Every time a truck ventures off-highway, the risk of tire failures increases exponentially. Scrap metal yards, landfills, the bush – these are places tires go to die.
“Most guys, when we start talking tires, their jaw drops when they hear how many we go through,” says Brent Edmonson, truck and coach technician who works for Guelph, Ont.-based Kenwill Carriers, overseeing 18 trucks that haul everything from aggregate to scrap metal.
Not only does Kenwill Carriers load at sites that are rife with hazards, it also pulls spread axle trailers, further abusing trailer tires, especially at the most rearward positions. Those tires are also the first to encounter pieces of jagged metal and nails when backing up into position at scrap metal yards and landfill sites. Springtime is the worst, Edmonson says, as the snow and ice melts to reveal a veritable minefield of hazards that can puncture a tire upon impact.
Some things are outside the trucking company’s control; it can’t expect the shipper or receiver to run a magnet over the loading area every time its trucks arrive to drop or pick-up a load. However, Edmonson still takes steps to get as much life out of his tires as possible – even if it’s only four to five months on the trailers. The company inspects the tires and monitors air pressures regularly, it keeps detailed records to monitor tire performance and it thoroughly services all equipment every 15 days.
“There’s no tire that’s bulletproof,” acknowledges Stephane Beaudoin, segment product manager, Michelin North America (Canada). “But what you are looking for is extra protection in the casing, an extra belt package, extra wall thickness and a hard rubber compound that’s going to offer chip and cut resistance.”
Even so, you have to keep service life expectations reasonable. Fleets that run rigorous applications such as construction and oilfield services, often grow frustrated with the short life provided by their tires. Some maintenance managers we spoke to have even resorted to running cheap throwaway tires, particularly on the most rearward trailer positions, as those ones are the first to pick up nails and other debris when backing. However, this strategy can cost more in the long run, Beaudoin warns.
“If you are going to buy a cheaper tire, it may last two months. If you are using a better tire, maybe it lasts you six months. Yes, six months is not long when compared to other applications but if you’re doing twice or three times the length than the cheaper tire, there’s still a savings. Even though when you purchased them they were cheap at the get-go, at the end of the day they might be more expensive,” Beaudoin reasons.
The only way to determine which tires deliver the lowest total cost of ownership (which should also consider retreadability) is to keep good records. Michelin representatives help fleets of all sizes to make sense of this data.
“We are not going to be there every time they’re going to mount a new tire, but if they’re keeping some kind of records, we can input that into our system and come out with a nice report for them,” Beaudoin explains. “Sometimes perception can be different from reality, and when we’re using their data, they can’t argue with that.”
Another risk of using throwaway tires is that there could be compatibility issues on a tractor-trailer configuration. As a rule, like tires should be mounted on any given axle.
“If you mix (tire types) on the same axle and side, then yes, you can have uneven wear,” Beaudoin says. “The tires are not reacting the same. They’re not going to deflect the same way and they may not be at the same pressure. If you put two different brands of tires side by side on a dual application, you may run into irregular wear.”
Another challenge faced by fleets in construction, oilpatch and other on/off-road applications is that with frequent tire replacements comes a greater likelihood of mismatches in tire tread depth. Michelin recommends keeping tires in a dual configuration within 4/32nds of each other to avoid irregular wear and other mechanical issues.
“If the first tire is at 20/32nds and the second is at 16/32nds, the differential is working harder to compensate for the difference between the tires, so you’re going to bring wear to other parts of the truck,” Beaudoin warns. She recommends keeping tires to within 4/32nds of each other even if it means swapping tires of similar tread depth from other trucks and trailers in the fleet. It’s a painstaking process that can yield big savings.
“It’s a little bit harder to manage but in the long run you will save on mechanical issues as well as tire wear,” she says.
Of course, the easiest way to stretch tire life is to ensure they’re inflated to the most appropriate pressures, and no tire article would be complete without mentioning this.
“The pressure is what’s carrying the weight,” Beaudoin points out. “You need to have the right pressure for the load you’re carrying. In applications with a lot of off-road (driving) where you’re not regulated by load carrying capacity and you’ll load the truck to the max, the tires are taking a beating. If you are going to do that, make sure you increase the air in your tires.”
Dave Klus, director of maintenance for William Day Construction in Sudbury, Ont., says his company has found success in inflating tires to the upper limit of the allowable inflation pressures: 120 psi.
“We are seeing more even wear,” he says. The company also has changed rims from 80/20 offset to 50/50 offset. “We have noticed a lot better, more even tire wear across the face of the tires and better bearing life,” he claims.
However, air pressures should be determined in consultation with your tire rep, or by referencing tire manufacturer recommendations. There are dangers inherent to both over- and underinflating the tires. A tire that’s overinflated is more likely to fail, just as a balloon that’s filled to capacity will pop more easily when you poke it with a pointed object. The same balloon with less air in it will, to some extent, mould itself around the object and be more resistant to popping.
In addition to increasing the failure rate, overinflation also reduces tread life. Beaudoin says a tire that’s overinflated by 10% will reduce tread life by 18%. An underinflated tire will incur more sidewall and casing damage.
For fleets in rigorous on/off-road applications, fuel economy was once an afterthought. But that’s changing as diesel prices rise, Beaudoin says. Now, carriers are looking for less compromise between durability and fuel efficiency. For that reason, Michelin has come out with an X One wide-base single tire that’s winning fans in logging, cement mixing and other applications traditionally not associated with fuel-efficient wide-base single tires.
The X One XZY3 trailer tire fits the bill for several such applications. But while the wide single tire was originally designed for improved fuel economy, it’s showing other benefits in the field as well. Many off-road tire failures occur when objects such as rocks become wedged between two dual tires causing sidewall damage, Beaudoin notes. This doesn’t happen with single tires. There’s also a tendency to ignore tire pressures on the inside dual in on/off-road applications where the inside tire often becomes caked in mud. This neglect eventually can lead to premature tire failures. And wide-base singles have the ability to ‘float’ atop soft surfaces such as sand or mud much better than duals.
Of course, all the greatest tire technology in the world won’t completely eliminate failures. When a puncture occurs, sealants are often used to get the truck back in service, which is okay, as long as the right ones are used, Beaudoin says.
“Tires will support sealant as long as they’re not water-based,” she says. “The large amount of water in it can expose the cables to the water and there may be oxidation and that’s not good; oxidation will lead to tire failure.”
Edmonson says he’s seen many tire sealants that do more harm than good.
“They might work, but the problem is, now the tire’s lined with that stuff and if the hole is too big for that slimy stuff to seal it, then you can’t patch the tire because you can’t get the goop off the inside of the tire to get the patch to stick,” he says. “At that point you’re throwing out the whole tire and casing. Usually I can get a minimum of $30 for the casing, so you’ve lost that value too because those guys won’t touch it (once sealant has been used).”
Sealants of any type can limit a tire’s retreadability and yes, with some proper care, even tires in the most demanding duty cycles such as construction and oilfield services can – and should – be retreaded. Fleets should discuss with their retreader the application the recap will be placed into.
“You need to let the retread plant know what the spec’s are to get the maximum life from the casing,” Beaudoin says. “You may not get 100% of your casings retreaded – you’ll lose some. But you can still get a fair amount of casings through the retread process so you’re still saving
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