My BMX bike front tire went flat on me for no reason. My room wasn’t warm at all, but it was cold. I don't know if that caused it because only my front tire went flat not my back. Any suggestions? I don’t have holes in them.

  • 5
    I'm 100% sure it didn't go flat for no reason. If it's flat then something made it go flat.
    – Andy P
    May 1, 2019 at 13:41
  • 3
    How long was it between when the tire was last aired and when it went flat? Over several weeks a tire will seep air and eventually go flat. If it went flat relatively quickly then there is a leak. Air leaks because of a bad valve or a hole in the tube.
    – David D
    May 1, 2019 at 13:54
  • 4
    Avoid hyperbole when phrasing your question. Nothing can happen for "no reason" and we all know that... But now anyone trying to answer your question has to try to guess at what is really going on because what you've stated is technically impossible. Maybe let us know what you've done to check for holes so far instead of saying "I don't have holes." Otherwise every answer is going to be some variation of, "check for holes" even though you're already said there are none. May 1, 2019 at 16:39

3 Answers 3


You can try taking the tube out, add a little air, and then submerge it in water.

Sometimes it's easier to find a tiny leak when bubbles are coming out of it. There's a chance the leak is at the valve so check there too.

Just take care not to inflate the tube too much. Without the wheel and tire constricting it, the tube will expand much easier and you risk making the tiny leak into a ruined tire.

  • 3
    Don't add "a little air", add a fair amount. The tube should swell up to maybe 1/3 larger than it's "normal" diameter. But go by tube size, not pressure. (And if you over-pressure it will not ruin the tire, just the tube (and maybe your hearing for a couple of hours).) May 1, 2019 at 15:19

I don’t have holes in them.

For the air to get out there must be a hole somewhere.

Check the inner tube for punctures. Check the inside of the tire for anything poking through the tire. Check the valve, if it’s got a bit of contamination in it it may not be closing properly.

  • 1
    If the bike had been sitting for two weeks then it may just be "normal" leakage -- diffusion through the rubber. Some robust tubes can hold air reasonably well for 3 months, other "hoity-toity" ones struggle to hold air for 3 days. May 1, 2019 at 17:45
  • @DanielRHicks. Seems unlikely in the case, even porous tubes take a while to go completely flat and the rear wheel was OK. May 1, 2019 at 18:06
  • Could be different brand tubes in front vs rear. And I have seen new, highly touted tubes that wouldn't hold air for two days. May 1, 2019 at 21:47
  • I currently have a tube that goes down slowly and sometimes fast as the valve is very hard to get to sit right. (Too lazy to replace it when pumping once in a while will keep it going.) So no holes needed if the valve is to blame.
    – Willeke
    May 3, 2019 at 17:33


  1. There's a hole somewhere. (there has to, or #3) Look for it by Henry's answer and check tire by Argenti's answer.

  2. There's still a hole, and it's on the base of your valve. File down the valve hole on your rims. For extra measure, cut an old piece of inner tube or rubber strip, cut a hole a tad smaller than your tube's valve, and slot it on your valve. It'll function as extra protective layer. Also, if your valves are Presta or threaded-through Schrader, don't tighten you valve nut too much.

  3. Your valve core's not tight enough (for some reason). Get a valve core wrench/driver and tighten it down.

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