Today’s corn hybrids and soybean varieties are designed to withstand wind damage, as well as disease and insert pressure. While that helps to reduce crop losses that can run into the millions of dollars, this plant technology has resulted in some unexpected consequences.
The stronger stalks and stubble are causing damage to agricultural tires that range from sidewall cuts and punctures to chipping of large tractor tires. In some cases, damage can be so severe it may require the farmer to replace tires.
“We see more puncture issues with implement tires, but tractor tires are not exempt from damage,” says Scott Sloan, product engineering manager for Titan Tire Corp. “The industry has experienced an increase in damage since the mid-90s and worked to develop stronger compounds to resist damage, but has had difficulty keeping up with the pace of change in plant genetics.”
Another factor leading to the increase in tire damage is the design of corn headers being used by farmers. These heads are devised to leave a 3- to 4-inch stalk and when combined with the added strength bred into the plant, it's like leaving a perpendicular piece of rebar in the field.
“In the past, corn headers left a taller stalk that would lay over when contact was made with the tractor and implement tire,” Sloan says. “Now, with a much shorter stalk, you might as well be going over a bed of rebar.
"Some farmers tell us they won’t even drive their pickups out in the field anymore, for fear the stalks will damage a tire. Add in a hot, dry summer or a harsh winter and you have a real dilemma.
There are two different forms of stubble damage to tires. Implement tires seem to be more susceptible, as they do not have the number of plies in the tire or a heavy tread compared to tractor tires.
Stubble can become stuck in the tread or the groove of the tire. As the tire rolls, the stubble can actually work its way through the tire and cause a leak. However, not every piece of stubble will actually pierce and puncture the tire.
With tractor tires, farmers may notice a pecking phenomenon, where the stalk pecks at the tire and pieces of the tire come loose. This pecking is similar to taking a pocket knife and chipping away at a piece of wood; that’s the same thing stubble does to a tractor tire.
While this may not seem serious, the repetition of that action can lead to gouging of the tire in the tire deck — the space between the tire lugs — and, in some cases, across the leading edge of the tire lug.
“It’s rare to see substantial damage on tractor tires if they are set to run down the middle of the row,” Sloan says. “Where we see the most damage — in terms of pecking — is on the wider tractor tires, such as 710, 800 and 900 tires, where the tire actually runs over the row. You can really tell where the row was on the tire.”
Some discussion also needs to focus on radial versus bias tires, Sloan says. Since radial tires have a tendency to envelope and roll over objects, they have more give and may resist pecking better than a bias tire that is more rigid and less forgiving.
Sloan says manufacturers have been working over the past decade to develop compounds that will resist stubble damage, but it has been a challenge to keep up with the rapidly changing plant genetics that is making stalks stronger with each new generation.
The industry has explored options, including hybrid compounds that may produce a super-hard, puncture-resistant compound on the outside. However, you can’t put a concrete-like tire out there, as it must also perform in the field. At some point, hardness can become your enemy because the tire will be extremely brittle. Other ideas include Kevlar-protected treads and decks.
“It’s really a balancing act that all manufacturers are dealing with right now,” Sloan says. “We want to create a harder tire compound, but you cannot give up performance in the field, let alone operator comfort when traveling down the road. The industry is working to catch up with plant technology.”
Tire age can also be a benefit. Rubber is a living, breathing substance and is in a constantly changing state. As a tire ages, the rubber compounds become harder and stronger.
Sloan uses, as an example, a pencil eraser that sits in a desk for 18 months. When it's used at the end of that period, the eraser is smooth and hard. That, Sloan says, is the same thing that happens to a tire.
As the rubber hardens, it become less susceptible to stubble damage. However, in a time of industry shortages, many tires leave the factory and are installed on the tractor or implement within weeks. These fresh tires are more susceptible to stubble damage.
“It’s important for the farmer to think ahead and order and install their tires well in advance of major fieldwork,” Sloan says. “Allowing the tires to age before hitting the field lets the tire compounds and oils dry, making the tire more resilient or tougher.”
Beyond installing aged tires on your equipment, what steps can you take to protect your investment?
“It begins with choosing the right tire for the application,” says Skip Sagar, sales representative with Titan Tire Corp. “If the task at hand is heavy spring and fall tillage, then make sure the tire is designed for that application.
"Then select a tire width that will fit in between the rows and stay in the row. By selecting a tire width that is too wide, you are just asking for trouble; instead, look at duals or triples for additional flotation. Selecting a tire with a heavier ply or load rating can also help provide additional tire casing protection.”
Sagar also recommends setting the tractor axle spacing to run in the row not on top, as well as run with the row when working in the field as opposed to against the row.
Proper tire inflation is also another important key to tire wear as low tire pressures can lead to excessive flexing in the tire, which can result in sidewall damage from contact with the stubble.
Another option is to modify your equipment. Sagar says a number of farmers are installing stalk stompers onto their combine corn headers. Stalk stompers attach to the head using existing bolts and force the corn stalk and bean stubble to the ground before it has a chance to cause damage to tractor and implement tires. A down-pressure spring provides constant pressure on the stalks whenever the combine header is in the down position.
“Stalk stompers do a good job of moving the stalk from a perpendicular to a 45-degree angle position, allowing the tire to easily roll over the stalk with minimal impact or damage,” Sagar says. “There are a number of aftermarket suppliers offering these attachments. They are a wise investment to help limit tire damage.”
Sloan also recommends talking to other farmers to explore what steps they are taking to limit stubble damage. He says all farmers are suffering from this issue and there is a lot of discussion within online forums regarding farmer-designed ways to limit tire damage. What works for one farmer may not be ideal for your operation, but the more information the better.
“So when do you know the tire is damaged and needs to be replaced? Inspect your tires daily during spring and fall field work and look for pecking damage,” Sloan says. “Technically, a tire is considered unusable if the pecking effect has exposed the cord of the tire to the point it will not hold air and is unserviceable. At that time, it’s important to contact your local independent tire dealer and explore your options.”