Both bias-ply and radial tires hold an important place in the agricultural tire market. While radial tires bring many important benefits to the farm, such as less soil compaction and more traction, there are a few reasons that bias tires continue to hold a share of the market. In order to make the best decision for your next farm tire purchase, you need to understand the differences between bias and radial tires and how their attributes affect their performance in the field (and on the road).
Bias Tires: Old-Tech, Rugged Tires
Tractors have been wearing bias-ply tires ever since farmers ditched metal wheels for pneumatic tires in the 1930s. Bias tires feature multiple plies of rubber in a diagonal pattern from bead to bead. Because of this construction method, the tread and sidewall of a bias tire function as one unit. This results in a stiff and strong sidewall that can fend off damage from stumps and rocks. And because they’re stiff, bias tires can offer excellent stability on hilly terrain. Let’s face it: not everyone’s land is flat, so it’s especially important not to gloss over this strength of bias tires.
However, a bias tire’s stiff construction can lead to a punishing ride for the operator. And when the sidewall of the tire flexes, so does the tread. This tread deformation can lead to a smaller or distorted footprint, which can increase wheel slip, reduce traction, and result in additional compaction in your fields.
Bias Tire Advantages
- Lower initial purchase price.
- Stiff sidewall prevents swaying on hillsides
- Durable sidewalls protect against punctures from rocks, sticks, etc.
- Rounded tread profile is easier on turf.
Bias Tire Drawbacks
- Increased compaction and rutting/sinking in the field due to their small footprints.
- Higher fuel consumption due to increased rutting/sinking in the field.
- Rough ride.
- Lower load capacities compared to modern radials.
- Will wear quickly with extended road travel due to heat buildup.
When to Buy Bias-Ply Farm Tires
As you’re about to learn, radial tires are the preferred option for most farm uses today. However, that’s not to say that old-fashioned bias-ply farm tires are obsolete. Because they cost less, bias tires are a great purchase for your secondary or utility tractors. This could be the tractor you use for mowing ditches, cutting and raking hay, and performing chores around cattle lots and other livestock sites. Bias tires also excel on skid steers and ZTR mowers. A bias-ply tire’s rounded tread profile can help minimize damage when making tight turns on turf and will limit how badly livestock lots are torn up when you’re forced to work in the muck.
Radial Tires: The Better Option for Most Farm Uses
In 1957 Pirelli became the first company to bring a radial tire to the agriculture market. Two-part construction is what sets radials apart from bias tires. The cord plies are arranged at 90 degrees to the direction of travel, and the under-tread area is wrapped around the circumference of the tire by radial belts of steel or fabric. With a radial tire, sidewall flex is not transferred to the tread, allowing for more even wear. This means the tread on a radial tire can last 2 to 3 times longer than a bias tire’s tread.
A radial tire’s construction allows for a larger, more uniform tire footprint. As you load up a radial tire, its footprint actually grows longer (not wider). This puts more lugs on the ground for less slip and more traction, and the larger footprint also limits soil compaction, which can decrease your yields. Radials are designed to operate at lower inflation pressures, which is critical in preventing yield loss and lower profitability from soil compaction.
Radial Tire Advantages
- Less soil compaction (when properly inflated).
- Longer-lasting tread and more durable thanks to better heat dissipation.
- Lower cost per hour due to longer-lasting tread.
- Better fuel economy thanks to increased traction and decreased slip.
- More comfortable ride.
- More secure handling.
- Higher load capacities.
Radial Tire Drawbacks
- More expensive than bias tires initially.
When to Buy Radial Farm Tires
You want to mount radial tires on any tractor (or other machine) that will be tracking across your fields. Sure, you can get by with bias tires on your smaller chore tractors and implements, but when it comes to planting, spraying, harvest, and tillage, you should be driving across the dirt on radial tires.
IF & VF Radials : For Your Largest & Heaviest Farm Machines
Since the early 2000s, two new classes of radial tires have been available to meet the needs of today’s larger and heavier farm machines: IF- and VF-rated radial tires. IF stands for increased flexion, and VF stands for very increased flexion. IF and VF radials put more tire—a larger footprint—on the ground thanks to lower air pressures and sidewalls engineered to allow more flex. This larger footprint puts less pressure on your fields, which helps prevent deep-soil compaction from lowering your yields and profitability.
- IF radials can carry the same load as a standard radial at 20% less pressure.
- VF radials can carry the same load as a standard radial at 40% less pressure.
- Or, you can increase their maximum loads by 20% or 40% above a standard radial’s limits.
Your Success Depends on Tire Pressure
If you invest in radials—or even if your machine still rides on bias-ply tires—you should always pay close attention to tire pressure. In order to see the benefits we’ve discussed here, you must correctly set your tire pressure for specific applications. If you don’t, problems such as power hop, uneven wear, and increased compaction can rear their ugly heads. Some tire manufacturers have online calculators that will give you the correct pressures after you provide them with information such as axle position, number of tires, and load. You can always call NTS Tire Supply too, and we’ll be happy to help you set your tire pressures.
So . . . Which Do You Choose?
Tires are no different from any other agronomy decision: you can increase your farm’s profitability by mounting the right tires on your machines. Durable, dependable bias tires are perfect for chore/secondary tractors, ZTR mowers, and skid steers.
For most every other application on the farm, however, radials are going to bring you the best return on your tire investment. Sure, they cost more up front, but radials also last longer, save fuel, and may even increase your yields by mitigating the effects of soil compaction. And for today’s largest and heaviest tractors, combines, sprayers, and implements, you’ll want to look for an IF- or VF-rated radial to maximize all the benefits of radial tires we’ve discussed above. At NTS Tire Supply, we’re here to help Drive Your Farm Forward. If you want to know the best tire options for your budget and application, give us a call and talk to one of our tire experts.