It is hard to understand how it is possible that the supporting QA lab at
Firestone doesn't have delamination and interface bonding profiles on all of
its products. If they really maintain that they don't have a clue, people
need to run not walk away from these products. The Bridgestone group in Japan
has a major QA and R&D investment and I expect that tires made in Japan would
not be suspect. Too often multinationals are joined at the top and
financially, but operate as completely independent entities at the bottom.

But the other question in my mind is the instability in the Explorer
platform. Propensity to rollover is a well known phenomena with high CG
machines. It is readily corrected by suspension geometry or track width
changes. A solution such as a 4 psi change in tire pressure would seem
totally inadequate to me.

This brings up a related Vanagon topic. The tire pressures front and rear and
particularly the front to rear bias critically effect handling. As larger
tires (eg. the 27-8.50x14) are mounted for better wear, handling etc, the
factory numbers are no longer correct. The proper way to determine tire
pressures and recommendations would be to do a pyrometer scan across the tire
tread to measure the thermal profile after a series of road runs. These road
runs should include some twisty-turnies, but do not have to be very well
controlled. The point is that all the loading parameters  that effect proper
inflation including load, tread adhesion, tracking geometry etc. are resolved
in the tread surface temperature. For some time I have been planning such a
test. I have access to differential scanning pyrometers, but have only one
point (ie. one '82 Westphalia, heavily loaded with 27-8.50x14 BFG's). Perhaps
we could organize a local SoCal group with different Vanagons for a morning
or evening of tire tests. Perhaps others on the list have access to similar
equipment? Another possibility is the use of liquid crystal thermal strips.
Once we know the actual temperature range, we could purchase a set of these
for others to profile/tune their machines, even developing a data base.

Oh well, back to Mars.

Frank Grunthaner