I'm no expert either. Logically, the pressure would be slightly higher when
inflating on the ground and supporting the weight of the aircraft; but should
be the same as the chart is the plane is jacked up. Thus, hypothetically,
you could again check the pressure after lowering the plane onto the tire and
determine the reinflation pressure.

I am really not trying to be a jack-ass.

I really doubt that it is critical or a C150, C152, or Piper Tomahawk; except
that I would be sure to heed any caution in the POH regarding hyper-sensitive
steering with an overinflated nose wheel tire. I don't know whether the tire
chart pressures are correct for low performance aircraft. However, the time
that I pumped up the tires of a C150M to the "recommended" pressure in the
POH, the resulting handling was inferior to that at the lower pressure where
I had found them. The plane gained speed on the taxiway with the engine
idling, rolled "forever" on landing, and was "bouncy" even when "greased on".

On the other hand, mechanics who work on high performance aircraft (especially
jets) treat the matter as one of great importance; and are probably right.

Peter


JH wrote:

Paul, I went to the address and looked at the chart. Unlike most in the
newsgroup, I am not an expert on anything. Anyway, the chart mentions
pressures "Unloaded". Is the same pressure used if re-inflating the tire
while on the plane?

I have an RV-4. The gross would be about 2000 max. There are two tires plush
tailwheel. The tires are 5.00x5 4 ply. Does that mean I should carry about
31 to 35lbs?

Thanks,
Joe

"anon" wrote in message
...
(Paul Lee) wrote:

Thanks for the leakage comments... but anybody know about the
proper tire pressure? Or is that a mystery?

45 psi for mains and 55 psi for the nose. Use six ply tires for the
mains. Check pressure 12+ hours after initial inflation and add air
if necessary. After that, pressure loss will be due to
leakage/diffusion.

The 70 psi nose tire pressure suggested by another poster is not only
needlessly high but is over the maximum pressure specification for
most 10x3.50-4 tires (1). Another poster's comment to "blow 'em up
until the sidewalls come off the ground" is, of course, idiotic.

Tire And Rim Association tire pressure chart:
http://www.desser.com/pressurechart.html

- anon

1: The ply rating is an indication of tire strength and does not
necessarily specify the actual number of carcass plies within the
tire. The term is used to identify the maximum rated static load
capability and corresponding inflation pressure applicable to specific
operational requirements.