Re: [A/S] tires on tow vehicle AND other related factors

["Carol and Oliver Filippi" <ofilippi@xxxxxxxxxxxxx>]

Yes, the load range is key.  This is the load that the tire manufacturer
says the tire is capable of handling at a given air pressure.  The stiffness
of the sidewall is immaterial. It does not directly support the load.

How many more pounds of weight will a stiff sidewall support vs. a thinner
one?  It's the air pressure in the tire that gives it its strength and load
capacity.  Obviously, the sidewall must be strong enough to contain the air
pressure.  Stiffness is not the issue, strength to resist blowing out is.

Radial tires, by design (and the laws of physics which apply to them - as
they roll) require a more flexible sidewall than the older bias ply design.
Although the radial's sidewalls are more flexible, they are clearly
sufficiently strong to handle air pressures (in truck tires anyway) in the
100 PSI range.

I don't believe that the stiffness of the sidewall has any direct
relationship to the lateral stiffness of the tire.  Rather it is other
design parameters and the inflation pressure.

So far as tires for your vehicle are concerned, check the owner's manual. It
will probably list the various tire sizes, inflation pressures and load
capacities offered on the vehicle.  If there is insufficient info, call the
manufacturer.  A dealer's parts department might also be able to help you.
He will also have information on the load capacities of the various wheels
offered with your vehicle. [Often there is a sizeable difference in the load
capacity of the rim.  When ordered from the factory with a high load
capacity, the manufacturer will not only put higher capacity tires, but
often stronger wheels, springs, shocks, brakes and other related components.

Oliver Filippi