rubber to lose contact with the metal for long enough that air will leak out leading to loss of pressure and even a flat if bad enough.
When it happened to me, a mechanic ground the rust off of the rim, put the tire back on, and I was on the road shortly.
posted by strelitzia at 1:21 PM on May 4, 2017
When it happened to me, a mechanic ground the rust off of the rim, put the tire back on, and I was on the road shortly.
posted by strelitzia at 1:21 PM on May 4, 2017
This thread is closed to new comments.
The tire held air when the pinhole was at the bottom. The weight of the car squeezed the hole shut against the pavement.
Take some dish soap and mix it with water. Pour it over the top of the tyre and spread it all over. Look for bubbles. If you see none, move the car a foot forward and try again.
posted by JoeZydeco at 5:54 AM on May 3, 2017