What is a retread?
Since the early 1900s, retreading, or “recapping” or “remolding”, as it’s also called, has been a popular option for commercial tires. It’s a great way to get more service life out of a tire casing while using less resources than manufacturing a new tire.
Because retreading tires is an excellent way for fleets to save on costs, by getting more miles out of their tire casings, it isn't surprising that there are as many retreaded tires in service today as there are original-tread tires. In fact, most of the cost of a new tire is in the casing, sidewall and bead design. The tread itself only accounts for a fraction of the total cost. The material cost for retreading a tire is only about 20% of that of a new tire, and studies show that after multiple retreads a tire can be good for as much as 600,000 miles of service.
Regardless of what method is used for retreading a tire it always involves an application of heat, time, and pressure.
How is a retread done?
There are a couple of different processes for retreading a tire, which are referred to as “mold cure” and “pre cure.” No matter which process is used, it always has to start with a casing that’s in good shape and structurally sound. The casing is inspected thoroughly using non-destructive testing, looking for any embedded debris or other internal problems that could cause a tire to fail; some casings can be repaired before retreading while others will have to be scrapped. The old tread then has to be mechanically buffed off of the tire before anything else can happen.
In this process, a previously-prepared strip of tread rubber is cemented to the casing (using a special compound called cushion gum) after the old tread is removed. The new tread is already vulcanized (hardened), and the pre cure tire then goes to a chamber to complete the curing process. Pre cure retreads mean a much greater degree of flexibility in tire sizes, but it unavoidably leaves a slight seam where the two ends of the strip join up. Additionally, the bonding of a pre cure tire may not be as secure in the long run as a mold cured or remold tire.
This method is a lot closer to how a new tire is manufactured, with the original tread removed and raw, un-vulcanized rubber applied to the tire in one continuous piece. The tire and its new tread area then go to a rigid mold where they are cured, and the new tread pattern is applied into the rubber. Like new tire manufacturing, dedicated molds are used for each tire size and tread design .The higher pressure of the cure means a tighter, more secure bond and a cleaner, finished look.
In some mold cure processes, the sidewall can be remolded as well, with new branding and stamps embossed into the sidewall material. This method is called “bead to bead remolding.”
All retread tires are then subjected to a careful inspection process to ensure they meet industry standards, and come with a warranty identical to a new tire’s.
Vehicles That Rely on Retread Tires
It’s important to note that quality control is key to the retread process. Around 30% of casings are rejected due to stone drilling, rust in the belt package, excessive age, road damage or sidewall damage. Sometimes the damage is easily visible, in other cases a casing will need to be analyzed via shearography or other methods.
Usually, vehicles that are rated at two tons or over are good candidates for retreads, including box trucks and straight trucks. One-ton trucks will usually use light-truck tires, which typically aren’t retreaded.
Some of the types of vehicles that roll on retreads include:
- Fire trucks
- Semi trucks and trailers
- School buses
- Medium trucks
- Military vehicles
Tires that are in local pickup & delivery service are usually retreaded more times over their life cycle than tires for long haul service. For the hard urban miles that a route truck for a company like Sysco, UPS or Amazon sees, this solution makes even more sense.
While tires can be recycled, when it comes to the environment, retreading has its advantages with a direct impact on the demand for oil and natural rubber used in tire manufacturing.
A 2016 study from Ernst & Young, a multinational consulting firm, shows that retreads can actually reduce natural resource extraction by 70%, land use by 29%, carbon emissions by 24%, air pollution by 21%, and 19% of water consumption. Retreads also reduce the number of scrapped tires that have to be disposed of in landfills or through recycling. In fact, rubber that’s buffed off of old tires’ tread surfaces is easier to recycle and repurpose.
That’s an all-in price that's about 70% the cost of a new tire purchase, offering 80% of the tread life of a new tire. In the end, it just makes sense to retread old commercial tire casings and get more life out of them.
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