Tires on a loader, transporter, or industrial equipment in a steel mill undergo the kind of abuse that would make standard tires scream in agony. Most car tires have a limit of 185°F (85°C), and running tires higher than this will result in premature wear, traction loss, and blowouts. As you can probably imagine, things are different inside a steel factory. Blast furnaces can reach up to 2,900°F (1600°C) to melt or purify raw steel, while hot slag can reach up to 2,732°F (1500°C).
At those temperatures, standard pneumatic tires stand no chance against the extreme demands of working in a steel mill. The heat will soften and deform the rubber to the point of failure. When this happens, a tire blowout is imminent, or the tire will be extremely unstable under heavy load, leading to potential accidents and costly downtime. This is why heavy-duty equipment in steel factories is equipped with purpose-built, heat-resistant solid tires, which are not used in cars for a number of reasons, but are better suited for heavy-duty work.
These purpose-built tires do not require air to support the weight of the carrier and are much like the solid tires of children’s bicycles. The difference is the rubber compound and structure. Heat resistant tires are made from a unique blend of pure rubber, synthetic rubber and additives that are formulated to withstand extreme heat. The special material makes the tire more tough and durable against cuts. Steel Mill tires also feature a layered or ventilated construction for efficient heat dissipation, while the sidewalls are further reinforced to reduce flex and provide better stability under load.
It’s all in the mix
Many car and truck owners don’t think much about the tires on their vehicles. They’re round, black, and threaded, but modern tires aren’t just circular patches of rubber. A typical tire contains 19% natural rubber. The remaining 81% consists of synthetic rubber, fillers, steel, textiles and antioxidants, which work together to increase the tire’s durability, heat resistance, traction, wear and rolling resistance.
Adding more or less additives and fillers to the mix can significantly increase the performance properties of a tire. For example, carbon black (a filler additive used in most tires) not only contributes to the black color of the tire, but also reduces wear and tear, making the tire last longer. Silica is another filler that improves wet grip and rolling resistance. In the car world, such differences in structure are the primary differences between street tires and racing tires. For OTR (off-the-road) steel mill tires, a similar chemistry of mixing and matching is involved.
Natural rubber is resistant to high temperatures. Adding synthetic rubber polymers such as styrene-butadiene rubber (SBR) and butadiene rubber (BR) can increase the heat resistance of a tire. Meanwhile, carbon black, silica and curing additives make the rubber formula tougher and more durable. Manufacturers will make changes to the recipe, test the tire, and evaluate its performance to determine whether the tire can meet the demands of a particular vehicle or industry.
Chains provide more security
The punishing work environment puts a lot of stress on even the best steel mill tires. Tire protection chains can be used for additional reinforcement and protection against extreme abrasion, extreme heat and slug impact. Chains are usually made of hardened alloy steel and are wrapped around the tire, serving as the primary layer of defense to extend the tire’s lifespan.
Helpfully, OTR tire chains also help increase traction on loose, muddy or slippery surfaces, much like the snow chains preferred by semi truck drivers in the winter. They also help reduce cuts and heat damage from hot slag. Still, tire chains aren’t set and forgotten. To work as intended, they must be sized and fitted correctly to the tire, and they must be regularly inspected by trained technicians to prevent uneven tire wear or unintentional damage caused by a loose chain.
