A Partially flat tyre

[Wester]

When i got on my bike this moring for my commute to work i noticed that one of my tires was partially flat i guesed that it was a slow puncture I did not have time to look for a puncture so i just pumped it up and it got me to work

Now 5 hours later the tyre is still normal no air loss what caused the problem ? i am certain that it has something to do with being left out in the hot sun for about 4 hours yesterday evening

 

[Ed no-more-lemons]

Some really tiny hole somewhere?
In the past I have found the road and or sun has sealed the gap after a few inflations.
After not being out for 4 or 5 days found same the other day, now still has good pressure after 2 days and 20 odd miles yesterday. Last time I looked this auction part looked like it had seen better days.

 

[andrew_s]

Suggestion:
A bit of talc from the inside of the tube prevented the valve from sealing properly, and got dislodged when you pumped the tyre up.

 

[Ed no-more-lemons]

Surely the manufacturerers don,' talc the inside of the tube? But what do I know after an evening in the pub. after a burn!

 

[screenman]

The reason tubes have talcum powder inside is that in manufacture, they become hot enough that, otherwise, they could become inseparably stuck when folded. That is why most butyl tubes have talcum inside.

 

[goody]

When you say partially flat do you mean just flat at the bottom?

 

[deptfordmarmoset]

When you say partially flat do you mean just flat at the bottom?

And is it partially inflated or partially deflated...?

 

[tyred]

Take the tube out and put it in a bucket of water and watch for bubbles. Add some soap or Fairy liquid for better effect.

Very slow punctures are usually valve related in my experience. It might be best to submerge the valve in water before taking the wheel apart just to confirm. Sometimes Schrader valves get bits of grit that stick it. They can usually be unstuck and can be unscrewed using a very cheap and simple tool for further inspection.

 

[Steve Saunders]

I had one of these the other day. It was the tiniest of tiny holes - tyre had dropped about 60psi overnight (might have been two days).
It needed a bucket of water to find as the air was releasing that slowly - a bubble every 5-10 seconds.

In my case it appeared to have been caused by a previous puncture that had penetrated the tyre leaving a small gash in the tyre. Over time the tube had worn against the inside of this creating a tiny hole. Repaired the tube and put a repair patch on the inside of the tyre. Been fine since.