A Look At Some Of The Latest Off-The-Road Tire Innovations And How They Are Intended To Be Used.
By Johni Francis
|Titan’s STL3 radial off-the-road tire features an E-3/L-3 non-directional tread pattern for excellent traction, a smooth ride and long tire life in earthmover or loader applications.|
There has been a great deal of tire innovation for aggregate producers in the last decade – in tread styles, compounding and tire construction – however, many of these innovations were created with a specific intended use in mind. It’s important for fleet managers to understand what technologies are available and how to best implement them. This article takes a look at some of the latest tire innovations and how they are intended to be used.
Tread Compounds: Standard Vs. Custom
The three most common categories of tread compounds for equipment used in the aggregates industry are cut-, wear- and heat-resistant.
- Cut-resistant compounds are formulated for sites that pose a high risk of puncture damage and for equipment that isn’t necessarily hauling at high speeds with high loads the majority of the time.
- Wear-resistant compounds are designed for work requiring frequent starts, stops and sharp turns on hard surfaces – ideal for prolonging tire life on loaders.
- Heat-resistant compounds are designed for high-speed, high-load hauling – as heat buildup is a leading cause of tire fatigue on haul trucks.
While many applications can benefit from these standard compounding options, there are many instances in which a jobsite may require something not so standard. In these cases, some tire manufacturers will develop custom compounds to meet their unique needs.
It’s important to understand that in the process of formulating a compound, designing it to get performance in one area often means sacrificing performance in another. In other words, if you want to move more toward the extreme heat-resistance end of the spectrum, expect that you’ll be sacrificing some wear- and/or cut-resistance.
However, there are instances where going to the extreme end of the spectrum 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 refining 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 applications 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 Kilometer 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 conditions 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
|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.|
There are generally believed to be two types of tire construction – bias and radial. However, there are actually several different ways to build a radial tire, each with its own benefits when used in the intended application. The primary 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 drawbacks. A steel casing tends to generate a great deal of heat and can be difficult to repair. Likewise, a single-bead construction 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 stability, 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 radial has a stiffer sidewall than a traditional steel-carcass radial, which provides some benefits, particularly on large loaders.
Less sidewall flexibility means less wind-up when digging into a pile, potentially improving breakout force. It also provides additional stability for the machine. With less rocking and swaying, a large loader may experience less material spillage, particularly on high-lift models with large-capacity buckets that put a great deal of stress on the tires when fully loaded and extended.
The downside to a nylon, multi-bead construction is that it’s a heavier tire – and although it provides some additional penetration resistance in the sidewall area, it also comes with a lower TKPH rating. However, some manufacturers are currently working to design and test nylon radials in a single-bead construction, which will improve TKPH ratings.
Radial Or Bias: Is The Latest Always The Greatest?
|Deeper L-5 treads and a bias design may prove beneficial over a radial on loaders that don’t require a great deal of tramming.|
The short answer is no. Over the last several decades, tires have seen a predominant shift to radial due to the increase in size, power, weight and speed of equipment. While radial technology outperforms bias in many instances (justifying the increased cost), bias tires, when used in the proper application, can provide significant cost savings and performance benefits over radial – proving the latest isn’t always the greatest.
On the spectrum of sidewall stiffness, bias is the stiffest of any tire construction, which can further enhance the stability and breakout force benefits. Bias tires are also generally easier to repair than radials and, because of the sheer amount of layers, offer the most penetration resistance in the sidewall. For a loader working in a small foot-printed area with limited tramming, bias may be the best option for achieving a low cost per hour and excellent performance.
Alternative Sizes: Larger Rims, Lower Aspect Ratios
In addition to innovating treads, compounds and constructions, some manufacturers are even exploring entirely different sizing combinations between tire and rim. For instance, Low Sidewall Technology (LSW) is a concept inspired by the automotive market.
This technology’s larger rim diameter and shorter sidewall allows for less sidewall flex, which eases stability concerns and improves breakout force. LSW has already proven successful in the high-horsepower agricultural market. Since 2011, the concept has also seen success in the mining industry with the 58/80R63 on a Cat 994K. LSW is currently being tested in smaller construction equipment applications.
Don’t Forget The Wheel
With so many choices in the selection of tire technologies, it’s easy to forget about a critical component of the assembly – the wheel. One of the latest advancements in wheels is quick-change technology, also known as Accelerated Change Technology (ACT) or Quick-Change Rims (QCR).
These quick-change technologies allow the inner tire of a rigid haul truck to be removed without having to remove the outer wheel. Typically, these systems consist of a two-piece lock ring that can release the tire assembly from the wheel while the outer wheel stays mounted to the truck, thereby eliminating the need to torque and re-torque.
On a complete tire change-out or whole-truck rotation, using a quick-change technology can reduce associated downtime by up to 50 percent. While the cost of these types of wheels is more than standard wheels, the return on investment in the form of uptime can pay for itself in a relatively short period of time, dependent on production and maintenance schedules.
With an end goal of reducing the cost per hour of a fleet’s tires, there are many considerations to be made. Striking the perfect balance between tread style, tread compound, tire size and wheel type requires looking at both site conditions and intended use of each individual machine. Consult with a tire expert to ensure you’re getting the most out of the technology you invest in.
As global OTR product manager at Titan International, Johni Francis oversees the research and development, design, and introduction of the company’s off-the-road tires for construction and mining. He has spent a great deal of his career consulting with job sites throughout the world in the development of tire management and tire procurement.