It’s (the ability to carry) load at the lowest possible pressure,” says Ken Allen, president of Firestone’s ag tire division, as he discusses the advantages of new IF (improved flexion) and VF (very high flexion) tire designs. “That’s the biggest consideration. Keeping in mind, at the same time, the genetics (of GM crops) and how we ensure the durability of the tire.”
Even with ever-increasing size and weight, and stiff stubbles left behind by new crops, farm machines need to put down a light footprint.
The IF and VF technologies that have emerged in the ag tire marketplace are what tire companies see as the way forward in dealing with those modern challenges. Firestone management considers their new AD2 (Advanced Deflection) tire offerings in the IF and VF categories a “next generation” technology. IF tires can carry up to 20 per cent more weight with the same inflation pressure as a standard radial. And the VFs take that advantage to 40 per cent.
Allen thinks tires based on Firestone’s AD2 technology can even compete with tracks when it comes to minimizing ground pressures. “We think our AD2, IF technology comes very close, is equal to or better in some cases than what a track does in terms of ground contact pressure,” he says. “The interesting thing is, remember, gross pressure is not contact pressure. That might be the fallacy of tracks because you have to understand where your highest contact pressure is. With a track, it’s usually under one of the idlers or the boogie. So when we look at a dynamic contact pressure, we see, actually, an advantage with low-pressure tires.”
But in order to make today’s low-pressure tires work on large machines, there is a need for increased tire sizes. “The equation is we have this load, and we have this pull we’re going to put on it, and we’ve been typically trying to be in around a 10 to 14 p.s.i. range,” he continues. “That, itself, will drive what the tire has to be in terms of size.”
To keep pace with machine evolution, tire sizes are now growing faster than ever before. “Typically, over the past several decades about every 10 or 15 years we’ve increased the OD (overall diametre) of the drive tire, and we’re in a situation now where we’re going two RCI (Rolling Circumference Index) groups. We’ve only done one at a time in the past several decades. Group 48 was introduced in late 1999, 2000. Now we’re seeing group 49 and 50 introduced at the same time. We have to be able to provide not only the load capability, but something that can efficiently transfer that amount of horsepower to the ground.”
In January, Firestone had several new tires to introduce that management believes will go a long way toward meeting those challenges in all tire-size groups. Included in the announcements were new radial implement tires with IF and VF designations. They will be able to support implements at lower inflation pressures, provide larger contact areas and use steel belts for increased stubble resistance.
“For implements, we’re bringing in a product that is steel belted to prevent stubble penetration,” explains Allen. “Our compounds are a little bit harder in that case for stubble resistance. For larger tires we have a product, like truck tires, that is steel bodied and steel belted for added durability. Stubble has been a problem for a long time. That corn is becoming like a tree, almost.”
For sprayers, the company introduced its All Traction RC tires. Available in both IF and VF designations, these tires now incorporate wider, curved and deeper tread bars. The wider width better distributes the load while the curved design makes for a smoother ride at high speeds. And these tires are capable of a maximum of 70 kilometres per hour. The 20 per cent increase in tread depth makes for longer wear life.
Finally, the company introduced its CFO (Cyclical Field Operations) combine tires. They are designed specifically to handle the high and changing load conditions typical of combines. But they won’t be available until the fall of 2013.
“If we take a look at the conventional radial tire, it has to have an increase in pressure to take a load bump for cyclical field operations,” says Allen. “Our new CFO tire can have that load bump at the standard pressure in an IF.”
“When we look at technology of the future,” Allen says, “it’s trying to understand from an agronomy standpoint what exactly the soil wants to see or doesn’t want to see, in terms of pressure.” †