Editor’s Note: This Q&A originally appeared in AG Track Talk to provide answers that farm equipment dealers have about farm track technology. This series features a trending question followed by an abridged version of the answers. For the complete answers, check out www.agtracktalk.com
Question: Why are implement tires gravitating toward larger overall diameters with more varied tread (higher void ratio) and how do you see segment evolving further?
Alliance Tire Americas, Nick Phillippi, National Product Manager: The growth in the outer diameter (OD) size of implement tires is being driven by several forces. The primary one is that equipment keeps getting heavier and faster, which requires a bigger air cushion and new manufacturing technology. For decades, we addressed that challenge by building wider tires, getting into larger and larger flotation sizes. But the tires have to fit in the wheel wells, and the machinery itself is also getting wider, so now we’re coming up against limits on how wide a machine and its tires can be and still be legal on the roads. If we can’t increase the width to create a bigger air chamber, the only way to grow is up.
A taller tire creates a longer footprint. That maximizes the total number of square inches of rubber we can put in contact with the ground at any time. Just as important, steel belts create a wider overall footprint, especially as speed increases. That’s an effect that’s even more dramatic when you combine a high OD and steel belts with flexible VF sidewalls. The result is a large, rectangular footprint that maximizes not only length, but width, and distributes load very evenly across the contact patch.
Evenly distributing the load across the largest possible footprint reduces soil compaction, and it also reduces pull drag by increasing flotation, which cuts down on fuel consumption. Radial sidewalls—whether conventional radial or VF — also deflect more to absorb shock and improve handling on the road, for a safer, often faster drive.
We’re also seeing significant improvements in tread patterns, even though some of them can be pretty subtle to the casual observer. Our designers have pioneered new designs to offer better roading, reduced wear and more lateral traction on hills. Using the latest in computer assisted design (CAD) tools, they can optimize for wear and roadability on pull-type implements, taking into account lateral traction as well as low-friction, free-rolling operation.
I think the surprise in all of this development of taller, more purpose-built tires is that we’ve gotten so efficient at manufacturing them that we’ve really narrowed the price gap between highly specialized radials and more conventional bias-ply tires. There has really never been a better time to buy farm tires.
I expect to see these trends continue. Advances in compound formulation, tread design, and manufacturing technologies that we are developing in drive wheel tires will drive further improvement in tires for towed implements—and although it seems equipment can’t get bigger or faster, I expect OEMs will keep challenging us to create tires that rise to even greater challenges. We’ll be ready.
BKT USA Inc., Dave Paulk, Manager Field Technical Services: Implement tires have gone through quite a transformation over the past several years. Farm equipment is getting heavier and bigger all of the time. Since most farmers must travel from field to field on the highway, tires must be able to hold the weight of the equipment with the wings folded up. This equipment is transported at faster speeds since most tractors will run at least 30 mph, but some of the new high-speed tractors will run between 40 and 45 mph. Therefore, not only must implement tires carry the heavier weight, they must do it running at faster speeds.
Bias implement tires have been around for years. In the past, they were adequate for the smaller equipment. Road use was not as necessary in years past as it is today and tractors didn’t drive as fast. Modern equipment simply outgrew the weight carrying capacity and speeds of standard bias implement tires.
Farm Highway Service tires took the place of the standard implement tires in some applications because they can carry much more weight and are rated at higher highway speeds. They are bias tires, but the higher load ratings can be difficult to mount, and the air pressures are typically very high (11L15 F-I 12 ply Max Inflation is 90 psi).
Radial implement tires have been introduced in the past several years and are beginning to gain acceptance in the market. They have the weight carrying capacity needed, are easier to mount on the wheels, and have the needed speed ratings. Because of the radial construction, they generally wear better when used for transporting equipment on the road. Radials can be used in the field at lower air pressures than bias tires which helps to minimize soil compaction.
Implement tire sizes continue to get larger with bigger wheel diameters to handle the weight of the equipment they are being used on. There are often size constraints to allow the tires to fit the equipment now being produced. This is leading to IF and VF technology being used on implement tires to allow the tires to stay within the size constraints and still enable them to carry the required weight. Since most are transported on the highway, tire manufacturers must develop a tire that carries the increased weight at the faster speeds and will still wear well with both field and road use.
Since these tires are being used more on the highway, tread patterns must be designed to allow for even and long-term wear. The more land to sea ratio used, the better life implement tires seem to have. Most are free rolling tires, so they don’t necessarily need the traction that drive tires demand. But, some are made with deeper or curvy ribs to stabilize the equipment (such as planters or cultivators) to minimize sideways movement on hills.
With the many changes in implement tires, tire manufacturers must keep up with the changing demand to provide tires with larger diameters, higher speed ratings, and special tread patterns. BKT offers a full-range of IF/VF radial and bias tires that meet this demand.
CEAT Specialty Tires Inc., Jim Enyart, Technical Manager: Implement tires by necessity have grown larger in diameter as well as section width! This increase in size was due to the increasing sizes of equipment and additional attachments to existing equipment.
The original implement tires were barely adequate at best in many fitments, but as the equipment size and more importantly the weights increased, there was a need to increase the weight carrying capacity to minimize tire failures. Increasing the diameter, as well as the section width, increases the size of the air chamber and can increase the tires’ weight carrying capacity along with raising the ply rating.
Also, farmers are becoming more concerned with compaction. They are looking for options to minimize compaction during all operations in their fields. Implement tires are now in their sights!
There are some IF and VF implement tires in the marketplace now but this trend will grow due to the increased load carrying capacities, the compaction minimization and the reduction in tire failures. We may even see some implement designers increase the envelope for tires where possible to enable larger more adequately suited implement tires to be fitted.
Precision Inflation LLC, Ken Brodbeck, VP of Technology:
Why are implement tires growing in size? Because Bigger is usually Better!
Larger, heavier and more complex implements require more load and speed capacity.
We all know a WIDER tire is better for reducing soil compaction in most applications as it provides larger footprint. But why are we seeing trend to TALLER tires with larger overall diameters?
1. Taller = + LENGTH of Footprint (Reduced Soil Compaction)
2. Taller = + AIR CHAMBER SIZE (Reduced Air Pressure)
An extreme example can be seen in the Horsch Maestro Planter, where increasing overall diameters from standard 32 inch to 75 inch coupled with IF technology can make a huge difference.
Video with Jeremy Hughes, Product Manager from Horsch and AG Tire Talk archive provides further explanation
The other future trend we are seeing is use of Central Tire Inflation Systems in implement tire applications. Why? The weights are extreme.
In fact, on a common Deere planter, we are seeing rear axle weight swing from planter fold up position of approximately 30,000 pounds, to in field of approximately 20,000 pounds — CTIS does a great job of reducing air pressure for in field applications for popular smaller overall diameter implement tires, dramatically reducing soil compaction.
So what are future trends?
1. Taller Diameter
2. IF / VF Technology
3. On the Go Tire Inflation Systems, High psi for transport, and Lower psi for field.
Maxam Tire International, Greg W. Gilland, Business Development & Ag Segment Manager: Agriculture is a prime example of the Axiom: “Necessity is the mother of all invention.” Tire technology has evolved dramatically in the last twenty years in this unending quest to achieve greater crop yields to produce more food and greater profits.
In the last 20 years we have seen tire technology evolve from primarily bias ply constructed carcass tires to radial constructed carcass tires capable of greater loads, from lug profiles at 23 degree now at 45 degree construct designed for improved wear and traction, and finally to IF or VF technology that has fundamentally changed the tire load capability without changing tire geometry. The agricultural industry has been quick to see the value and benefits of the above tire technology in powered equipment but reticent to adopt the same solution for the non-powered towed implements that carryout the work in the field. As a result, some of the benefits that could be achieved with tire technology on the powered equipment impacting soil compaction was completely negated by old tire technology used on implement operating at higher air pressures pressing against the soil as they rolled or were dragged through the field.
Radial tires by design provide a larger “Gross Flat Plate” or footprint that distributes the tread evenly across the ground contact patch reducing soil compaction while simultaneously increasing the traction capability of the tire. As implements are becoming larger and heavier to increase field productivity their traditionally small tire wheelbases are evolving in area to allow larger tires that can carry more load and reduce soil compaction. This trend has opened the door for radial tires with their larger air chamber to deliver performance solutions with new designs that depending on the need can incorporate either wider lug designs for greater road traction or larger lug to void ratios to increase field traction all the while reducing soil compaction. The agricultural industry is now evolving by necessity towards larger radial solutions for implement tires incorporating all the above lessons learned to ensure that towed equipment can effectively employ tire technology to achieve greater yields and profits. The primary difference in tire construct technology between bias ply and radial tires is how each type of tire carries the load and displaces the soil:
All Ag tires are designed by size or footprint to fulfill following specific functions:
- Carry the Load
- Transmit the Torque (or driving power)
- Resist the lateral forces
- Allow the Chosen Equipment to fulfill its purpose whether in a powered or towed function
By design, radial tire construction accounts for 20% of the carcass load or pressure on the soil, while the compressed air in the tire chamber accounts for 80% of the carrying capacity. Whereas bias ply constructed tires relies on 40% of its load carrying capacity on its material and design construct.
The ongoing challenge to any grower looking to increase yields is to find solutions that reduce ground compaction by reducing the ground pressure pushing down into the soil ultimately compressing the soil:
As the need for greater yields and machine productivity is driving OEM’s to design and manufacture larger heavier implements that can work the field faster, radial tires present a flexible solution for use on towed implements reducing soil compaction and improving crop yields. Therefore, the greatest trend in implement tires evolution is the transition from bias ply constructed tires to radial constructed tires that will eventually employ IF or VF technology to achieve greater equipment loads without compromising soil compaction ensuring improved crop yields and greater profits.
MAXAM agricultural tires are designed to deliver an optimized footprint ensuring the best possible traction and flotation for the grower’s powered and towed vehicle needs.
Michelin Ag, David Graden, Operational Market Manager – Agriculture: Implement tires consist of mostly tires being used on trailed or pull behind farm equipment. They can range in size from something as small as a golf cart tire to something with a diameter of 5-6 feet and half that and more in width. Generally, implement tires will operate in a free rolling wheel position.
On a constant basis, producers are looking for ways to cut costs and increase productivity. As a result, machines are getting longer, wider, heavier and faster. Manufacturers of implement tires are working feverishly to keep up with this equipment growth.
When we take a look at why tires are growing in size to meet this need of larger equipment, we first need to understand the basic construction of tires and how they carry weight. Very basically, the air chamber of a tire is what carries the weight of a machine. The larger the air chamber, the more weight that tire can carry. Additionally, if we can change the flex point in the sidewall of that tire, we can spread the foot print and carry even more weight. This is referred to as IF, increased flexion, or VF, very increased flexion technology.
With regard to implement tires having more varied tread designs (higher void ratio), these larger tires have a higher capacity to carry mud and dirt with them. In fact, in Europe, a producer is required by law to clean all mud off the road after their machine has left a field. By outfitting your machine with tires that have a larger lug to void ratio, the ability for that tire to clean out is improved.
In summary, implement tires are evolving with the needs of producers to cut input costs and increase productivity.
Titan International, Inc. (Manufacturer of Titan and Goodyear Farm Tires), Pat Shelby, Ag Specialist: With compaction becoming an ever-increasing worry among growers, specifically pertaining to agricultural tires as a whole, there are common approaches being taken to combat the issue.
- Conversion to radial from bias construction
- Use of flotation tires
- Use of duals and triples
- Operation of tires at the minimum inflation pressures needed to perform a certain task
- Selection of tires constructed with IF and VF technologies
- Selection of tires of larger overall diameter to achieve maximum footprint length
- Evolution of tread patterns to more modern designs
Implement tires are no exception to the incorporation of some of these tactics.
Similar to the shift from bias to radial drive tires in the past, implement tires are now moving to radial, providing one more layer of defense against soil compaction. It’s no secret that radial tires result in a flatter tread profile- a key factor in achieving footprints with maximum square inch results.
Combined with this radial shift in the implement tire segment, technologies that improve deflection by allowing lower inflation pressures such as Increased Flexion (IF) and Very High Flexion (VF) construction are materializing, enabling more square inches in their footprints than ever before.
Tires constructed with IF technology can operate at 20% lower inflation pressures than their counterparts with standard construction, or can carry 20% more load at an equivalent inflation pressure. VF technology allows the same but increases the allowances to 40%. With implements following the same trends as other agricultural equipment becoming ever larger, heavier, and faster, IF and VF construction is helping to carry the extra load at lower inflation pressures, all equating to less damage to the soil profile.
Wider section widths commonly seen in flotation tires also allow maximization of footprint, but the trend towards larger overall diameters is equally important. As seen below, the tire illustrated by the black circle below creates a contact patch longer than that of the tire illustrated by the red circle. This directly affects depth of soil disturbance, which is significantly less as footprint length increases.
Tread patterns on implement tires play an important role as well. Tread patterns in this segment have traditionally been straight rib designs only with low void ratios. Straight rib designs have more of a tendency to skid or push soil, which is detrimental to soil health. Designs that incorporate more variation in tread elements with higher lug-to-void ratios not only promote better roll but aid in cleaning of the tire as well.
Titan produces both the Goodyear FS24 and the Goodyear Radial Implement which are both great examples of the incorporation of the above mentioned technologies. The FS24 is a smooth, cool running option for road transport and provides up to 210 square inches of flat plate and a 42.2 inch OD with the 480/55R22.5 size. The Radial Implement incorporates IF construction with steel belting for reduced soil compaction as well as improved puncture resistance.
As field working windows decrease and weather conditions become more unpredictable, improved efficiencies in the field are of utmost importance- all which can be enhanced with better yields and reduced inputs by maximizing use of implement tire technology, maximizing footprint, and promoting roll.
Trelleborg Wheel Systems, Norberto Herbener, OE Applications Engineer: Implement tires have been on the back burner of development for a long time by the North America implement and tire manufacturers. Globally, implement equipment sizes are increasing because growers want to work more efficiently. This is now possible with the availability of larger and higher horsepower tractors from many manufactures. To accommodate the higher capacity demands, the North America market is starting to incorporate higher technology tires capable of holding higher loads following the trend in Europe.
The primary functions of implement tires are to carry the load of the piece of equipment during transport and to serve as depth control during field work. Previously when specifying tires for implements, the only requirements were how much load will it carry, will it fit in a tight space, it does not get stuck and be low cost. Compaction mediation and self-cleaning capabilities were not a requirement, but now they are with the increases in size and weight.
With these new requirements tire specifications must be upgraded too. Radial tire constructions have started to be more common and needed. Implement tires with steel belts, that are capable to handle higher loads, are being used in new implement tire designs. Implement manufacturers and tire designers are working together in creating the right tire for each implement configuration.
First, comparing radial to bias (X ply) tires, radial tires allow for higher loads, more sidewall flexibility and provide a larger footprint for the same tire width and outside diameter. Unfortunately, some of the new equipment has grown too large for a simple changeover from bias to radial tires. In this case, an increase in the tire diameter, or width, to support the higher loading is required. As mentioned in a previous article, it is the air chamber inside the tire that carries the load. The bigger the air chamber the more load carrying capacity the tire has. This helps mediate the soil compaction problem with larger and heavier implements by spreading the weight over a larger tire footprint.
Second, steel-belted tire carcasses, combined with rims designed with 15-degree bead sitting area, allow higher loads at increased speed, most are D rated / 40 mph, for better transport capabilities. Steel belts allow the tire to run cooler at higher speeds for reliability.
Third, newer tread patterns are shifting away from the traditional rib type, F2 design with no traction and limited cleaning, to I-3 or HF-2 tread designs that provide some traction but more importantly excellent self-cleaning properties and flotation capabilities.
This trend will continue as we are now seeing smaller bailing equipment arriving from Europe, round balers specially, that are equipped with higher technology tires. In time you will see this change happen to North American manufacturers as they change from the traditional “balloon” rib tires to tires that address the new requirements of producers — just not as fast as tillage equipment.
As producers are demanding larger and faster equipment to get more work done in less time. They are looking for tires that provide lower soil compaction, lower rolling resistance and have higher performance capacities. Tires with innovative solutions that incorporate newer technologies and capabilities are being incorporated into the new implement designs. These new tires may require new rim designs and will have an impact on implement cost. Even though there is only a small cost increase in tires, multiplied by the number of tires, it will cause implements to cost more. This increase in price is offset by the improved performance that will allow for less time in the field and less damage to the soil structure. This is all possible by the innovating technologies now being incorporated into newer implement tire designs. At Trelleborg we will continue to work closely with implement manufactures to provide the most innovative tire solutions that will lower your input costs and improve yields will protecting the soil.