QUESTION: What is the average lifespan of a large ag drive tire, in terms of years of service; what steps can a producer take to prolong it; and what specific attributes should you look for when choosing a tire to maximize longevity?
NICK PHILLIPPI: product manager, technical support, North America, Ascenso Tires North America: Rear ag tires, using the 80% rule, should last eight years with no issues in normal conditions: correct PSI for weight and speed, normal torque, about 20% roading and stored under cover when not used for longer periods.
I base that on the fact that most warranties today are seven to 10 years and someone knows the statistics to set those timelines. I have seen tires last 20 years and some that didn’t make it four. Some of this spread is due to the quality of the product, no doubt, and some is due to the care of the product.
With more science involved, compounding has become very technical and very important. The use of chemicals and other ingredients, done correctly, has helped in the areas of ozone cracking, stubble damage, wear and flexibility for all types of applications.
The proper use of these ingredients adds cost to a tire and can’t really be noticed or appreciated by observation.
Of course. good practices will add to the life of a tire. Proper inflation is key, even when the vehicle is sitting. Washing off the tires from manure, oils or other foreign substances is a good practice. Storing tires out of direct sunlight when possible will also certainly pay off in tire life over time.
DAVE PAULK, manager, field technical services, BKT USA Inc.: The lifespan of an ag tire is dependent on how it is used and for what purposes. If an ag tire is used only in the field, they will last much longer before they wear out. Unfortunately, with farms scattered and tractors traveling on the road, the life of ag tires is diminished because of the road wear.
On mechanical four-wheel drive tractors, the fronts are drive tires, but wear out about 2:1 to the rears, especially where traveling on the road is required. The reason is that the fronts usually turn 1.3 to 1.5 times faster than the rears.
The crown of the road also plays a part in how the tires wear. The right front tire will often wear out faster than the left front. The right rear (tires) will exhibit signs of road wear, but are larger and don’t turn as many times as the fronts. The road wear doesn’t show up as quickly. Rotating the fronts from right to left will prolong the life for a while longer.
Using correct, recommended wheels is important in several ways. Generally, there is a recommended wheel with alternates. The recommended wheel will give the tire a better footprint on soil and on the road. Where compaction is important, the tire is spread out over a larger area - longer and wider. Recommended alternate wheels will work without damaging the tire, but sometimes don’t give the optimum footprint.
If wheels are too narrow, it pulls the sidewalls of the tires in and puts more pressure in the middle of the tire tread. If wheels are too wide, the beads are pushed out, which creates undue pressure in the bead area and lower sidewall. Very high-flexion (VF) tires play prominently into this, as they can be run at lower air pressures and give a wider and longer footprint with the correct wheels.
The use of steel belts in ag tires can serve a dual purpose. Tires can be made with a steel belt in the tread area or made with an all-steel casing. A steel belt strengthens the casing and offers a measure of resistance to punctures in the tread area. It doesn’t make tires bullet-proof, but the steel belt does help.
They also help the integrity and form of the casing stay intact. Some tires are made with all- steel casings. These tires have steel running from bead to bead in a radial design. This helps to minimize damage to the sidewalls and tread area of the tire.
GREG GILLAND, vice president, global agriculture, Maxam Tire North America Inc.: In the agricultural industry, it is how the equipment is utilized or the inherent operational requirements that will affect tire life. As agricultural tires are considered (to be) off-road and not U.S. Department of Transportation (DOT)-regulated, there are no firm rules to determine when an ag tire needs to be replaced.
However, how the tires are utilized will determine the usable service life of a tire. In all instances, the type of machinery, soil conditions, application (intensity of use) and air pressure maintenance will have a direct impact on its ability to deliver an improved service life.
In all instances, whether working in the field at slow speeds or transporting machinery (while roading) from field to field at higher speeds, managing proper tire inflation pressures for every work application will ensure that the tires can deliver the optimal performance and long service life by reducing ground compaction, as tire load is based on the actual load per axle or per tire as needed; greater crop yields, as the compaction impact on the soil is minimized by the improved tire footprint; improved fuel efficiency, as the tire is optimized for each work application or towed implement; and greater productivity in the field, as the tire’s footprint and traction provide increased efficiency.
DAVID GRADEN, operational market manager, agriculture, Michelin North America Inc.: While working around tires of all brands, I have personally witnessed an average of about a 14-year rubber life for higher-end tires and as little as eight to 10 years for low-cost tires.
The next question is: how do we care for these tires, so they have a better chance to reach this rubber lifespan? Well, rubber is negatively affected by heat, excessive or continued work under torque, storage practices, etc. If you want to take steps to prolong the life of your tires and get all the life the rubber compounds have to offer, I recommend the following:
- Keep a close eye on air pressures. Try not to let the air pressure fall too low over the winter months;
- If possible, take the weight off your customer's tires by lifting the machine slightly during prolonged periods of storage. This will help to prevent stress at the top of the tire casing and cause flat-spotting;
- When the machine is not in use, customers should store in a cool dry place. Heat is the enemy of rubber and will cause it to fatigue much faster;
- Make sure tires remain clean and free from any petroleum based products. I have seen many tires where oil has puddled under or on top of tires for a long period of time. This causes rubber to become brittle and crack, and;
- During operational months, pay close attention to tire pressure levels. Make sure to have them set at the proper recommended pressure for the load, speed and application. This will prevent unnecessary damage and wear on the lugs and casing of a tire.
I firmly believe you get what you pay for when it comes to tires. Much like your pickup truck or family vehicle, if you take care of them, they will last for a very long time.
James Crouch, national segment manager — agriculture and forestry, Yokohama Off-Highway Tires America Inc.: There is a huge range of variables influencing the lifespan of a farm tire, from the construction and quality of the tire to how it’s used; local soils and conditions; and even how a particular operator drives and turns. But farmers can pull a few levers that can help them get the most life out of their tires.
The first way to maximize tire life is to buy high-quality tires. Radials tend to last longer than bias-ply tires. Pay attention to the materials used in their construction. For instance, all-steel construction is best for durability and heat dissipation, while casings made out of polyester plies will hold their shape and wear better than nylon. Stubble guard compounds minimize punctures and stubble damage. And special design features ranging from reinforced sidewalls to bead guards can boost tire life, too.
Tread pattern has a huge influence on tire life and not always the way people think. For instance, deeper lugs are not always better when it comes to choosing among R-1, R-1W and R-2 tires because tire life is not just a matter of how much rubber you have.
If you’re operating primarily in mud, the deeper lugs of the R-1W or R-2 can be a great investment. But if you’re operating primarily in dry or hard soils or (are) doing a lot of roading, deep lugs will scour off more quickly or flex and crack, actually reducing your tire’s life. In those cases, you’d be better off with a shallower R-1 tread.
Or you could get away from the standard curved R-1 lug altogether. For tractors doing a lot of roading, a denser, hybrid block tread can reduce abrasion wear and dramatically increase tire life. And you’ll have a better ride, too, which can actually increase the life of your tractor.
The most important factor in extending the life of most farm tires is minimizing the buildup of heat. As one of our engineers used to say, 'A tire is born in heat, and it dies in heat.' Don’t overload your tires. Don’t operate at speeds higher than they are built to handle. And the single best thing you can do for your tires is to operate them at the correct inflation pressure, which minimizes the chance of overheating.
CHRIS NEIDERT: ag marketing, training and development manager for Trelleborg & Mitas Tires — North America, Yokohama TWS: Unfortunately, trying to predict the average life span of an ag tire is like trying to pick the best automobile. There are a lot of variables and it depends on the application, environment and others.
But there are steps a producer can take to prolong tire life.
Adjust air pressure more often. There is no average pressure at which you can do everything. Type of ground, speed and the type of load all contribute to making an air pressure decision.
Overinflation. Many farmers tend to increase the inflation pressure in their tires as a precaution, to avoid having to check tire pressure based on load in order to save time.
Overinflation also can lead to premature wear in certain conditions. Practically speaking, an overinflated tire is more rigid, which is more suitable for the road. However, in the field, it will have a reduced contact patch with the ground. This will reduce its traction capability, increase slippage, and increase ground pressure leading to soil compaction.
On the road, an overinflated tire will bulge in the middle, reducing contact with the ground in the center of the tread, which is likely to lead to faster, more marked wear on the central part of the tire.
Underinflation. There are different drawbacks to driving with underinflated tires. (We do not recommend this under any circumstances. It leads to excessive wear.)
When driving, an under-inflated tire tends to flatten out into a characteristic form. Excessive casing deflection occurs at the level of the sidewalls and the tire cannot regain its original shape. This leads to a rise in internal temperature (and) the structure of the tire deteriorates progressively and irreversibly, which may lead to a sudden puncture or break in the casing. Although wear does not appear immediately, it may become visible later, even after the inflation pressure has been adjusted.
Studies have shown that a tire’s lifespan will be reduced by 25% if you drive frequently on the road with underinflated tires, especially if this type of surface is highly abrasive. The tire effectively overheats, making the rubber more supple and therefore more vulnerable to wear. Ideally, you should adjust inflation pressure based on the load, the application and the type of ground.
