Spec the Perfect Tires

John Baxter | February 01, 2011

With products becoming increasingly specialized, learn to pick the designs that fit your business and save money.

Just as a truck with improperly geared rears will incur extra costs for its owner, so, too, will a truck with the wrong tires. There are many more factors than size that account for having the right tire for a specific truck in a specific application.

A tire that runs even 20 percent of the time off road needs a different tread design and compounding or it will suffer an early demise. If running off road most of the time, a model with more rugged specs is needed.

The variables to consider when spec’ing tires are many. Among them are the size and number of plies and related weight rating, the tread design, tread depth, tread compound and wheel position (steer, drive, trailer).

Smart spec’ing can save costs in two ways: lowering fuel cost per mile and lowering tire cost per mile. Attributes that lower one cost can have the opposite effect on the other cost, so spec’ing needs to be done carefully.

That’s easier said than done in an era when specialization abounds. “There are more choices and more opportunities to optimize performance,” says Guy Walenga, director of commercial products engineering and technology at Bridgestone/Firestone. “In such an environment, it’s all-important for owner-operators to rely on the expertise of a good dealer salesperson to help them find just the right tire.”

The M726 is a popular solid shoulder Bridgestone drive tire.

The industry is moving more toward “developing products that are ultra-specialized to precisely meet specific service options,” says Giti Tire Technical Service Director William Estupinan. “There are versatile tires, however, that can offer a fair balance between two operating conditions if the conditions are close to each other on the spectrum, medium haul and regional, for instance.”

Goodyear marketing spokesman Tim Miller says his company offers mixed service tires intended for high-scrub applications, like trash pickup, that also are rated for some off-road use with an 80/20 on/off-highway mix. Tires are available for the reverse mix, as well. “It is important to understand which situation the tires are designed to address,” Miller adds.

Fuel economy

Cutting costs through fuel use usually holds more potential than through extending tire life. “Buying a low rolling resistance tire that wears a little faster to save fuel will save money,” says Don Baldwin, Michelin Americas Truck Tires product marketing manager. “The ratio between the value of the fuel saved and the extra tire cost is 10:1.”

This deep lug tire from Continental is for highway use but designed for extra snow traction. The complex lug design is intended to optimize performance.

He adds that some regional fleets are “going to long-haul steers for low rolling resistance rather than tires with more scrub resistance” designed for regional operation. The tires may wear faster, but they save enough fuel costs to more than cover the extra tire replacement costs, he says.

“Low rolling resistance, fuel-efficient tires only need to be considered for over-the-road operations that do very little starting and stopping,” Miller says. “An off-highway truck or a pickup and delivery type truck would gain little fuel usage advantage from a fuel-efficient tire. On the borderline is a truck that runs in regional-type service.”

He says the tread compounds that resist the abuse of on/off-road operation or the hard braking and abrupt and frequent cornering typical of pickup and delivery service tend not to be as fuel-efficient as tires designed primarily for efficiency.

Baldwin says, “The qualities that make for a good city tire tend to make rolling resistance higher. These include a deeper tread and compounding that enable the tire to handle scrubbing and impacts with curbs.” But he thinks you should worry about rolling resistance even in the city because “it’s not like aerodynamics. It varies with the load and distance you travel, so the drag effect is the same at any speed – a straight relationship – while aerodynamic drag varies much more with the speed.”

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