Few farmers and just a handful of machines will ever experience the kind of stress and strain that farmers in the Palouse encounter every year: the remarkable challenge of harvesting on 40-, 50- or even 60-percent slopes. Farming some of America’s steepest fields is a task that requires immense skill and finesse from the operators of combines and tractors, and one that puts almost impossible strain on equipment as loads build up and shift from one side to the other, and back to front.

Kurt Druffel’s family has farmed a steep piece of the Palouse outside of Pullman, Washington, for five generations. His grandfather remembered pulling combines across the steep slopes with horse teams, and he followed the emerging technology that led to mechanization and massive, 4-wheel-drive, self-leveling combines. Kurt started helping with harvest as a 13-year-old at the wheel of a 1974 John Deere 6602 combine and developed an eye for tackling the hillsides, a skill that has helped him in the decade he’s been home farming with his father and uncles.

In recent years, Druffel says, a new type of tire with a broad, flat footprint and rectangular blocks arrayed in a curved, lug-like pattern has been a game changer on his combines. The tire, called the Alliance 550 Multiuse radial, brought its unique block tread—which Druffel describes as “industrial-type” and which Alliance is beginning to call “R-5 technical tread”—and its seven-year warranty to sprayers and tractors before finding a new niche on sidehill combines.

Prior to the introduction of the block tread design on sidehill combines, operating on steep slopes was more art than science.

“You really had to think about how you were going to approach a hill,” Druffel says. “How am I going to get to that spot? More angling? Work my way to it, or come down on it? The industrial-type tires sat different on the hill, so we didn’t have that effect. Maybe it’s because they sit so flat and you’re on a lug that won’t slide sideways.” 

More Spin

Old tire designs, including the curved bars of tractor-style R-1 tires or the diamond-shaped lugs on R-3 tires, were having trouble keeping up with the demands of heavier, more powerful equipment. Druffel notes that as combine drivetrains became increasingly powerful, combine operators had to learn to factor in more tire spin, especially in lighter soils. 

“The transmissions have way more torque—it seems like we used to spin our wheels a lot because we had so much torque,” he says. “R-1s spin and dig a hole like they’ve got paddles on them, but the 550s kind of sit on top and get traction without digging up the field.”

In Culdesac, Idaho, Jared Schwartz says the lack of spin makes running on 550s much more efficient.

“With the old tires, you’d try to pull up the hill and either spin out or have to back down and go back up,” he says. “With these new tires, you can make the full turn without backing up. You can turn a corner and not miss a beat.

“It’s kind of a safety deal for us,” Schwartz adds. “I just feel a whole lot more comfortable putting a hired man in a combine that’s not sliding around.”

Schwartz points out that with fields spread out over 40 miles, his combines also spend a lot of time on the road. He immediately noticed the improvement on the road when his family switched to the flat contact patch and even surface of the block-tread radial.

“It’s nice in the cab—not rough,” he says. “They road nice, and they wear good.” 

Market Takeover

Farmers in the steep loess hills started experimenting with the Alliance 550 on sprayers, says Conrad Arnzen, Director of Sales and Marketing for Hillco Technologies in Nezperce, Idaho.

“Palouse farmers first got the tire on some sprayers and they seemed to work well. Then Rahco put them on combines. Our customers started asking about them, and we started in 2015 with six sets of combines. The next year, there were more. By ’17, there was not another tire that was sold other than the 550s. For something to take over the market so fast, that really speaks to how much the customers liked it,” Arnzen says. Hillco ended up purchasing Rahco, its Spokane-based competitor.

Hillco’s engineers liked the tires, too. At 6 mph and 29 psi of inflation pressure, each Alliance 550 in the 650/65R38 size is rated for 14,440 pounds of load. To engineers fitting leveling systems to today’s massive combines, a high load rating is crucial for practical and legal reasons.

“On a level-land combine, if you’re going 0 to 6 miles per hour, you can take 150 percent of the load capacity of a tire for cyclical field operations, but on any slope over 20 percent, you cannot take any additional load rating,” Arnzen explains. “And the loads on these combines are huge. Some of these combines have 410-bushel tanks. At 60 pounds a bushel, that’s 24,000 pounds in the tank, plus another 10,000 pounds from the header. We have to model the center of gravity shifting side-to-side and front-to-back on the steer tires and drive tires, and figure out the load in the worst-case scenario.”

Adapting to the Application

Adapting a specialized new tire to a specialized combine is about more than just finding a tire with enough rated load capacity, notes Arnzen. Hillco engineers have been working closely with Alliance Tire Americas, Inc. (ATA) to smooth out some unique challenges, including the fact that the improved grip provided by the Alliance 550 has shifted a lot of strain to the combines’ rims that used to be released as tire spin. Alliance 550s are being used successfully on tractors and sprayers around the country, but the extreme demands of sidehill combines have required some extra engineering.

“There’s a combination of factors in play here, including the fact that the tire isn’t slipping to bleed off extra horsepower, and the fact that the sidewalls of the 550 are stiffer than the R-1 and diamond-tread tires that people are used to,” explains Nick Phillippi, ATA’s Product Manager—Agricultural Tires. “The result is that all the horsepower of the combine and all the force it takes to move the weight of that load are focused on the rim. Every piece of the system needs to be up to par.”

Phillippi also notes that Alliance has developed a special stubble guard compound for the 550 radial in response to Hillco customer feedback.

“The 550 has been extremely successful in the Midwest, where farmers and custom applicators have been driving over corn, soybean and wheat stubble,” he says. “But we found out the hard way how tough garbanzo bean stubble in the Palouse can be on tires. We’ve developed a formulation for a new generation of 550s, which will be available next year, based on the puncture-and-chunking-resistant compounds in our mining and logging tires.”

Still Loyal

Despite the rim challenges, some Hillco customers don’t want to be caught without their 550s.

“I bought a year-old combine and traded one in that has 2.5 harvests on it,” says David Carlton of Dayton, Washington, a wheat farmer and custom harvester who says most of his 550s have lasted a surprising four harvests. “I’m giving them their tractor tires back and putting my old 550 tires on the newer combine. We run five combines, and they all have these tires. They’re less trouble than anything else. I’ll take my chances with the wheels because I like these 550 tires so much.” 

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