Rolling in the dough

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DON MILLS, Ont. – Tires represent one of the largest costs for truckers, but that also means they offer one of the greatest opportunities for saving costs.

The challenge is to work smarter – not harder – in finding those savings, Vic Wintjes, maintenance manager for Canadian Tire and a past winner of the Volvo Fleet Maintenance Manager of the Year Award, told delegates attending the 37th annual Canadian Fleet Maintenance Seminar.

It’s well known, albeit not as well followed, that working smarter begins with proper tire inflation. More than three quarters of the “alligators” on our highways are a result of improper inflation practices, according to Goodyear Canada’s Gary Blake. The second most important step to maximizing the investment in truck tires is proper selection. That requires buyers to understand the type of operation the truck tire will be running in, the average speeds and axle weights it will be subjected to, as well as any special operational complications.

“No matter how good your preventive maintenance program is, you can’t realize the best performance for your tires if you don’t select the right tires for the application,” says Bridgestone/Firestone’s Brian Rennie.

And finding the right tire is not always as easy as opting for the most common spec’. For example, conventional tire sizes make up about 75 per cent of commercial tire purchases, but low-profile tires have their advantages, according to Rennie. He says low-profile tires offer lower weight and “their most stable footprint can theoretically improve tread life and fuel economy.” However, those advantages must be balanced against the fact low-profile tires are more susceptible to sidewall damage and don’t provide as much traction. “And they may or may not be available when you need them, and that’s a big consideration,” Rennie said.

One item that truckers neglect at their peril is matching tires’ rated speed against the speeds their trucks are actually running. Truck speeds have been creeping upwards since the mid-1990s. There are now 40 U.S. states that have posted truck speeds of 65 mph or higher – 22 more than in 1995. The move to higher speed limits is having a spillover effect north of the border, even if the posted speed limits haven’t been changed.

Rennie said that a random survey of 688 trucks in the U.S. found that 20 per cent were running over the speed limit, 17 per cent were regularly at speeds over 75 mph and some at speeds as high as 100 mph.

Yet high speeds take a terrible toll on tire life.

Almost 80 per cent of fleets surveyed with trucks running at higher speeds reported a drop in tire durability; 60 per cent complained of irregular wear; and 78 per cent reported higher tire costs associated with higher speeds.

Rennie outlines what happens when a truck running with tires spec’d at 65 mph starts regularly doing speeds of 75 mph: As the operating temperatures increase, so does the likelihood of damage such as rib tearing. The footprint also becomes distorted, leading to irregular wear. And while rolling resistance remains the same, the tire’s contribution to fuel savings is cut in half.

The problems associated with higher speeds don’t stop there. There are also weight penalties to consider. Tires rated at 65 mph (105 km-h) and running 10 mph (16 km-h) faster require a 12 per cent decrease in load weight and a five per cent increase in inflation pressure.

Over the last couple of years, tire makers have responded to the higher speed trend with drive and steer tires rated at 75 mph (120 km-h), but many trailer and on/off road tires remain rated at 65 mph (105 km-h).

Working smarter to find savings in your tire program also includes being committed to casing management. Bandag’s Tom Coutu says that means working out standards for the age of your tires, tread depth at which they’re pulled off for retreading, the amount of times you’re willing to have them retreaded, the type of repairs that should be done to them, and figuring out which brands offer the best retreading potential. n

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