I’ve been working in the tire retreading business for over 8 years, but I still remember when I had no idea what this process was. I ended up in this industry by chance, without experience and a lot to learn.
In this article, I’d like to explain the meaning of retreading, going beyond its literal meaning, and the many shades of this field that are not easy to see. I was lucky because I had the chance to visit several tire retreading shops in different parts of the world. Each time, I was able to focus on new aspects.
It is not a simple, trendy, chic, or glamorous topic, but, it has a huge ecological impact.
In the following paragraphs, I’ll explain how this process works. I’ll share valuable information and my point of view on the topic. I hope to catch your interest in this niche industry.
THE 7 STEPS OF TIRE RETREADING
Every tire type can be retreaded, and the best-case scenario sees a tire getting up to a 4th life.
Tires need to be adequate and respect some standards to be remoulded. They undergo a rigorous selection.
- TIRE INSPECTION
- BUFFING
- REPAIR AND SKIVING
- CEMENTING
- MOLD AND PRE CURE SYSTEMS
- CURING
- FINAL INSPECTION
- TIRE INSPECTION
A specialist inspects the casings, performing a visual and tactile test.
Only the best-proven casings pass this step and are suitable for retreading.
Some retreading facilities use special equipment that can detect even the smallest injury. For instance, with shearography people can XR the casings and get some images of any deformity.
Another instrument is the nailhole detector, whose name is self-explanatory.
The scrap percentage for passenger tires is almost 85%, while the percentage for truck tires is better.1
Several causes are influencing the rejection rate and are not often considered.
- It is extremely important to change tires within the tread worn-out limit point.
We tend to run our tires for as many km as possible, but it compromises their re-use.
- Fleet management: verifying the pressure, balancing, and overloading of the tires.
This first inspection will not be the only time the casings’ health will be monitored.
Before going back on the road, the tires will have to go through two additional exams.
- BUFFING
Buffing the casings means removing the old tread. This step marks the beginning of the official retreading process.
The tread is the rubber part of a tire that provides the road-holding and allows you to safely drive your vehicle. The different tread patterns are designed for:
- the weather conditions (snow, ice, rain, extreme heat);
- the vehicle purpose (cargo or passenger transport);
- the terrain they will ride (agriculture, off-the-road,
earth-moving);
When a tire reaches its minimum tread allowance, it needs to be replaced. If we have handled our wheels properly, they could be retreaded.
The casing surface is buffed to get a precise texture and to correct any tire circumference anomaly.
During this step, the operator uses the Buffing Machine. The casing is loaded, inflated, and turned to allow the buffing blade hub to remove the old tread.
Depending on the tire retreading process we want to perform (integral or semi-integral), the machine uses tungsten wheels or brushes for the sidewall. The Buffing Machines are high-technology instruments able to manage this process independently. They know how much rubber to remove and when to stop.
From this moment, the casing will not touch the ground anymore and will be moved from one station to the other by a monorail.
- REPAIR AND SKIVING
The buffing reveals injuries, like nailholes or rips, and this is the second tire inspection.
The damages must be repaired using high or low speed air buffers, buffout tools, stones, and brushes. The damage exposure creates a “hole” that needs filling. This procedure requires extruder guns and rope rubber.
It is similar to when we paint our houses: before applying the paint, people must level the walls and plaster the holes.
- CEMENTING
Cementing is the application of a solution made of rubber and a solvent. This action will help the material to bond to the casing.
After this step, the retreading process will diversify into 2 systems.
- MOLD AND PRE CURE SYSTEMS
a. MOLD CURE
The mold cure system is also called hot curing. The buffed tire is covered with uncured rubber by an extruder machine.
b. PRE-CURE SYSTEM
The precure systems is also knows as cold curing. The casing is covered with cushion gum and pre-cured tread. This procedure is also called building for the use of a so-called machine storing the data about the tire sizes and calculating the precise tread length needed for the specific casing.
The new tread is available in strips or closed-ring.
- CURING
a. In the MOLD-CURE SYSTEM, the casing, covered with uncured rubber, is placed into a press. The press is equipped with molds with the new tread design.
Do you remember when I was talking about the different tread patterns and their use? At the beginning of this step, the retreaders decide which design they want for their tires. While in the pre-cured system, the pattern is created by companies producing the pre-cure tread.
In the mold-curing system, it is essential to manage the time, pressure, and temperature.
For instance, truck tire retreading requires the temperature to be 150-160 °C, and the pressure 14-16 atmosphere.
Curing bladders and curing tubes are used to get the best adhesion between the tire and the molds.
Imagine them as a life belt inflating and keeping the tire outstretched.
b. In the PRE-CURE SYSTEM, the casing with the new tread is lifted on a machine to apply the envelopes (the machine name is envelomatic). The tire is vacuum-sealed because there can’t be any air between the envelopes and the tread.
The envelope is like a tight dress.
The tire will then go into an autoclave, where it’ll remain for 2-3 hours at a temperature of 110-115 °C.
- FINAL INSPECTION
The retreading process is finished. An operator controls the inside and outside of the tire. He needs to make sure it is suitable to go back on the road.
The 7th step ends the part of the story dedicated to the technical aspects of tire retreading.
I’ll now talk about the reasons why we should choose a recapped tire.
THE ENVIRONMENT
Explaining the tire retreading steps helps to create an image of how these tires acquire a new life (and I hope the photos do too).
They are a product of reuse, one of the hot topics for those who care about sustainability.
Retreaded tires are an eco-friendly choice.
How do they help the environment though? 2
- Reduced use of raw materials
A retreaded truck tire saves 50 kg of raw material, with an average of only 20 Kg of new material used for casing. Crude oil is among the raw materials used. A retreaded tire saves between 56% and 70% of the crude oil necessary to produce a new one.
- Reduced CO2 emission
100 retreaded tires reduce the emission of 6 tons.
- Fewer tires to dispose
Lower soil consumption
- Reduced use of energy and water
GOOD FOR YOUR POCKET
Taking care of the environment is our duty, but choosing a retreaded tire also helps our finances.
Truck tires cost 40-50% less than a good quality tire.
ARE YOU PERSUADED?
The data I have laid out could have awakened the interest of some, but I know retreaded tires are a source of doubt. This is also the reason why I’m writing this article. To help throw off perplexities and get you to consider a new option at the next tire change.
There are many myths3 to dispel:
- Retreaded tires can’t run as many Km as new tires.
FALSE: a quality retread can have the same performance or even higher than a new tire.
- The rubber on the roads comes only from retreaded tires.
FALSE: it comes from both new and retreaded tires in equal proportion.
The majority comes from wrongly inflated, overloaded, and not checked truck tires.
- Retreaded tires are not safe.
FALSE: quality controls are checking a retreaded tire respects the standards. In Europe, both tires and plants are subject to homologation4.
Fun fact: you may find it interesting that airway companies use retreaded Avio tires.
THE CHOICE
Some tire retreading steps remind me of the make-up application. There’s the foundation. You choose the right accessories and the style you want. You follow precise steps to get the best outcome.
Or baking! We have a recipe informing us about the ingredients and instruments we need. We know that compactness is important, and we must be precise with the cooking time and temperature.
The ecological and economic meaning follows the same theories that gave birth to Apps to sell second-hand but still in good conditions clothes (and not only), or why we think twice before throwing them away and we rather fix them.
Would you throw away some unstitched trousers, or would you sew them?
At home, we are now used to sorting our waste. We care about plastic being recycled because of its abuse. Why don’t we do the same with our tires?
For many years now, I’ve chosen retreaded tires for my car. Initially, the price attracted me. Someone would say you can find new passenger tires at the same price as a retreaded one. And this is true. But sometimes, behind this cheap price, there’s a different quality. It will not ensure you the same mileage and the same safety.
Due to this price situation, too many passenger retreading shops shut down. Some still resist, and it means you have an option.
The impact of cheap tires also hit the truck retreading industry, forcing smaller businesses to close. Fleet managers had to face a hard choice, price-wise, but retreaders became more specialized, and the quality of the product improved.
Finally, I want to point out that an alternative exists, and we need to look beyond the money. To me, the choice is easy: RETREAD.
Safe, reliable, and eco-friendly.
¹ Source TRIB https://retread.org/copy-of-dual-wheel-positions-matchi-1
2 Sources Euromaster France https://bit.ly/3PMCy8q and Bandag https://www.bandag.eu/it/think-environment
3 Source Bandag https://www.bandag.eu/it/why-retread/myths-about-retreading e TRIB https://www.retread.org/retread-myths
4 Source AIRP https://www.asso-airp.it/it/omologazione.php