AKRON—Since Harvey Firestone's campaign in the 1930s to ``Put the Farm on Rubber,'' change traditionally has come slowly to this segment of the tire industry. Not any more.
Tire manufacturers have been compelled to respond to changes in farming practices and advances in farm equipment by developing new types and sizes of tires, which are coming into the marketplace at an unprecedented rate.
Dealers who hope to remain competitive in the agricultural market will have to keep abreast of these changes and make sure they have the knowledge and equipment to provide farmers the level of service they require.
Interviews with representatives of the three major players in the U.S. farm tire market—Goodyear, Bridgestone/Firestone Inc. and Titan Tire Corp.—shed some light on the changes taking place in this market segment and what may lie in store—including, in some cases, a move away from tires altogether.
These three manufacturers collectively account for more than 95 percent of all original equipment farm tire shipments in the U.S. and more than three-quarters of replacement shipments.
Radials, metric sizes
Just as tractors and farm implements were the last vehicle category to adopt rubber tires, they've been the slowest to accept radials, despite some pretty clear advantages.
Compared with a bias-ply tire, a radial rear tractor tire has a larger footprint for greater traction with less slippage. As a result, farmers spend less time per acre, thereby improving fuel economy. Radials also offer better flotation for less soil compaction.
``These advantages are very measurable,'' said Larry Hurst, Goodyear's farm and Terra-tire manager. And the data indicate that, overall, radials represent about a 10-percent improvement over bias tires, said Len Wagner, manager, field engineering for BFS' Firestone Agricultural Tire Co. division.
In 1996, 23 years after B.F. Goodrich introduced the first rear tractor radial in North America, radials still accounted for only about 14 percent of U.S. replacement shipments in this category and 26 percent of the OE shipments.
Cost has been a factor—radials are more expensive—as have the facts that farm equipment and tires have relatively long service lives, so turnover is slow, and that there has been limited radial production capacity within the U.S. tire industry.
But that is changing, as the tire companies boost radial capacity, driven in part by OE demand. ``Original equipment manufacturers want 100 percent radial,'' said Jim Bamer, Goodyear product manager for farm and Terra-tires, who expects the radialization rate ``is going to explode starting this year. . . . The (Rubber Manufacturers Association) is forecasting 15 percent growth in radial farm tire shipments this year.''
But the replacement market is apt to radialize much more slowly. ``The average tractor is 19 years old,'' Mr. Hurst pointed out, `` and may well stay with bias tires.''
There's been little change in the radial share of the replacement farm tire market since 1992, said Skip Sagar, director of replacement tire sales for Titan Tire Corp., and it probably won't change dramatically for several years.
In fact, Mr. Sagar added, ``bias-ply can be a better choice from a value standpoint—especially with tractors that do minimum tillage.''
``Bias tires will be a big factor in the farm tire market for a long time,'' agreed Tom Ford, Goodyear's marketing director for off-the-road and farm tires. And the manufacturers said they plan to continue to introduce new bias sizes.
As for the trend toward metric sizing, all three tire makers agreed it is a result of the more global nature of the business, especially for the farm equipment manufacturers. Expect virtually all new farm tire sizes to be metric, they added.
By way of background, Rich Coonce, Titan's director of tire development, indicated that metric sizing originated in Europe. Its original advantage was to put a lower profile tire on a narrower wheel, thereby getting a larger footprint and more flotation without changing the rim diameter.
Pressure & power hop
Radials generally are designed to operate at lower inflation pressures than their bias-ply counterparts. It is this lower pressure that gives them the characteristic sidewall deflection that increases their footprint, as well as their flotation.
According to Mr. Hurst, in their initial encounters with radials, many farmers tended to do what they'd always done with bias tires: overinflate them.
As Mr. Wagner put it, ``If you overinflate radials, you might as well use bias tires—you're wasting your money.'' Overinflation stiffens the tire's sidewalls, he said, preventing them from flexing and delivering the radial's advantages.
On new four-wheel-drive and mechanical-front-wheel drive tractors, the combination of overinflated tires and certain soil conditions gave rise to a new phenome-non: power hop.
This ``intense, vertical bouncing'' of the tractor, as Titan describes it, can occur when pulling a drawbar-towed implement—generally in dry conditions in which there is some loose soil over a hard pan.
The solution: setting the total weight and weight distribution per the equipment manufacturer's recommendation and operating the tires at the lowest inflation pressure needed to handle the load.
Both tire and equipment makers offer charts indicating the correct inflation pressure at a given load. But in all cases it is imperative to have accurate information regarding the weight on an axle in any given set-up—either from the equipment manufacturer or by actually weighing it.
Often the correct inflation pressure for a rear tractor radial will be below 10 psi, Mr. Coonce said, and for large tires in dual configurations, can be as low as 6 psi.
The goal in seeking to operate at the minimum acceptable inflation pressure, Mr. Wagner said, is to optimize the size of the tire's footprint/contact patch, where larger means more efficient.
One method of weight balancing is to inject a liquid ballast—typically a mixture of water and calcium chloride—into the casing.
Although used traditionally with bias-ply tires, all three tire makers said they now discourage the practice, agreeing that it definitely should not be used at all with radials, as it stiffens the sidewall, reduces the air cavity inside the tire and prevents the tire from compressing, negating the radial's advantages.
Instead, when extra weight is needed, the makers recommended hanging weights: either wheel weights or ``suitcase'' weights that attach to the tractor's frame.
However, if liquid ballast is to be used, it should be spread across all the tires on an axle, Mr. Hurst said, and not confined to the innermost wheel positions.
In recent years, a combination of plant genetics, changing weather conditions and new farming practices has increased the amount of damage tires suffer from corn stubble.
New corn hybrids have been developed to be hardier and stand more upright, while the lack of traditional snow cover in many parts of the country hardens, rather than degrades the stalks, many of which have been cut at sharp angles by harvesting equipment.
Add to that the trend toward limited tilling or no-till operation, encouraged by government soil conservation regulations, and what greets farmers and their equipment in the spring are fields of little pungi sticks ready to penetrate tire treads and sidewalls.
Goodyear's response, according to Mr. Hurst, has been to re-engineer the tires most likely to be exposed to these hazards, improving tread and sidewall toughness.
New radials are more susceptible to stubble damage, said Firestone's Mr. Wagner, as the new rubber is softer and hardens with age—especially in the first year.
With tubeless radials, it's possible to install a very viscous, fiber-filled liquid sealant, Mr. Wagner added, making the tires self-sealing if punctured in the tread area.
As the federal government reduces its influence over how much of which crops are planted, farmers are increasingly looking for ways to maximize their crop yield per acre.
One method that is gaining popularity for row crops is to reduce the amount of space between the rows, thereby increasing the number of rows per acre.
To work these narrower rows, farmers require narrower tires, and to maintain their performance characteristics with a narrower section width, these narrow tires require a deeper body cavity and larger diameter.
The challenge, from a tire design standpoint, Mr. Hurst said, is to optimize the combination of width and diameter so that the tire can successfully transmit the torque of the tractor and carry the desired load at a reasonable inflation pressure.
To accomplish this, narrow, large-diameter tires must almost always be run in dual configurations (four per axle), he said, while triples (six tires per axle) will become increasingly common, to keep individual tire inflation pressures down and maximize flotation.
All three tire makers see this as an area of strong growth within the farm tire market and are preparing to introduce new sizes this year.
Mr. Wagner predicted that farm tire diameters will continue to increase over the next two years, from a current high of about 42 inches at present to as large as 54 inches by 1998.
Other trends, tracks
In addition to a greater market share for radials, universal metric sizing and the growth of narrow, large-diameter tires, other trends the interviewees said dealers should be aware of include:
Highway-rated implement tires. These tires, built on a light truck carcass but with an agricultural (I-1) tread, are becoming increasingly popular, said Goodyear's Mr. Bamer, because they can carry more weight, are more practical and may reduce users' liability.
R-1W rear tractor tires. In the U.S., the most popular drive-wheel tire for tractors has been the R-1 (regular tread) design. But according to Firestone's Mr. Wagner, many farmers are moving to the R-1W (for wet conditions) design, which has tread 20 to 50 percent deeper than the R-1, but not as deep as the R-2, which is designed for use in rice and cane fields.
Whether or not they're concerned about soggy fields, many farmers equate the deeper tread with longer wear, Mr. Wagner said.
Larger tractors with higher horsepower. As tractors (and combines) get larger and more powerful, they will increasingly be fitted with large flotation-type tires and tires in dual or triple configurations to reduce soil compaction, said Messrs. Bamer and Wagner.
Such large tires will challenge dealers' service capabilities. The difficulties involved in transporting these large pieces of equipment will place more emphasis on providing on-the-farm service, said Goodyear's Mr. Hurst.
To win farmers' business, ``you'll need to be seriously equipped,'' Mr. Hurst added, meaning larger service trucks with hydraulic booms, jacks, bead-breakers and compressors.
Dealers who meet the challenge may reap the rewards. ``An independent tire dealer using advanced products and services probably can charge a little more,'' said Titan's Mr. Sagar, ``because he can demonstrate to farmers it's worth more'' in terms of shorter down-time for critical equipment.
Rubber tracks. Tracks provide an alternative to flotation tires on large, costly pieces of equipment, said Mr. Ford, adding that Goodyear is heavily involved in this emerging market segment. Tracks offer much less ground compression than a comparable radial tire set-up, he said, with about half the slippage, thereby increasing vehicle efficiency in the field.
In the long term, Mr. Ford said, tracks may eventually account for 20 percent of the market, and are most likely to be used by large-scale operators on large, expensive vehicles.