Going low

By James Jaillet | December 01, 2010

Bigger’s not always better, especially when it comes to tire sidewall height. When spec’ing a truck for long-haul, you can give it a big boost of efficiency by choosing shorter sidewalls.

For long-haul, on-highway applications, Tim Miller, marketing communications manager for Goodyear Commercial Tires says he doesn’t “see a lot of rationale for why you wouldn’t want to change to a low-profile setup. The handling advantages, fuel-efficiency advantages – all of the pieces of a low-profile tire would seem to be something you would spec on a new vehicle, if not converting over midstream.”

Low-profile tires, like the Bridgestone R287, offer long-haul drivers advantages in weight savings and rolling resistance.

And because low-pro tires have as much load-carrying capacity as standard-profile tires, there is no loss in that regard, says Michelin Product Category Manager Don Baldwin.

Here are the low-pro advantages:

LOWER TRUCK HEIGHT. A low-pro tire’s shorter sidewall means the vehicle’s floor sits a little lower. “As shippers require bigger trailers and more cubic volume,” low-profile tires allow for a taller trailer and therefore more capacity, says Larry Hess, sales manager at Midway Truck Service in Bethel, Pa. A shorter vehicle also equates to better aerodynamics, stability and handling, Miller says. The shorter sidewall also offers “better turning abilities because there’s less flexing,” he adds.

The Michelin XDA Energy is sized as 275/80R22.5. The tire weighs 124 pounds and has compounds engineered for fuel efficiency.

REDUCED WEIGHT. Because low-pro tires are smaller, they reduce the weight of the vehicle. A lighter base weight allows for more carrying capacity or fuel savings. “If you extrapolate that over a year, you’re starting to see the result financially,” says Curtis Decker, commercial product development manager for Continental Tire.

REDUCED ROLLING RESISTANCE. The stiffness of the low-pro sidewall accounts for the improvement in rolling resistance over a tall tire, says Guy Walenga, director of engineering for commercial products at Bridgestone. “Technology could change, but generally speaking, they’re the more fuel-efficient tire right now.”

Miller says long-haul operations are the best application for low-pro tires partly because “that’s where you can take advantage of the fuel economy benefits” related to weight, rolling resistance and aerodynamics.

Goodyear’s G305 LHD Fuel Max is a cool-running tire with dual-compound construction that lowers rolling resistance. The tire is sized at 295/75R22.5 and has a 26⁄32-in. tread depth.

EXTENDED TIRE LIFE. “Low-profile tires tend to have a wider, shorter footprint than a taller tire, which tends to have a longer and narrower footprint,” Walenga says. The wider footprint carries the load more effectively, as the narrower footprint has to work harder to carry the load. Consequently, Walenga says, the low-pro tire’s life cycle can be longer than that of a standard-profile tire.

Baldwin says low-pro tires have the same tread depth and tread volume as standard-profile tires, and, because of the smaller amount of materials, run slightly cooler than taller tires. n

When not to go low-pro

RETROFITTING. Using tires with a shorter sidewall than what the unit was spec’d to run causes the truck’s engine to run differently because the tires turn more revolutions per mile. This, in turn changes the engine’s rpm range.

“You literally change the gearing of the truck,” Bridgestone’s Guy Walenga says. “You change the engine performance. It’s not recommended that you go changing tire sizes.”

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