DON MILLS, Ont. - A medium-sized fleet of 100 tractors and 300 trailers has more than $600,000 invested in tires so even a 10 per cent increase in tread life would result in phenomenal savings. Yet, a...
DON MILLS, Ont. – A medium-sized fleet of 100 tractors and 300 trailers has more than $600,000 invested in tires so even a 10 per cent increase in tread life would result in phenomenal savings. Yet, as a collection of tire industry experts at the recent Canadian Fleet Maintenance Seminar pointed out, a prevalence of improper tire maintenance practices and ignorance of certain tire principles is keeping many motor carriers from realizing those savings.
Retreading is one of the surest ways to prolong the life cycle of tires but there is a general misunderstanding about how to properly ensure tire casings are retreadable and also misconceptions about the quality of retreaded tires in general – retreaders are often unfairly singled out as the major cause behind tire carcass remnants on our highways.
“There is this misperception that prevails that the rubber that litters our highways is there as a result of the retread industry. Regardless of many roadside studies that have confirmed that new tires as well as retreads litter our highways, there is still this misunderstanding that if the tire retreading industry was to suddenly go away these gators would disappear,” laments Greg Filer, a fixture in the Canadian retreading industry in charge of national accounts for Bandag. Yet not only do the public and legislators incorrectly attribute road gators to retreading – there have been several government attempts on both sides of the border to restrict the practice – even people in the trucking industry seem willing to point fingers.
“The elimination of the retread industry and legislative control of the retread application will not eliminate or even begin to reduce the problem of roadside rubber. What these extreme measures will do is dramatically increase fleet operating costs, dramatically increase all costs for consumers in all product lines and eliminate thousands of jobs in an environmentally conscious $2 billion North American industry,” says Filer.
As Ralph Beaveridge, director of marketing, Truck Tires, for Michelin Canada notes, however, gators don’t discriminate.
“They eat young and old tires, new tires and retreaded tires. The bottom line is gators attack tires,” he says pointing out to a Virginia study that showed that at least a quarter of the gators collected from roadsides are actually from new tires. He also points out that the belief that gators are just the retreaded rubber coming off a tire is wrong. In fact, closer inspection of a gator reveals it includes both rubber and steel, and retreading facilities don’t put steel on tires.
Beaveridge explains the conditions that can give birth to a gator can begin inside a tire in areas where the stress and strain of use has begun to degrade from the shoulder towards the centre.
“If the tire is run in improper conditions this kind of effect would begin. If you were to cut a section from this tire you would find an element where the rubber is no longer spongy but powdery. This rubber has been degenerated. These bruises inside tires don’t heal; they become a permanent part of that tire. That degradation can continue towards the centre of the tire and end up in tread separation between the two working plies,” he says.
John Segato, national accounts manager, Mississauga Tire Centre outlines best practices necessary for an effective tire maintenance program:
Tire inflation: The majority of tire problems can be traced back to inflation-related issues. The low pressure inside a tire created by underinflation forces the tire to operate under severe lateral stress while overinflation can lead to excessive tire wear as well as rough ride, suspension failures and premature parts wear.
Segato says it’s important to keep in mind that the 100 psi inflation pressure indication common on many truck tires also comes with a load rating. The appropriate air pressure for a tire should only be determined once the maximum load it is expected to carry is known. Inflation/load are available from tire manufacturers and are specific to each tire size and tire brand.
Speed is also an influencing factor. “As you increase speed from 55 mph to 65 mph, the tire pressure needs to be increased by five psi over the recommended pressure and the tire load needs to be decreased by four per cent,” Segato points out.
Tire inflation pressure should also be specific to each fleet application. For fleets with over-the-highway applications, checking tire pressure every two weeks is a good standard.
Rotation: It’s a good idea to set a standard for rotating steer tires – typically at 40-50,000km. “Take them off the wheels, rotate them side to side and rebalance them. What that allows is for the left side tire, which typically wears faster because of the grade of our roads, to be placed on the right hand side and for the outside of the tire, which typically wears faster, to be placed on the inside on the other side,” Segato explains.
Drive tires should be rotated on a visual inspection, he advises, typically at 4/32nds between front and rear. Criss-cross the axles to smooth out any irregular wear.
Rotation of trailer tires is not very common but in circumstances where fleets are running multi-axle configurations, certain axles will wear at quicker rates than others, so tire rotation would be warranted.
Dual matching: It’s important to ensure that in a mated couple the two tires are running within 4/32nds of each other and that the air pressures are equal, the casings are comparable and the tread widths are comparable. Depending on the model, the tread width can vary by up to two inches.
Demounting and mounting: Mounting on a machine is recommended; it’s easier on a tire’s bead area, rims, and, of course, the maintenance technician. And lubrication is absolutely critical to protect the tire.
“I’m sure everyone has seen the practice of mounting on the vehicle. That practice should be stopped at all fleets. First, you are losing an opportunity to check the wheel assembly for broken studs, nuts and rims. Secondly, when you mount the tire on the vehicle, just because of gravity the tire is going to hang down and not sit correctly,” Segato says.
Roadside replacement: Carriers need to identify when to fix a flat. Segato recommends not fixing anything over a 1/4 inch and not within one inch of either tread edge. Depending on applications, anywhere from 15 to 40 per cent of tires that travel through the retread process will require at least one nail hole repair. Yet those repairs are often not properly handled.
“We in the tire industry have witnessed all sorts of imaginative ways that people have used to plug the hole. These incorrect procedures create not only a serious safety hazard but also cost the trucking industry significant losses through the premature rejection of what should be perfectly retreadable casings,” Filer warns. Proper hole repair requires a patch and plug, with the patch sealing the air inside the tire while the plug seals the hole to keep water from seeping in and working its way to steel belts and casings.
“If you need to replace a tire, good practice is to replace it with a steer tire. It’s usually 19/32s compared to a new drive tire which is at 28 so you will have the closest matching of those two tires as is possible,” Segato adds.
Looking specifically at retreading, Filer says it’s important for fleets to determine how the worn casings will be categorized. Bandag dealers, for example divide casings into three categories:
Premium casings are deemed of the highest quality and capable of the most demanding applications – long distance drive axle and multi-axle trailer applications.
Things to be considered in making this decision include the brand of the casing, age of the casing, number of times this type of casing can be retreaded for a specific fleet application, type of repairs done to it and its tread design.
Level 1 casings are considered to be closer to the end of their lives but still have a fair bit of value in them. They can be used for less demanding applications, such as local and regional hauls.
Level 2 casings can be used for
some applications but Filer recommends only using them after getting authorization from an informed manager.
“Lay these categories inside your application matrix, which identifies every application within your operation and which tires, new, retread, premium, downgraded fall into which category. Once you implement this there should be no deviation,” he adds.
Filer: Could nitrogen be your tire savior?
Imagine an old rubber band – brittle, cracked and displaying decreased elasticity – and you have a pretty good idea of the war oxidation can wage inside tires.
Tire manufacturers do compensate by using antioxidant agents, of course, but they can be depleted over the life of the tire.
Oxidation is part of the two-edged sword provided by oxygen inflation. On the one hand oxygen presents an economical way to inflate a tire; on the other hand when rubber is exposed to oxygen it begins to oxidize. Also, when a tire is filled with oxygen, moisture and other contaminants are added and keep on being added every time the tire is inflated.
“When tire pressures are checked, fine particles of rust from the wheel well get picked up in the escaping air and get trapped in the valve stem compounding tire inflation problems,” says Bob Hammond, national maintenance manager of Praxair Canada.
What’s the solution? Hammond believes it may be found in using nitrogen, an inert gas that makes up about 78 per cent of the air we breathe and which contains no oxygen to create oxidation or moisture that leads to rust.
“The racing community has used nitrogen for years,” he told the recent CFMS. “They recognized that nitrogen inflation can maintain a more stable tire pressure. In Europe and South America the domestic market has exploded with nitrogen inflation.”
He adds initial testing has shown an up to 30 per cent improvement in fuel mileage over oxygen-inflated tires and an up to 50 per cent reduction of road gators.
The U.S. and Canadian governments are testing this approach to tire inflation as is Praxair, which is currently running nitrogen-inflated tires on its trailer fleet.
“Testing is in the early stages but our expectations are quite high.”