Radial vs. Bias Tractor Tires
Tractor tires continue to evolve to meet the needs of today’s farmers, but whether to choose a bias or radial tire remains a constant question asked by farmers when purchasing tractor tires.
Though the technology is nearly as old as pneumatic tires themselves, bias-ply tires still present a viable option for many machines. Bias tires are manufactured by lapping multiple plies of rubber-coated fabric diagonally over each other—also called “on the bias”— to create a single carcass. Because of the way bias tires are engineered, the tire’s sidewall and tread are connected and work together rather than independently.
The advantage of bias construction is that it creates a stiff, strong, durable tire with rugged sidewalls, making it a great choice for machines threatened by stumps and rocks, or equipment that requires a lot of stability—for instance, tractors that often drive across hillsides. Bias-ply tires are also typically less expensive than radials. Negatively, the stiffness of a bias tire also means that bumps in the field are transferred throughout the entire machine, diminishing a tractor’s ride quality and stressing welds and bolts. And because of the way the diagonal plies transfer movement across the tire carcass, when a bias tire’s sidewall flexes, so does its tread, reducing traction and potentially increasing rutting and soil compaction.
Over the years, radial tires have grown to account for 4 in 10 farm tires. As tractors have gotten larger and more powerful and the variety of tasks tractors are asked to perform has increased, radial tires have been better able to meet the demands made of them. Unlike bias tires, radial tires are constructed in two parts that are designed to work independently of one another—the body plies run perpendicular to the bead, and the undertread area is wrapped around the tire’s circumference by radial belts of fabric or steel. The belts create a broader, flatter footprint and provide increased resistance to tread punctures.
One of the distinct advantages offered by a radial tire’s two-part design is that flex in the sidewall isn’t transferred to the tread, so the tire’s footprint remains larger and more consistent. That results in better traction, increased fuel efficiency, and reduced soil compaction and field damage (radials can have a 15-25% larger footprint than a comparably sized bias tire). All of these qualities ultimately add up to more productivity and efficiency around the farm. Radial tires will also last longer and provide a smoother ride than bias tires.
Of course, for radials to outperform their bias counterparts, it's critical that they be run at the correct tire pressure, so if you’re going to invest in a good set of radial tractor tires, pick up a good tire gauge at the same time.
Whether you’re looking at a bias or radial for your next tractor tire, we have a bunch of great choices for your machine. The Alliance FarmPro 324 is an excellent option for farmers looking for an affordable do-everything bias-ply tire. Purpose-built to handle the numerous jobs tractors are tasked with around the farm, the 324 is a reliable, durable, affordable option that’s ideally suited for general-use tractors.
As for radials, we’ve got a wide range of designs, from classic tractor lugs to our venerable Alliance 550 MultiUse, which is designed to handle whatever job you can throw at it. In the field, the Alliance 550 provides great traction, low compaction, and excellent stability while also being capable of achieving high speeds on the road. The 550 is even great in snow and works great for snow removal.
Still wondering if a bias or radial tire is right for your tractor’s needs or want to learn more about our other great tractor tires? Contact your local dealer today to find the right tire for your machine.