Some useful tips to identify the causes of
most types of tyre wear:
| Problem |
Cause |
| Shoulder Wear |
|
|
| Both shoulders wearing faster than the
tread |
|
| Under-Inflation |
| Repeated high speed cornering |
| Improper matching of rims and tyres |
| Tyres have not been rotated recently |
|
| Centre Wear |
|
|
| The centre of the tread is wearing faster
than the shoulders |
|
| Over-Inflation |
| Improper matching of rims and tyres |
| Tyres have not been rotated recently |
|
| One-sided wear |
|
|
| Once side of the tyre wearing unusually
fast |
|
| Improper wheel alignment (especially chamber) |
| Tyres have not been rotated recently |
|
| Spot wear |
|
|
| A part (or a few parts) of the
circumference of the tread is (are) wearing faster than other parts |
|
| Faulty suspension, rotating parts or brake
parts |
| Dynamic imbalance of tyre / rim assembly |
| Excessive runout of tyre and rim assembly |
| Sudden braking and rapid starting |
| Under-Inflation |
|
| Diagonal Wear |
|
|
| A part (or few parts) of the tread are
weaning diagonally faster than the other parts |
|
| Faulty suspension, rotating parts or brake
parts |
| Dynamic imbalance of tyre / rim assembly |
| Improper wheel alignment |
| Tyres have not been rotated properly |
| Under-Inflation |
|
| Feather-edged wear |
|
|
| The blocks or ribs of the tread are
wearing in a feather edge pattern |
|
| Bent axle beam |
| Improper wheel alignment (faulty toe-in). A
toe-in is where the front edge of the wheels are closer together than the rear |
|
|
|
| Some useful tips on
the storage of Tyre covers and tubes |
|
These recommendations set
out the best conditions of storage for covers and tubes, so that the maximum service life
can subsequently be obtained. Whilst these are specially applicable to bulk storage, the
same principles apply to the storage of small quantities.
Covers |
|
|
Recommended Method
| Where sufficient space is available, racks
made of tubular piping provide an admirable structure which combines lightness with
strength. These can be erected in sections, the distance between the vertical supports
depending on the size of the covers to be stored; obviously large truck covers will
require closer supports than car covers. Depending on the ceiling height of the building two or three tiers
can be accommodated. Horizontal piping, fixed at suitable heights on the up-rights to suit
the size of the covers, provide the support for the covers.
The covers are stored vertically and side
by side so that their weight is supported by the tread at two points. The supports should
be arranged so that approx. ¾ of the circumference of the cover is above the supports and
¼ below.
By this arrangement the weight of the cover
is taken by the tread and distortion is reduced to the minimum. The placing of more covers
horizontally on top of the covers in the racks should be avoided. |
|
|
|
| Alternative Method
|
Where space is limited, or
where the cost of metal racks is considered unjustified, the following method may be
employed provided that the limitations on the height of the stacks are observed. This
method is not considered to be quite as suitable as method 1 (recommended method), but is
frequently used.
Select a clean, level floor and build up a
stack of covers by laying them flat one on top of the other, being careful that the covers
are centered properly, otherwise the stack will be unstable and accidents may result. The
height of the stacks should be limited to 1829 mm. It is most important that this
precaution should be carefully observed, otherwise the sidewalls and treads of the bottom
covers will be distorted to a dangerous degree, and the subsequent service life may be
adversely affected. If the stack exceeds 1829 mm in height the excessive weight of the
covers causes the grooves of the tread pattern of the bottom covers to gape open, thereby
putting a heavy strain on the rubber below the pattern - this may lead to cracking and
splitting when the covers are put into service. |
| |
| General Precautions
|
| These apply irrespective to
whether storage method 1 or 2 is used. Factors that contribute to the deterioration of
stored covers and tubes are: |
| 1. |
Light (particularly sunlight, which is rich in
ultraviolet rays) |
| 2. |
Ozone (from electrical generators, etc.) |
| 3. |
Heat |
| 4. |
Air Currents |
| 5. |
Oils |
| 6. |
Water |
| 7. |
Dust and Dirt |
|
| Any storage place should therefore be
protected from these deteriorating agencies, which adversely affect the physical
properties of the rubber, and hence the useful life of the articles. |
| 1. |
The storage place should be
kept as dark as possible, windows and skylights should be covered with a dark paint and doors and be left burning beyond the time necessary for work to be
carried out in the stores. |
| 2. |
If the store cannot be
darkened for some reason, the racks should be covered with tarpaulins or other closely
woven fabric to exclude light, air and dust. |
| 3. |
Covers and tubes should not
be stored near electric motors, switchgear, etc., as these generate ozone which is very
destructive to rubber. |
| 4. |
The storeroom should be
kept at a reasonably low and uniform temperature (20° - 25°C). In hot territories where
this cannot be achieved the store building should be insulated from the direct sun as far
as possible. Such materials as corrugated iron should be avoided. In cool territories
covers and tubes should be kept away from radiators and steam pipes. |
| 5. |
Draughts should be avoided
where possible, as these supply fresh oxygen which increases the rate of deterioration of
rubber. |
| 6. |
Excessive changes in the
humidity of the air in the store should be avoided as far as possible as moisture will
condense and collect inside the casings. |
|
This is not so serious with
new covers, which usually have an adequate layer of rubber protecting the inner ply. Used
covers often have cords exposed due to cuts, etc., which allow ingress of water. Rotting
of the casing can occur under these conditions. |
| 7. |
It is not good practice to
"lace" or stagger the tyres in piles, as this tends to distort the bead wires
and casing. If the stack method is used, the covers should be carefully aligned and the
height restricted to 1829 mm. |
| 8. |
If the stack method is
used, the mixing of sizes should be avoided. Larger and heavier covers should never
be stacked on smaller sizes; if mixed sizes must be stacked, the sizes should be
graded so that the smallest and lightest is at the top of the stack. |
| 9. |
Before storing used covers
they should be inspected and any necessary repairs made. Oil and grease should be cleaned
off if present. |
| 10. |
When making issues from a
tyre store the principle of "first-in, first-out" should always be adhered to.
|
|
| Tubes |
| 1. |
New tubes are usually
received packed in cartons or bags and they should not be taken out of these containers
until required for use. |
| 2. |
Large stocks of tubes
should not be carried, as physical properties tend to deteriorate on prolonged storage,
especially in hot climates. |
| 3. |
In cases where tubes are
received fitted in the covers, with or without flaps, the pressure should be reduced to
the minimum to retain the tube in the cover. The assembly can be stored in the usual way
for covers, but it is most important to keep light away from the portion of the tube
exposed between the cover beads. |
| 4. |
Used tubes should be
deflated by removing the valve core, examined, and any necessary repairs made. The valve
core should then be reinserted and a small amount of air put into the tube, which is then
folded carefully and stored in a carton or bag of suitable size if available. Used tubes
can be stored slightly inflated inside covers as in paragraph 3 above. Whichever method of
storage is used, care should be taken to exclude light from the tube. |
|
|
|
|