Reading: 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.

Tags: michelin zp, puncture repairs, run-on-flat

This entry was posted on Friday, October 20th, 2006 at 1:51 pm and is filed under Michelin. You can follow any responses to this entry through the RSS 2.0 feed.