Rock Products

APR 2019

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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www.rockproducts.com ROCK products • April 2019 • 31 expect that you'll be sacrificing some wear- and/or cut-resistance. However, there are instances where going to the extreme end of the spec- trum is justified. These decisions can best be made after a site assessment conducted by a qualified tire dealer or a tire manufacturer's specialist for aggregate producers. Tread Styles: Endless Nuances Tire manufacturers are continually refin- ing and introducing new tread patterns. Small nuances between lug angle, lug depth, lug pattern and void-to-lug ratio can all impact the tire's performance and longevity – and once again, it comes down to knowing how to strike the right balance between these nuances to get the best possible performance for specific applica- tions and working conditions. Just as with compounds, choosing a tread style that provides increased performance in one area may mean sacrificing performance in another. A few examples of the give-and-take relationship between performance and tread style include: Lug Depth – The deeper the lug, the longer it will take to wear out the tread. However, the deeper the lug, the heavier the tire and the lower the Ton Kilome- ter Per Hour (TKPH) rating. Choosing a lug depth ultimately comes down to whether TKPH is an important factor in the intended use. If not being used in hauling, or if the haul route doesn't push the tire to its TKPH limits, then a deeper lug will likely be justified. Void-To-Lug Ratio – Tires with larger void-to-lug ratios help better dissipate heat and often provide better traction; however, they are more susceptible to puncture damage between lugs, may wear more quickly and provide less stability than a tire with more lug on the ground. Ultimately, the tread style should be evaluated based on site con- ditions and intended use. One area in which the tire industry has seen innovation is in the design of tread siping. Siping, essentially small notches in the lugs, is a design feature that helps with both heat dissipation and providing a more even wear across the tread base. When siping first became popular, most sipe designs were deeper and larger than what's available today. While the sipes did offer heat dissipation and even wear, some designs experienced issues with rocks getting stuck between them. Designs have evolved into smaller, narrow strips – which based on tread design, may take the form of a zig-zag or straight-line pattern. With these latest sipe styles, the lugs are able to work together as a single unit rather than individual lugs, helping reduce uneven wear. Sipes are most useful in haulage applications for heat dissipation and even wear. Tire Construction: More Than One Way To Radial There are generally believed to be two types of tire construction – bias and radial. However, there are actually sev- eral different ways to build a radial tire, each with its own benefits when used in the intended application. The pri- mary differences between one radial and another are in the carcass material (nylon versus steel) and the number of beads used in construction (single-bead versus multi-bead). Most radial tires are built with a steel casing, steel belts and a single-bead design. This design is lighter-weight than other radials, which allows for high TKPH ratings – making it a good design for high-speed, high-load hauling. However, there are also some draw- backs. A steel casing tends to generate a great deal of heat and can be difficult to repair. Likewise, a single-bead con- struction may also be more susceptible to sidewall punctures as compared to a multi-bead. On the spectrum of sidewall stiffness, a steel-carcass radial is the least stiff design, which also has benefits and drawbacks. A flexible sidewall has better distribution of stress on the center of the sidewall – as opposed to on the beads where the tire and wheel meet – but perhaps less machine sta- bility, which is important in certain applications. An alternative radial design features a steel carcass with nylon body plies and a multi-bead construction. A nylon Titan's LD 250 features the deepest L-5 treads, providing excellent rock- type damage resistance and long tread life in a proven bias design for loader applications.

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