TORONTO, Ont. –Tires, themselves, don’t consume fuel. However, they can have a significant impact on the fuel consumption of a tractor-trailer combination. There are several characteristics of tire design that will impact the fuel consumption of your vehicle.

They include: tread depth; tread design; compound; and casing architecture, Francois Beauchamp, special projects coordinator with Michelin explained during a demonstration last summer. Reducing rolling resistance by 3% can reduce a fleet’s fuel consumption by 1%, he said.

That’s because rolling resistance accounts for about 35% of the fuel consumed by a tractor-trailer as it travels down the highway.

John Overing, heavy trucks segment manager, Michelin North America (Canada), said during SmartWay’s Same Roads, New Challenges conference that there are six key contributors to poor fuel mileage that can be attributed to tires:

• Low air pressure: Causes casing fatigue and decreases fuel mileage;

• High air pressure: Increases the likelihood of tire failure and reduces tire life expectancy due to more wear along the center;

• Missing valve caps: Leaving valve caps off the hard-to-reach inside tires may be tempting, but “you need to have valve caps” Overing insisted;

• Duals with mismatched pressures: Causes irregular wear;

• Duals with mismatched wear levels: Even a 3/32 difference in tire height results in one tire wanting to rotate more than the other, Overing explained. A new tire paired with a tire that’s 50% worn will cause irregular wear and decrease tread life;

• Misalignment: Trucks that are not properly aligned will cause tires to suffer toe-in, toe-out and other wear issues, Overing said.

Overing said that while many fleets track their tire purchases, they often store their records in a greasy binder in the shop and rarely take the time to analyze the data.

A $500 tire, for instance, can provide a lower cost of ownership than a

$400 tire, but fleet managers need to study the life-cycle performance of each tire and discuss options with suppliers.

Tires can be a crucial piece of a fuel management program.

Overing urged fleets to study their tire data, discuss options with suppliers and to dedicate a percentage of the fleet to testing new technologies.

Bridgestone Bandag Tire Solutions (BBTS) has also been helping customers understand the effect tires can have on fuel economy, most recently through publication of a guide entitled Tires and Truck Fuel Economy – a New Perspective, available on the company’s Web site: www.bridgestonetrucktires.com.(Select ‘Real Answers Magazine’ to find the guide).

The guide suggests the role tires play in a fuel conservation strategy is heightened as vehicles become more aerodynamic.

“Once, tire rolling resistance accounted for about 15-20% of total fuel consumption,” the guide reads. “As truck designs became more aerodynamic, it represented 25-35% of fuel used. With continuing improvements in aerodynamics, the importance of tires increases.”

BBTS promotes a multi-pronged approach to maximizing fuel consumption.

However, maintaining the appropriate air pressure is the simplest way to ensure optimal fuel mileage. The company researched the effect air pressure has on fuel mileage and found that a 40-psi swing in pressure can reduce fuel economy by 2%.

“Inflation pressure has a definite effect on fuel economy, and is something you can begin monitoring and maintaining immediately – regardless of the type of tires you use,” the company says.

Goodyear also addressed the impact tires have on fuel consumption in the Fall issue of its magazine Tire Logic.

In addition to maintaining the correct tire pressure, the company suggests controlling speed, using fuel-efficient retreads and maintaining a tire rotation schedule. This will reduce irregular wear and can also improve fuel mileage.