Lower tractor tire pressure can help reduce soil compaction by producing a bigger “footprint” in the field.

Phil Duesing, who grows corn, soybeans, wheat, milo and alfalfa near Garden City, KS, believes by-the-book tire inflation is important for any field operation. He runs three John Deere tractors, each with dual rear tires and front-wheel-drive assist. They each have at least 200-250 hp to handle big jobs. And they're all equipped with radial rear tires to help increase the efficiency of field operations.

“I like radial tires better than biased tires,” says Duesing. “Radials can pull more and they ride better.”

He sets tire pressure at the lowest possible recommended inflation for specific jobs, then adjusts the pressure for separate tasks. “I like that I can run at a lower tire pressure for a job that requires less pulling,” he adds.

That practice should help alleviate any harsh compaction, says Vern Hofman, agricultural engineer at North Dakota State University.

“Current recommendations call for tire pressures as low as 6 psi as long as the load-carrying capacity of the tire isn't exceeded,” says Hofman. “Previously recommended tire pressure rates were 15-20 psi. Lower pressures are possible because radial tire construction provides greater strength and flexibility than bias-ply tires.”

Pressure in the tire is closely related to the force on the soil surface. “If a producer has a soil compaction problem, lower tire pressure can reduce the effect,” says Hofman.

John Friedrich, agricultural tire sales manager for Goodyear in Springfield, MO, says many growers are going with larger tractor tires. “Tires and rims are getting larger and the widths are getting wider,” he says. “The larger dimensions provide a bigger footprint at a lower inflation rate. And the bigger footprint creates less compaction.”

The right tire pressure can reduce tire slippage by as much as 20%. Reduced slippage can extend tire life and reduce fuel consumption, says Hofman.

“Reducing the pressure also can prevent ‘tractor hop.’ When a tractor is pulling hard, tires tend to break loose from the soil and then grab again. The improved traction from reduced tire pressure will reduce that effect,” he says.

To adjust tire pressure properly, growers should know how much load each tire is carrying. This information is available from tractor manufacturers or by weighing the tractor.

Hofman also recommends reducing tire fluid to no more than one-fourth to one-third of the tire volume. “Fluid reduces the flexing of tires,” he says. “If fluid amounts are reduced, producers may have to replace the weight lost by adding cast iron weights.”

He advises growers not to be fooled by the bulging appearance of radial tires. “Sometimes people are hesitant to reduce tire pressures because they see so much flexing on the sidewalls,” he says. “They figure that the flexing will ruin their tires.”

Tire damage from sidewall flexing was common in bias-type tires. But radial tires are built to flex like radial tires used on cars and pickups. You can reduce tire pressure in radial tires without causing any problems as long as you don't exceed the load-carrying capacity of the tire.

Tire pressure should be checked regularly, and with an accurate gauge designed for low pressures in the range of 6-10 psi, Hofman says. Growers should also watch for damage to air gauges from corrosive fluid in tires.