4, 6, 8 ply tires?

[201er]

I thought all tires were 6 ply but I just discovered they come in 4 and 8 ply. When they have more ply, how does that work? Are the ply thinner on the more ply options so that the overall tire thickness is the same? Or is it literally more of the same thickness plies?

What are the pros/cons of 4 and 8 ply and is 6 the best of both or best of neither?

Is there an advantage to getting a cheaper brand tire with more ply? Or an advantage to getting an expensive brand fewer ply over a cheaper brand with more ply?

[RobertGary1]

You don't get to choose unless you find an STC or something that authorizes you do change ply. The ply of the tires is part of the type certificate.

-Robert

[kortopates]

Ply rating does not necessarily mean the number of physical plies but an equivalence to a old standard fabric ply. Your typical 6 ply tire has less than 6 physical plies.

Pilots mistakenly think more ply's are better, when in actuality we need to stick to the ply rating the manufacturer specified in the plane's type certification data sheet (TCDS) and maintenance manual. Otherwise the plane is no longer conforming with the type certificate without it being an approved alteration (with accompanying documentation). Could you argue its a minor mod? Perhaps a retractable gear airplane is not the best choice to experiment on in case of any unexpected results. More background here: https://www.avweb.com/news/maint/193372-1.html

[201er]

Great article. I didn't even realize there was anything other than 6 ply and now I'm even more surprised that 6 doesn't even mean 6. So how many ply do they really have?

[Yetti]

It's a tire strength thing that if I recall involves a blunt spike and when things tear.

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=55

[Raptor05121]

In the D's TCDS, we are authorized for either 4ply or 6ply on the nose. Pros/Cons?

[Hank]

I think my C has 5 ply nose tire and 6 ply mains. I need to confirm that, it's almost time to replace the nose tire again.

[Tommy]

Yes Mooney calls for 6 on the main. But I wonder if the physical dimension / weight is the same or very similar, wouldn't 8-ply be better? 

[Hank]

10 minutes ago, Tommy said:

Yes Mooney calls for 6 on the main. But I wonder if the physical dimension / weight is the same or very similar, wouldn't 8-ply be better? 

If the Type Certificate specifies 6 ply tires, then no, 8 ply would not be better. Probably like some retreads, will jam in the wheel wells when retracted, and that will make for a bad day . . . . .

[Tommy]

But it will only jam when the physical parameters are not the same, right? Am I missing something

8-ply gives an average loading of 2350 compared to 6 ply of 1750. So in theory, it will take a slightly more brutal landing, right? 

All the relevant when you consider that there is no price difference between a cheap 8-ply and an expensive 6-ply.

[RLCarter]

Tires are actually part of the suspension, an 8 ply rating will give a harsher ride over a 6 ply. As far as wear goes that depends on the compound of the rubber, softer compounds give better traction but wear faster than a harder compound.  Tire pressure plays probably the biggest role in a failure, air pressure changes roughly 1.5 psi per 10*F, low pressure on landing can allow the tire to rotate (slip) on the wheel at touch down which generally rips the valve stem from the tube, the harder the landing the more likely the tire will slip on the wheel. Here's the scenario, you take off with 25psi in a main on a 95*F day, at altitude the air temp in the tire drops to 50*F, rubber is a good insulator so the air temp in the tire only gets to 65* before landing, now your landing with less than 20psi in that tire, the tire spins on the wheel tearing the valve stem and then the fun begins......

[carusoam]

Wow, @RLCarter/RLC has some interesting knowledge!

To get the ° for °F...  press and hold the 0 (zero key), if you are using an idevice...

Best regards,

-a-

[RLCarter]

@carusoam thanks for the reminder, maybe it will "stick" this time, or not.

[Alan Fox]

Cheap tires , are cheap tires..... Buy Goodyears....I put a set of G/Y Flight custom 3's on my Bonanza , 5 years ago , and they are still like new , (over 300 hours of use) Probably close to 500 landings..

[Tommy]

10 hours ago, RLCarter said:

Tires are actually part of the suspension, an 8 ply rating will give a harsher ride over a 6 ply. As far as wear goes that depends on the compound of the rubber, softer compounds give better traction but wear faster than a harder compound.  Tire pressure plays probably the biggest role in a failure, air pressure changes roughly 1.5 psi per 10*F, low pressure on landing can allow the tire to rotate (slip) on the wheel at touch down which generally rips the valve stem from the tube, the harder the landing the more likely the tire will slip on the wheel. Here's the scenario, you take off with 25psi in a main on a 95*F day, at altitude the air temp in the tire drops to 50*F, rubber is a good insulator so the air temp in the tire only gets to 65* before landing, now your landing with less than 20psi in that tire, the tire spins on the wheel tearing the valve stem and then the fun begins......

So a "stiffer" and "thicker" tires is not necessary better? 

And the correct tire pressure is a more important factor? 

[201er]

2 hours ago, Alan Fox said:

Cheap tires , are cheap tires..... Buy Goodyears....I put a set of G/Y Flight custom 3's on my Bonanza , 5 years ago , and they are still like new , (over 300 hours of use) Probably close to 500 landings..

They must be great tires if they can last so long with you flying them! Results don't lie.

[cliffy]

In addition, Section 32-40-01 of the J Service Manual calls for a gear retraction check 5 times  to make sure the tire does not interfere with the retraction of the gear. SO to sign off the tire change by reference to the MM you need to jack the airplane and do the retractions as specified in addition to using the tires specified in the TCDS. 

Technicalities, technicalities, technicalities. :-) :-)

[RLCarter]

2 hours ago, Tommy said:

So a "stiffer" and "thicker" tires is not necessary better? 

And the correct tire pressure is a more important factor? 

Short answer is yes, tire manufacturers develop tires that meet the requirements for a variety of applications. When shopping tires, match the ply and load ratings and generally the speed rating will be there as well, then it just boils down to what your willing to pay. Keeping the tire pressure correct is the easiest way to get good life out of a tire.

[Tommy]

So with exactly the same number ply and same loading / speed rating. What's the difference between expensive and cheaper tire then? 

[cliffy]

Quality control in manufacturing and composition of rubber compounds. Types of fabric used in plys, design of bead cables, etc. 

What's the difference in a Toyo car tire and a Firestone of the same size and load rating? Lots of variances in manufacturing. 

[Tommy]

31 minutes ago, cliffy said:

Quality control in manufacturing and composition of rubber compounds. Types of fabric used in plys, design of bead cables, etc. 

What's the difference in a Toyo car tire and a Firestone of the same size and load rating? Lots of variances in manufacturing. 

"composition of rubber compounds. Types of fabric used in plys, design of bead cables. variance in manufacturing."

If the loading and rating are the same why and how do composition, type of fabric, and bead cables etc matters?

I don't look at those things when I buy tires. Should I? And why? 

QC is pretty subjective. I think Japanese's QC is in every way just as good as American's QC if you are suggesting the opposite. 

 

[Tommy]

On 7/30/2017 at 1:04 PM, 201er said:

They must be great tires if they can last so long with you flying them! Results don't lie.

Lab results don't lie. Individual testimonies do. 

 

On 7/30/2017 at 10:09 AM, Alan Fox said:

Cheap tires , are cheap tires..... Buy Goodyears....I put a set of G/Y Flight custom 3's on my Bonanza , 5 years ago , and they are still like new , (over 300 hours of use) Probably close to 500 landings..

This  is music to the marketing department's ear!

I take issue with this approach. Cheap automatically means bad.

There is simply no good objective evidence to say Goodyears is any better than say Condor or Air Trac / Hawk etc. 

I had a set of Air Hawk for 4 years, put on by the previous owner, also still like new (close to 400 hours of use) and also close to 500 landings. Unfortunately I flat spotted one with 40kt gust wind landing on a short strip couple of months ago which I am certain FC3 will have the same amount of damage 

Again, my own testimony, your mileage may vary! But I will be the first guy to rush out and buy FCIII if there are objective evidences.

[ArtVandelay]

Condors don't seem to last, Air Hawk do, YMMV.

[wiguy]

 I went through this tire decision a year back, non-Mooney retract. This was for the nose gear. The parts manual stated 4-ply in the specs. I know many who just put a 6 ply there. Much of the time tires get changed out due to age or cracking, with a non-training aircraft. I also saw that the 4 ply was a bit lighter in weight, every pound counts.

 

  I ended up going with a 4 ply, Desser retread, not the 'Monster' retread. The dimensions of the Monster tire gave me a little pause, so I went with the standard tire. Anyhow, it's been working out so far.

[cliffy]

Tommy- I didn't say one was better than another You asked what the difference was between them. I just stated what the differences could be with no judgement on quality either way.