AFTER fuel, tires are a fleet's biggest operating expense. So, it can be frustrating for fleet managers who see one truck getting barely 100,000 miles before the steer tires have to be pulled while another covering a similar route regularly runs more than 200,000 miles.
What gives? Why do some trucks achieve double the tread wear of others? Both are expensive questions for those not dialing in all the mileage they think they should be getting.
To get better mileage, it's important to look at tires in three parts: the technology used in the tire, driving habits, and maintenance practices.
Selecting top-quality tires, fortified with the latest technology, is essential to maximizing tire mileage, according to Tim Richards, project manager for linehaul commercial tires at Goodyear. The old adage that “you get what you pay for” definitely holds true with tires.
Major tire manufacturers, such as Goodyear, produce tires with materials, reinforcements, and tread designs to maximize tire performance. In addition, Goodyear's commercial tire group develops tire casings that support multiple retreadings, which helps increase a tire's cradle-to-grave value.
“At Goodyear, we combine extensive research and exhaustive real-world testing to find the right custom mix of technologies that help our customers gain the maximum performance from their tires,” Richards says.
“In commercial tires, it's all about the casing, which is built for multiple retreads. Truck fleet customers ultimately evaluate cost per mile with that tire and wheel position, which is determined by how many miles are delivered by the original tread, as well as the cost and mileage of its first and second retreads.”
According to Richards, lesser-performing tires typically provide fewer miles in the beginning and might not be capable of multiple retreads. “Yes, they cost less, but you end up buying more tires and forgoing multiple retreads that save money in the long run,” he says. “Those in the know, focus on cost per mile, not initial tire cost.”
Driving habits
Another major contributor to long tire life is driving style, which can boost tire mileage and lower cost per mile.
Driving style has a major impact on tread wear, just as it does on overall fuel economy, according to Richards. “An experienced driver following good driving and maintenance practices could achieve up to twice the removal mileage of a less experienced driver.”
Cornering cuts a tire's overall mileage. Smart drivers plan ahead and know their routes to minimize sharp turns. “Most tread wear occurs during cornering maneuvers,” Richards says. “Any high wheel cuts, or sharp turns — particularly high wheel cuts at highway speeds — will contribute to excessive tread wear. Even high wheel cuts in parking lots or highway off ramps accelerate tread wear.
Excessive tread wear is caused by “scrubbing” the tread elements in the tire footprint, Richards says. “Any maneuver that contributes a lot of scrubbing of the rubber across the road is going to be a detriment to long mileage to removal. Experienced drivers make subtle lane changes and maneuvers that are gentler on the tire.”
The route traveled and how the driver reacts to changes in elevation also affect tread wear, according to Richards. While a driver whose routes cover mostly flat terrain will likely achieve better tread life than a driver running over hills, a driver who maintains constant speed on hills will win the mileage race.
“Drivers sometimes don't have much control over the load pulled or the route followed, but they have total control over how fast they take those inclines,” Richards says. “Putting more torque on the tires and making them work harder reduces tire mileage.”
Overall, higher speeds reduce tire longevity. Fuel economy and tire cost per mile are impacted by vehicle speed. Jackrabbit starts and hard braking will increase tread wear.
Tire Maintenance
Good tire maintenance practices work in concert with smart driving practices to achieve longer tread life. Richards says that closely monitoring inflation pressure is critical in extending tire life. Technicians also should check for proper alignment, wheel bearing and wheel condition, and suspension components.
Largely overlooked in extending tire wear is choosing the right tires for the application. Tires with the correct tread depth and composition for driving conditions will last longer. “There's a misconception that a tire with deeper tread grooves achieves more miles to removal,” Richards says. “If you put too much rubber — particularly in linehaul applications — on the road surface, tread elements and blocks will ‘squirm,’ leading to irregular wear and faster tread wear.
“Many fleets have a cost-effective policy to remove steer tires at a tread depth of 6/32nds or 8/32nds (to ensure the casing can be retreaded),” he says.
Richards points out that while some linehaul drivers are able to achieve 200,000 miles on steer tires and double that on drive tires, many operators would be happy to simply improve their tire mileage. “Starting with top-quality tires and a sensible tire management program can deliver tire mileage and fuel economy that result in competitive advantages,” he says.
For more information on tire care, go to www.goodyear.com/truck.