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Tire sidewall deterioration
Is your
vehicle susceptible to tire sidewall deterioration?
Vehicles which are parked for extended periods often
experience tire sidewall deterioration. Sometimes called tire
dry-rot, these sidewalls literally dry, check and eventually crack
and split. Each year the loss for RVers, trailer boaters and owners of
classic cars adds up to millions of dollars. This article examines this
problem.
Tires today commonly contain chemical ingredients which lessen
damage from ozone and ultraviolet light, the main environmental enemies
of tires. Ozone is an odorless gas, which some people call the electric
train smell. Although it is more concentrated in cities and
manufacturing centers, ozone is a normal part of the air we breathe
everywhere. When combined with ultraviolet (UV) light, ozone causes
rubber to dry and become brittle and results in tire sidewall
deterioration.
Black Tires
To protect rubber against UV damage is why tires are black.
Tire makers use a common type of UV stabilizer called a competitive
absorber. Competitive absorbers capture and absorb the UV light instead
of the tire's rubber. Carbon black, a very cheap ingredient, is
used as a competitive absorber whereas, all other UV stabilizers are
extremely expensive. This is why tires are black and are not made in
designer colors.
UV stabilizers are called sacrificial, meaning they are
gradually used up and reach a point where they can no longer protect
the tire against UV damage. As carbon black loses its ability to do
this job, it turns gray, which explains why tires appear gray as the
get older.
Ozone Protection
Waxes are used to protect tires against ozone. When tires are
being driven they flex. This flexing causes the protective waxes to
move to the surface where they form a physical barrier between the air
--which contains ozone and oxygen-- and the tire polymer. This is
called blooming.
When tires are not regularly used, such as a parked RV, boat
trailer, or classic car, this blooming does not happen. Ozone then
starts eating away the protective wax and before long reaches the tire
polymer. Often by this time, the surface carbon black has lost its
ability to protect against UV. With UV light and ozone working
together, deterioration starts. The tire dries, checks, and will
eventually crack.
Other Degradants
Petrochemicals and silicone oils can also remove protective
waxes and increase the rate of decay. Common automotive protectants and
tire dressings can contain chemicals and/or silicone oils which
dissolve protective waxes and can actually attack the sidewalls.
In the event of failure, one of the first things tire manufacturers
look for is evidence of the use of these types of products. If it is
found it may be a cause for invalidating a warrant against
manufacturing defects.
Solutions
The most effective solution for this problem is to remove the
tires from their rims and store them in a cool dry location which is
not exposed to sunlight.
Because this is not always practical or convenient, some
specialized products have been developed to deal with this problem and
lessen the loss. One product I've seen is described at :
http://www.303products.com/main.php?infopage=protectant
I have no first-hand experience with this product nor the
company which makes it, but if you know of anyone who has, we'd just
love you to visit this forum
and tell us about it.
Did you know we have a special
place to show-off your favorite wheels?
See the Hot Wheels Show Room
Is your
vehicle susceptible to tire sidewall deterioration?
