Tire pressure

Discussion in 'Maintenance Bay' started by NealRomeoGolf, Aug 3, 2016.

  1. NealRomeoGolf

    NealRomeoGolf En-Route

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    Now that I'm an aircraft owner, I think (worry?) a lot more about its systems and other nuances vs renting. Today's thought was about tire pressure. I hadn't checked the pressure since I bought the plane last month. So I checked and the mains were at 32 PSI vs the POH recommended 24 PSI. So I let some air out to fix that.

    My question is, what are the consequences of over inflated tires? I'm guessing uneven tread wear and the possibility of blowing a tire on landing? What else?
     
  2. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    What airplane??
     
  3. GlennAB1

    GlennAB1 Ejection Handle Pulled

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    Over inflation can damage cords on tubeless tires, initially causing a bubble, then a rupture, I'm going to guess tubed tires are less prone to that damage.
     
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  4. NealRomeoGolf

    NealRomeoGolf En-Route

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    It's a 1981 Piper Archer II
     
  5. pigpenracing

    pigpenracing En-Route

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    The 1981 book may not be up to date with the 2016 tires? What does the pressure on the side of the tire say?
     
  6. pigpenracing

    pigpenracing En-Route

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    All planes are completely different. I run 15 in the Cub, 35 in the Pitts and 42 in the 172.
     
  7. Dan Thomas

    Dan Thomas Final Approach

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    They should be at whatever the POH says, when they're "cold." Overinflation wears them in the center, underinflation at the edges.
     
  8. kgruber

    kgruber En-Route

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    What the maximum pressure reads on the side of a tire has NOTHING to do with the pressure determined optimal by the aircraft's designers.
     
  9. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    yes, disregard stamped pressure ratings on sidewalls. Even in ground vehicles.
    When you will have to watch pressures closely is the first temp drop in the fall.
     
  10. Tom-D

    Tom-D Taxi to Parking

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    The OP asked what the results are of over inflation...which is the tire will wear in the center of the tread.
     
  11. Bill

    Bill Touchdown! Greaser! PoA Supporter

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    That, and with only the center of the tire making contact to the runway, one may have much longer braking distances in an emergency brake situation. It will also ride harder, transmitting more shock/vibes to the struts and airframe. RTFPoH.
     
  12. Tom-D

    Tom-D Taxi to Parking

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    True.. So can you look at a tire and tell if it is properly inflated?
     
  13. Bill

    Bill Touchdown! Greaser! PoA Supporter

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    Grossly underinflated? Yes. Otherwise it's darned hard to tell. I check the plane's tires with a gauge as part of every preflight. I check all the car tires[1] once a month and before a long trip. I check the motorcycle tires[1] once a week and before a long trip. I like for the tires to perform in the manner intended by the vehicle manufacturer.

    [1] As well as oil and all of the other fluids. And I windex the insides of the windshields and put rain-x on the outside. OK, yeah, I'm kinda anal about that, but vehicles are expensive. It pays to take good care of them.
     
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  14. MooneyDriver78

    MooneyDriver78 En-Route

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    Overinflated tires on a retract may not fully retract if tolerance is minimal, although they probably have to be grossly overinflated
     
  15. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    Asked previously by new pilot, "I take my potato chips to 10000' and boom, why don't my tires do that?"
     
  16. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    because a few psi difference won't matter on your tires.
     
  17. GlennAB1

    GlennAB1 Ejection Handle Pulled

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    Tell them to try landing on their bag of chips.
     
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  18. brien23

    brien23 Cleared for Takeoff

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    How is it I can buy the cheapest tire at walmart and a year later it still holds 32psi I buy the most expensive aircraft 600 x 6 and I have to add air in 20 days.
     
  19. MooneyDriver78

    MooneyDriver78 En-Route

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    Because you didn't buy a quality inner tube?
     
  20. brien23

    brien23 Cleared for Takeoff

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    Why would a person buy the best tire and not the best inner tube.
     
  21. brien23

    brien23 Cleared for Takeoff

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    anybody ever add a little green slime fix a flat in your 600 X 6 and you will probably go years without having to add air to your tires.
     
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  22. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    could be one of those things you'd get ripped a new one for on internet forums, but if done judiciously might work and never cause a problem!
     
  23. Timbeck2

    Timbeck2 Final Approach

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    Um, no I wouldn't suggest that. That stuff will cause more problems than it fixes such as imbalance problems and clogging up the valve.
     
  24. SoCal RV Flyer

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    Too little pressure with a tubed tire can cause flats due to the tire shifting a little on the wheel on touchdown, potentially scything off the valve stem. Just the differential action between the tire casing and tube can cause a little tear. This may be more of an issue with the tiny wheels/tires fitted to Van's aircraft...well documented on the VAF forum. I run 40 psi all around, a little higher than average.
     
  25. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    ya.....fix-o-flat is much better. :stirpot::wonderwoman:
     
  26. Tom-D

    Tom-D Taxi to Parking

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    Lots of off airport operators will disagree with that.
     
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  27. Tom-D

    Tom-D Taxi to Parking

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    What's the difference? color?
     
  28. Tom-D

    Tom-D Taxi to Parking

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    Does the POH tell you a pressure for every weigh configuration? should the pressures be the same for max gross weight take off and a minimum take off weight?
     
  29. jadatis

    jadatis Filing Flight Plan

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    Found this topic Googling for tirepressure, wich I do almost every day.
    Once got hold of the official European Formula for car tires and went running with it.
    Got wiser in time and now use my own formula, wich is saver , and also found out much about tires.
    Live and was born in Holland ( Europe) and call myself nowadays "Dutch Pigheaded Selfdeclared Tirepressure-specialist.
    Dont think its usefull to introduce myself in a seperate topic , because I dont own a plane, but if wanted I will do so.

    Tirepressure advice is all about to give the tire a deflection that gives not to much heatproduction when driving the speed its determined for.
    The tiremaker calculates a maximum load for the reference-pressure , and reference speed, so it gives a sertain deflection, wich gives heatproduction so no part of rubber gets to hot.
    Higher speed means more cycles a second of tire, and so more heatproduction , so deflection must be less.
    And that is important for airplaines, the speed when landing and starting up, the speed you wont go over for even a minute on the ground.

    On sidewall of car-tires mostly is written something like this "maximum load xxxx lbs AT yyy psi( cold)" Or behind sises Loadindex ( LI) and speedcode ( Q or higher for 160km/99m/h calculated maximum load), and tirekind determines the reference-pressure, wich is not the maximum allowed cold pressure , as given on Standard Load P-tires and XL/reinforced/Extraload.

    My bet is that for the smaller airplaines , yust normal car tires are used.

    So what you have to do is determine the weights on tires, wich can be different for nose wheel .
    Second determine the maximum speed you wont go over for even a minute on the ground.

    Then of tires read from sidewall the 3 things , 1 maximum load or loadindex, 2.Kind of tire to determine the reference-pressure wich I will call AT-pressure furtheron, 3. speedcode of tire.

    then give that here and I will calculate an advice pressure.
    Cant give you links to my public map of hotmail adress yet , with spreadsheets and info, only after 5 posts.

    Greatings from a Pigheaded Dutch Self-declared Tirepressure-specialist.
    Peter
     
  30. flyingriki

    flyingriki Ejection Handle Pulled

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    As an aside, a fellow in the repair hangar at Oshkosh said they had about 20 flat tires this year mostly with Chinese tube failures. Just a note.....
     
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  31. hotprops

    hotprops Line Up and Wait

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    a good rule of thumb is 1 to 1 1/4 lbs for every 100 lbs of aircraft gross weight.also a big risk in over inflation in older aircraft is damage to the rims as in cracking them, i destroyed one some 50 years ago on those fragile champ rims .good thing it was on the inside brake surface side and it was dragging badly so i never got airborn.
     
  32. James331

    James331 Ejection Handle Pulled

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    YES

    I replaced BOTH the bow wheel tubes on my plane last annual, so far BOTH have failed, first one one failed along the seem between the tube and the valve, second one failed during a job, cost me $120 to replace (didn't have any spares or tools on me) and it failed perfectly along one of the ribs that goes around the tube, not sure if it helps, but here the markings that were on the tube.

    Absolute crap, funny how this junk can find its way to our certified fleet, but a dynon sky view is no Bueno

    [​IMG]
     
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  33. Checkout_my_Six

    Checkout_my_Six Touchdown! Greaser!

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    you obviously didn't use.... GoldBond......medicated powder. :lol:
     
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  34. wsuffa

    wsuffa Touchdown! Greaser!

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    Also check the pressure gauge you use. I have found any number of them to be grossly inaccurate.
     
  35. sourdough44

    sourdough44 Pattern Altitude

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    I usually go for 5 psi on the high side, it's easier to push around.