Nose tire 1964 M20c

[Jim Peace]

My brother made it halfway back to our parking spot and the nose tire deflated.  Airport ops came out quickly and got the plane safely to its normal parking spot.

Upon review it looks like I will now need a new tube and tire.

I just learned that there is a 6 ply tire on the nose.  This was installed prior to me buying the plane 3 years ago.  I have always kept the pressure at 30psi thinking that I had a 4 ply.  I never bothered to check it, after all why would someone go against the manual?

I thought I read in other threads on MS that if a plane has a 6 ply tire on the nose the pressure must be at some value over 45psi.  And the 6 ply tire was only for later models.

Questions:

1.  Was it wrong of the mechanic to install a 6 ply tire on the nose of this plane?

2.  If it was OK to install it,  should I have kept the tire pressure around 45psi or is 30psi OK in a 6 ply nose tire?

3.  If you had to replace it would you put 4 ply or 6 ply on the nose and disregard what the type certificate says?

 

Here is the page from the M20c type certificate.

[Hank]

I have the 5.00-5 nose tire, I think 4 ply. I keep all three at 30 psi and have not had a problem. I think the fuel injected models with heavier engines have a different tire and higher pressure. 

Edited September 25, 2016 by Hank

[Jim Peace]

Just now, Hank said:

I have the 5.00-5 nose tire, I think 4 ply. I keep all three at 30 psi and have not had a problem. 

That is what I thought I had until today.  I was so surprised to see the nose say it is 6 ply.  And I am not sure if I was under inflating it all this time.

[Jim Peace]

Also I could not believe how much dry rot there was.  I look at the condition of the tires all the time and the dry rot was not apparent until the pressure was gone and sitting on its side.

So I think I will just get all new tires and this way I have a much better idea of the history of them.  

Also I park outside and I think I will get some sort of cover for the nose tire.  I see covers on tires all the time in Alaska but never thought I would need it down here.

[macosxuser]

Typically people end up putting on the 6 ply because it's more readily available, and sometimes cheaper. The two things to think about here are:

1. It's heavier, but not that much.

2. It has a stiffer sidewall, so you'll get less cushion out of it at the same pressure. DO NOT run a higher pressure, but do check to make sure you maintain rated pressure. It will not *appear* to be as low as it is.

Many people run one ply rating up, and I've never heard of an issue.

[Jim Peace]

Just now, macosxuser said:

Typically people end up putting on the 6 ply because it's more readily available, and sometimes cheaper. The two things to think about here are:

1. It's heavier, but not that much.

2. It has a stiffer sidewall, so you'll get less cushion out of it at the same pressure. DO NOT run a higher pressure, but do check to make sure you maintain rated pressure. It will not *appear* to be as low as it is.

Many people run one ply rating up, and I've never heard of an issue.

So are you writing this as a A&P or an IA?

If you had to Monday morning quarterback an incident as an insurance company dealing with a tire issue and the nose tire is not as per the manual would you still give the owner a check?  

I work as a 121 pilot for a company that turns its own pilots in to the FAA for their bad mx practices.  So it is just ingrained in me to cover my ass on legal issues.  

[macosxuser]

Sorry, just trying to help. Someone has to sign it off. I am an A&P and IA, but that has no bearing on the advice I give online as I'm not signing it off. I've seen this a LOT on Cessna 172's, spec a 4 ply, and I'm guessing more than half the fleet have 6 ply on them.

Insurance is not going to look at that at all, I've been involved with investigations, and that is not the kind of thing they're looking for.

So talk to whoever is going to sign it off if you want to put another 6 ply on for some reason. My main point was that pressure requirements do not change regardless of what ply you use. Tire pressures have effect on braking effectiveness and hydroplaning resistance among other things, you don't want to mess with those too much.

[Jim Peace]

Just now, macosxuser said:

Sorry, just trying to help. Someone has to sign it off. I am an A&P and IA, but that has no bearing on the advice I give online as I'm not signing it off. I've seen this a LOT on Cessna 172's, spec a 4 ply, and I'm guessing more than half the fleet have 6 ply on them.

Insurance is not going to look at that at all, I've been involved with investigations, and that is not the kind of thing they're looking for.

So talk to whoever is going to sign it off if you want to put another 6 ply on for some reason. My main point was that pressure requirements do not change regardless of what ply you use. Tire pressures have effect on braking effectiveness and hydroplaning resistance among other things, you don't want to mess with those too much.

OK thanks.....points noted.

I am on Aircraft Spruce now looking up tires.

[carusoam]

Jim,

Caution: aged fuzzy memory follows....

There has been some History of tires being changed and the gear not being swung before flight, resulting in some form of binding.

Wish I could recall more, or even where to look that up...

There is tight clearance between the tires and the airframe.

It may come up in discussions of flight custom 2 or 3 tires.

Old fuzzy memories,

-a-

[flight2000]

47 minutes ago, Jim Peace said:

OK thanks.....points noted.

I am on Aircraft Spruce now looking up tires.

If you're replacing all the tires, don't forget to pick up new tubes as well.  I've heard nothing but good things about the Michelin AirStop tubes...

Cheers,

Brian

Edited September 25, 2016 by flight2000

[Guest]

7 hours ago, Jim Peace said:

My brother made it halfway back to our parking spot and the nose tire deflated.  Airport ops came out quickly and got the plane safely to its normal parking spot.

Upon review it looks like I will now need a new tube and tire.

I just learned that there is a 6 ply tire on the nose.  This was installed prior to me buying the plane 3 years ago.  I have always kept the pressure at 30psi thinking that I had a 4 ply.  I never bothered to check it, after all why would someone go against the manual?

I thought I read in other threads on MS that if a plane has a 6 ply tire on the nose the pressure must be at some value over 45psi.  And the 6 ply tire was only for later models.

Questions:

1.  Was it wrong of the mechanic to install a 6 ply tire on the nose of this plane?

2.  If it was OK to install it,  should I have kept the tire pressure around 45psi or is 30psi OK in a 6 ply nose tire?

3.  If you had to replace it would you put 4 ply or 6 ply on the nose and disregard what the type certificate says?

 

Here is the page from the M20c type certificate.

You are limited to the type certificate or an STC or field approval to change the ply rating.  I doubt an insurance company would deny a claim based on a tire, the FAA may not be happy.

Clarence

[Hank]

I second Michelin Air Stop tubes. I almost never add air to my tires, which are GoodYear Flight Custom 1 for the mains and Condor on the nose.

Edited September 25, 2016 by Hank

[Cyril Gibb]

Underinflation is a bad thing.  Much more sidewall flex that can generate heat and damage the tire carcass from within. Also, underinflation can allow the tire to spin on the rim on touchdown or hard braking which can lead to leaks in the tube valve or a sudden flat if it shears off.

I overfill about 5%-10% when it gets down to the M20F spec 30/49 lbs.

[Vance Harral]

13 hours ago, macosxuser said:

Insurance is not going to look at that at all, I've been involved with investigations, and that is not the kind of thing they're looking for.

Concur.  The idea that aviation insurance companies nitpick trivial maintenance issues as an excuse to to deny claims is a myth.

For further insight, here's a paper on the subject from Avemco: https://www.avemco.com/Articles/ART0006-2011.pdf  Their claim denials are for issues any reasonable person would agree are legitimate: pilot not approved on the policy, in-flight claim on a policy with no in-flight coverage, etc.

Avemco is just one aviation insurance company, but the market is small (lots of agents, but not many underwriters).  If any company was nit-picking claims, word would get around quickly.

Disclaimer: haven't been an Avemco customer for many years and have never had an insurance claim.  Not trying to shill for Avemco, just doing a little myth-busting.

[rbridges]

15 hours ago, carusoam said:

Jim,

Caution: aged fuzzy memory follows....

There has been some History of tires being changed and the gear not being swung before flight, resulting in some form of binding.

Wish I could recall more, or even where to look that up...

There is tight clearance between the tires and the airframe.

It may come up in discussions of flight custom 2 or 3 tires.

Old fuzzy memories,

-a-

The only thing I've seen mentioned are some retreads. I have a 6 ply front tire on my 65. The fender well has a big sticker that says to inflate to 49lbs. 

[Jim Peace]

The more I think about this I am just going to buy the best tubes I can find.  Probably the Michelin Air Stop.

Then I will put a 4 ply tire on the nose and the 6 ply on the mains and keep the pressures at the POH recommended 30psi.

Also being that my plane lives outside a lot I will get some sort of cover for the nose tire like I see on most RV's etc when they are parked in a driveway or storage for a long time.

Thank you all for your input......

[rbridges]

I've seen many people mention the tubes were probably more important than the tires.

[carusoam]

The right tubes will have you adjust air pressure twice a year...  not bad when annual is one of the times...

The wrong tubes will be every month.... which doesn't seem like a lot if you fly every day.

My C was a monthly bird.  The O is the twice a year deal...

Best regards,

-a-

[jetdriven]

16 hours ago, rbridges said:

I've seen many people mention the tubes were probably more important than the tires.

I've had 3 tube failures and zero tire failures in 5 years. Fwiw the only tubes I can trust anymore are Michelin airstop.  

[kpaul]

1 hour ago, bluehighwayflyer said:

I've got 10 years and 500 hours on my Goodyear Flight Custom IIIs with Michelin Air Stop tubes now with nary a problem.

10 years is impressive.  Hours don't really mean anything to a tire...how many landings in that 10 years?

[Cyril Gibb]

I looked at the Goodyear specs for aviation tires (type III). 

My M20F, according to the type certificate, has a 5:00-5 6 ply rating nose gear and 6:00-6 6 ply rating main gears.

My POH says nose gear inflation should be 49psi and the mains 30psi, but the inflation spec according to Goodyear is 50psi and 42psi respectively.

Now if I look at Goodyear 6:00-6 4ply Goodyear recommends 29psi and the rated load is only 1150 lbs.  If rated load for a given size of tire is proportional to inflation, it would appear that I'm underinflating (according to Goodyear) my 6:00-6 6ply to only 30psi and I'm reducing the rated load to less that what I expect a "solid" main gear landing at gross would be.

Is there a reason that Mooney would recommend a tire inflation less than the tire manufacturer?

https://www.goodyearaviation.com/resources/pdf/databook_7_2016.pdf

[ArtVandelay]

Just a guess, but maybe Mooneys unique landing gear system requires a softer tire.

[Cyril Gibb]

I got quick response from Goodyear GA technical support.  The rated load for a given tire is linearly associated with tire pressure.  Half the published pressure is half the rated load.  So 30 psi in my M20F does result in a rated load of about 1250 lbs.

Overinflation leads to centre wear.  Underinflation leads to heat and flex damage. I see that M20Ms have a POH tire pressure of 42 psi which is the maximum for a 6:00-6 6 ply and confirms that Mooney adjusts tire pressure based on airframe weight.

Apparently, tire pressure determination is up to the airframe manufacturer.

 

 

[mike20papa]

I've used a Condor on the nose and it's given reasonable service, but the tube is not an Air Stop and so I am constantly checking/adding air.  I bought some retreads from Dresser for the mains and use  Michelin Air Stop tubes.  What a difference the tubes make!  The Dresser Elite Premiums are great tires.  It's been a while since I bought them, but Dresser is great to deal with.  You buy them direct, you can call and speak to someone on the phone and discuss their various tires.  Great.  If I remember correctly, I believe their STC requires they use Goodyear Flight Custom carcasses.   I remember the Air Stop tubes were more expensive than the tires!

http://www.desser.com/prodcat/aircraft_tires_and_tubes.asp

[Jim Peace]

I ended up getting all Michelin Air tires all around and using the AirStop tube for the nose.  I wanted to use that tube for the mains but apparently the Cleveland wheel I have can only accept a 90 degree valve stem.  So being that I never had to add air to my mains before I decided for the time being to reuse the tubes with the new tires.  If anyone else has this problem with the 90 degree stem please let me know what tubes you use.

By the way using changing the 6 ply tire on my nose to the factory recommended 4 ply and using the 30PSI for some reason makes the tire look like it is properly inflated.  I never could see it this way when I had the 6 ply on and using 30psi....

Enclosed is a picture of my nose tire now and a picture of my main wheel:

 

Edited October 1, 2016 by Jim Peace