Tire Pressure

[Bob_Belville]

Bet you can really bounce 'er real good with ~50 psi in the mains! 

[Dave Marten]

Bet you can really bounce 'er real good with ~50 psi in the mains! 

NO. 49 Nose 42 Mains!

[Bob_Belville]

NO. 49 Nose 42 Mains!

Closer to 50 than 30  . 

[Dave Marten]

Closer to 50 than 30  . 

Bob. What ply tires are you running? If 4 ply (as originally equipped) then your limit is 30 on the 4 plys. If you have 6 ply, then the rated pressure is 49psi nose and 42psi mains.

 

From Gary's post: http://www.goodyearaviation.com/resources/pdf/db_airdatabook.pdf

 

Good tire ed here:

 

http://www.airmichelin.com/uploadedFiles/MichelinAirDev/StandardContent/Resource/databook.pdf

 

Only gotcha is don't inflate 4 plys past 30!

[scottfromiowa]

McCreary (AirHawk) says 30PSI mains on 6 ply. I may have 5ply in nose...Not 4 or 6. No doubt tht 30psi in nose LOOKS LOW...I have run by the book, but agree that 35 would DEFINITELY be easier to push/pull with tow bar...especially as I get older.....HMMMMmmm, want to be safe, but tire compounds are different than back in 66 and Mooney is not changing guideance...that I know of. Remember to check what your mfr guideance is...as well as airframe guidance. Interesting that F Models have 49psi in nosegear...Same gear on C-F, right?

[Dave Marten]

Take a look at the TC to see the ply rating your Mooney was certified with:

 

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/2fb25685d0303ab1852567ed004f59b8/$FILE/2A3.pdf

 

Most likely your mains are indeed 6 ply. However, many of the short bodies specify 4 ply nose tires - hence the 30psi limit. With a short body 30 on the mains (per POH) is just fine since there is no 'need' to fly at full 6 ply rated pressure (42psi) on the mains since your planes don't have the weight of the long bodies. I short body with 42+ in the mains may indeed be a pogo stick.

 

Technique: I do prefer a firmer ride so if I had a short body I'd bring the mains up toward at least 35 and adjust for personal taste. With the 6 ply you've got some room to tweak the setup for pilot preference, but again the 4 ply's call for 30psi.

 

If you want the strict interpretation - if your plane lists 30psi all around in the POH and the TC calls for a 4 ply nose then a 4 ply tire is the 'correct' replacement tire.

 

Would I put 6 ply nose tire on a short body as opposed to the TC specified 4 ply? - Yes. I could run the nose tire at 30 or increase PSI if desired a firmer ride. (I would be up closer to 45 in the nose and adjust from there) Would the purists slap me? Yes.

 

I bet a good number of the short bodies out there have 6 ply nose tires on anyway since its a more common tire than the 4 ply. No I'm not going to start a poll

[Dave Marten]

McCreary (AirHawk) says 30PSI mains on 6 ply. I may have 5ply in nose...Not 4 or 6.

Interesting? I have never heard of a 5 ply tire. The nose tire size is 5x5 on all M20s. Ply is an additional variable at 4, 6, 8, etc (even numbers). The mid/long body planes call for 6 ply - driven by aircraft weight/cg/gear loading. On your aircraft tire the ply rating will be listed immediately following the size label. You'll have either a "-6 or -4" listed following the size text or a "4/6 ply rating" stamp

[scottfromiowa]

Interesting? I have never heard of a 5 ply tire. The nose tire size is 5x5 on all M20s. Ply is an additional variable at 4, 6, 8, etc (even numbers). The mid/long body planes call for 6 ply - driven by aircraft weight/cg/gear loading. On your aircraft tire the ply rating will be listed immediately following the size label. You'll have either a "-6 or -4" listed following the size text or a "4/6 ply rating" stamp

Not saying THAT is what I have got...just that it is listed online. Been a few years since tires were installed and log doesn't note the ply. KNOW mains are 6 ply, but will need to look at the tire size/ply and then go back to Mfr. tables...

[Bob_Belville]

I frankly do not know whether I have 4 or 6 ply. I have not had to buy tires in the 2 years I've had this E. I seem to recall that there might be some kind of an issue with some tires (brand?) being a problem. Slightly oversize in some dimension cause the tire to rub in the wheel well. I do not recall the details....

[Marauder]

McCreary (AirHawk) says 30PSI mains on 6 ply. I may have 5ply in nose...Not 4 or 6. No doubt tht 30psi in nose LOOKS LOW...I have run by the book, but agree that 35 would DEFINITELY be easier to push/pull with tow bar...especially as I get older.....HMMMMmmm, want to be safe, but tire compounds are different than back in 66 and Mooney is not changing guideance...that I know of. Remember to check what your mfr guideance is...as well as airframe guidance. Interesting that F Models have 49psi in nosegear...Same gear on C-F, right?

Scott - I have the McCreary Super Hawks on my bird. Are we looking at the same tires? Both the Air Hawk and Super Hawk show more air than 30 psi allowed for the 6 ply. Only the 5.00-5 in 4 ply show 30. http://www.stausaonline.com/aircraft-tires/superhawk.html

[scottfromiowa]

Not sure. I did not have my tire specs when I looked online at the McCreary site...I should have waited to post. My mistake. My real point was to check MFR inflation as it could possibly vary from Goodyear to Michelin to others...I am going to experiment with 35psi in mains and nose gear as pushing if down at all is a challenge...I had issues with leakage until replacing tires and tubes with upgraded tubes. They just don't leak anymore which is great...but temp changes due make a difference.

[Hank]

Scott - I have the McCreary Super Hawks on my bird. Are we looking at the same tires? Both the Air Hawk and Super Hawk show more air than 30 psi allowed for the 6 ply. Only the 5.00-5 in 4 ply show 30.

http://www.stausaonline.com/aircraft-tires/superhawk.html

 

The rating that the tire will accept is not necessarily the amount of air that you should put in them. How many other aircraft, of various different weights, use the same tire? The tires on my car are stamped to accept 40+ psi, but the car itself recommends 32 psi. No, I don't put over 40 in it just because the tire is rated for that pressure. Seems like Firestone had problems a few years back with underinflated SUV tires causing accidents . . . wonder what overinflated aircraft tires will do? It will certainly make for exciting landings and poor ground handling [think taxi turns, not pushing into your hangar].

[SkyBound]

+1 for Nitrogen.  I fiound that once I switched I need to inflate less frequently than when using air.

[scottfromiowa]

The rating that the tire will accept is not necessarily the amount of air that you should put in them. How many other aircraft, of various different weights, use the same tire? The tires on my car are stamped to accept 40+ psi, but the car itself recommends 32 psi. No, I don't put over 40 in it just because the tire is rated for that pressure. Seems like Firestone had problems a few years back with underinflated SUV tires causing accidents . . . wonder what overinflated aircraft tires will do? It will certainly make for exciting landings and poor ground handling [think taxi turns, not pushing into your hangar].

Jesus Hank....I am talking about 5 frigging psi. 35 PSI to see how it flies. Others have done with zero problems. I am neither worried about taxi/turn out or pushing in out of the hanger. I DO think the latter will be easier. Your comparison to Ford Explorers and Firestone tires is B.S....IMO. Some times the "by the book" stuff on Mooneyspace gets taken to a level that borders on absurd...

[Marauder]

Jesus Hank....I am talking about 5 frigging psi. 35 PSI to see how it flies. Others have done with zero problems. I am neither worried about taxi/turn out or pushing in out of the hanger. I DO think the latter will be easier. Your comparison to Ford Explorers and Firestone tires is B.S....IMO. Some times the "by the book" stuff on Mooneyspace gets taken to a level that borders on absurd...

 

Well just to add a datapoint to this conversation. My Ford F350 tires are all the same on front and back. The sticker says to fill them to 60 psi when they are on the front and 80 psi when they are on the back. BTW -- which is a pain in the arse since I need to reset the TPMS for the new pressures.

 

As for my airplane, I routinely run the mains at 35 psi. Why? Because I believe a slightly overinflated tire is better than an underinflated one. The downside (and I have had 23 years of doing this) -- none that I can tell. My tires wear evenly and I don't notice a difference handling on wet or snow covered runways. I would be more worried about those guys who run theri tires to almost baldness. In theory, there may be a small gain in resistance to hydroplaning with more pressure in them:

 

However, with respect to airplanes where runway surface conditions, tire tread, tire pressure, and other factors are maintained to a more consistent standard, the generally accepted rule of thumb is 9 times the square root of the tire pressure. For example, if the nosewheel tire pressure is 90 lbs., the square root would be 9.5, which, if you multiply by 9, would give you an expected nosewheel hydroplaning speed of 85.5 nmph.

[fantom]

My POH say 29 psi in the mains and 49 in the nose.

 

I've been using 35 in the mains and 55 in the nose for almost 20 years.

 

Flight Custom tires.

[AlanA]

I check it monthly or when there is a big change in the outside temperature.

[Oscar Avalle]

Well just to add a datapoint to this conversation. My Ford F350 tires are all the same on front and back. The sticker says to fill them to 60 psi when they are on the front and 80 psi when they are on the back. BTW -- which is a pain in the arse since I need to reset the TPMS for the new pressures.

 

As for my airplane, I routinely run the mains at 35 psi. Why? Because I believe a slightly overinflated tire is better than an underinflated one. The downside (and I have had 23 years of doing this) -- none that I can tell. My tires wear evenly and I don't notice a difference handling on wet or snow covered runways. I would be more worried about those guys who run theri tires to almost baldness. In theory, there may be a small gain in resistance to hydroplaning with more pressure in them:

 

However, with respect to airplanes where runway surface conditions, tire tread, tire pressure, and other factors are maintained to a more consistent standard, the generally accepted rule of thumb is 9 times the square root of the tire pressure. For example, if the nosewheel tire pressure is 90 lbs., the square root would be 9.5, which, if you multiply by 9, would give you an expected nosewheel hydroplaning speed of 85.5 nmph.

I agree with Maurader, my I inflate my mains to 34 PSI and my front 38. I use a tire pressure monitor (the same they sell for the cars) to monitor my tire pressure. Works really great.