In Focus: Tires

After fuel, tires are a fleet’s largest nonpersonnel expense. Unlike fuel, tires come in many different varieties and prices, which allows fleets the freedom to spec the brands and products best suited to their business needs.

So how do fleets keep tire costs contained? Experts say that just like every other area of the truck, it’s important to evaluate tires in regard to total cost per mile – and not just the tire’s initial cost. “A tire’s cost per mile is not known until the last retread is worn out,” says Dave Taylor, vice president of technical services at Toyo Tires.

Six experts offered their opinions on whether or not a more expensive tire always equates to a longer life – and lower overall cost per mile. The group was divided into two camps of equal size.

“I agree that better, more expensive tires reduce overall cost per mile, but I would have trouble providing data to prove my point,” says Tim Miller, Goodyear’s marketing communications manager. “I think that doing business with a manufacturer of premium tires assures high-quality products, a comprehensive warranty, consistent nationwide services, and new tire and retread availability.”

Doug Jones, Michelin North America’s customer engineering support manager, agrees in principle that a more expensive tire yields lower cost per mile, “but it is not absolute.” Jones gave the example of a $200 tire delivering 100,000 miles, and a $250 tire delivering 200,000 miles; the first tire costs $.002 per mile, while the more expensive tire costs $.00125.

“Generally speaking, the greater the initial cost, the better the cost per mile due to longer running miles,” says Jones, who also agrees with Taylor’s point about retreads and provides a comprehensive formula for cost per mile: (new tire costs + repair or retread costs) + disposal costs – casing values / (total original miles + total retread miles).

“Generally, yes, a more expensive tire yields a lower cost per mile,” says Guy Walenga, Bridgestone’s director of engineering for commercial products and technologies. “You tend to get better wear per 32nd, more resistance to irregular wear, the tire tends to be more durable, and it stays in place on the wheel, so you get more miles, and then it’s more retreadable. Low-price tires generally don’t last and don’t produce retreadable casings. Many fleets can quantify the fact that you do get what you pay for.”

But Toyo’s Taylor looks at it another way. “We think that cost per mile cannot be determined by the tire’s invoice price alone,” Taylor says. “Considering the steady technological advancements that are being offered by tire manufacturers including Toyo, a prudent fleet will continuously track tire performance to determine for themselves the true CPM of their tires.”

Phil Boarts, director of marketing at Cooper Tire, says there may not be any direct relationship between price and performance at either end of the price spectrum. “Some of the highest-priced products may not perform much better than some moderately-priced products,” Boarts says. “The lowest-priced products may not deliver performance, either, because the technology is just not adequate.”

Walt Weller, vice president of strategic business and OEM at CMA International – makers of Double Coin tires – says other fleets have abundant data to prove that “more expensive does not necessarily mean better” for most products. “Some new products made in other countries far exceed expectations because they are made on state-of-the-art equipment with the latest manufacturing techniques,” Weller says.

As a result of making technical agreements with American tire companies years ago, and its own research and development capability today, Double Coin tires get the same tread life as more expensive ones, “in some cases a little better,” Weller says. “We are a Tier 1 or Tier 2 tiremaker disguised as a Tier 3 tiremaker.”

Fuel for debate
Aside from tread life, a big issue is fuel economy. Using low rolling-resistance tires to improve fuel economy can be a slippery slope, experts say. “Many other factors affect fuel use, including the habits of the driver,” Goodyear’s Miller says. “We also know that if you take the time to run an SAE fuel economy test and find an improvement with a certain selection of tires, the real-life improvement will typically be half of what was demonstrated in the test.”

“Fuel economy is not the only thing,” says Bridgestone’s Walenga. “You can strive for low rolling resistance or look at overall lifecycle costs. You can’t save enough in fuel alone.”

Cooper’s Boarts assumes that rolling resistance is more important with higher-speed fleets that travel in a straight line for long periods. “Shorter-haul or slower fleets turn and start and stop more, which I think would tend to mask any benefits of lower rolling resistance,” Boarts says.

Toyo’s Taylor says smart fleets will spec the optimum engine rpm range, axle ratio and tire size (diameter) to achieve the best fuel economy that suits their operating plan and optimum cruising speed. “The short answer is that the most significant effect on fuel economy is vehicle speed,” Taylor says.

Picking the proper tread depth for different wheel positions also is important. “There seems to be a race as to who can build the deepest-tread drive axle tire – 30/32 or even 1 inch deep,” Taylor says. “Although these ultra-deep drive axle tires can produce more miles – especially on single-screw, high-torque drive axles – they may not be the optimum fuel-efficient design for twin-screw applications, although some tire manufacturers claim low rolling resistance for these deep tread designs. As a rule of thumb, shallower tread-depth drive tires will be more fuel-efficient, and it is true that any tire will be more fuel-efficient as it wears down its tread.”

Bridgestone’s Walenga says a deeper tire will be worse in terms of initial fuel economy, but as it wears, it will improve – but not as much when not designed for fuel economy. “Maintenance is a big issue for a 30/32 tire,” Walenga says. “Proper concentric mounting is important, and duals should be kept at the same air pressure. Smaller tires don’t roll as smoothly and scuff more easily, leading to irregular wear.”

None of our experts had data, but all agreed that tire inflation and monitoring systems probably pay for themselves because of the positive effect proper inflation has on tire life and fuel economy, as well as the savings in downtime.

Regarding drivers’ effect on tire life, the consensus was clearly that drivers should be taught that hard braking, hard cornering and even abrupt acceleration can reduce tire life.

Adjusting toe and aligning drive and trailer axles also are important for tire life and fuel economy, and the process should be proactive because by the time you see alignment wear, it’s almost too late. CMA International’s Weller suggests an alignment check “at least every six months if you don’t see anything wrong.”