is not static. A vehicle with a heavier load requires a higher pressure, granted, but higher-than-necessary inflation pressure does not
add to vehicle stability . . it may in fact
reduce the ability of the vehicle to maintain adequate contact with the road surface. Tire type, tire pressure, vehicle suspension all must work together.
When one is out-of-whack with the others is when TV performance declines.
On my diesel-engined pickup, for example, the FF tire pressure does not change
for any increase in weight from empty upwards. But if I leave the RR tires at too high a pressure for unhitched or unloaded or both, the rear can quickly
lose traction. Some sidewall flex is expected
and beneficial (depending on a given vehicle). Same for tread flex.
The word stability
is possibly a stand-in for "road feel" . . that higher pressures than necessary seem
to add to rig performance. A TV with poor steering feel (4WD straight-axle pickup is classic in this instance) will seem
more stable with higher than necessary pressures . . until it matters.
We'd have to go into understeer
to possibly clarify this, but let's keep in mind that hitch rigging guidelines are, currently, about maintaining the same steering and braking response as when not hitched together to another vehicle.
That is a given.
The pressure range specified by the vehicle manufacturer must be respected. Another given. The range
of pressure values available in their recommendations has to do with loads carried by that vehicle. Their extensive testing -- especially since the Ford Explorer/Firestone fiasco of a few years ago -- ought to be respected. None
of the rest of us, not even the tire manufacturers, can state "what works best" for a given vehicle under different loadings.
A tire dealer can reference the pressure values for a set of tires to confirm close match of pressure and load for those who wish to come closest within the vehicle manufacturer guidelines.
Start with numbers -- a baseline -- using weight scale values and the vehicle info. Same as with setting up hitch rigging (and done concurrently). Test
with pressure rise and monitor temps as well as can be done.
Diagnosis of better and worse is dependent upon agreed values for given states of mechanical relationships.
Setting tire pressure is -- like hitch rigging -- a formula. If A, then B
. . weight per wheel position mandates a minimum pressure. Then,
past a certain given
point are other relationships to be addressed as contributing or compounding effects.
The interaction of components -- of systems
-- can be diagnosed when given
numbers are adhered to in a baseline (as is done so well in this thread.
Experimentation with pressure past that is on the owner . . but it cannot be a recommendation to others as general advice when, in fact, it may be that new shock absorbers and the replacement of some worn bushings is all that the TV "needs" for "stability". Or a hitch rigging adjustment. Etc.
We can play around with definitions of stability
but in the end it will come down to tires maintaining traction in a familiar way.
And that is best found when the baseline is composed of numbers
that can be verified against guidelines.