Why no run flats?

[aviatoreb]

I had a flat tire yesterday.  See the details on

http://mooneyspace.com/topic/9048-flightaware-and-canada/

 

...it was at the customs ramp in BTV ...luckily also in front of the repair station.

 

Thing is, my tire released all its air in like 2 min or faster.  I had no problem on landing and no problem taxiing, and the lineman who parked me said there was air when he parked me.  They eventually found a good size crack in the tube, and all I can guess is that sitting on the hot taramac was enough to let all the air go.

 

Wow - that is spooky because that tire you can see is completely flat and that would be QUITE a handful on the front wheel if it had happened while landing.  In fact the moment I saw the flat I shuddered for a moment and immediately inspected my prop - but all clean.

 

So here is my question - WHY are we using the 1920s tire technology?!!!!!  Why don't we have more modern car like tires, run flats and all?  A simply inner tube blow out, or even fast flat, could result in some very very expensive bent metal.

[David Mazer]

I've had three flats, all on the mains, two on landing and one sitting on a ramp.  Landing with a main going flat isn't a big deal with respect to control.  I'm not sure what landing with a flat nose would be like and I would prefer to stay that way.  I suppose your answer can be found in the thread dealing with the new Garmin AP.  If you can call that an answer.

 

BTW, do run flat tires weigh more than regular tires?

[co2bruce]

I had a flat (nose tire) just after landing a few months ago. It was a handfull. It occured just after touching down the nose gear. My rudder pedals just shuttered back and forth full deflection. I was able to slow down and taxi (very slowly)  just clear of the runway and shut down. Luckily a new tube and its good as new. To answer your question :

 

tube $ 45.00

run flat tire on car  $200.00  for plane  $ ?????????? 

[fantom]

Not saying you don't, but a fine example for always changing tubes when you change tires.

I know a few 'thrifty' Mooney owners who don't.

[N601RX]

I had a flat tire yesterday.  See the details on

http://mooneyspace.com/topic/9048-flightaware-and-canada/

 

...it was at the customs ramp in BTV ...luckily also in front of the repair station.

 

Thing is, my tire released all its air in like 2 min or faster.  I had no problem on landing and no problem taxiing, and the lineman who parked me said there was air when he parked me.  They eventually found a good size crack in the tube, and all I can guess is that sitting on the hot taramac was enough to let all the air go.

 

Wow - that is spooky because that tire you can see is completely flat and that would be QUITE a handful on the front wheel if it had happened while landing.  In fact the moment I saw the flat I shuddered for a moment and immediately inspected my prop - but all clean.

 

So here is my question - WHY are we using the 1920s tire technology?!!!!!  Why don't we have more modern car like tires, run flats and all?  A simply inner tube blow out, or even fast flat, could result in some very very expensive bent metal.

How old were your tubes? Could you tell if it had a wrinkle in it that eventually turned into a crack?

[co2bruce]

I think I had low pressure in the nose wheel. I now check all the time. I am told its common to have the tube blow when the nose sits down and the pressure is low. I guess the tire shifts on the rim and the tube gets pinched.

[aviatoreb]

Hi David, Yes, of course I know the answer is - because it is too expensive to certify so nobody has bothered.  I bet they would weight more but not that much more since it is still a very small tire after all.  I would happily put it on the front tire at least.

 

co2bruce, good to hear of your successful landing with a flat.  I bet a run flat for a front tire would be at least $500.  But how much is a prop strike.  It is spooky seeing that proper lowered another 3 or 4'' and thinking what a flat tire could possibly cause. Was your flat a complete loss of air during rollout or was it partial?

 

Fantom, I do change tubes when I change tires as a practice.  On my last plane, my DA40 all the way around, and on this airplane I changed the mains, but not yet the front tire as the tire is in excellent shape - but apparently not the tube!  I have had the plane for two years.  

 

N601X: This evening I will be researching the logs for signs of the tube's age.  I have a new tube now!  By wrinkle do you mean a pinch flat?  I doubt it since they lasted >2 years since I owned it at least, and on my bicycle at least a pinch flat shows itself as two small holes side by side - we call it snake bite since it looks like a snake bit into the tube.  In my mooney yesterday there was a single hole that looked as if it just decided to open up.  No signs of an offending nail or glass or anything in the tire either.

[1964-M20E]

My MX insists on changing the tire and tube for a flat. I can understand if a flat happened during landing but a  little excessive in my book.  However, new tries do get a new tube.

[201er]

My theory why car like tubeless tires are not used on airplanes is:

 

-Rims are not perfect and they are smaller

-Pressure from hard landing could deform tire enough to push it away from rim and let out air?

-We fly at different altitudes so again, air pressure on tire could be changing frequently

 

Maybe it has nothing to do with those but that's where I'd start to look for answers because that's how airplanes are different from cars.

[carusoam]

New design tubes hold air for nearly a year, as apposed to old tubes that need to be inflated monthly... The polymer chemistry was changed...

In the automotive world there have been two changes... Tubeless tires followed by runflats.

It seems like the tire technology is available, but a company would need to put the development effort in...

Size of the market is critical. Nice to have vs. need to have.

I would like to have a set of Gator-back Radials with low profiles for quick turns off the runway...

Best regards,

-a-

[Marauder]

I have run flats on my Vette and I wonder how hard the landings in an airplane would become. Between the donuts and the give in a tubed tire, there is some cushioning. The reason run flats work is because the side walls are capable of supporting the vehicle without air. Considering the size of an airplane tire relative to a 19" or 20" car tire, I'm willing to bet my dentures would fall out on a hard landing... (where are my teeth) Since we are speaking about tires. I had been using Goodyears Flight Customs for years. My mechanic suggested a high end McCreary tire this time around. He said he has had good success with them. Anyone else running McCreary's? My only experience was with them on flight school planes! (Sorry for the hijack!).

[KSMooniac]

I think the weight and harshness of a run-flat would be awful for a Mooney.  Our "little" tires don't have a lot of vertical compliance, and using stiff run-flats would make for a terrible experience on the ground IMO.  

 

I switched to leak-stop tubes at my last tire change and have been very happy with them.  Additionally, our two-piece wheels require a tube as far as I know, otherwise the halves wouldn't hold air!

[RJBrown]

A tire with a tube generates more heat than a tire without a tube. The "speed rating" of a car tire is directly related to heat. Radial tires flex more than bias ply tires. Using a tube in a radial is then more harmfull than in a bias ply tire. Going tubeless provides a significant advantage for the speed rating of car tires. Airplane tires are not run for prolonged periods of time at high speed. 30 to 60 seconds of high speed running wont over heat an airplane tire. Changing to tubeless airplane tires would involve compatible wheels and their certification also. The main disadvantage of tubes in cars is heat generation at high speed, this is not an issue for our planes.

 Run flat tires IMHO are a bad idea. Stiffer, harsher tires with a significant cost disadvantage. Sounds great in the showroom but car owners learn to hate them at replacement time.  

[Marauder]

 Sounds great in the showroom but car owners learn to hate them at replacement time.  

 

Tell me about it! $1,600 for all 4 corners on my Vette.

[fantom]

My J came from the factory with McCreary tires. Very light and thin sidewalls back in '94, that didn't wear very well. Maybe they've improved over time.

 

Goodyear on my plane and Michelin on my cars

[aviatoreb]

Okay guys, thanks.  This has been informative.

 

How about this stuff? Anti-flat-seal stuff?  Does such a thing exist for airplanes?  Here is the bicycle version - it actually works reasonably well for bicycles and remember they run 100psi.

"slime":

http://www.performancebike.com/bikes/ProductDisplay?storeId=10052&langId=-1&catalogId=10551&productId=1035359&utm_source=Google_Product_Search&utm_medium=pla&utm_campaign=datafeed&cm_mmc=Google_Product_Search-_-PLA-_-Datafeed-_-Slime%20Tube%20Sealant%20Null%20Null&CAWELAID=1009375174&catargetid=1572650445&cagpspn=pla

[aviatoreb]

I have owned two Vettes (a flawless '84 and a well worn '89) before but never had to replace the tires on either of them.  They were toy cars to me and I didn't drive them very much.

 

 

Driveway candy.  Nothing wrong with that!

[fantom]

Jim and Marauder....with many high performance cars either not having spares, or maybe little donuts, one new technology option that minimizes the risk of being stranded with a non-run-flat tire is the wonderful handling and comfortable Michelin Pilot Sport PS2 ZP, but it ain't cheap.

[chrisk]

 By wrinkle do you mean a pinch flat?  I doubt it since they lasted >2 years since I owned it at least, and on my bicycle at least a pinch flat shows itself as two small holes side by side - we call it snake bite since it looks like a snake bit into the tube.

 

I can assure you that a pinch flat shows the same on an aircraft tube.  I don't like to admit it, but I managed this while flight training.   Not enough pressure in the front tire of a 172, and a hard 3 point landing at night.  --Clearly my technique could have been better (and is now).  Anyway, the tire didn't go flat immediately. 

 

And by wrinkle, I think he was referring to a folded area of the tube.   Eventually, these can wear through.

[Bennett]

I'm running Michelin Pilot Sport PS3 ZPs on my SL.  Awesome tires, but hardly cheap. You don't see the SP3s much, but I think they are worth the slightly extra cost.  Bought them through Tire Rack, and had them shipped to a local shop for installation.  I would use Tire Rack again - great service.  I do not want run-flats on my cars or my Mooney.  No spare in the SL, just a can of goop. I'm even sure where it is stowed. When the retractable hardtop is in the trunk, there isn't much space left over beyond a couple of overnight bags. 

[KSMooniac]

I know the run-flats are universally despised in the BMW community, especially first-gen cars that had suspension originally designed/tuned for conventional tires.  They didn't last as long, were noisy, harsh, and didn't handle as well.  Subsequent generations got better as the suspension design adapted to the new tires, but owners still don't like them, especially at replacement time.  Many new cars aren't even provisioned for a spare donut anymore too!  Fortunately my "new" BMW (a 2004 330i ZHP) has a donut but it is pretty much just a local driver anyway since I use the Mooney for long trips.  If I ever get a newer one, I'll just carry my motorcycle kit with a 12V compressor and some plugs and hope that will get me mobile again until I can get to a shop for a proper patch or replacement.

[Marauder]

My J came from the factory with McCreary tires. Very light and thin sidewalls back in '94, that didn't wear very well. Maybe they've improved over time.

 

Goodyear on my plane and Michelin on my cars

 

According to my mechanic, McCreary has improved their tires and offer a high end line comparable to the Flight Customs -- but at a lower price. Call me Guinea Pig, oink oink. I told him to put them on.

 I will PIREP them once I see how they work out. oink oink.

 

[Marauder]

Marauder,

 

I have owned two Vettes (a flawless '84 and a well worn '89) before but never had to replace the tires on either of them.  They were toy cars to me and I didn't drive them very much.

 

I have a question, though.  I will probably buy another old C4 when my kids go off to college and I no longer need four seats.  This one will be a driver, though, so tires will be a consideration.  Is there a cheaper alternative than the run flats that you are running? 

 

Thanks!

 

Jim

 

There is. You can run conventional tires and find a way to store a spare. I like the run flats simply because you won't be stranded. You can do 50 mph until you find a place to have it repaired.  Not sure about the older Vettes, but the new ones run a smaller tire upfront. I have a 19" on the front and 20" on the rear. BTW Jim... With my last avionics upgrade, the financial officer told me to sell my Vette. If you are looking for a 2004, Lemans Blue limited edition with 6,900 original miles and which has NEVER seen rain, let me know. I haven't advertised it yet, but will need to move it this summer.

[Marauder]

Okay guys, thanks.  This has been informative.

 

How about this stuff? Anti-flat-seal stuff?  Does such a thing exist for airplanes?  Here is the bicycle version - it actually works reasonably well for bicycles and remember they run 100psi.

"slime":

http://www.performancebike.com/bikes/ProductDisplay?storeId=10052&langId=-1&catalogId=10551&productId=1035359&utm_source=Google_Product_Search&utm_medium=pla&utm_campaign=datafeed&cm_mmc=Google_Product_Search-_-PLA-_-Datafeed-_-Slime%20Tube%20Sealant%20Null%20Null&CAWELAID=1009375174&catargetid=1572650445&cagpspn=pla

 

I use Stan's on my mountain bike and I forget the stuff in my road bike (both tubeless wheel sets). Both work, but do they leave a mess inside the rim. If you ever need to put a tube back in, it is a job cleaning it all out again. When you consider a road bike is using 120 psi and it can stop the leak, it is pretty impressive.

[Marauder]

Jim and Marauder....with many high performance cars either not having spares, or maybe little donuts, one new technology option that minimizes the risk of being stranded with a non-run-flat tire is the wonderful handling and comfortable Michelin Pilot Sport PS2 ZP, but it ain't cheap.

 

Surprisingly they are in the same price range as Goodyear run flats and the rest of them -- aka expensive. With the number of miles I am putting on my Vette each year, the originals will go quite a while...