What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Random flat tire / tyre ?

humptybump

Well Known Member
What might cause the following:

  • Went to the hangar and one tire was flat.
  • It wasn't flat the day before or the day before that.
  • I had flown 7 days prior.
  • Put air in the time and it's been 24hr and it's still at same pressure. (will continue to monitor for multiple days.)
  • No externally visible signs of trauma.
  • Local weather has been moderate. Hangar temps have remained in the range of 48F-64F.
  • No climatic evidence on the airplane.
  • No visible stresses evident on the plane.

I want to monitor for another 48 hours before I remove the wheel and do a soap-bubble test.
 
BLUF- look for a tube manufacture flaw, a pore in the surface that leaks, removed from tire, with about 8psi in the tube to stretch it enough. Mine was stem outlet side wall location across from the stem outlet. - no way it was a puncture. It was a flaw that looked like a little pit/pore.

Longer version:

This year I had very similar on on a Michelin Airstop tube molded 10/2014. Random flat in hangar. No obvious damage, cut, tear pinch or recent work.

Funnier part was I had a metal valve stem cap that would over-screw and was misformed and actually give a hiss of air when unscrewed. I thought the stem seal was bad, it was not. Fix- I then thought- new valve cap.

Glad I left the wheel pant off overnight because the real leak was a pore in the innertube manufacture defect. I had to put 8 psi in the tube, free of the tire to find it. That was the hard part- that seemed excessive, but without it the leak did not show uo readily.

http://www.vansairforce.com/community/showthread.php?t=176098&highlight=Tube+stem+leak
 
Last edited:
If tubeless, I'd say a nail or similar is in tire.

Normally nail will plug hole.

But if you happen to stop 'just so' on the nail, air leaks out.
 
Tubed tires. No nails or damage to tyre. Could be minute damage to stem. These tires and tubes are 3 seasons and have been rotated once.

I'll monitor for another 1-2 days and the. Remove to test with soapy water.

I doubt I would find anything definitive without doing the water test and it provides that next-level confidence.
 
Last edited:
Had similar situation but had checked air pressure days before. Like you flew no issues, landed, stored 5 days later flat. Inflated back up, has held for 6 weeks. I blame the schrader valve for not seating properly and created a very slow leak, only visible after days of leaking.
 
Tubed tires. These tires and tubes are 3 seasons and have been rotated once.

I think many folks under estimate the importance of tires and brakes, failures of either can really make for a bad day and be very expensive!
Personally if I remove a tire it generally get a new tire/tube, or at least a new tube, I don't 'flip' tires for this reason.

From the good folks at Goodyear Tire:

"It is recommended that tubes not be reused; they can grow as much as 25% in service. Reusing them can result in folded, pinched tubes which can fail or create an imbalance."
 
Last edited:
Tube problem

I have had a similar problem with tires with a tube in them. What I think happens is the tire itself retains some air in it while the tube is filled, and that air balances with the pressure in the tube at 25-30 psi. Then after a couple days, the air that was left in the tire leaks out leaving only the air in the tube and a partial flat. When this occurred I refilled the tube to the 25-30 psi, and it was fine after that.
 
"It is recommended that tubes not be reused; they can grow as much as 25% in service. Reusing them can result in folded, pinched tubes which can fail or create an imbalance."

I always replaced tubes with tires But kept tubes with tires. Each of the A&P 's who have done my condition inspection have instructed me on the process of flipping the tires and never suggested replacing tubes during the process.

Walt, does this mean that tubes should be replaced every time the tire comes off - even when flipping the existing tires?
 
I always replaced tubes with tires But kept tubes with tires. Each of the A&P 's who have done my condition inspection have instructed me on the process of flipping the tires and never suggested replacing tubes during the process.

Walt, does this mean that tubes should be replaced every time the tire comes off - even when flipping the existing tires?

Unless it's a field repair/emergency, new tubes should be installed when the tire is removed, this includes 'flipping'.

I know lots of folks won't agree with me because it costs to much, try having a flat at an airport away from home and then tell me how much you spent fixing it.
 
Losing all air in one day is not a slow leak, it is something significant. It could have been an issue with the shrader valve, but that is only likely if the valve was used just before the leak event. If you haven't touched the shrader valve in some time, it is far less likely to be a stuck or mis-seated valve.

Whatever it was is likely to happen again, so either identify the issue or replace the tube, lest you get stranded some day or worse, find yourself landing with a flat tire. A tire can't lose that much air in a day without a major fault.

Larry
 
Last edited:
I have had a similar problem with tires with a tube in them. What I think happens is the tire itself retains some air in it while the tube is filled, and that air balances with the pressure in the tube at 25-30 psi. Then after a couple days, the air that was left in the tire leaks out leaving only the air in the tube and a partial flat. When this occurred I refilled the tube to the 25-30 psi, and it was fine after that.

A tire installed on a traditional aviation wheel can't hold any air. The seam in the split wheel prevents any compressed air from being retained, not to mention the unsealed hole for the stem.

Larry
 
Whatever it was is likely to happen again, so either identify the issue or replace the tube

I mostly agree. However, replacing the tube without identifying the issue still has the potential to repeat.

I won't have 100% confidence unless I know the cause and address it specifically.
 
I had a bad batch of fancy tubes several years ago they both went flat within a month. There were multiple micro cracks found along the bigger circle.
 
That's what you get for teaching Nick how to use a valve stem tool, and then leaving him in Doggie Daycare too long. ;)
 
It did happen!

A tire installed on a traditional aviation wheel can't hold any air. The seam in the split wheel prevents any compressed air from being retained, not to mention the unsealed hole for the stem.

Larry

And if the tube fills from inside to out, temporarily sealing against the tire and not allowing the air trapped access to the split rim? I have learned that cannot happen are not a words to use in aviation maintenance.
 
I have had a similar problem with tires with a tube in them. What I think happens is the tire itself retains some air in it while the tube is filled, and that air balances with the pressure in the tube at 25-30 psi. Then after a couple days, the air that was left in the tire leaks out leaving only the air in the tube and a partial flat. When this occurred I refilled the tube to the 25-30 psi, and it was fine after that.

I definitely had this issue in a non-split aviation rim. Tube and tire was installed by a professional tire shop and they filled the tire with air. Correct air pressure but somehow there was air trapped between the outside of the tube and the rim. By the next day tire was 1/2 full of air. Refilled it and it has ben fine since.
 
I posted this years ago on VAF, so it is somewhere in the archives:

When I installed my tubes/tires on my 9A, I used plenty of talcum powder and was careful to follow the staged inflation recommendations.

What I did NOT do was to remove the smal paper part number labels stuck onto the inside of the tires.

These labels cause abrasive wear on the tubes and pinhole leaks. Probably less than 100 takeoffs/landings in service. I have photos somewhere in a dusty corner of my backup files.

V
 
Ran into only one instance where low inflation actually tore the stem away from the tube body, the stem was at an angle sticking out the rim.
Years ago ran into repeated instances where nose tires would go flat, some tubes had multiple side wall leaks, eventually realized inside of tire was wearing into the tube because of rough manufacturing 'nubs' inside the tires. I dremmeled them smooth and problem didn't come back. I always check for moulding defects inside tires now before mounting.
I sprinkle only enough talc to cover inside of tire & tube, I ran into one tire with enough talc in it that it turned to grinding compound paste & resulted in multiple visible wear spots on the tubes.
I advise new tubes used anytime tires are changed or rotated.
 
Underinflation? Valve stems?

We had two issues:

1. Underinflation. Allows the inner tube to rub against the tire, eventually causing a leak. We use 42 psi.

2. Bad valve stems. New inner tubes. Came from the manufacturer that way.

Good luck!
 
If it were me, I would replace the tube before you fly again. Having a flat with the plane in motion can cause lots of wheel fairing damage (I know from experience), and is harder to replace than in your hangar. There is no such thing as an isolated random occurrence for something like this. There is a defect in the tube and it will happen again. How hard will you be kicking yourself when it happens and you damage the plane?
 
Valve Stem, Maybe?

In a conversation with an automobile designer/entrepeneur many years ago, he told me "An intermittent leak is ALWAYS a valve stem!" Reading previous posts makes me doubt that this is always the case, but it might be a good idea to replace the valve stem. It only costs pennies although you will need to support the airplane when the tire is dead flat, but it might be worth a try.
 
Intermittent Leak

Many years ago, an old automotive designer, entrepreneur and pilot told me that "an intermittent leak is ALWAYS a valve stem!" Shouted it, actually. Reading previous posts to this thread convinces me that the valve stem is not necessarily the only answer. But it only costs pennies and it's fairly easy to do... you will need to support the airplane to keep weight off the tyre until you're done. Worth a try.

jerry
 
I experienced the same problem this past weekend. Saturday morning, I found the left main dead flat on my -4. The week before, I flew and it was fine. The last time I touched the wheel was to add some air in November. (I add air about every 6 months.) I have flown every weekend since adding air.

I pulled the wheel and while doing so, decided I should replace the brake pads since I had everything open. Once I decided to do the left pads, I thought I might as well do the right.

So my flight was scrubbed, I and pulled off both wheels instead. I have ordered replacement pads, Airstop tubes, and Condor tires (>$500). Yesterday, I submerged the bad tube in a sink full of water, but could not find a leak. After 24 hours, the flat tube appears to be holding pressure.

Airstop tubes cost more than the tire, so I do find this exercise a bit frustrating...
 
Closing out my post ...

I replaced the valve core and it appeared to solve the problem ... but it didn't. It did dramatically slow the leak but it still wasn't "done".

I replaced the tube.

Case closed without solving the mystery.
 
Glen I know how you like to experiment. Over inflate the discarded tube and do a bubble test. The offending micro crack will reveal itself :)
 
I had a similar issue with the rear tire on my Goldwing.
I had new tires installed before we left home in Oklahoma to Williams, AZ. Two day trip to AZ was fine, along with the couple of days we were there. On the way home, at one fuel stop, I didn't think the rear tire looked quite right. Sure enough it was really low, so I aired it up at the pay pump. It remained good all the way home.

When we got home I took it to the Honda shop where I had the tires installed. They couldn't find any air leaks at all. It was there a few days, so they called me to say it was ready. Went to pick it up, the back tire was flat.

The only thing we could figure, was it was separated on the inside and when parked in just a certain position it would open the separation enough to leak.
They put on a new tire under warranty, I haven't had any trouble since.
 
Glen I know how you like to experiment. Over inflate the discarded tube and do a bubble test. The offending micro crack will reveal itself :)


I may just do that.


I will point back to Walt's post to replace tubes even when flipping tires. When I did the mild inflation test of the tube to check for leaks, it was definitely not uniformly round any more.
 
Glen I know how you like to experiment. Over inflate the discarded tube and do a bubble test. The offending micro crack will reveal itself :)

I just fixed my flat by replacing both tubes, both tires, (and brake pads for good measure). I inflated both old tubes (the one that flatted and the one on the other side) to 8-10 psi. Neither showed a leak by submerging. After 7 days, I could not discern a pressure difference between the two. It's still a mystery to me.

To what level can a tube without a tire be pressurized without rupturing the tube?
 
-10 flat

I had a tire go flat in a similar time frame. I pulled the tube out and pumped it up to about 150% of of its size and found a small crease in the tire had worn it through. I will not re-use tubes.
 
Back
Top