Sudden Flat Tire

On Thu, 13 Oct 2005 11:05:03 -0700, "Seth Masia"
wrote:

I can't conceive of an operational situation that would cause a steel cord
to come adrift from inside the molded rubber.

I can. I was an auto mechanic for 9 years. Tires that had steel
reinforced tread could and did expose them if the tires were run at
low pressure for too long. Happened all the time. Don't see why
airplane tires wouldn't become damaged in the same manner if run with
low pressure.

The tire pressure for a Cessna 172S is 35 psi mains and 43 psi front
according to the POH. Last time I flew the rental, which was during
my biennial flight review a few weeks ago, I noticed the front tire
was low. The instructor had a pressure guage with him and admonished
me to keep one with me at all times myself. We found the front tire
was at 8 psi and both mains were around 10.

According to the CFI, land a bit cockeyed with tire pressures that low
and you could easily blow out a tire.

Corky Scott

wrote in message
...
I can. I was an auto mechanic for 9 years. Tires that had steel
reinforced tread could and did expose them if the tires were run at
low pressure for too long. Happened all the time. Don't see why
airplane tires wouldn't become damaged in the same manner if run with
low pressure.

One main reason might be the duration of operation required to cause a
problem. Airplane tires do warm up, but not nearly to the extent that an
automobile tire would. They simply aren't used for the distances and speeds
that an auto tire experiences. The heat that is the cause of failure at low
tire pressures is much less likely to become a factor for an airplane tire
than for auto tires.

[...]
According to the CFI, land a bit cockeyed with tire pressures that low
and you could easily blow out a tire.

I can believe that the tire would separate from the rim, allowing the tire
pressure to be completely relieved. Technically, that would be a "blow out"
IMHO, but it's not the same as a failure of the actual tire material.

Pete

Actually what is more common with low tire pressure is that on landing the
rubber tire "slips" on the rim during spin up.. putting pressure on the
valve stem and cutting it or wearing a hole near the valve stem.
BT


According to the CFI, land a bit cockeyed with tire pressures that low
and you could easily blow out a tire.

I can believe that the tire would separate from the rim, allowing the tire
pressure to be completely relieved. Technically, that would be a "blow
out" IMHO, but it's not the same as a failure of the actual tire material.

Pete

"BTIZ" wrote in message
news:MfG3f.5812$MN6.547@fed1read04...
Actually what is more common with low tire pressure is that on landing the
rubber tire "slips" on the rim during spin up.. putting pressure on the
valve stem and cutting it or wearing a hole near the valve stem.
BT

That has been a problem with tube type tires since the days of the Model T.
It is mostly forgotten nowadays.

On Thu, 13 Oct 2005 16:21:20 -0700, "Peter Duniho"
wrote:

wrote in message
.. .
I can. I was an auto mechanic for 9 years. Tires that had steel
reinforced tread could and did expose them if the tires were run at
low pressure for too long. Happened all the time. Don't see why
airplane tires wouldn't become damaged in the same manner if run with
low pressure.

One main reason might be the duration of operation required to cause a
problem. Airplane tires do warm up, but not nearly to the extent that an
automobile tire would. They simply aren't used for the distances and speeds
that an auto tire experiences. The heat that is the cause of failure at low
tire pressures is much less likely to become a factor for an airplane tire
than for auto tires.

You are coming up with reasonable conjectures as to why steel threads
might not work through the sidewall. The problem is the threads DID
work their way through the sidewall.

Rolling them at low pressure would flex the sidewalls more than they
are designed for.

Corky Scott

wrote in message
...
You are coming up with reasonable conjectures as to why steel threads
might not work through the sidewall. The problem is the threads DID
work their way through the sidewall.

My point is simply that absent a manufacturing defect, the usual mode of
failure due to low tire pressure doesn't apply.

Rolling them at low pressure would flex the sidewalls more than they
are designed for.

But assuming no manufacturing defect, would not result in tire failure.

Pete

On Thu, 13 Oct 2005 16:14:12 -0400, wrote:

The instructor had a pressure guage with him and admonished
me to keep one with me at all times myself.

I have a bicycle pump with a gauge on it in the cargo part of my plane. I
fly to some airports that are unattended and while there may be a self
serve fuel pump, air is not an option.

I check the pressure once a week on my plane. Not unusual to lose 2 pounds
or so in an extended period of idle time, and the bicycle pump takes less
then 15 seconds to get the tire back up to speed.

Allen