tires aren't much different in terms of materials of construction/compounds than regular
automotive tires, but they are different. Treat them as such.
One key difference we need to think about though is
the intended use. An automotive tire (if you listen to the vehicle
manufacturers) is there to give you a soft comfortable ride. To do
this they have lower air pressure and softer side walls which flex a
lot. How many of us learned to keep 32 psi in the tires?
Trailer tires on the other hand
are meant to carry a load, your pop-up. If we follow the 32 psi
rule, the trailer tires side wall will flex too much and quickly
overheat, possibility leading to a tire failure. More on tire pressure
is a little further on.
A big difference however lies
in construction of the tires. There is a huge difference in the plies
and belting of automotive tires versus many trailer tires. There is also
a huge difference in trailer tire between manufacturer's and some are
just down right garbage! In trailer tire world, Duro is like Michelin is
to automotive tires... For example, Duros bias-construction tires are
actually designed to meet light truck standards and exceed trailer
manufacturer's requirements by far! They are even constructed with 4-6
plies for strength and puncture resistance! Most other trailer tire
manufacturer's can't claim this.
The weight carrying capacity of your tires is computed with the
tire inflated to the max pressure. Look on the sidewall of the tire and
you will see something like "Capacity 1068 Lbs at 50 PSI". This should
be measured COLD (before you tow the trailer) and you should always use a
quality pressure gauge to check tire pressure. If you do check the
pressure while the tire is hot understand that the pressure will rise,
so 50 psi cold may be 60 psi after a few hours on a Texas highway.
DO NOT bleed air pressure out in this situation. The tire is
designed for this to happen.
For some interesting
information on how the load carrying capacity can change when under inflated,
check out the Goodyear
Load and Inflation Information Chart for RV Tires. Note that
this chart is intended for use with Goodyear tires, but will give you an
idea of the drop in load carrying capacity with under inflated tires.
Check the pressure every day
before you tow. It's cheep insurance. While you are bending down
why not check the lug nuts at the same time. It
is recommended that you use a torque wrench to tighten the nuts
to the correct setting.
Then recheck after driving 50 miles, 250 miles, 500 miles, or before
every trip as they tend to loosen up as they seat with the rim.
Rot, UV damage, flat spots are
of equal concern for any tire regardless of application - difference is
in usage/application, construction, and care.
Say you have a vintage roadster
or classic car stored exactly like a pop up outdoors exposed to the
elements (who would, but this is hypothetical) and stationary for long
periods of time, what do you think the tires would look like? A very key
difference is exposure time to the sun and intensity of the suns rays. A
automobile is used often and therefore you're always moving it about so
the tires aren't exposed at the same times, intensities, etc. Now
picture your trailer in the same place for months on end getting daily
doses of UV. Great examples of this are the trailers where one side
facing the sun all the time and the other is in the shadows. The tire on
the sun sides is browned and cracked while the shaded side looks new.
Another factor is how we care
for the tires. Those that are neglected will show it, and those cared
for with the wrong products are just as bad as neglected tires! For
example, tires should never be cleaned with Spray Nine, 409, Fantastic,
and most other household cleaners, nor should they be cleaned with
2/3rds of the products on automotive store shelves!!! Many of those
cleaners are tough on the plasticizers in the tire compounds and break
them down at an accelerated pace shortening tire life. This holds
equally true for tire dressings! Most popular brands are BAD NEWS unfortunately to the
ignorance of the public. Anything petroleum-based is BAD.
Tire manufacturers also use waxes (both synthetic and petrochemical-based) to protect the tire polymer
compounds against ozone. Regular usage of tires keeps the protective waxes at the tire surface where they
form a physical barrier between the air (which has concentrations of ozone) and the tire polymer. When tires are not regularly used (a
parked trailer, “garage queen”, even a lawn tractor), the wax subsides
into the polymer matrix – i.e., it no longer stays at the near surface. So, ozone begins eating away any
thin residual of the protective wax quickly, and before long, reaches the tire polymer and begin to
break it down (this is why even tires that have been dismounted and stored in a garage or basement will
still rot, although more slowly). Now at the same time, carbon black, which is the UV protectant for
tire polymers, has lost its ability to protect against
UV radiation at the tire surface. So, with both ozone and UV radiations acting on the tire compounds at the
same time, severe levels of degradation initiate. Thus, the tire “dry rots” and exhibits the telltale
signs in the form of sidewall cracking.
Now to expand a little more on how so-called “cleaners and protectants” can actually act as degradants to
PROMOTE more rapid deterioration of the tire… Many household cleaners (those mentioned and more) and
so-called “tire cleaners” available in quantity at the auto parts store actually contain grease-fighting
chemicals as well as very caustic chemicals (to remove brake dust residuals). These very chemicals WILL
remove the protective waxes from the tires and also negatively impact the polymer plasticizers, which
results in more rapid promotion of deterioration! Also, most popular tire dressings are
petroleum or silicone-based (base stock) for the glossy or “wet” look and to provide an easy and even application.
Basically, these base stocks are BOTH solvents for the
protective waxes and plasticizers and increase the rate of degradation too!!! In addition, most of the
popular parts store “protectants” and “tire dressings” more often than not DO NOT contain UV stabilizers,
which act as sun-screen for your tires!
I actually find it amusing how the companies that manufacturer the cleaners, protectants, and dressings
know this all very well, but instead supply products based on the demand of aesthetics and not the science…
Also, another thing that might get your attention is
how tire manufacturers often view this… In cases of so-called warranty sidewall failure, one of the first
things tire manufacturers look for is evidence of the use of these types of products. In fact, there is a
very simple test to determine their presence and EVERY
tire manufacturers has the test apparatus in the quality assurance/quality control
laboratory. Anyway, if evidence of these products is found, this is often
basis for not honoring the warranty because if you ever read the fine-print of a tire’s warranty you will
find this very clause where they will either tell you no products whatsoever or explicitly describe products
that are useable…. If you think I’m wrong, do a little
research on the web and look at the tire manufacturer’s websites and conditions of their
are quality car wash soaps (Meguiars or Mothers) or Eihman
Fabrik High-Intensity Cleaner and dressings such as 303
Aerospace Protectant and Eihman
Fabrik Black Opal Dressing. Every RV store I've ever walked into
and Mothers car washes and 303. Dressing tires that are stored for long
periods is an absolute must!
When storing your pop-up for
long periods of time (like over the winter) try to move it on a regular
basis to avoid getting "flat spots" where the tire contacts
the ground. If possible, set the trailer on blocks (follow your
manufacturers recommendations for jacking/blocking) and reduce the air
pressure in the tires. Some people even remove the tires and bring
them indoors for the winter. If you do leave them out side, try to
cover them to reduce damage from the UV rays of the sun.
Remember, a trailer tire may
need to be replaced long before the tread wears out. Generally rot
or UV damage will be the death of the tire long before the tread wears
out. Maintain them properly and keep a good eye on them for signs
of dry rot like side wall cracking. While I had originally planned
to replace mine
around age 4 - (long before I thought they would become a problem) I
actually had to replace them after the second season. Upon close
inspection mine started to develop severe cracking/splitting in the
bottom of the treads.
Trailer tires are available as
just a tire or in a tire-rim sets. If your current rims are
rusted, go for the sets. When you replace them make sure you get
at least the same load rating or higher. If you do buy a higher
rated tire don't automatically assume you can pack more stuff in your
camper. The tires are only one part of the system which determines
the capacity of the trailer.
Another idea when purchasing
new tires is to get tire-rims sets the first time you replace, no matter
what the condition of the rims. This then gives you a second
(older) set of tires & rims that you can put on the pop up for
winter storage, keeping the good tires for travel only.
When you replace your tires
remember the spare!
- Always inflate the tires to the pressure indicated on the
sidewall, check it every day of towing.
- Tow the trailer level when both the tow vehicle and trailer are
loaded for camping.
- Don't overload the trailer axle. This requires knowing the
axle rating and weighing the trailer.
For an explanation on changing a
flat tire, click here
My thanks to Bob
Scott, P.E. - Geotechnical Engineer, as well as other members of the
Pop Up Times Message Board for information on this page.