Commercial Trucks
Re-Capping (re-Moulds)
The heat generated from an under inflated
tire often contributes to re-mould separations. Tubeless tires
are particularly susceptible to tread separation. Frequently,
small holes in the inner liner are overlooked in the pre-retread
inspection. High pressure air passes through the hole to the
new rubber of the tread. With the escape route cut off, its
spreads out between the old casing and new tread until separation
and failure occurs. In sealing these small inner holes, Permaseal
reduces the pressure on the new tread, so the full service
life is achieved without incident.
Re-Capping vs New tires
With the use of various modern compounds
and better tread quality, the industry has come a long way.
Most fleet managers consider recapping a necessity as a means
of cutting cost. Some recapping tires will out live comparable
new tires. So, a re-cappers skill is much relied upon.
How many caps should each casing
provide?
This is a popular question that is difficult
to answer due to its broad spectrum of variables. With preventative
tire maintenance a fleet owner would expect to get one or
two caps from a casing. A stringent preventative maintenance
programme adds up to a considerable cost in labor and tire
repairs. However with Permaseal, once the tires have been
treated, porosity leaks, bead leaks and punctures have been
eliminated, thus cutting, labor costs, tire repairs and down
time. This added to the tire being constantly maintained at
the correct pressure, will ensure no weakening of the tire
wall due to under inflation and could add, up to another two
cappings per tire. (No tire maintenance programme can eliminate
tire side wall weakening due to impact)
NB- Permaseal is water soluble and should
be washed out of the tire before re-capping. Once this is
done there is nothing to prevent the normal re-capping process.
Fundamental to the proper use and maintenance
of tires is ensuring the tires are kept at the correct pressure.
Correct Inflation
A tire is an envelope consisting of
materials forming a long chain of macromolecules. The tire
itself does not carry the load, rather it is the air within
the tire that carries the load and provides the only support
between the vehicle and the road. The working of a tires are
dependent on correct air pressure and manufacturers agree
that under or over inflation will restrict tire life considerably.
According to Goodyear. “Correct inflation is the most
important fact in tire life. Neglect of tire maintenance,
and especially tire pressure maintenance, has cost fleets
thousands of pounds. Under inflation should never be permitted”.
Under Inflation
tire manufacturers aware that porosity
in their tires is one of the main causes of under inflation,
have passed on the responsibility of maintaining correct tire
pressure to the user. But it is difficult to programme the
human factor of the vehicle (the driver), on the necessity
of checking and replenishing the air in the tires on a routine
basis.
With out a way to eliminate porosity, it
is essential to establish a routine tirecare and maintenance
program. Additionally that programme must be followed stringently
in order to obtain good results.
Under inflation is the most detrimental condition a tire can
endure and will rapidly induce premature tire failure. A vehicle
can obtain up to an additionally 20% tire life and can cut
fule cost by 5% by simply maintaining the correct pressure.
The result of under inflation are:
- Increased rolling resistance, resulting
in higher fule consumption
- Poor pavement grip, decreasing safety
- Blow out risk, due to over heating
- Reduction in resistance of punctures
and cuts
- Destruction of casing carcass, making
re-treading impossible
- Ply separation
- Uneven tread wear
How does tire inflation affect
maintenance costs?
If a tire is correctly inflated it will
have less rolling resistance, which will result in maintaining
a cooler operating temperature, longer tire life and better
fuel mileage.
A god example is the wheelbarrow. If you have a barrow loaded
with sand and it has an under inflated tire, you will find
it very difficult to push around. Inflation the tire to the
correct pressure and you can push it anywhere. The same applies
to a vehicle; the only difference being the engine is using
more costly fuel than necessary.
| No.
Of pounds under inflated |
%
of tire tread loss |
Lost
fuel economy |
1
lb |
-5% |
0.9% |
5
lb |
-22% |
3.1% |
7
lb |
-28% |
4.4% |
10lb |
-37% |
6.25% |
Air loss
By their very nature all rubber tires are
porous and lose air albeit slowly and unless the tire are
checked very regularly tires will invariably be running at
below their optimum pressure. Porosity is one of the main
causes of under inflation. Tread separation and heat build
up caused by under inflation can occur and will in turn precipitate
tire failure and blowouts.
To eliminate porosity, the use of
Permaseal is strongly advised. |
