Mystery puncture
 

I have a strange puncture I can pump up my rear tyre real hard after it's gone real flat and it will stay inflated all day sitting there. I can even go out on it, return and then in about another day or so it's again gone as flat as a pancake, I pump it up again and the same cycle over again - I have checked the valve, spat on it, no bubbles etc - whats going on?

Latex tubes??

Slow leak. You just haven't found it yet.

This is usually an issue with a leak at the valve for me. Sometimes a cap is all that's needed.

Kevin g

Take the tube out and run a cotton ball inside the tire. Look for a piece of cotton that may have hooked on something sharp.

Might be one of those April 1st leaks.
That's when someone is inducing a false leak causing you to lose your mental state slowly. You have any vindictive furry critters that may have taught themselves how to deflate a tire in order to keep you in the house with them longer? Deny any kids of sugary items recently that put you in debt to retaliation? Sweet revenge might be the dish being served. Could just be a bum tube/valve.

Really but its been 24 hours now and its still well pumped up, it was a new inner tube too, less than 2 weeks old.

Sorry can you elaborate?

Well yes I guess I will try this next, but also try to extensively examine the wheel/tyre surfaces, will try the cotton wool ball idea too.

Latex tubes don't hold air as well as butyl rubber and will slowly leak pressure through the latex skin of the inner tube. They need to be topped up more often than the more typical rubber tubes, which also leak some air through the tube itself, but much more slowly. Whereas you might be able to go a week between pumping up a tire with a rubber tube, you pretty much need to top off a latex tube every time you ride.

I also have had small "micro-punctures" that have only shown up in a sing full of water. Sometimes it was just a couple of bubbles.

One time in the sink I found nothing until I put pressure on the stem by pushing it in all directions. Then the bubbles started.

Another time I had to pump up the inner tube a lot more before the bubble started.

I usually just take one side of the tire off and run my hand around inside the tire until I find whatever caused the puncture. If you leave the tube in place and find the sharp object, that will show you where to look on the tube. I am assuming you are using tubes. If tubeless, this signals loss of sealant.

Yes. Fill the sink or your bathtub if you have one.

One time when I was out on tour I woke to find one of my tires completely flat. Could not find an obvious hole. Ended up inflating the tube and dragging it through a large puddle left over by heavy rain the day before. It revealed the tiniest of holes. So tiny a air bubble would come out only every two seconds or so. Checked the tire thoroughly and finally found a tiny piece of wire. Turning the tire inside out can help you locate debris.

carry a mini pump and don't worry

Well my tyre is still well inflated after going out on it today and it's now 35 plus hours since it went totally flat - weird or what?
What's this wire debris thingy?

Could have been a small piece of wire from a car or truck tire or a piece of a staple.

Surely unlikely...but will check when I finally do need to remove the tyre - as of Sunday at 10.30, the tyre is still well inflated with no discernable loss of pressure - the mystery deepens.

Gaslighting??

Fanciful, or paranoid...lol. Besides I live on my own.

what tube & tire brands & models are installed currently? Provide pictures of your wheel assemblies as they are fitted now.

Slow leaks are nothing new and they are infuriating to find sometimes. If a leak is really slow then just keep on riding and pumping them up every day until it becomes a faster leak. The risk though is that you may have a flat on the road one day. If the leak has now truly stopped, then maybe it was caused by some dust/dirt lodged in the valve somewhere.

Excellent point, maybe it was dust/dirt lodged now cleared when I re-pumped, but I have always had a dust cap fitted!

For the other query it's a 20 inch Schwalbe tyre, but cannot remember what make the tube was?

As it turns out, there are little slivers of wire everywhere on the roads, particularly on the shoulders. It comes mostly from truck tires, I think. I had a slow leak on a ride and couldn't find the cause. I put in a new tube and pumped it up and rode 100 miles on it that way. That was a spare set of tires, so after that ride I took them off. For some reason, before I used them again I checked the tire and found the sliver of wire. The difference might have been that the first time I checked was by the side of the road in the middle of the night, who could know?