Puncture repairs to Run-Flat tyres (only Michelin
ZP)
(Minor tyre repair to the BSAU 159 standard)
The position regarding puncture repairs to run-flat
tyres is muddled. Most tyre manufacturers state that
their run-flat tyres should not be repaired under any
circumstances. The reasoning behind this is that when a
run-flat tyre is punctured the weight of the car is
supported by the specially strengthened sidewalls. These
are designed to carry the weight of the car and
withstand speeds of up to 50 mph for a limited distance.
However the exact nature of the damage, the speed at
which it occurred and the distance subsequently driven
are all factors that would effect the internal integrity
of the tyre and it’s subsequent safe use of the tyre
following a repair. As these “known unknowns” (Thank you, Donald) represent a serious safety issue the policy is
that repairs are prohibited.
Michelin however have had a change of policy and now
state that their run-flat tyres can be repaired as long
as there is no visible internal damage and no more than
one repair per tyre is executed. As some Michelin
run-flat tyres carry a sidewall notice prohibiting
repairs the company state that this should still be
complied with. Consequently Michelin run-flat tyres can
be repaired, once, if the sidewall does not contradict
the new directive.
The Michelin run-flat tyres directive is in question and
answer form and is as follows:-
Why may Michelin ZP be repaired?
We have examined many ZP tyres after they have been
punctured in order to establish a position on
reparability. This statement is the result of
considerable study to ensure that ZP tyres may be
repaired safely.
New Michelin ZP tyre lines, such as PRIMACY HP ZP, are
repairable once and once only following the same rules
as standard car tyres such as Michelin PRIMACY HP.
Michelin have prepared this statement which dealers
should follow when dealing with the repair of ZP tyres.
However, it is the dealer’s responsibility to decide
whether an individual tyre is repairable or not.
What about existing ZP versions of tyre lines such as
Pilot Primacy, Pilot Sport PS2, PILOT Alpin PA2?
Existing ZP tyres from tyre lines such as PILOT SPORT
PS2 / PILOT PRIMACY / PILOT ALPIN PA2 are still
considered NON-REPAIRABLE when, “Do not reuse or repair
the tires after a low or zero pressure operation” or
equivalent is written on the sidewall.
Pirelli on the other hand adopt a completely different
approach and state that their run-flat tyres should not
be repaired under any circumstances. Their directive is
as follows:-
After low pressure warning is shown, the condition of
the remaining tyres and the TPMS should be immediately
checked by a specialised dealer. (Such as etyres)
A tyre should always be changed and not repaired after a
loss of pressure, as it is not always possible to
establish the time and conditions under which the tyre
has been used with insufficient inflation pressure.
Damaged Run-Flat tyres, or Run Flat tyres that have
experienced a loss of pressure should be immediately
replaced with another Run-Flat tyre of identical size
and service description (Load Index and Speed Code).
Pirelli recommends that a tyre of a different type, or
which contains a different load index or speed code,
should never be mounted on the same vehicle.
After a loss of pressure, the rims should be inspected
to ensure they haven’t been damaged. Damaged or deformed
rims should always be replaced prior to mounting a new
Run-Flat tyre.
etyres' position on the repairability of run-flat tyres
is that we will comply with the official policy of the
manufacturer concerned. We will therefore carry out
minor repairs to Michelin but not to other brands. If
the position of other manufacturers changes will comply
with whatever recommendations they may make. |
|
