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Trailer-Tire
Safety - Introduction
To paraphrase Thomas Edison, most people don't recognize opportunity
because it comes calling wearing overalls. When it comes to getting the
most from trailer tires, the best chance to enjoy good tire life and
avoid blowouts does come mainly in work clothes. Excitement or romance
have little to do with checking tire pressures or studying load ratings,
but such effort pays major performance and safety dividends.
In fact, considering your trailer as a vehicle, there is no other area
where so little time and effort can pay off so handsomely. There's also
no other area so commonly overlooked. Because tire underinflation can
lead to a rather large inconvenience at best and a tragedy at worst,
we're here to discuss trailer tires and how you relate to them. While
there is plenty to know about the tires you tow on, in the end, it really
boils down to buying the right tires and keeping them properly inflated.
Trailer-Tire
Construction
Commonly encountered tires are P (passenger car), LT (light truck) and
ST (special trailer). While each tire series shares basic construction
methods, such as bias or radial belts, a bead, tread plies and so on,
the details vary meaningfully among the three. Considerations in designing
tires used on trailers include the need to carry heavy loads, the relative
lack of cornering loads, long duty cycles (the tires can be expected
to sit for a year, then rotate for days on end during long trips). Furthermore,
because the design of most trailer suspensions dates back many decades,
ST tires are designed for as soft a ride as possible so they don't transmit
too much shock to the trailer and its contents.
Trailer-tire sidewall stiffness is a compromise between P and LT designs.
The desire for stiffer sidewalls is still occasionally cited as the reason
for choosing a bias-belted trailer tire. While passenger-car tires are
nearly all radials these days, ST tires are still available in bias-belted
construction. Radial trailer tires are superior in all respects to bias-belted
tires except in sidewall stiffness. Reduced tire heat, lower rolling
resistance and softer ride are among the benefits of radials, not to
mention extended wear. On the road, ST tires share some characteristics
of passenger-car tires, but are closer to the design of light-truck tires.
Trailer tires typically employ heavier steel or polyester cords and somewhat
lighter sidewall construction than light-truck tires, and trailer tires
typically run lower air pressures than their truck counterparts. This
gives ST tires good load-carrying capacity, but with the desired softer
ride, ST tires also have the advantage of rubber compounds that are specifically
designed to resist deterioration from the elements, including sunlight
and ozone, during extended storage.
Next
- Tire Inflation
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