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painless

Well Known Member
Now that I took a closer look at my Airhawk tires that came with the kit, I see that I mistakingly ordered 4 ply Desser retreads instead of 6 ply.

Any issues with using them on my 6A? Should I send them back and get the 6 ply??

Thanks in advance.


Regards,
 
RE: 4 ply tires

I use the Dresser retread 4 ply tires with no leak tubes on my -9A, no problems noted. I think they are softer and absorb the bumps better, just my opinion. Dan
 
Actually if you cut them open I think you will find that they are ALL 2-ply. They just carry a 4 or 6 ply "rating".
 
Won't really affect anything, the sidewalls may be a little softer, and they won't last quite as long...
 
The "ply" rating should not really matter except in terms of resistance to puncture, splitting, stiffness. The tire has to be replaced once any cord shows, so it really shouldn't matter a bit.
 
ply rating = load rating

Actually the ply rating deals with load rating.

5.00 x 5 4 ply 800 lbs
5.00 x 5 6 ply 1285 lbs
 
So Cam, I am going to reveal some of my prolific ignorance here, does that mean that with 4 ply tires, the mains will have a max load of 1600 lbs total? If so, factoring in the weight distributed to the nosegear, I should be ok with the 4 plys?

I received them from FedEX yesterday and I am impressed with Desser's retreads so far. Looks like a quality product. Course, what do I know? I can't tell the difference between 4 ply and 6 ply!! :eek:
 
http://www.aircraftspruce.com/catalog/lgpages/mcairtrac.php

If you look at the chart on this page you'll see a couple of interesting things about the MacCreary 500-5's. The 6 ply tires actually weigh a little less than the 4 ply, while the load rating of the 4 plys is almost 40 percent lower. Also, the rated max inflation PSI is 50 PSI for the 6 ply as opposed to 31 PSI for the 4 ply tire. If you want to run your tires a little harder you may want to go with the 6 ply tire.

A friend of mine who is a tire manufacturing guy explained to me once that the difference in ply rating is largely determined by the type and the tightness of the weave of the cord material. The material the manufacturer chooses for the cord determines the strength, stiffness, and cost of the final product (the type of rubber compound is also a factor). Obviously, a tire made with a kevlar cord is going to be stronger and more expensive than a tire made with nylon cord of equal weight and weave. The number of plies is also a factor but ply ratings are primarily determined by strength testing. My understanding is that aircraft tire load ratings have a built in 100 percent safety factor because of the nature of what we subject them to on landing. However, I still wouldn't want to exceed the stated load rating of a tire at the all up weight of the airplane. Personally, preferring a little safety factor I would go with the higher ply rating if the total load was close to the max tire load rating and also have the option of filling them up a little firmer if the situation warranted it. Also, the stiffer side wall of the 6 ply rated tire might be a little less prone to catching the edge of a wheel pant opening under side or impact load.

I guess the question to ask yourself is: Do I plan to frequently operate the plane at its maximum gross weight...and can I always grease it on?

Here's some additional info from goodyear: http://www.goodyearaviation.com/img/pdf/datatires.pdf
Scroll down to the Type III tires.

P.S. I'm not advocating that you return your 4 ply tires, they'll work just fine. Just providing additional info for anyone trying to make the decision about which tire to buy.
 
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painless said:
So Cam, I am going to reveal some of my prolific ignorance here, does that mean that with 4 ply tires, the mains will have a max load of 1600 lbs total? If so, factoring in the weight distributed to the nosegear, I should be ok with the 4 plys?
Click to expand...

Originally I was going to tell you to stick with 6 ply but when I started researching this if appears the tire manufacturers are just changing part numbers and inflation pressures to get the higher load rating. In the case of McCreary they aren't even changing part numbers. This is quite common in the auto tire industry. In fact some tires will be labeled with two different max inflation pressures and load capacities. Although the auto industry only makes small load increases this way. The load difference between the 4 and 6 ply are quite a bit.

I'll see if I can get some better info and post it here.
 
Thanks Cam for taking the time. I really appreciate your, as well as all those who have responded, input.

I am still on the fence regarding keeping the 4 plys.

Regards,
 
Tire info from Michelin

I finally found the correct engineer at Michelin to talk to about this issue.

Here's what I found out:

-Most tire manufactures are making only one 5.00-5 tire
-Some label the tire with three ratings 4, 6, and 8 plys.
-Others make three different labeled tires, even though it's the same tire.
-The ones that label it as separate tires sell it either with different part numbers, or only one part number. The distributor seems to be the major player when it comes to part numbers.
-So what does this mean to RV's? You should be safe with a 4 play labeled tire, but the tire pressures are very important.
-Of course when I asked the guy for his recommendation, he said to check the POH. Many aircraft manufacturers run different safety factors if it's a nose tire versus a main tire.
-So what tire pressure should you run? See the chart for the 4, 6, and 8 ply tires. The load capacity is linear in this region of the tire, so linear interpolation is just fine.
-In the end it's up to the manufacturer (YOU) to set the proper tire pressures, based on aircraft weight and safely factors.
-FWIW, I run 38 psi in my RV9 with a gross weight of 1750.


Data from the Tire and Rim Association Aircraft Year Book 2008
5.00-5
4 ply 800 lbs @ 32 psi
6 ply 1285 lbs @ 50 psi
8 ply 1800 lbs @ 70 psi

tire pressure examples
35 psi = 900 lbs
38 psi = 980 lbs
40 psi = 1030 lbs
45 psi = 1160 lbs


This info came from one tire manufacturer, that doesn't mean that all manufacturers use the same construction for a 4 and 6 ply tire. You have to make your own decision.
 
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