Spec the Perfect Tires

John Baxter | February 01, 2011
Cross grooves form lugs and a greater tread depth than a steer tire in order to enhance forward traction on this Goodyear drive tire.

Keep in mind different shoulder designs’ effect on wear rates and traction. “Solid shoulder drive tires can have center lugs for good traction,” Walenga says. “The solid shoulders control irregular wear, while open shoulder designs have independent lugs that give better traction in snow, but move around.” This means more susceptibility to irregular wear, and a greater need for perfect air pressure maintenance, he adds. “But most drivers won’t know the difference, and in snowy mountain passes you’re required to chain up anyway. And it’s much easier to put chains onto closed-shoulder tires. Closed-shoulder drives with lugs in the middle give the best of both worlds.”

On snow tires, Baldwin notes the practice of switching tires seasonally, using tires built for snow in the winter and “putting the regular tires on as early as March in some areas.” But, he says, “We have also developed a snow tire you can run year-round. It will handle most snow conditions, and there is much less need to change back and forth. We have a version of the X One wide single called the XDN2, an open-shoulder tire that has been used successfully in Yellowstone Park with eight feet of snow pack.”

Walenga also knows fleets that switch tires seasonally. They move from open-shoulder drives to a more aggressive, closed-shoulder version in the fall. But, he points out, fuel-efficient tires normally have less tread. “You’ll get better fuel economy, but you’ll give up some life.” n


2010 tech’s extra weight can affect axle, tires

The addition of emissions controls may increase the weight of 2010 model and newer tractors by 500 to 800 pounds.

The added weight comes from the diesel particulate filter, selective catalytic reduction device and diesel exhaust fluid tank and pump, plus a larger cooling system. Weight increases so much that, depending on where components are located, the standard 12,000-lb. front axle is often being replaced with one that has a much higher rating, so that different tires are needed.

The load range G tires normally used would allow an axle weight up to 12,350 lbs., as each is rated for 6,175 lbs. at 110 psi. If running a heavier than normal axle, load range H 16-ply tires would be the choice. They’d allow an axle up to 14,000 lbs. Michelin’s Don Baldwin says his company makes a 295/60R22.5-size tire that sustains a front axle weight of 14,600 lbs.


Tread by position

STEER

• Four or five straight solid ribs that will support lateral forces created during normal handling and cornering and by wind drag.

• Tread pattern design and a tread compound that’s resistant to irregular wear in long/medium-haul service or that’s cut-and-chip resistant for on/off-road service.

• Tread depth balanced to deliver long tread life while delivering low rolling resistance for higher fuel efficiency.

DRIVE

• Tread pattern design with closed shoulder (shoulder ribs) for long-haul service to prevent irregular wear and provide good handling.

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