Diagnosing tire leak

[Draker]

Was away on a cross country flight, on the ground for about 2 hours, and when I walked back to the RV, I noticed my left main tire was fully deflated! By great luck, I was visiting another RV builder, and he had an air compressor and tire inflator in his shop. So I filled it back up and determined the air loss was gradual and that I had enough time to return home.

Got a new tire and tube installed now, but I'm puzzled about the cause of the deflation. Happened out of nowhere. My previous landings were not particularly rough. And no visible damage to the tire surface or punctures. The grooves in the tire tread are still about 5/64" deep (compared to about 11/64" on a new tire). I flew my previous tires down to the point where there was no groove left at all. I even inflated the tube and held it under water in a swimming pool and no bubbles, so the leak must be extraordinarily tiny. Should I agonize over figuring this out or just toss the old tire and forget about it?

Tire is Goodyear Flight Special II 5.00-5, tube is an original stock Vans tube.

At least lesson learned to keep a portable tire pump in my flight bag from now on.

 

[ve0kog]

my last tube had a pinhole leak which opened up only with a touch. soapy water and took a few minutes to find. they like to trick ya

 

[RV7 To Go]

What tire pressure do you run? I have seen a couple guys on our field end up with small pinhole leaks because they ran low (20 ish psi) pressures. I use plenty of talc when installing the tube and run 45 psi. Never a flat so far in 20 years. The best tubes to buy are the Leakguard or the Michelin Airstops. They hold air better than the standard tube. Might also check the schrader valve in case a small piece of FOD got into it.

 

[RWoodard]

Funny you should mention this. I parked my RV3 in a neighbor’s hangar for about a week. When I went to retrieve it, the right tire was completely deflated. I aired it up and put it back in my hangar about 3 weeks ago. It’s been sitting there ever since and hasn’t lost a single PSI. I won’t fly it again until I have time to take the tire/wheel/tube apart to find the cause of the leak. The prevailing guess right now is that there was some sort of FOD in the schrader valve.

 

[Draker]

What tire pressure do you run? I have seen a couple guys on our field end up with small pinhole leaks because they ran low (20 ish psi) pressures. I use plenty of talc when installing the tube and run 45 psi. Never a flat so far in 20 years. The best tubes to buy are the Leakguard or the Michelin Airstops. They hold air better than the standard tube. Might also check the schrader valve in case a small piece of FOD got into it.

I run 35PSI. I'll try the soapy water trick!

 

[D-Dubya]

The tire itself is likely not the cause for the leak, but it may not be in the best of shape now if it went completely flat with weight on it. Just carefully examine the tire for cracks or damage, but you may be able to reuse it. As far as the old tube goes, it's nice to have a spare on hand. But by the time you need it again, it may be getting too old to use. With that said, I keep some stuff around the hangar just in case someone ends up stranded and needs help right then.

The tube or the Schrader valve was most likely the culprit for a leak. The valve may have just gotten some schmutz in it. BTW, I'm a big fan of the Michelin Airstop tubes. Their leak-down rate is much slower than the stock Van's tubes. You'll find many people here on the Forum that are big fans of them as well. They're kinda pricy, but you get what you pay for.