JOLIETTE, Que. – In 2001, looking to capitalize on their promised fuel and weight savings, Joliette, Que.-based Dan Freight Systems tried using wide-base tires. Pleased with their performance, the carrier converted its entire fleet of tractors and trailers to them in 2003-2004. To this day the company runs 100% wide-base tires on its 100 tractors and 120 two-axle trailers.
“We got 9-10% fuel savings without doing anything else,” says Claude Laporte, executive director, Dan Freight Systems. That is big coin, considering that each of the carrier’s trucks logs around 480,000 kilometres a year. There is also the advantage of some 200-250 lbs of weight savings for each axle. “We do the West Coast, California, Nevada, Arizona, etc. A paying load is very important,” Laporte points out.
As for weight restrictions in some provinces for wide-base tires, Laporte explains, “The maximum weight limit does not affect us at all. We always travel in the US and carry 80,000-lb GVW or less.”
Putting the frosting on the cake, in 2004 Dan Freight switched to nitrogen inflation. The value of inflating tires with nitrogen has been hotly debated and the chemistry and physics that would predict any advantage to running with it is hard to pin down. In the shop, Laporte acknowledges, “At the beginning, maintenance was very skeptical.” Over time though, Dan Freight collected data that indicated that the fuel savings attributable to nitrogen was just over 1%. The data also showed there was less over-inflation, less irregular wear and far fewer flats. Drivers also found the ride more comfortable.
“The improvement after we started using nitrogen inflation was dramatic. We went from four to five flats a week to less than one,” Laporte says
The cost of fixing a flat is a pain point, but the three to four hours of downtime is far worse.
“The savings are more on the level of the failure of the tires. The big cost is the loss of time,” Laporte says.
In the early days – its first Michelin brand was the XDA-HTA – the wide-base tires lasted only half as long as duals. Since then Michelin, which represents 95% of the wide-base tires Dan Freight runs, has improved its tires to the point where they run just as far as duals; ie., the Michelin XDN2 lasts 500,000 kilometres.
After years of research, Dan Freight has settled on the Michelin XTA on its trailer positions and the Michelin X One XDA Energy on the drive axles. The carrier continues to test Michelin wide-base tires and some other brands.
It is safe to say that the benefits of wide-base tires are conclusive for the right fleets. As for nitrogen however, its benefits are reminiscent of the pitch in the beer commercial: “Those who like it, like it a lot.”
One argument for nitrogen-filled tires is that they maintain their air pressure far longer than air. “When you roll with nitrogen it is easy to maintain the proper pressure with wide-base tires,” Laporte says. And it is a fact that properly maintained tire pressures yield the best fuel mileage.
Laporte also reports that the insides of nitrogen-filled tires heat up less than those inflated with air. They therefore wear better and are less susceptible to getting flats.
“The principle problem was the over-inflation of tires and irregular wear in hot states. The temperature can rise by 15-20 degrees Celsius inside an air-filled tire filled to 100 psi and running on a 40 C day, but only by 2 C in the nitrogen-filled tires.” This statement seems remarkable but Laporte simply states, “We’ve done all the tests.”
A challenge for fleets committed to filling tires with nitrogen is keeping them that way. Flat tires are likely to be refilled with air, since nitrogen inflation stations are not everywhere. Dan Freight gets around this problem with a rigorous tire maintenance program, aided by the fact that the trucks and trailers all return to Joliette every week. If a truck has a flat, the driver will call the person at headquarters responsible for receiving mechanical calls, who will then open a work order. The driver also makes an entry in his on-board computer. “There will be a note to check the tire because it has been repaired. The mechanic will know that a tire has been inflated with air,” Laporte says.
The tractors and trailers are inspected in the carrier’s scrupulously clean drive-through, seven-bay shop. An Ingersoll-Rand 80-cfm nitrogen generator feeds nitrogen through permanent piping to every workstation. Mechanics purge and refill any flagged tires with nitrogen. The pressure of all the tractor and trailer tires is checked with every weekly visit to the shop.
This kind of diligence would be the envy of any fleet running air-inflated tires and, Laporte adds, “It costs peanuts to check tire pressure every week.”