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Tire pressure

Low n Slow

Low n Slow

Well Known Member
It?s about time to add some air for the first time.

I was wondering if there is a standard tire pressure for a -4? Is there a recommendation from Van?s?

It was pretty common in the Aeronca community to use a little lower setting than what the factory recommended.
 
Low n Slow said:
It?s about time to add some air for the first time.

I was wondering if there is a standard tire pressure for a -4? Is there a recommendation from Van?s?

Tom....I like 40#.....seems to be a good compromise for both grass and hard runways....
Click to expand...
 
I was wondering if there is a standard tire pressure for a -4? Is there a recommendation from Van?s?
Click to expand...

Don't know if it is a recommendation from Vans, but a common pressure for years in many taildragger RVs is 24 lbs. The optimum pressure for your plane will depend on whether or not you have problems with gear shimmy. The speed at which shimmy occurs is often tire pressure related. As a general rule the higher the pressure, the lower speed shimmy will begin. Consequently many RVers have used low pressure (24 lbs) in order to move the shimmy speed band up to where it won't be hit during routine taxi operations and the plane will only experience shimmy for a short period of time during deceleration.

Before I installed air stop tubes I would bring the tires up to 35 lbs so it would take a few weeks for the pressure to drop below 24. This meant I tolerated some gear shimmy until the pressure dropped into the 20's. But with air stops, I use 24 since it isn't necessary to add air very often.

Feel free to use whatever pressure suits your needs, the tires will give decent service with inflation as low as the mid-20's.
 
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One thing I've found is that all air gauges are not the same. I typically used 24 PSI when measuring with my old gauge. Then it broke. Or I broke it. Same thing, right?

Anyway, the new gauge takes about 35 PSI to bring the tires to roughly the same condition according to my eyeballs.

So, I would suggest something between 24 and 35 PSI.
 
Sam's post summarizes the issue well. I would only add that my RV-3B tends to shimmy at a certain speed with any pressures over 22, so I run mine 20-22 and have talked to other RV-3/4 owners who go down into the teens.
 
The Air up there...

I used 30 psi in the Bandit for years. Any less and it's hard to push around, more and you get shimmy on paved strips. I use 50 PSI in the Rocket which works well with the heavier airframe.
Max Conrad flew a 260 Comanche from Tripoli, Libya to LAX non-stop back in the 60's. He added air to the tires but with the heavy load of fuel they were still flat. He called Good Year and asked the max psi. They said "fill em till they're round"...the rest is history. Max emerged from the Comanche in LAX after 22 hours of flying in a tuxedo...

Rob Ray
RV4 formerly
F16 sadly formerly
HR2 currently

ps: Michelin tubes leak-down very little if never. Well worth the $$$. Add some Slime and you're ready for anything...
 
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I fly from both grass and concrete. Having been told by several that gound handling when landing on hard surfaces is more difficult with higher tire pressures, I've always run 28-30 psi... until, I left my bird overnight at Bruce Bohannon's Flyin' Tiger Field and his crew chief, Gary Hunter, pumped them 45 psi. He told me that the Tiger and the -4 both run 50 psi and asked me to at least try the new pressure. I found all phases of gound handling on all surfaces to be much better at the higher pressure. I'm a 45 psi guy... well, on a good day!

Ernie Butcher
-8 Flying
 
Sam Buchanan said:
...Before I installed air stop tubes I would bring the tires up to 35 lbs so it would take a few weeks for the pressure to drop below 24...
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Thanks everyone. Wow, from 45 to the teens, that's quite a range.

I'm not familiar with the term 'air stop tubes' are they just high quality tubes, or something else?
 
I'm not familiar with the term 'air stop tubes' are they just high quality tubes, or something else?
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Air Stop are Michelin's tubes that do not leak down like conventional tubes. They are a little pricey but you only need to add air every few months.

I buy them at Desser:

http://www.desser.com

Desser also has their own brand of "air stop" tubes.
 
Too much?

A respected mechanic on our field cautions against high air pressures due to the possibility of overstressing, and failure of the wheel through bolts. This could lead to serious injury. Comments?

Mark
 
Air 'em up

I use the air stop tubes in my RV-8 mounted in Condor tires.
50 lbs of pressure.
195 hours TT and 353 landings.
No uneven wear on the tires (no shims either).
No shimmy.
Lots easier to move the aircraft around the hangar than at lower pressure.

Chris
:)
 
strahler13 said:
A respected mechanic on our field cautions against high air pressures due to the possibility of overstressing, and failure of the wheel through bolts. This could lead to serious injury. Comments?

Mark
Click to expand...

Tensile strength of aircraft bolts is around 125,000 PSI... they won't even notice the 20-40 PSI in your tire. The tire will fail long before the bolts.
 
Torque

Dan, what do you use on those bolts? I've had conflicting input and have just been snugging them up firmly..... :confused:
 
AC43.13 specs out torques for AN4 bolts and MS20365 nuts, 50-70 in-lbs in shear, 100 in-lbs max allowable.

I consider those bolts holding wheel halves together to be primarily loaded in shear. I figure the axle nut handles the tension, and the wheel bolts keep the wheel halves aligned with each other. Just my non-engineering take on it.

Personally, I tighten those AN365/AN4s to 70 in-lbs.
 
Cleveland 40-78B wheel bolt torque is 90 in-lbs dry per the Cleveland Tech Manual. Caliper 30-9 back plate bolts are 75-80 in-lbs.

I just sent an email to the tech desk at Parker asking about maximum inflation pressure; will report.

Neal Willford's excellent landing gear spreadsheet is (or was) available at the EAA site. Plug in RV numbers and prepare for a surprise if you run low tire pressures.
 
I use 50 PSI on all 3 now

No problems with the nose wheel, the airplane is noticeably easier to move by hand, and I still have plenty of pressure left at the next oil change when I air up again.

With autos, bikes, etc, low pressure cause heat build up, not high pressures. As long as you stay within ratings (which are above 50psi) I can't see where the problem would be in running high.
 
Nosewheel...??

Guys,

I ran 40-50 psi in my RV4 mains for 14 years, same with the 380X150X5's on the Rocket. The only downside to higher pressure was shimmy on pavement...fix: avoid pavement!!!
The Desser generic butyl tubes equal the Michelins for less$$$.

Smokey
BTW, last I checked, there are no RV4A's...:)
RV4ormerly
HR2
 
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smokyray said:
Guys,

I ran 40-50 psi in my RV4 mains for 14 years, same with the 380X150X5's on the Rocket. The only downside to higher pressure was shimmy on pavement...fix: avoid pavement!!!
The Desser generic butyl tubes equal the Michelins for less$$$.

Smokey
BTW, last I checked, there are no RV4A's...:)
RV4ormerly
HR2
Click to expand...

Somebody did make a tri gear RV4, pictures are somewhere, saw it at some fly inn many moons ago. I believe it was even before the first 6A.
Just looked wrong in so many ways. :)
tm
 
I remember....

I remember that too.... The guy had trouble flying it and decided to convert it to a trike. That was a loooong time ago. Don't forget that "back in the day", there were no RV checkouts or instructors. You just had to hop out of your champ, hop in your RV and hope for the best....

John
 
Me too...

Amen brother John, my first RV flight was an RV3...checkout? See ya, have fun!
The highest RV number then was the FOUR...

Rob Ray
 
pressures on

I heard a rule of thumb being 2psi for each 100lb of empty weight. This was for a starting point. It worked on the Champ and the J3 I flew, my 4 liked 24, 20 was hard to push and 28 I would dribble down the runway. I had the wood dampners and never had the shimmy problem.

RT

Hey Smoky, met you at Miguels, I helped him build the Moose for 3 years. Hurts to look at the pictures.
 
Small world...

Hi Randy,

Yes, it was sad to see the Moose a mess. Good news is I think it will fly again. I am running bigger tires (380X150X5's) on the Rocket with 40 PSI and it is perfect, especially since 90% of my landings are off pavement. The Bandit liked 35-40...Great hearing from you...

Smokey
HR2

What are you flying now?
 
Tire Pressure Monitor?

About 10 minutes ago I got an email from Onstar with a diagnostics report for my Chevrolet Pick-em-up truck. This email thing telling me the condition of the vehicle is a new and unusual concept to get used to, but it is really neat also. One of the things that is provided is the tire pressure on each of tires and they are according to my HP laptop computer LF 30psi, LR 30psi, RF 29psi, and RR 29 psi. So naturally it got me thinking about the plane and how to set up something like this. A quick google search for tire pressure monitors came up with different products, but systems for three wheels will be challenging. There are motorcyle systems if having a readout on only the mains is okay and these appear to just screw on the valve stems. It looks like the car ones mount inside the rim for tubeless tires and most likely wouldn't be adaptable for use on an RV. Question, is anybody out there using a tire monitoring system in their plane? If so, what, how, how much, and does it work?
 
I use 35 lbs by my tire guage. When the airplane starts getting a little hard to push out of my hangar, I bring em back to 35 lbs again. When the tires are hard, I get a little shimmy now and then, but not often.


Taking our RV-6 to my grandaughter's high school graduation in central California next week. I'll air them up before I go. Seems like just a couple of years ago she was driving her Barbie Corvette.
 
Ok, got an email back from Parker/Cleveland technical. The rated max inflation pressure for a 40-78B wheel is 50 psi per the official factory drawing.
 
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