Using a laser, technician Ryan Bales with the Titan Grizz Squad measures the roundness of a wheel-tire assembly before repositioning it.
If you’ve ever tried riding a bicycle with a flat tire, you probably remember it was an unpleasant experience. Now imagine the same scenario, known as road lope, with a high-horsepower tractor traveling 25 mph down the highway.
"I decided I’d had enough because I couldn’t drive it over 15 mph," says Steve Krause, a farmer near Adams, Neb., describing the road lope he experienced while driving his Case IH Magnum 225. He generally only travels five miles or less between farms, but the discomfort forced him to act.
Tractors that normally travel at highway speeds up to 27 mph might have to be slowed to 18 mph or less because of too much bounce, decreasing productivity, explains Scott Sloan, agricultural product manager, Titan and Goodyear Farm Tires.
Thankfully for drivers, tire experts say, tuneups paired with new technology can make travel smooth and safe.
Technology to go. To ease road lope, technicians can inspect the wheel-tire assembly for misalignment with a full runout, Sloan says. A laser focuses on the center line of the tire, and the technician gives the tire a spin. He then measures high and low spots on the tire and wheel, as bouncing can occur when high points align. In general, a gap of 0.16" or less between the top of the wheel rim and the bottom of the tire is permissible, Sloan explains. If the gap is larger, technicians can adjust the wheel-tire assembly.
Krause called on the Titan Grizz Squad in early January to fix the road lope on his tires. The technicians diagnose and correct road lope on-site on any brand of tire for free. Now, Krause is able to travel up to 26 mph.
Additionally, Titan/Goodyear has introduced low-sidewall (LSW) technology for several of its tire lines. A conventional 81"-diameter tractor tire accompanies a 38"-diameter wheel and has 21" of sidewall, but a comparable LSW tire has a 46"-diameter wheel and a 17" sidewall.
That results in less bouncing, Sloan says. While subtle, the modification points to opportunities for ag tires, largely unchanged since the 1940s.
Easy fixes. Other causes of road lope are off-center wheels, poor weight distribution and mismatched tires, says James Crouch, farm segment marketing manager, Michelin North America.
Check front-to-rear weight distribution against the manufacturer’s guidelines, then add or remove cast-iron weights at the front of the machine and in the wheels as needed. Also, verify that tires are pressurized to the correct level, Crouch says.
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Power Hop Versus Road Lope
Road lope can sometimes be confused with its close relative, power hop. It’s understandable: Both result from similar problems, such as improper air pressure and weight distribution.
But power hop occurs in the field—not on the road—and is a function of traction, explains Scott Sloan, agricultural product manager, Titan and Goodyear Farm Tires. Tires must maintain a certain percentage of slip, generally between 5% and 10%, so that implements can crawl across the field without breaking. Increase that slip beyond 10%, though, and the bouncing can require an operator to slow down or quit using the implement to prevent damage.
Click the play button below to watch a video explaining how to diagnose road lope and correct it in the field using a tire runout:
- Mid-February 2014