Modern Tire Dealer has partnered with AG Tire Talk to provide answers to insightful questions that farm tire dealers have about farm tire technology. This is the next installment in our ongoing series, which is designed to help farm tire dealers better connect with their customers. A trending question, followed by answers, will appear in our Commercial Tire Dealer section every other month. For complete answers, click on www.agtiretalk.com.
Question: What tactics can be used to reduce fuel costs, what types of tires can further enhance fuel efficiency and how much savings can end users anticipate?
Dave Paulk, manager, field technical services, BKT USA Inc.: There are several factors to consider when working to enhance fuel economy in the field. When these things aren’t working right, it can increase the cost of fuel and time, as well as wear and tear on the tractor.
The correct amount of wheel/tire ballast is important for a tractor because it helps to transfer the power from the tractor to the ground. With too little ballast, the end user is limited to the size of the implements/wagons he can pull. This can create too much tire slippage and can cost your customer fuel and time. Eight percent to 15% slippage is in the recommended range per industry standards.
Proper air inflation and proper ballast are important to ensure that a tractor performs at an optimum level. Tractors in the field used at lower speeds can run less air pressure to allow for a longer and wider footprint. This helps with traction, minimizes soil compaction and saves fuel. Overinflation in the field can cause excessive wheel slip and fuel use.
When the tractor is on the road and used at higher speeds, tires need more air pressure to carry the weight of the tractor and implements. Load capacity decreases as speed increases. Therefore, more air is needed to protect the integrity of the tire. More air also creates a smaller footprint for the road that gives less rolling resistance and better fuel economy.
Central air inflation systems (CTIS) on tractors and combines are starting to be more widely considered and used. A compressor mounted on the tractor and air lines connected to the tires allow for air pressure levels to be dropped in the field and air to be added to the tires before road use. Incorrect air pressures for diverse applications can cause a variety of problems with tires, including premature wear, casing failures and impact breaks.
One survey has stated that by using the correct air pressures - minimum pressure levels that will carry the weight of the tractor and implement – end users can save up to 20% in fuel. Another study suggests that eliminating excess slippage by using the correct amount of ballast can lead to up to 10% in fuel savings.
Very high-flexion (VF) tires carry 40% more weight than a standard tire at the same air pressure. They can also carry the same load as a standard tire at 40% lower air pressure. The VF tire is a good option to consider if no till/minimum till is used on the farm. Air pressure dictates the ground bearing pressure of a tire. The lower the pressure, the less ground bearing pressure on the soil. The more air, the greater the ground bearing pressure that is applied.
VF tires provide a larger footprint to reduce slippage, minimize soil compaction and save fuel. At times, the weight carrying capacity and speed rating of a VF tire is needed. For heavy tractors, sprayers and
other equipment, the VF tire is the best choice to consider. Also if less air pressure is desired for field work, the VF-rated tire is the better choice.
Several hybrid tread designs have been introduced into the market in the past few years. They work best for tractors that are on the road most of the time. When the correct air pressures are used, this tire design will wear smoother and provide good road traction in the summer and winter. Tires will deliver better fuel economy on the highway as they are made to have less rolling resistance.
Hybrid designs aare gentler on the ground as they have more of an R-3 design than an R-1 or R-1W bar design.
Austin Fischer, ag field engineer, Firestone Ag: To truly optimize fuel usage, tire dealers must set the correct inflation pressure for each application. Other tactics to reduce fuel costs include replacing worn tires, removing unnecessary ballast, replacing liquid ballast and using CTIS.
Most growers use their tractor for more than one application throughout the year. Examples include planting in the spring and knifing once crops are growing or spraying in the summer and pulling a grain cart in the fall. To reduce fuel costs, it’s important to determine the appropriate inflation pressure for each application and to be sure to maintain it.
If a grower doesn’t plan to adjust tire inflation pressure throughout the year, we recommend setting the pressure for the maximum load the tires will see all year. But the best way to maximize fuel efficiency is to adjust the inflation pressure for each specific application throughout the year.
The tread of a tire is what transmits the power from the tractor to the ground. As the tread depth decreases below 20% of its original depth, consider replacing the tires. This is when the customer’s tires may start losing traction, especially in wet soil conditions. Growers should also replace tires when signs of damage or degradation become apparent.
Adding liquid ballast to tires increases the maximum amount of draft a tractor can exert, but it can reduce fuel efficiency in some situations when compared to using wheel weights. This is due to the stiffening effect of the liquid on the tire’s carcass, which causes it to deflect less and results in a smaller footprint. The smaller footprint translates to less lug surface area available to develop tractive force. Moving away from liquid ballast, and calcium chloride also removes the chance for corrosion of the tire rims, which would eventually necessitate tire replacement.
Two options that can help enhance fuel cost reduction include upgrading to increased flexion (IF) and VF tires. When switching from standard to IF/VF, growers can increase fuel efficiency up to 4%. Those using bias tires can experience an increase in fuel efficiency up to 14% when upgrading to radial tires, which also provide better tire longevity and fuel economy, as well as reduced soil compaction.
IF and VF tires offer elongated footprints by either permitting the same load at a lower inflation pressure or a higher load at the same inflation pressure. In turn, this extended footprint increases the contact area between the tread lugs and the soil, improving the ability to transmit the torque of the machine to the soil without slip. This equals better fuel economy and less time in the field due to decreased slippage and increased traction. Per unit of fuel, growers should be able to travel further and get out of the field sooner than they would otherwise.
Also consider switching your customers from bias to radial tires. The unique construction of a radial-ply tire allows the carcass to be more flexible and develop a bigger and squarer footprint than a similarly sized, bias-ply tire. The increased footprint size leads to reduced contact pressures exerted on the soil, increased flotation and more lug surface area available to develop tractive force without slipping, which enhanced fuel economy. The squarer footprint shape leads to improved wear performance, ride comfort and handling when roading.
While some specific agricultural needs and equipment may call for the bias-ply option, Firestone Ag recommends radial tires in nearly all cases, given their long life, smoother ride and better performance characteristics.
David Graden, operational market manager, agriculture, Michelin North America Inc.: There are many things that can be done to reduce fuel consumption and add money to your customer’s bottom line.
To start with, make sure you fit your equipment with the right tires for the application. Next, be sure tires are set to the manufacturer’s recommended air pressure, based upon speed and weight of your customer’s machine. If air pressures are set higher than the recommendation, you risk lug damage, punctures, fuel consuming slip and soil compaction, which negatively affects your yield in the long run. By using recommended air pressures, your fuel consumption is reduced due to the larger footprint on the ground. Keep in mind, this is contrary to what we know about passenger car tires. In the soil, a larger footprint means more tractive capacity/less slip.
Make it a VF tire and you have significantly improved upon this idea, as VF tires are designed to carry the same weight at 40% less air pressure. Less slip translates into improved productivity and, therefore, less fuel is consumed to do the job. In fact, independent studies at Harper Adams University in the United Kingdom show fuel consumption can be reduced by 10% simply by changing to VF tires.
Chris Neidert, training and development manager, ag, Trelleborg Wheel Systems: Getting as much horsepower as possible transferred from the engine to the ground is the end target. Ballasting can help accomplish this by either adjusting existing weights or placing additional ballast either on the front or rear of the tractor. The goal isn’t to have zero wheel slip, but to shoot for a preferred slip of between 8% and 15% for tractors.
Having too high of a slippage rate means spending more time than necessary in the field and wasting money on fuel as the tires are forced to spin more. Having too little slip means risk of overload on the tires, higher soil compaction, power loss, increased fuel consumption and lower productivity. Getting the proper ballast and tire inflation pressures can optimize traction, reduce compaction, increase the life of the tires and increase productivity.
Regardless of the tractor horsepower that your customer is using, the goal is to capitalize on the machine’s engine power. Getting the tractor to be heavy enough to apply that power from the engine to the ground is paramount.
Blaine Cox, national product manager – agriculture, golf and turf, Yokohama Off-Highway Tires America Inc.: Because they are the point of contact between the machine and the ground—and the point of friction when unnecessary motion takes place—tires have a significant impact on fuel efficiency. That means good decisions on tires can have great impacts on fuel costs.
The most important decision is inflation pressure. When manufacturers design a tire, we determine how much its sidewalls will flex in order to create a contact patch with an optimal size and shape. Too much inflation pressure means less contact patch, more slip and less engine power turned into forward speed. That all adds up to more fuel consumption.
In practical terms, we can be talking about a lot of fuel. In fact, scientists at the University of California, Davis found that correctly inflating tractor radials - in their example, 13 psi front/11 psi rear rather than overinflated at 24 psi - reduced fuel consumption by 20%.
If your customer is experiencing too much slip because your equipment is too light, ballast his tractor to optimize it. If the slip is the result of worn-out tread failing to provide enough traction, consider replacing the customer’s tires. Whatever the reason for it, slip is just another word for turning your wheels and burning fuel without getting work out of the process.
Selecting the right tire can pay off in lower fuel bills. Because IF and VF tires have added flex in their sidewalls, longer and wider contact patches and can operate at lower inflation pressure, they improve fuel economy over standard radials.
When you are looking to upgrade your client’s tires, look for tread patterns that maximize traction and minimize rolling resistance. We’ve come a long way from the lug designs that were in fashion for more than 100 years. You’ve got great choices for the soil types, roading needs and chores your customer needs to accomplish.
Finally, when diesel prices are as high as they have been this season, a CTIS - which allows you to adjust inflation pressure on the go, right from the cab - can pay itself off more quickly than ever. And not only does CTIS improve fuel economy, it also helps your customers get longer wear and better performance out of their tires.
When you start thinking about fuel consumption, take a minute to glance away from your gas cap and take a look at your tires.
