Fleets See Longer Tire Life with Monitoring Systems

This story appears in the May 25 print edition of Transport Topics.

Trucking fleets and tire makers said increased use of tire-pressure monitoring systems and automatic inflation systems is saving lives and money.

Although some disagreement remains as to exactly how much benefit various systems offer, executives told Transport Topics they generally can prolong tire life and increase fuel economy, while enhancing safety from fewer on-road tire failures.

“If you keep your tires properly inflated, you use less fuel, because you have less rolling resistance. Your tires aren’t generating as much heat, so you have less chance of catastrophic tire failure,” said Chris Nau, national sales manager for Doran Manufacturing, Cincinnati, a manufacturer of TPMS.

These monitoring systems can be used on a tractor, a trailer or both, alerting a driver when air pressure drops below a preset threshold.

However, inflation systems are for use only on trailers, which have hollow axles. They pump air from the brake system through the axles to automatically fill tires when the pressure drops. Tractor axles aren’t hollow like trailer axles and therefore don’t lend themselves to inflation systems.

Frank Sonzala, executive vice president for Pressure Systems International Inc., San Antonio, said the company is working to develop inflation systems for tractors, but so far they have been cost-prohibitive.

Some systems also communicate changes in air pressure back to fleets through telematic devices.

“There is no question today the trend in trucks is to provide more information to the drivers and to the fleets,” said Don Baldwin, product marketing manager of commercial truck tires for Michelin North America. “Certainly, tire pressure is an important aspect, and it is something, I think, we’re going to see more and more on fleets, whether they are using duals or singles.”

TPMS use a battery-operated sensor on the valve stem or rim of the tire and transmit air pressure readings via radio frequencies as the tire rotates. Those readings typically are displayed on a monitor screen in the cab.

In October, Con-way Truckload began testing two TPMS on tractors: Wabco Vehicle Control Systems, its headquarters in Brussels, Belgium, and SmarTire Systems, part of Bendix Commercial Vehicle Systems, Richmond, British Columbia.

Bruce Stockton, vice president of maintenance and asset management for Con-way Truckload, Joplin, Mo., said both systems have operated relatively error-free. They appear to be extending tire life and boosting fuel economy by about 2%, a potentially “huge savings.”

Failures were prevented on two separate occasions since the systems were in place, Stockton said.

Michelin has partnered with Wabco to market a system called integrated vehicle tire-pressure monitoring, which is predominantly used in longhaul applications for Class 8s running Michelin’s X1 wide-based tires.

The system uses a battery-powered sensor attached to the outside of the wheel rim. A dashboard display allows drivers to see current tire pressures and receive warnings when the tire pressure changes.

Bendix manufactures the SmarTire and SmartWave lines of TPMS. Kevin Romanchok, director of the electronics business unit at Bendix, said the systems detect temperature and air pressure to give a more complete reading.

“There is a significant need to monitor and adjust for the rise and decrease in pressure due to temperature. That can vary by 20 to 30 psi during the use of the vehicle,” he said.

Temperature-sensing capabilities also serve as an indication of issues beyond tire pressure.

“Some of the feedback from the fleets is you can use some of that data as an early indication of brake pads that might be sticking, bearing issues where heat will start to show up in the sensing capabilities in that sensor,” Romanchok said.

Curtis Decker, product development engineer at Continental Tire North America, said his firm is in the process of releasing its first tire with pressure monitoring.

“With the higher inflations and a body ply that is metallic, inflation becomes much more critical, because the tire is less forgiving to being run underinflated,” Decker said.

“We want this to last the life of a casing,” he added.

Doran’s Nau said the number of tires on a truck equipped with a tire-pressure monitoring system varies based on the fleets’ needs.

The Doran 360 tire-pressure monitoring system can monitor up to 36 tires, which is especially useful for trucks running more than one trailer. It uses battery-powered sensors screwed onto the valve stem and can withstand temperatures up to 257 degrees Fahrenheit. Drivers begin to receive alerts when the monitor in the cab detects a 12.5% or greater drop in air pressure.

Unlike a tire-pressure monitoring system, which re-quires human intervention to fill tires, tire inflation systems fill trailer tires automatically as a vehicle travels down the road.

P.A.M. Transportation Services Inc., Tontitown, Ark., uses tire-pressure inflation systems on 4,500 trailers but does not monitor tire pressure on tractors.

“We haven’t seen the need,” said Carl Tapp, vice president of maintenance at P.A.M. “The [over-the-road] truck driver takes care of his truck. He doesn’t necessarily take care of his trailer.”

Before adding the Meritor Tire Inflation System by P.S.I. to all trailers, P.A.M. conducted a yearlong test and found a 50% advantage in total tire costs on trailers with the systems, Tapp said.

Perry Krieger, fleet equipment specialist for Praxair Inc., Danbury, Conn., said the company has been testing systems for two years. Praxair monitors both tractors and trailers, so it uses a system that has a “drop-and-hook” application, which means any trailer can work with any tractor.

Besides reducing fuel and tire costs, Krieger said, the fleet has benefited from reduced down time.

“Being able to identify a tire failing before it fails gives you a lot more opportunity to make a correction,” he said. “It becomes a preventive repair instead of a required repair.”

Truckload carrier U.S. Xpress Enterprises, Chattanooga, Tenn., has tire-pressure inflation systems on about 1,500 of its trailers.

“We started installing those two years ago on trailers we chose to take with wide-based tires,” said Marty Fletcher, director of equipment technology, research and development for the fleet. “We felt like it was good insurance.”

Trailers often receive the least amount of maintenance in a fleet. Tapp said the average driver at P.A.M. owns the trailer for 48 hours.

“When they get done with the trailer, they can dump it, and it is someone else’s problem if there is a tire problem,” he said.

Kevin Rohlwing, senior vice president of training for the Tire Industry

Association, Bowie, Md., said he expects the popularity of tire inflation systems for trailers to increase.

“I estimate that you will see continued growth in that area and that it almost becomes a standard upgrade,” Rohlwing said.

However, not all fleets see the benefits of automatic inflation. When Con-way Truckload acquired Contract Freighters Inc. in 2007, trailers with tire inflation systems were integrated into the fleet.

“We have found that the cost to maintain those systems has not proven a return on the investment in the system,” Stockton said.

He said Con-way Truckload doesn’t plan to install or retrofit trailers with inflation systems but would consider tire-pressure inflation systems on trailers if they can communicate data to the driver in the cab.

Tapp, who favors inflation systems, said he would like to see the tire inflation and monitoring camps get together. Inflation systems don’t identify which tire is being inflated — unlike a tire-pressure inflation system, which pinpoints which tire is having a problem, he said.

“Right now, I know that I have a problem, but I don’t know where,” Tapp said. “I have to tell the truck stop to figure out where it is. If I had a TPMS attached, then I could tell them to check the tire that is sending the signal.”

For fleets that do use the systems, many take advantage of the telematic reporting options.

“The trend lately is for tire-pressure monitor systems to hook up with telematics devices so they can get the information back to the fleet,” said Peggy Fisher, TireStamp Inc.’s chief executive officer.

TireVigil Pro from TireStamp, Troy, Mich., is a subscription-based service that monitors air pressure and temperature and communicates the information via telematic devices. The system can send tire alerts via cell phone or the Internet.

“Drivers don’t really believe it is their job to handle the maintenance,” Fisher said. “Fleets want to know so they can correct the situation on the tires.”

P.A.M. has 483 test units that report to its main office via Qualcomm satellites when the tire inflation system runs longer than 10 minutes. At that point, P.A.M.’s road-rescue department can locate the driver’s current position and find the nearest repair shop.

“We call the service provider and tell them the truck is coming in with a trailer tire problem and then message the driver on the truck to pull into the truck stop and let him know we’ve detected the tire problem,” Tapp said.

Fleets that would like the added security for their tires without investing in tire-pressure monitor systems or inflation technology could turn to the Goodyear Tire & Rubber Co., Akron, Ohio, which has introduced a self-sealing tire. Its dual trailer tires with a built-in sealant are designed to allow longhaul trucks to continue operating after a tire is punctured. The puncture must be in the re-pairable tread area and can be up to a quarter-inch in diameter.

Steve McClellan, vice president of Goodyear commercial tire systems, said the technology “helps reduce fleet downtime, helps lower a company’s cost of operation and enhances retreadability.”

Fleets interviewed by TT said the additional costs for the added technology are less than just one roadside service call.

Phillip Zaroor, president of PressurePro, Harrisonville, Mo., said the average return on investment for its system, in which sensors screw onto the valve stem, is eight to 10 months.

The system is designed to allow any tractor to read any trailer with the sensors. It can read up to 64 tires at once, for example, a tractor and three trailers.

Similarly, truck maker Navistar Inc. offers TPMS by BERU F1 Systems on its ProStar model, which is the company’s largest volume, longhaul tractor. It estimates that the return on investment is one year.

However, Ken Fogelstrom, Navistar project engineer, said it is important maintenance tech-nicians are familiar with TPMS before working on units with the device.

“We have a label we install on the wheel of these trucks to point out the tire has a TPMS, and we have service documents that tell how to properly demount the tire,” Fogelstrom said.