Two flat tires in three weeks?

[AlleyCat67]

This is probably a long shot, but I'd feel dumb if I was neglecting something tricky or systematic, so here goes...

At my last annual in March, I had the right main tube and tire replaced on my Tiger in response to normal wear. Two weeks later I noticed that the new tire was riding a little low, and made a note to add air before my next flight. Three days later I came out and it was completely flat. Grrr. So the local airdrome shop replaced the tube (and had to replace the tire as well since the rim had sat on it). They ascribed the flat to a pinhole leak in the tube, location unknown, with no external damage to the tire. Maybe the shop that did the annual pinched the tube valve when installing the tire?

Three weeks later I came back from a XC, and notice the *left* main tire is low. I add some air, but sure enough I come out two days later and it's completely flat. Exact same syndrome, but this tire had been on the plane happily for about two years. Back to the airdrome shop for yet another tire and tube.

Mind you, I've owned the plane for eight years and have never before had any flat tire. In fact, I've only had to add air a few times between annuals. No hard landings since the annual. The plane has always been tied down outside, and while we've had some hot days in Virginia, certainly nothing that the plane hasn't experienced before (and that the other planes on the ramp didn't also experience).

This is starting to get expensive. At the moment I'm just willing to explain this as coincidence or bad luck. If it happens a third time I may buy some incense and bells, and conduct a ritual purification ceremony around the airplane.

 

[FORANE]

I'm not familiar with the tire size on a Tiger but on some of the smaller tires running a low psi will allow the tire to pinch the tube on the side leaving small pinhole leaks. The 11x4.00-5 tires on Lancairs are notorious for it; we routinely run 50-70 psi to prevent it.

 

[AlleyCat67]

I'm not familiar with the tire size on a Tiger but on some of the smaller tires running a low psi will allow the tire to pinch the tube on the side leaving small pinhole leaks. The 11x4.00-5 tires on Lancairs are notorious for it; we routinely run 50-70 psi to prevent it.

That's a viable theory. Could be at the annual they simply didn't inflate to the proper PSI on both sides. We're supposed to be at 35 PSI according to the POH.

 

[Dan Thomas]

Before I retired eight years ago I had trouble with Goodyear tires going flat. I started investigating and found that Goodyear had a decal inside the tire, and they protected it from the tube with an overlay of clear, rather hard plastic. That overlay was coming loose as the tire flexed, and then it chafed a hole in the tube. I started removing that overlay and decal when I installed new tires or replaced a leaking tube, and the problems went away.

I filed Service Difficulty Reports (SDRs) on the problem several times with Transport Canada, who forwards them to the manufacturers involved, but nothing changed by the time I retired. Maybe nothing has changed even yet. I SDR'd Kelly and Hartzell alternators, too, since they both put way too much grease in the rear bearing, and it ended up on the slip rings and brushes, disabling the field current and thereby the alternator. Nothing changed there either. The stories I read here indicate that they're still doing it. I can't remember if I SDR'd Champion spark plugs, but should have. Several of us complained about them here on POA for a long time and Champion finally (very quietly) changed their resistor design, thereby tacitly admitting that they had resistor problems, but hoping we wouldn't notice. That didn't work, of course. We noticed. Champion had, about a decade earlier, bought out the Auburn spark plug company, an outfit that had made the best plugs I ever encountered. Champion should have incorporated the Auburn design immediately instead of waiting that decade to do so.

 

[TCABM]

A couple of thoughts come to mind, but I’ll start with had either tube been installed with talcum powder?

 

[Gary Ward]

Running them at a slightly lower air pressure shorten the life of the tube from a little extra flex.
They need air a 3-4 times a year. Not just at annual. IMO

 

[AlleyCat67]

A couple of thoughts come to mind, but I’ll start with had either tube been installed with talcum powder?

Not sure, but I could ask. Do you recommend talcum to reduce binding between the tube and tire?

 

[TCABM]

Not sure, but I could ask. Do you recommend talcum to reduce binding between the tube and tire?

From AC20-97
(2) Mounting Tube-Type Tires. Select a new tube of the correct size for the tire. Dust the tire interior and tube exterior with talc. Confirm that a new valve core is installed in the valve stem and partially inflate the tube to achieve a slightly rounded condition. Insert the tube into the tire with the yellow stripe on the tube aligned with the red spot on the tire. Mount the assembly on the wheel so that the valve stem is properly aligned with the wheel valve hole. Complete the tire and wheel assembly in accordance with the wheel manufacturer’s CMM recommendations.

Don’t sub baby powder for tire talc.

 

[Jim K]

Are they aero classic tubes? I've had multiple failures of that brand, just as you describe... pinhole out of nowhere after a year or two.

I also recently had two flats in my nosewheel tire within a couple months... the  second shop managed to find the loose cord inside the tire that was responsible for that.

 

[Hang 4]

Question for the tire knowledgeable. Would a new tire that went flat due to a tube leak need to be replaced, assuming the flat occurred just sitting in a hangar? That seems excessive to me, but not a airplane tire expert by any stretch. That caught my eye in the OP.

 

[Jim K]

Question for the tire knowledgeable. Would a new tire that went flat due to a tube leak need to be replaced, assuming the flat occurred just sitting in a hangar? That seems excessive to me, but not a airplane tire expert by any stretch. That caught my eye in the OP.

I noticed that too. I suppose it's possible a tire gets damaged by getting pinched under the rim, but I've never replaced one strictly due to a failed tube, nor has my mechanic suggested it.

 

[danhagan]

Someone already listed the tube brand name here ... but I had my mains replaced (tire and tube), and exactly 6 months later and only a few hours on them, at correct inflation, I lost one away from the home drome that took 8 hours to change out (had buddies flying me spare tube and tools). The following week I was going to change the other main out of caution, arrived at the hangar to find that tire flat as well

Put in a name brand tube and not the ones beginning with the letter "A" and all is well now. Flight school up the road in Las Cruces had 7 events in 6 months on the same brand with their fleet (all new tubes failing at about 6 months time).

 

[Bell206]

At the moment I'm just willing to explain this as coincidence or bad luck.

Make sure there is no localized issues with the wheel and tire internal areas. Have seen some repetitive flats caused by small physical defects of both items that would cause a tube issue.

 

[AlphaPilotFlyer]

Ditto what bell said….. I had replaced a tire and tube on my c172 and was flat next time I went to fly….replaced tube again and flat again next time went to fly ….it was a very slow leak…..I really took time then to feel around the inside of the tire and felt a tiny seemingly insignificant but sharp like bump which I was able to easily rub down with sand paper…. No issues since…..the bump was so small still not sure it was issue but considering the force on such small tires immediately spinning up to speed on landings- especially if that bad spot is first to hit runway and some of my less than perfect landings- could explain it.

I patched the old tube for an emergency spare and learned to do better job at inspecting new tire insides….. without gloves I rub my hand over internal surfaces, side wall included, and smooth out anything seeming imperfect, it only takes less than a minute.

 

[nrpetersen]

My then new 172M (yeah 1975!) had a thumbtack inside a main gear tire. I assume it was related to labor problems somewhere upstream.

 

[kyleb]

Old thread but check the valve stems to make sure they aren't leaking. Take the cap off and put a little little soapy water on each one. It will blow a bubble if it is leaking.

 

[texasclouds]

Learn how to change the tires and tubes yourself. You will take more care since it’s your bird.

I would feel the inside of the tire for sharp items. I also would air up the tube and dunk it in a water trough to see where the bubbles come out. That will help you find the culprit.

I can’t imagine a new tire getting destroyed from slowly leaking down onto the rim sitting in the hangar.

I run Goodyear tubes and tires on my C170. They are approx 5 yrs old now and have never gone flat. Installed myself, then a couple years ago I flipped them on the rim to get even wear. I fly about 75 hrs per year on mainly paved runways.

 

[Fffflats]

Could there be something to this? Yes. Does that mean that there is? No. Random noise tends to show in clumps and voids; see the night sky for your proof. It isn’t homogenous. Yet our minds seek patterns and stories to create coherence.