Remould tyres, also known simply as retread tyres, regrooved tyres, retreads or remoulds, are used tyres which get remanufactured in such a way that their worn tread is replaced with a new tread without changing their structure. Generally speaking, this implies adding a new tread to the carcass of an older tyre to make the tyre last longer.
Drivers may be tempted by retread tyres usually because of their cheaper price or for the cause of more environmentally-friendly driving. But are they really worth the consideration? We discuss the advantages and disadvantages of retreaded car tyres.
How much of a tyre is replaced when retreading?
In the case of remould tyres, it is only the tread of the tyre that gets replaced with new rubber material. On average, this means that just 20 to 30% of the overall mass of the tyre gets replaced. Using less material is, in turn, is the main reason why remoulded tyres are cheaper than their factory fresh counterparts.
Retread tyres are most frequently applied to trucks, buses and vans, sometimes also to racing cars and planes. Their mass is larger than passenger car tyres so it makes more sense to retread them.
How are remould tyres made?
There is more than one way to retread a tyre and retreaders will often rely on different methods, depending on the availability of their equipment and on the specific parameters of the tyre that needs remoulding.
Before retreading, however, the old tyre must first be prepared. Various tests and inspections, such as shearography, are conducted to find any potential tyre damage that may not be visible to the human eye, such as embedded debris or wear. This filters out which carcasses can and which cannot be used.
After that, the original tread is often buffed away, leaving just the carcass. This ensures a smooth, even surface for the new tread to be applied onto. The most common ways of applying the new tread on remould tyres are:
- Hot retreading, also known as hot vulcanised tyre repair - applying a raw rubber layer onto the prepared carcass and subsequently vulcanizing it in a press at a very high temperature and under a high amount of pressure.
- Pre-cure, also known as cold retread - applying the tread strip to the carcass with cement. This method can be used in the case of a variety of tyre sizes, but it usually creates a noticeable seam where the two ends of the tread strip meet.
- Mould cure - using mould to form the new tread. The rubber, while still raw, is applied over the carcass before the mould is placed over it. This is not a very common option as it requires moulds for each tyre size and tread variant.
- Bead to bead moulding - giving the retread tyre new sidewalls in addition to the tread.
What types of tyres can be remoulded?
Not every tyre can be retreaded. As mentioned earlier, inspections are needed to ensure that no damage has been done to the carcass itself. If the carcass isn’t strong, durable or in a good enough condition, it will not likely be used.
Similarly, matching the correct tyre tread to the correct carcass is important, too. The tread should always have the same depth as the base carcass used in the process. At the same time, this must be at least 2-3 mm deep - bearing in mind that the minimum tread depth, according to the UK law, is 1.6 mm.
As a result, any carcass less than 2 mm deep cannot be used, as it cannot handle a deep enough tread. Considering that an even thicker tread is preferred and it possibly increases the lifespan of such tyres even more, a thicker carcass is more preferable too.
In Europe, the manufacturing processes of all retreads must be under the EC Regulation 108 (car tyres) or 109 (commercial vehicle tyres). That implies testing in the same rigorous conditions that are applied to new tyres (with the same load and speed criteria).
Advantages and disadvantages of retread tyres
| Advantages of remould tyres | Disadvantages of remould tyres |
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- Optimally used truck tyres can be retreaded even 2 or 3 times which significantly reduces tyre maintenance costs.
- Retreads can be considered green tyres as the tyre retreading process uses less oil and emits less greenhouse gas than new tyre manufacturing.
- Retread tyres are more resistant to aquaplaning than worn tyres.
| - Retreads have shorter mileage until they must be replaced when compared to new tyres.
- Some of the tyre properties, such as tyre noise, grip and steering precision may get worse in the case of remould tyres.
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It should also be noted that many contemporary tyres for passenger cars are constructed as “one-life” tyres. This means that, when selecting materials for the carcass construction, a higher mileage (when compared to the rubber) is not typically considered. These tyres, ultimately, can rarely be retreaded, as the carcass isn’t designed to be as durable.
Common myths related to remould tyres
Even though the remoulding processes do not change how tyres are made, there are a number of misconceptions regarding tyre retreading in the UK. Many of the motorists’ beliefs are, in fact, nothing short of myths, with the two most common assumptions regarding:
- Tyre balancing. Many drivers assume car wheels with retreaded tyres cannot be balanced. Why should this be the case, though? Tyres with the same tread and design can still be balanced, especially when you consider that some of the most important factors, such as the correct tyre pressure, are not related to the tyre’s construction methods at all.
- Tyre bursting. Many drivers assume retread tyres can burst while driving, yet has anyone ever seen this happen? Remoulds rely on advanced techniques like vulcanisation or on strong adhesives like cement, to ensure a strong bond between the tread and carcass. Ultimately, used car tyres that had been regrooved are almost like new tyres so such models do not burst.
Buying new tyres with retreading in mind
As already mentioned, not every tyre is designed in a way that it can be retreaded. If you want to buy new tyres and are planning to have them remoulded one day in the future, check for the right models. For the best results, especially when considering truck tyres and van tyres, you should choose premium tyres.
To ensure that your tyres are properly retreaded and you get satisfactory long-lasting results, choose models from manufacturers that offer their own retreading services. Some of the leading brands have been doing this for decades, so opting for Bridgestone tyres, Continental tyres, Goodyear tyres and Michelin tyres will help ensure the longevity of your tyre choice through retreading.