OTR tyre sidewall repairs are part of any tyre maintenance programme and Monaflex systems are used worldwide to tackle them with consistently strong results.
While optimal tyre inflation and preventing overloading are the primary ways to avoid early onset sidewall damage, it is still especially common in harsh environments due to sharp outcrops of rocks and loose rocky material left on haul roads.
This article takes a look at the key steps involved in an effective sidewall repair programme. Can all sidewall injuries be tackled? What patch should be used? What is achievable?
1. Comprehensive training and robust processes are key
Thorough training equips OTR tyre repair technicians to make complex judgments about the viability of a repair scenario. Robust processes and regular training in both repair practices and the systems in use are key to ensuring best practice is adhered to. Look for suppliers, such as Monaflex, who offer ongoing training and support.
2. Is the damage in the repairable area?
The diagram to the right indicates the non-repairable zone for sidewall damage (see the A-B area).
The A-B area is measured from the bead seat following the contour of the tyre. Reference manufacturer guidelines or reputable sources such as the TRMG/ TIA for further information.
The size of this non-repairable zone varies hugely depending on tyre size – anything from a few inches up to 10 or 12″ in large OTR tires. It is always best to consult repair material and tyre manufacturer guidelines to determine the specifics for your tyre size.
3. Is the damage only located in the sidewall?
If the damage is in the shoulder or runs from sidewall to shoulder, then the repair is not classified as a sidewall repair.
Experience counts here. To understand the extent of the sidewall area, the repair technician must confirm where the shoulder begins using knowledge of the tire’s geometry and where the outer-most working ply edge is located.
4. Choosing the correct patch
Once the evaluation of the injury (size and location) has been completed, the technician must consult the consumables manufacturer guidelines and use the injury size, tire size and classification to select the most appropriate patch.
For short damage (in a radial direction) in the middle of the sidewall, technicians will choose a patch that “centres over the injury.”
If the damage is high in the sidewall, i.e. nearer to the shoulder, or long (in the radial direction), a patch that will begin and end in non-flexing areas of the tire (in the non-repairable bead area and the shoulder area) is appropriate.
Again, it is crucial to always refer to the patch manufacturer’s application chart and recommendations.
5. Don’t over fill the skive
Repair technicians often overbuild the filler rubber when using spotter style vulcanising equipment to compensate for rubber running away from the distorted repair area. This is particularly common in sidewall repairs.
However this wastes curing and buffing time, and the costly filler rubber, and can also increase tyre distortion. With a Monaflex system you don’t need this excessive overbuild. The flexible components conform completely to the shape of the tyre and, during the cure, the filler rubber is totally encased by the airbag eliminating rubber migration and leaving a feather edged finish.
6. How should an approach differ for bias vs radial tyres?
For bias tires, shoulder repairs follow the same guidelines as for those in the sidewall or tread. Bias ply patches should always be centred over the damage.
All Monaflex systems are designed to effectively vulcanise sidewall repairs. We also offer a range of dedicated OTR and Truck sidewall systems especially designed for quick and easy cures in this area.