Flat tire again

[terrykohler]

Starting to feel snake-bit. My RV has been pretty much bullet-proof with one exception - tubes. I've had way too many flats over the years (never a problem on my CT210). I've tried different tubes (now using Michelin), had others remount tires for me, gone to and maintain higher pressure (40-45 psi), all without much success. Interestingly, the failures are seldom on the tread side of the tube.
Perhaps it's the wheels??? I can't feel any burrs, but who knows. I've switched tires as well, so the problem isn't likely there.
Can't be over-use, as I'm only flying the plane 100-125 hours per year, and uneven or excessive tire wear is not evident. Brake wear is good.
Has anyone found other wheels to be a fix? Am I alone on this? Suggestions, SWAGS, spitballs, etc. appreciated.
Terry, CFI
RV9A N323TP

[RickWoodall]

Hey Terry.
I was having a similar problem. Had 4 flats over a couple hundred hours. All wheels. I have switched mains to mich tubes and now have dessser (sp?) retreads and run a little higher pressure. Also, have sanded inside of rims, used tire talc etc etc..and knock on wood no issues this past year.

I know others with standard vans stuff, never had a single issue. Will be interested what others say. Merry Christmas.

[RV6_OKLA]

I have used the same set of Michelin Air Stop tubes for 8 years. I add a couple of pounds of air during the conditional inspection and that does it for the rest of the year. Pricey, but worth it!

[FORANE]

Originally Posted by terrykohler

gone to and maintain higher pressure (40-45 psi), all without much success. Interestingly, the failures are seldom on the tread side of the tube.

These small tires are more prone to flats. In my experience your pressure is too low. I try to maintain at least about 45 psi. Many Lancair guys with the same tire/wheel as the nosewheel in our RV-9A maintain 55-60 psi.

Some have the theory that the tire will spin on the wheel pinching the tube. My theory is the tire will flex on the rim pinching the tube. This happens when the pressure decreases. Wheelpants on the RV's make it more of a PITA to check pressure. Also, on the Lancair without wheelpants I can just glance at the tire and tell if it needs air. So, less checking for needed air leads to operations with lower air pressure leads to flats.

There is another option but it'll cost you. Beringer makes a wheel / brake combo that takes a tubeless tire. I hear rave reviews on it for smoothness and no flats...

[turbo]

my thought is the tubes are low quality. i now carry a bike tire inflator in case i need to reinflate to get home. mine was a slooow leak. do what you can, carry some spare tubes and a way to air up, and enjoy the flying.

[FORANE]

Originally Posted by turbo

my thought is the tubes are low quality. i now carry a bike tire inflator in case i need to reinflate to get home. mine was a slooow leak. do what you can, carry some spare tubes and a way to air up, and enjoy the flying.

Every time I have had a flat there was evidence of pinching on the lateral aspect of the tube. Cannot blame the tube for failure when it gets pinched.

I carry spare tubes and all the tools required to change it other than air. I just need to locate air on site.

I know of some who carry a whole spare tire/rim ready for installation.

[Ron B.]

Are you using plenty of tire talc powder?

[terrykohler]

Originally Posted by Ron B.

Are you using plenty of tire talc powder?

Yup. Plenty of talc. I've been running 45 psi, but based on comments so far, I'll likely disassemble, sand/polish the wheel surface, and try 55-65 psi. If that doesn't work, I may be headed to tubeless.
Terry

[AlexPeterson]

Originally Posted by terrykohler

Yup. Plenty of talc. I've been running 45 psi, but based on comments so far, I'll likely disassemble, sand/polish the wheel surface, and try 55-65 psi. If that doesn't work, I may be headed to tubeless.
Terry

I think the talc is indeed the key for the problem as you've described. It needs to be rubbed all over the tube and on the inside of the tire.

Re sidewall tears in the tube, my theory is that there is a progressive stretching of the inner tube where it contacts the sidewall, due to flexing from rolling. If the friction between the tube and the tire is high enough, the tube can be stretched past its limit. The OP did not say specifically where they were other than not on the tread.

Also, use caution with the higher pressure - you may get quite a bit of shimmy. I missed which wheels were having flats - main or nose or both?

[terrykohler]

Originally Posted by AlexPeterson

I think the talc is indeed the key for the problem as you've described. It needs to be rubbed all over the tube and on the inside of the tire.

Re sidewall tears in the tube, my theory is that there is a progressive stretching of the inner tube where it contacts the sidewall, due to flexing from rolling. If the friction between the tube and the tire is high enough, the tube can be stretched past its limit. The OP did not say specifically where they were other than not on the tread.

Also, use caution with the higher pressure - you may get quite a bit of shimmy. I missed which wheels were having flats - main or nose or both?

Alex:
I think I've got plenty of talc. Most of the tube failures have been on the ID or part contacting the wheel. Flats are happening on mains. My touchdowns are typically not high speed (55-60kts on final), very little braking used (long, paved runways), and turnoffs pretty gentle. I do, however, operate quite often at or near gross (1750-1800). Still scratching my head on this one.
Thanks,
Terry