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  #1  
Old 05-01-2014, 09:33 PM
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jdhmotor jdhmotor is offline
 
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Default RV-8 Tire Pressure

Hi All,
I have been on the site for awhile getting all the information I could on a RV-8. I just sold my Pitts and purchased an 8 and was looking for the correct tire pressures for the mains. I did not get a answer from the previous owner. I search the forum but could not find it. If I missed it, I am sorry to bother anyone with silly questions. Thanks.
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  #2  
Old 05-01-2014, 09:41 PM
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I'm running 34 at present. Not sure there is a "right answer". I asked my local RV8 guru and he told me what he uses....so I copied him....again.
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  #3  
Old 05-01-2014, 11:09 PM
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I run 50 psi
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  #4  
Old 05-02-2014, 12:06 AM
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Thanks to all for your answers....
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  #5  
Old 05-02-2014, 06:59 PM
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50 psi on my Goodyear Flight Custom II and Michelin Air Stop tubes too. If I recall correctly, under pressure on airplane tires is a bad thing due to flexing. I'm sorry, I can't remember where the article is, but it might be a Goodyear publication. Anybody else know?
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  #6  
Old 05-02-2014, 07:12 PM
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Quote:
Originally Posted by Gash View Post
If I recall correctly, under pressure on airplane tires is a bad thing due to flexing. I'm sorry, I can't remember where the article is, but it might be a Goodyear publication. Anybody else know?
Not a hard and fast rule as the POH for a c140 calls out 17psi. One of the only things in the 1 page POH.

Goodyear manual link
http://www.goodyearaviation.com/reso...raftmanual.pdf
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  #7  
Old 05-06-2014, 08:50 PM
precession precession is offline
 
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I found that the rolling resistance, and hence takeoff distance, was significantly increased when experimenting with dropping from my normal 50 to 35 lbs (on my -4). I didn't notice it at first when flying by myself; however, I took a passenger and bags and was surprised at the increased length of the takeoff roll -- well beyond what I expected based purely on the increased weight. Actually, I found afterwards that my tire pressure had dropped a few pounds so I was in the low 30's. If you push your plane by hand on the ground with the tires at 50 and then again at 30 I think you'll find the increased rolling resistance very noticeable - I did. And once you're attuned to the issue you may also notice you're using more power to taxi at the same speed with lower pressure tires. I'm back up to 50 with no intention of going lower again. I now think tire pressure is an important factor to pay attention to, particularly if you are carrying a heavier load and dealing with a situation where runway length is critical on takeoff.
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  #8  
Old 05-06-2014, 11:34 PM
jcbarker jcbarker is offline
 
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50 psi on my -8. I re-fill when it gets down to 40 which doesn't take very long on these little tires.
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  #9  
Old 05-07-2014, 12:41 AM
Sig600 Sig600 is offline
 
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How does ground handling on landing differ with 50 vice say 35?
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  #10  
Old 05-07-2014, 12:37 PM
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Default Shorter roll out

Quote:
Originally Posted by Sig600 View Post
How does ground handling on landing differ with 50 vice say 35?
In my experience it's not as easy to notice the difference on landing as on takeoff, as there are more variables on landing, such as the fact that you might touch down at a higher or slower airspeed, which will obviously cause a longer or shorter roll out independent of tire rolling resistance factors. Nevertheless, I think its undeniable that your roll out (taking brake application out of the equation) will be shorter when you are running at a lower pressure with more rolling resistance than vice versa, and my experience has shown that to be the case. You don't need as much braking to slow down.

Of course in the real world we apply brakes if needed and I'm sure there are experts who would be capable of saying how braking effectiveness, for example in an emergency situation calling for maximum braking, varies with tire pressure, but that's a separate issue.
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