RE: [VAL] Goodyear Marathon blowouts and valve stems

["dtidmore" <dtidmore@xxxxxxx>]

This is exactly what I encountered and reported back about a year ago.
Since this time several others have had the same type of failure (ie
catastrophic, sudden valve stem failure).  After a blowout, few people would
think to investigate if the stem or tire was at fault as the end result is
the same (and the tire typically gets blamed).  The "D" rated Marathons for
instance are recommended by AIRSTREAM to be run at 65PSI on the 19' Bambi
and the larger tandem setups (interestingly, the recent model, 19' Bambi has
the highest per tire wheel loading of any A/S).  But Airstream continues to
use rubber stems rated at 65PSI.  Having installed tire pressure monitors on
our A/S after the valve stem failure, I can tell you that with a cold
pressure inflation of 65PSI, the tire pressure increases to 71 to 72 PSI at
highway temps.  If you run tires at 50PSI or so, the rubber stems are
adequate but at 65PSI, it does not take a rocket scientist to see the
problem.  After the valve stem failure, I had the remaining tire pulled and
sure enough, the same wear pattern on the stem was present (flexing where it
enters the rim). It was only a matter of time until the other stem would
have failed as well.  As reported the "D" rated Marathons did have a recall
due to sidewall failure.  The new, totally redesigned Marathons have a
circle S on the sidewall to indicate the new design.  The sidewalls are now
4 full plys and the tread is 6 full plys as well as other improvement.  The
fact that many "D" rated Marathons have been reported to fail is interesting
in that ONLY the "D" rated version supports or recommends 65PSI running
pressures, so the "C" rated version with rubber stem would most likely never
see this type of failure, nor would "D" rated tires running with a lighter
load not requiring 65PSI.

Everyone should know the ACTUAL weight of their loaded A/S and ensure that
the tires on the trailer are inflated to a pressure recommended by the
manufacturer as adequate to carry the per tire loading (pressure vs loading
charts are available at manufacturers websites).  Running a tire
underinflated causes it to run hot and will ultimately cause premature tire
failure, typically in the sidewall.  

It is interesting that Airstream actually assured a good friend prior to the
delivery of his new '05 28CCD that the larger Airstreams all came with metal
stems and that would include his model, but when it arrived, it had the same
65PSI rubber stems, same tires/wheels and recommended cold inflation
recommendation as our 19' Bambi.  He contacted A/S and they indicated to
have the stems switched to metal and they would reimburse.  When the
Airstream dealer did the switch to metal stems, A/S then refused to
reimburse.  I suspect some lawyer in A/S advised against reimbursement after
the fact as it was an admission of neglect.  Metal stems only cost $2 a
piece and the in the case of my friend, the entire cost of removal,
refitting metal stems, rebalancing and remounting was around $25, so a small
cost and inexpensive insurance.  BTW, my friend also installed tire pressure
monitors on his 28CCD after having the metal stem installed and he too is
finding the operating pressures increase to just over 70 PSI at highway
speeds.

Regardless of the cost of tires, stems, etc, just remember that the tires
are a fraction of the value of trailer riding on them not to mention the
potential for an accident involving the people in the tow vehicle or in
vehicles that might be near the trailer under tow.

David Tidmore